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  • 1985-1989  (796)
  • 1985  (796)
  • Chemical Engineering  (658)
  • Atomic, Molecular and Optical Physics  (138)
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Years
  • 1985-1989  (796)
Year
  • 101
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985) 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
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  • 102
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 1139-1144 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Equations of state for polymers above and below the glass transition temperature are derived. Comparisons of the predicted P-V-T relations with the experiment are quite favorable. From the obtained equations, both the Anderson-Grüneisen constant and the Grüneisen constant can be determined, and the Tait equation is derived.
    Additional Material: 2 Tab.
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  • 103
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 1148-1154 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Dynamic mechanical analysis (DMA) was used to characterize cured epoxy resin formulations from -150°C to temperatures above their α transitions. The resins were aromatic amine and aliphatic amine cured and were modified with carboxylterminated acrylonitrile-butadiene (CTBN) rubbers to improve their toughness, A DuPont 981 dynamic mechanical analyzer was used to measure the modulus and mechanical loss factor (tan δ) of the samples. Changes in the α and β transitions in the scan of tan δ as a function of temperature were related to changes in the formulation. Relations were also sought between changes in the DMA data and fracture and impact toughness of the cured formulations obtained using an instrumented impact test. Impact tests were performed at -196°C and at room temperature. Results indicate that fracture toughness and the dynamic mechanical properties are affected by the amount of rubber, the compatibility of the rubber and epoxy, and changes in the curing agent stoichiometry.
    Additional Material: 8 Ill.
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  • 104
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 1155-1163 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The diversities existing among published kinetic studies on activated anionic polymerization of ε-caprolactam are closely examined. A kinetic model derived from a regular, linear reversible reaction mechanism is employed to explain the experimentally observed autocatalytic character of the polymerization system and to examine the dependence of the apparent activation energy on the experimental method. Several existing kinetic models tested with our experimental data show that the autocatalytic type rate equation best describes the polymerization process.
    Additional Material: 5 Ill.
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  • 105
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 1179-1187 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An experimental technique is described for producing fiberreinforced polymer films by inserting needle-like obstructions in a film-extrusion die. The, needles act as nucleation sites, generating a highly extensional local flow field, which causes sufficient orientation to induce the formation of oriented fibrillar crystallites embedded in a much less oriented matrix. To study the effectiveness of the above technique, linear low density polyethylene (LLDPE) and blends of linear low density with high density polyethylene (HDPE) were extruded through a film die with converging walls, with one or five needles inserted parallel to the extrusion direction, Microscopy observations, birefringence, and differential scanning calorimetry (DSC) measurements performed on the produced films showed in all cases that the presence of the needle induced the formation of a more oriented phase, which in most cases had a birefringence at least an order of magnitude higher than the film matrix. The best results were obtained in the case when blends of HDPE and LLDPE were extruded. The oriented structures obtained in this case consisted of HDPE and exhibited not only high birefringence but melting point elevation as well, indicating their fibrous nature.
    Additional Material: 10 Ill.
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  • 106
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A new method to obtain a rubber-modified polyamide 6 (PA6) directly during the polymerization of the caprolactam (CL) is described. Binary and ternary blends containing ethylene-propylene random copolymers (EPM) and/or a fictionalized EPM rubber (EPM-g-SA) were prepared and their morphology as well as their mechanical properties were investigated as function of composition and reaction conditions. It was found that the morphology of the blends is strongly dependent on the method of preparation. More complex structures are observed in blends obtained with the “Solution” preparation. For a better resolution of the morphology, the smooth ultramicrotomed surfaces were exposed to boiling xylene before SEM (scanning electron microscopy) examination. The rubbery phases are selectively dissolved whereas the PA6 matrix is left. The tensile mechanical properties and the Izod impact behavior are related to the mode and state of dispersion of the rubbery components. The impact properties of ternary PA6/EPM/EPMg-SA (80/18/2) and (80/15/5) blends, prepared during the CL polymerization are comparable to those of similar blends obtained by usual melt mixing procedures.
    Additional Material: 16 Ill.
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  • 107
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 6-18 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A general-purpose finite-element program has been used to simulate the flow of Newtonian, power-law, and viscoelastic fluids in calendering. The analysis is fully two-dimensional and does not make use of the lubrication approximation. Isothermal and nonisothermal calendering is studied and the results are compared with predictions from the lubrication approximation. The free surface is determined and circulatory flow patterns are predicted in the melt bank. Detailed calculations have been performed for a rigid poly(vinyl chloride) (PVC) resin that exhibits slip at the wall using rheological data for the melt and machine parameters. The results include determination of the shape and location of the free surface, vortex patterns, temperature and pressure distributions, and predictions of roll-separating force, torque, and power consumption. Comparisons are made with experimental data available in the literature.
    Additional Material: 23 Ill.
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  • 108
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 29-31 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: If the tetraethylorthosilicate (TEOS) used to end link hydroxyl-terminated poly(dimethylsiloxane) chains is present in excess, there are two effects on the resulting network structure. First, some of the excess TEOS hydrolyzes to give in situ precipitation of reinforcing silica particles. In addition, some can cause extension of the polymer chains, particularly of the shorter chains in the case of a bimodal network. In the present investigation, the ultimate strength and toughness of such bimodal networks was found to go through a maximum with increase in the amount of excess TEOS used in the curingfilling procedure.
    Additional Material: 3 Ill.
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  • 109
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 37-47 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The simulation of tubular, high-pressure low-density polyethylene reactors is performed using a comprehensive kinetic scheme which includes branching reactions as well as reactions leading to vinyl and vinylidene group formation. The variation of the physical properties of the reaction mass with position has been accounted for. In addition to predicting the conversions of the monomer and initiator, the temperature, and the number-average molecular weight, this study enables the computation of the polydispersity index and the concentration of vinyl, vinylidene, and methyl groups as a function of position. These have important implications in terms of product properties. Detailed simulations have shown that the steady-state approximation can be used for obtaining the concentrations of the initiator and the polymer radicals. In addition, some simple closure conditions have been established. The effect of multiple intermediate feeds is also investigated and it is found that under certain operating conditions the reactor performance becomes inherently unstable.
    Additional Material: 17 Ill.
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  • 110
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985) 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
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  • 111
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 75-82 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A semiquantitative bubble formation mechanism is presented for the baking of polymer films, utilizing poly(methyl methacrylate) (PMMA)-ethyl acetate (EA) solutions as the model system. It is shown that bubble growth phenomena can he accounted for in terms of the competition between vapor pressure buildup and the rate of vapor dissolution. According to the proposed mechanism, the local pressure buildup of solvent in the polymer film is controlled by the solvent partial pressure above a solution having a planar interface at the corresponding temperature and solvent concentration. This pressure can he estimated by Raoult's law. The vapor dissolution rate, on the other hand, is dominated by the liquid-phase diffusion of the solvent. A method of obtaining the diffusion coefficient as a function of temperature and solvent concentration from isothermal thermogravimetric analysis (TGA) is also given.
    Additional Material: 8 Ill.
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  • 112
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 232-244 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Free-radical polymerization of methyl methacrylate in a tubular reactor has been conducted at above-Tg temperatures. A salient feature of these experiments is the very efficient control of reactor temperature by vapor-liquid equilibrium of the polymerizing mixture via monomer evaporation. The system pressure thus provides a powerful control variable, restricting the temperature in the entire reactor by changing the monomer evaporation rate. In the range of our experimental conditions, the temperature and pressure in the reactor follow the Antoine equation closely. High temperature runs also reduce the length requirement of the reactor. However, molecular weight averages of the products are not impressive, unless slow-burning initiators are used. Modeling of above-Tg reactions has been attempted at two-levels of sophistication. A plug-flow model gives predictions in good agreement with our experimental temperatures and conversion data. The predicted molecular weights are also consistent with the experimentally observed values. However, the more elaborate rheokinctic model suggests that the superficial agreement between model and experiment is due to initiator burn-out, which limits the final conversion to within 40 percent. The liquid layer next to the reactor wall can never be so viscous as to form a stagnant deposit, due to this conversion limitation. The velocity profiles are thus not very much distorted, and a plug-flow model is adequate. With a slow-burning initiator and a sufficiently long reactor, skewing of velocity profile and reactor channeling will eventually emerge. Hence, the rheokinetic model must be evoked to model the system under such conditions.
    Additional Material: 11 Ill.
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  • 113
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985) 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
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  • 114
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 264-270 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In an attempt to further understand the flow of polymeric melts through gates in injection molding, the present investigation deals with measurement of pressure drops during isothermal extrusion of fiber-filled and unfilled polystyrene, polypropylene, and polycarbonate melts in short tubes with sudden contraction at high shear rates typical of injection molding. Flow curves for these materials have been determined over a wide range of shear rates at various temperatures by using a capillary rheometer and extruder. Measurements indicate that rheological properties of fiber-filled melts after injection molding differ from those of fresh samples. Moreover, it has been found that decreasing the tube length increases the slope of the curve for pressure drop vs. Volumetric flow rate. Extra pressure losses due to end effects have been determined which show that at high shear rates these losses can reach levels as high as 100 bar, with the effect being higher for the fiber-filled melts. By using a viscoelastic consitutive equation, the extra pressure losses have been separated into entrance and exit losses. Model parameters required for this calculation have been determined from viscosity-shear rate curves for the melts. For various polymers, master curves useful for industrial applications have been constructed for the extra pressure losses.
    Additional Material: 16 Ill.
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  • 115
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 857-862 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Silane-grafted polyethylene materials are processed in conventional thermoplastic fabrication machines. The shaped articles are then crosslinked in water by the formation of Si-O-Si crosslinks. This paper represents studies on the crosslinking progress in different environments at various temperatures. Molecular orientation is shown to become permanent and mostly irrecoverable even at 150°C, in the silane-grafted solid state crosslinked specimens (the crosslinking temperature in water is well below the polymer melting temperature). These frozen molecular orientations have a significant effect on the tensile properties of the crosslinked materials causing higher yield stresses and lower elongations at break. The thermal and tensile properties of some silane-grafted crosslinked polyethylene samples and peroxide-crosslinked materials are compared and analyzed.
    Additional Material: 10 Ill.
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  • 116
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    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 896-902 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Mixtures of 90, 80, and 70 percent by weight bisphenol-A-polycarbonate (PC) and 10, 20, and 30 percent by weight styrene maleic anhydride (SMA) copolymer were melt-blended in a single screw extruder. Differential scanning calorimetry (DCS) and scanning electron microscopy (SEM) were used to determine the miscibility of the blends. The viscosity, as a function of shear rate and temperature, was measured by an Instron capillary viscometer. The notched impact strength as a function of temperature was measured by an Izod impact tester.The results of DSC showed two glass transition temperatures which merged slightly towards each other, indicating marginal miscibility of these blends. There was a decrease in viscosity as the fraction of SMA copolymer was increased. The most significant decrease occurred with the initial addition of SMA copolymer. The viscosity also decreased with increases in temperature. The impact strength of the blends was also dependent on SMA copolymer content. The blends showed six to ten times lower impact strengths at room temperature than the 100 percent polycarbonate. SEM analysis helped to determine the reason why the impact strength was lower for the blends. High magnification showed the presence of SMA copolymer inclusions dispersed throughout the PC matrix. These inclusions, which increased in size as SMA copolymer content was increased, acted as defects in the system.
    Additional Material: 16 Ill.
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  • 117
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 903-908 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The impact response of a glass fiber reinforced polypropylene was studied in a 3-point drop-weight impact test between -15 and 85°C and at a constant impact velocity of 2.2 m/s (5 mph). The response is a combination of tension and shear and can be expressed in terms of an apparent modulus, EA: 1 \documentclass{article}\pagestyle{empty}\begin{document}$$\frac{1}{{E_A }} = \frac{1}{{E_{11} }} + \frac{6}{{5G_{12} }}\left({\frac{d}{l}} \right)^2$$\end{document}.Where E11 is the tensile modulus, G12: shear modulus, d: specimen thickness, and l: specimen length.For a 40 weight-percent glass reinforced polypropylene, E11 was found to have a room temperature value of 5.8 GPa, and shear modulus of 0.43 GPa. Both decreased with temperature increase, with the shear modulus showing greater sensitivity to a temperature change. The fracture initiation and propagation energies were relatively independent of temperature. The fracture initiation energy per unit deformed volume was of the order of 1 MJ/m3. The total fracture energy was found to be sensitive to l/d: about 7 MJ/m3 at l/d of 5.3 and about 1.7 MJ/ m3 at l/d of 16.
    Additional Material: 6 Ill.
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  • 118
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    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 355-361 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Oriented poly(aryletherketone) (PEEK) rods have been produced by drawing isotropic polymer through a conical die. Room temperature Young's moduli were measured by three-point bending and ranged from 5 GPa at a draw ratio of about 2 to 11 GPa at a draw ratio of about 4. Dynamic mechanical properties were explored in the range -150 to 200°C; two loss peaks were observed, with the higher corresponding to Tg.
    Additional Material: 9 Ill.
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  • 119
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 968-979 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Capillary flow studies on bulk molding compound (BMC) using an instrumented injection-molding machine are reported. The significance of extensional flow effects with fiber-reinforced materials is emphasized. The extensional flow behavior in converging dies is modeled, and a means of evaluating both extensional and shear viscosity from capillary flow data is proposed. Methods of correcting results for the effect of deformation heating are discussed. The shear and extensional flow behavior of BMC in the temperature region 18 to 58°C can be fitted to a simplified Arrhenius Law.
    Additional Material: 15 Ill.
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  • 120
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    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 1001-1007 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A systematic study of wall effects on the shear viscosity of short glass fiber-filled polypropylene and polystyrene is presented. The dependence of these effects on capillary radius, shear rate, temperature, and polymer matrix is examined. The “true” viscosity curves of these materials (free from wall effects) can be obtained by an extrapolation procedure. Breakage of glass fibers in the high shear-rate processes of extrusion and injection molding lead to an appreciable reduction of the viscosity of these materials and is probably the more important effect to take into account in these processes.
    Additional Material: 8 Ill.
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  • 121
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 1026-1034 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This review is mainly concerned with the conformational changes that depend on the dielectric constants for solvents for chlorinated polybutadienes (Cl-PBD) and their model compounds. The conformational equilibria of the rotational isomers of both meso and racemie 2,3-dichlorobutanes and 3,4-dichlorohexanes as the model compounds are discussed by analyzing infrared and NMR spectra. The solvent effect on the conformational parameter in Cl-PBD is explained by the variation in the conformation of the chlorinated part having polar C-Cl bonds. The matrix method is also described to calculate the temperature and solvent dependences of conformer populations.
    Additional Material: 17 Ill.
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  • 122
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 1055-1055 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 123
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 1074-1080 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Over the past two decades, membrane technology has found application in a variety of industries, ranging from water desalination to gas separations. These new applications have come about because of the availability of high-performance, permselective membranes. A key element in the development of these new membranes has been the discovery of “skinned” or asymmetric membranes. These membranes typically have an effective thickness on the order of 0.1 to 0.2 μm. They are essentially composite structures, consisting of a dense skin supported by a finely porous substrate. We now recognize that an understanding of the mechanism of formation of these asym-metric membranes is available through binary and ternary phase diagrams. Membranes for microfiltration, ultrafiltration, reverse osmosis, and gas separations are now routinely produced by some form of “phase inversion” process, amenable to explanation through phase diagram considerations.
    Additional Material: 9 Ill.
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  • 124
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 289-294 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In the production of polymers, particles and fibers are often added for coloring and/or improvement of mechanical, electrical, and thermal properties. Carefully choosing the electrical properties and size of these additives can allow manipulation of the electrical properties of the composite so that the material can then be heated in both the electric and magnetic fields. Heating can be induced by fields at microwave frequences, where the electric and magnetic fields tend to be concentrated in different regions, or by fields that are quasistatic. These features add a degree of freedom in smoothing the total heating pattern. Models for predicting the electrical properties with the addition of particles or fibers are developed and verified experimentally. Engineering guidelines are established in choosing the electrical properties and size of the additives. Experimentally, a rectangular cavity at 2.45 GHz is used to heat a casting resin with a 5.7 micrometer aluminum powder additive, demonstrating the dramatic smoothing in the heating, pattern made possible by using these additives. Some examples are also suggested to indicate the use of this technique in quasistatic heating configurations.
    Additional Material: 7 Ill.
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  • 125
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 318-322 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polycaprolactone samples were vacuum irradiated and subsequently immersed in aqueous methylamine solution, pH 10, and saline water solutions, Weight loss, solution viscosity, thermal analysis, tensile properties, and scanning electron microscopy were used to study the effects of immersion time and radiation. Irradiation accelerates all studied degradative and damaging processes taking place during exposure to the various environments. Degradation mechanisms in unirradiated and irradiated materials are discussed.
    Additional Material: 10 Ill.
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  • 126
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 348-354 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The antimony catalyst content of poly(ethylene terephthalate) has an appreciable effect on the tendency of the polymer to crystallize upon cooling from the melt. Nucleation density increases significantly as antimony catalyst concentration increases. The crystallization tendency of the polymer at a given molecular weight correlates strongly with both the antimony content and the diethylene glycol comonomer content. The behavioral patterns of nucleation by catalyst remnants are similar in polyester prepared from terephthalic acid or dimethyl terephthalate. The antimony catalyst is deposited in the polyester matrix in a form suitable to nucleate quiescent crystallization. The differences in tendency to crystallize that correlate with catalyst and diethylene glycol comonomer content are reflected in the crystallinity of injection molded samples.
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  • 127
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    Polymer Engineering and Science 25 (1985), S. 367-373 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The problem of minimizing edge curl in a solvent dated layered polymeric composite web is discussed. Basic material relations are presented, with experimental data, which can be used to optimize coating and drying conditions to produce a flat surface. Viscoelastic equations, derived to understand the effects of material and geometrical parameters on curl, are discussed and applied to minimize curl in a dried condition. The results clearly indicate that coating, material, and geometrical parameters can be understood and used to minimize curl.
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  • 128
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985) 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 129
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    Polymer Engineering and Science 25 (1985), S. 389-394 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Molecular weight determination in poly(butylene terephthalate) (PBT) is hindered by the inherent difficulties of intrinsic viscosity (IV) determination in general and toxic solvents used in particular. In any case molecular weight does not include information as to the identity of end-groups in the polymer chain. This report shows how the Fourier Transform Infrared method of Ward for PET can be adapted for alcoholic and acidic end-group determinations in poly(butylene terephthalate) (PBT) and consequently for the number averaged molecular weight of PBT. A statistical analysis was performed on comparative IR- and IV-derived molecular weight which revealed a correlation coefficient of better than 90 percent. The method is, therefore, recommended as an alternative to the standard IV technique, especially if simultaneous end-group analyses are also required.
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  • 130
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    Polymer Engineering and Science 25 (1985), S. 412-418 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A new comprehensive mathematical model has been developed for the melting zone of a single-screw extruder processing a (semi) crystalline polymer. It has been demonstrated that the cross-channel flow plays an important role in the melting mechanism. When incorporated into a non-Newtonian fluid model combined with the rigid solid bed concept, the present analysis leads to significantly improved predictions of the melting rate and axial pressure profile. This conclusion is supported by experimental data and by a quantitative examination of the flow and thermal patterns prevailing in the melting zone.It is suggested that under the constraints of the commonly accepted assumptions concerning the physico-chemical properties of the polymeric system the transport analysis of the Maddock mechanism is virtually complete.
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  • 131
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    Polymer Engineering and Science 25 (1985), S. 431-433 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Orientation-induced crystallization of crystallizable polymer melts can occur, under certain conditions, during flow through converging channels. Attempts have been made to achieve this phenomenon in a two-phase system, i.e., during simultaneous extrusion of a continuous concentric core of polypropylene within a polystyrene matrix through a conical duct. On one occasion, using Carlona P SY6100 (MFI = 11.0) with Hostyren N2000-V-01 (MFI = 25.0), a highly oriented polypropylene thread with a modulus of 14.6 GPa and a melting point of 178°C was extruded at a die temperature of approximately 170°C and a pressure lower than 40 MPa. It is, in principle, possible to form highly oriented, fiber-like structures as reinforcing elements in a polymer matrix.
    Additional Material: 4 Ill.
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  • 132
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    Polymer Engineering and Science 25 (1985), S. 446-452 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A brief perspective of the history and development of the plastics industry is outlined with special reference to engineering plastics and high performance resins. Since the birth of the synthetic plastics industry just over half a century ago, a myriad of polymeric structures have been created of which only a few generic types have attained commercial status. These basic resin types are combined in many ways as composites or blends to make available to industry over 6000 grades for use in fibers, films, coatings, adhesives, or molded shapes. Although plastics are characterized by their mechanical, electrical, chemical, or physical properties, it is their selling price that tends to dominate the volume production of each resin. Today, the modern plastics engineer employs remote-access interactive computer databanks to conduct design and feasibility studies employing the full inventory of resin grades in his assessment. A final section reveals current attempts by researchers to impart extraordinary strength and modulus to conventional plastics by means of solid phase processing, whereby polymeric chains are uncoiled and aligned to produce remarkably tough materials which are likely to challenge the supremacy of steel.
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  • 133
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    Polymer Engineering and Science 25 (1985), S. 462-466 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In recent years only a few totally new plastics have been developed, since suppliers are finding it quicker and less expensive to tailor existing resins to meet the requirements of a specific application by alloying. The properties of an alloy of polycarbonate and a proprietary copolyester have been fully characterized. Thermal analysis shows that the polymers are miscible in all proportions. Transparency, glass transition temperature, barrier properties, tensile, and flexural properties of the alloy all fall between those of the neat components. Certain synergistic properties were observed upon blending the polycarbonate and polyester. The tendency of the blend not to yellow during γ-sterilization is remarkably better than can be predicted by an additive relationship. Chemical resistance of the blends behaves in a similar manner. The excellent balance of properties exhibited by the blend such as transparency, impact strength, γ-radiation resistance, and chemical resistance makes it useful in applications such as medical disposables and filter bowls.
    Additional Material: 8 Ill.
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  • 134
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    Polymer Engineering and Science 25 (1985), S. 477-482 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Poly(phenylene ether)s (PPE) are a class of polymers which contain phenolic monomers attached via an ether linkage. Depending upon the monomer types used in the polymerization, a variety of homopolymers and copolymers can be produced. When compounded with polystyrene, these poly(phenylene ether)s combine to form single phase alloys in contrast to the separate phases obtained with most other polymer blends. Since polyphenylene ether and polystyrene are completely miscible, the alloy also has only one glass transition temperature (Tg) and behaves in a manner that is typical of single polymeric materials. By blending poly(phenylene ether)s with impact modified polystyrene at different ratios, opaque thermoplastic resins having a wide range of chemical, thermal, and mechanical properties can be manufactured. Commercially available material grades have thus been developed to meet special product requirements for flame retardancy, high impact, increased flexural and tensile strength, low creep, and good resistance to certain chemical environments. In comparison to other types of unfilled thermoplastics, poly(phenylene ether)s have a balance of properties which can overlap those of acrylonitrile-butadiene-styrene (ABS), polycarbonate, nylon, and other high performance polymers.
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  • 135
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    Polymer Engineering and Science 25 (1985), S. 507-513 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Conductivity of plastics and polymeric composites is reviewed. The use of various conductivity-enhancing fillers, such as graphite, metallized glass, or stainless steel fibers are discussed. Properties of composites containing rapid-solidified aluminum flakes are of particular interest.
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  • 136
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    Polymer Engineering and Science 25 (1985), S. 497-501 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polymer modification by addition of reinforcing agents represents a popular means of increasing physical property values. The polymer matrix has been forced to accept up to 55 percent by weight of fibrous reinforcement and 80 percent by weight of powdered types in order to meet application requirements. These materials demand sophisticated mixing equipment which must provide extensive intake and conveying capabilities, polymer wetting of reinforcement, and dispersion of reinforcement. This process must also be conducted with controlled shear intensity and excellent temperature and residence time control in order to respect polymer thermal sensitivity and product requirements. The extrusion process is a proven economical method for incorporating reinforcements into polymer resins. Co-rotating intermeshing twin-screw extruders are particularly suited for these tasks. Positive conveying, self-wiping, and shear intensive mixing characteristics provided by the screw mechanism satisfy requirements of reinforcement compounding. This mechanism allows interruption of streamline flow which is needed to disperse both high and low aspect ratio reinforcing agents into a polymer matrix. Mathematical representation of the benefits of twin-screw extrusion (relative to single-screw) related to pumping and mixing capability have been developed based on the classical pressure flow continuity equation with proper selection of boundary conditions.
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  • 137
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    Polymer Engineering and Science 25 (1985), S. 521-528 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Diffusion of water in a glassy epoxy resin has been studied by the sorption method. Film thickness scaling is used as a diagnostic tool for non-Fickian sorption processes. A sorptiondesorption cycle effectively increases the preexisting free volume in the resin and renders the subsequent sorption process different from the original. The effect is understood by considering the time scale for diffusion and that for molecular relaxation of the glassy polymer network. A non-Fickian sorption process is observed for an insufficiently cured resin and is caused by the resin undergoing further postcuring in the sorption process. It is shown that oxidation of the resin during sorption also gives rise to non-Fickian processes previously described in the literature as diffusion anomalies for epoxies. It is further shown that the difference between sorption and resorption curves is not caused by irreversible damage to the resin but due to reversible changes in network conformations.
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  • 138
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    Polymer Engineering and Science 25 (1985), S. 541-547 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The big success of the reaction injection molding (RIM) process has brought about a marked interest in reacting polymer processing. In the present work, we study the technical feasibility of a continuous process to coat metallic conductors using reacting polymers. In the envisioned system, RIM type reactants are mixed and then injected into a tubular reactor through the center of which we pass the cable to be coated. The predictions of the mathematical model developed show that a feasible process can be designed by adequate control of the heat transfer phenomena. The process needs in general, a low reactor temperature and a high cable temperature.
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  • 139
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    Polymer Engineering and Science 25 (1985), S. 570-576 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An analysis is presented which allows the sheet or film die designer to estimate when inertial and gravitational effects are important. General theoretical equations are developed for end fed dies with arbitrary variation of the cavity cross sectional shape, cavity taper, slot length, and gap over the width. The method assumes viscous flow and a two dimensional approximation for the cavity flow. For fluid flow properties, it is assumed only that the apparent viscosity is a single valued function of the shear rate. In the important special case of constant die geometry and power law fluids, three dimensionless numbers plus the power law index are the parameters controlling the uniformity of flow from the die. Results are presented that illustrate when die orientations with respect to gravity and when fluid inertia are important. When they are not, simple expressions for die inlet pressure and uniformity index are given.
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  • 140
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    Polymer Engineering and Science 25 (1985), S. 741-746 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Studies on plastic alloys consisting of particles of brittle polymers dispersed in the matrices of ductile polymers were undertaken using the miniature polymer evaluation system (CSI Mini-Max System). For the polycarbonate/poly(acrylonitrileco-styrene) system, which had been found to show improved impact strength by Kurauchi, et al. using the conventional methods of molding and mechanical testing, it was verified that the miniature evaluation system gave the same results as those from the conventional methods. Ten other different combinations of ductile and brittle polymers were evaluated by using the miniature evaluation system. Among them the polycarbonate/poly(methyl methacrylate) system is found to be a toughened alloy. From these results, the requirements for the development of toughening in the ductile/brittle systems are discussed.
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  • 141
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    Polymer Engineering and Science 25 (1985), S. 765-771 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A slit die viscometer (SDV) was built and evaluated extensively. A major advantage of the SDV is the ability to measure in-line rheological data in a continuous fashion, using a setup that most closely approximates the conditions encountered in a real extrusion process. Comparisons will be presented of viscosity data of the SDV to data from a capillary rheometer (CR) and a Rheometrics Mechanical Spectrometer (RMS). Viscosity values as measured on the SDV tend to be lower than those measured on the CR and RMS. Possible reasons for this disagreement will be discussed. The effect of temperature on viscosity, the effect of pressure on viscosity, and the effect of compressibility will be analyzed in detail. It will be shown that these effects can be substantial, particularly with certain types of polymers. Finally, the feasibility of using the slit die viscometer to determine first normal stress differences will be explored.
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  • 142
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    Polymer Engineering and Science 25 (1985), S. 635-642 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The kinetics of acetylene polymerization have been studied as a function of monomer pressure, catalyst aging and concentration, Al/Ti ratio, and temperature. The rate constants of chain propagation and termination and their activation energies have been determined, The Mn of polyacetylene has been obtained using a radioquenching technique, and was found to vary from 500 to 250,000. Wide angle X-ray diffraction showed the polymer to be highly crystalline but the crystallites are disordered. The crystal structures of cis and trans polyacetylene have been obtained from the fiber electron diffraction patterns. The c-axis is the polymer chain axis which is along the fiber axis. The basic morphological entity is the microfibrils of 2 to 3 nm diameter which aggregate to form 20 to 30 nm fibrils.
    Additional Material: 7 Ill.
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  • 143
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    Polymer Engineering and Science 25 (1985), S. 643-651 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The tensile crazing and Charpy impact behavior of polypropylene modified with styrene-butadiene copolymer (SBR) and ethylene-propylene-diene monomer (EPDM) was studied. Various rubber particle size distributions were obtained by varying the relative viscosities between rubbery phase and PP matrix. Transmission electron microscopy and computer-aided image analysis were used to provide particle size information. In general, PP blends with smaller rubber particles are tougher and more ductile than those with larger particles, probably because the former represents a more efficient use of rubbery phase in promoting crazing and/or shear yielding. Samples with average particle diameter D̄ ≥ 0.5 μm were found to exhibit pronounced crazing. Within a given sample, no crazes appeared to develop around individual rubber particles with D 〈 0.5 μm. The higher the D, the greater the propensity to form crazes. The behavior of samples with D̄ ≪ 0.5 μm appeared to be dominated by shear yielding; very few crazes could be found. That there exists a critical rubber particle size is explained by the requirement that sufficient stress concentration be maintained to a finite radial distance to permit the initiation and growth of a craze, which requires a finite volume. Small particles, inducing smaller stress-enhanced zones, are therefore not effective in initiating crazes.
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  • 144
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    Polymer Engineering and Science 25 (1985), S. 864-874 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The key to process-property control is a knowledge of the structural state of the product desired and the availability of methods to economically characterize the structural states produced. The present paper demonstrates that these goals are attainable. Examples illustrate both that the equivalent state concept leads directly to the use of structural state functions as the pivotal criteria around which property and process data can be organized, and that this approach is appropriate to many fabrication processes, including films, fibers, and moldings. Further, the development of process-structure-property correlations is seen to lead to new processes and the development of structures having unique properties.
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  • 145
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    Polymer Engineering and Science 25 (1985) 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 146
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    Polymer Engineering and Science 25 (1985), S. 931-933 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Photocurable materials such as photoresists, UV-curable inks and paints, etc., can be analyzed by a variety of techniques. Commonly, these analyses are performed in a discontinuous mode, i.e., samples are exposed to light for varying times and subsequently they are subjected to analysis. Rates of reaction, conversion, etc., are determined from the residual functionalities; in the case of differential scanning calorimetry, these parameters are derived from the residual heat of reaction. In order to determine “photo speed” or sensitivity, a number of exposures of varying duration are necessary to obtain rates of reaction. By combining an exposure unit with a differential scanning calorimeter, the photoreaction can now he observed in situ. Determination of speed or rate of reaction is reduced to a single experiment. As a consequence, effects of wavelength, intensity, temperature, and environment are quickly examined as is demonstrated here for a photoresist. During the second scan residual exotherms can be used to determine reaction extend or formation of new thermally active products. Conversion may be limited if Tg rises during polymerization to exceed exposure temperatures. In addition, the formation of inaccessable functionalities has to be accounted for during evaluation.
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  • 147
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    Polymer Engineering and Science 25 (1985), S. 951-958 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Kinetics of simultaneous interpenetrating networks (SIN) composed of a polyurethane resin (PU) and an unsaturated polyester resin was studied. A differential scanning calorimeter (DSC) was used to monitor the polymerization course. It was found that increasing the polyester content in a PU-polyester SIN enhanced the polymerization of PU due to the “solvent effect” of polyester. On the other hand, increasing the PU content in the SIN retarded the polymerization of polyester due to the “cage effect” of PU. Polymerization sequence of the SIN could be controlled by employing different initiators for polyester reaction. The degree of crosslinking in each SIN component had a significant effect on the dynamics of the SIN formation and on the limiting conversion of the polyester reartion.
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  • 148
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    Polymer Engineering and Science 25 (1985), S. 980-985 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Orifice flow measurements have been performed at high strain rates on bulk molding compound (BMC) using convergent dies. A range of die angles and bore diameters was examined. Two models for flow behavior have been compared. It appears that, with BMC, there is a transition from constrained convergence to convergence with recirculation at a die semiangle of approximately 56 degrees.
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  • 149
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    Polymer Engineering and Science 25 (1985), S. 965-967 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Interest in potential high-performance polymers, leading to characterization and development of the rodlike poly(p-phenylene benzobisoxazoles) (PBO) and poly(p-phenylene benzobisthiazoles) (PBT), has recently been extended to a related group of polymers referred to as AAPBO, ABPBO, AAPBT, and ABPBT. In this study, geometry-optimized CNDO/2 molecular orbital calculations have been carried out on AAPBO and ABPBO model compounds to determine conformational energies as a function of rotation about each type of rotatable bond within the repeat units. For AAPBO, which contains two types of rotatable bonds per repeat unit, the bond between the benzoxazole group and p-phenylene group prefers the coplanar conformation with a barrier to free rotation of 2.1 kcal mol-1, while the bond between the benzoxazole groups prefers a conformation approximately 60 degrees away from coplanarity with a barrier to coplanarity and to free rotation of 3.6 kcal mol-1. For ABPBO, which contains only the former type of rotatable bond per repeat unit, the coplanar conformations were preferred with a barrier to free rotation of 1.6 kcal mol-1. These results are in excellent agreement with the results of both theoretical and experimental studies on the structurally analogous PBO. They are also consistent with the liquid crystalline behavior found for ABPBO but not for AAPBO.
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  • 150
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    Polymer Engineering and Science 25 (1985), S. 987-1000 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: For batchwise radical chain solution multicomponent copolymerization, the minimum end time problem for the predetermined monomer conversion and number average molecular weight has been studied by considering the initiator concentration (or feed rate) and temperature as the two control variables. Applying the maximum principle and “unit segment treatment” (by which the co-polymerization can be treated as homo-polymerization in the kinetic analysis), it is found that for initiator addition processes the optimal initiator addition policy is to make the rate of initiation constant for the optimal temperature variation case, and the initiator concentration constant for the isothermal case as in homo-polymerization. For single charge of initiator processes, the optimal initial initiator concentration is such that it should be maintained at the lowest possible value (by which the polymerization is strongly dead-end) for the optimal temperature variation case without chain transfer steps, and at some optimal value (by which the polymerization is near dead-end) for the best isothermal case.
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  • 151
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    Polymer Engineering and Science 25 (1985), S. 1103-1109 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The phase transition and phase separation behavior occurring in mixtures containing an A-B block copolymer and an A homopolymer is discussed. With a pure block copolymer an order-disorder transition can be induced by raising the temperature, whereby the ordered lattice of segregated microdomains becomes unstable and gives way to a homogeneous liquid structure. Small amounts of a homopolymer added to a block copolymer can be accommodated in the microdomains consisting of the same type of monomeric units, up to a solubility limit that depends on the relative lengths of the homopolymer and the copolymer block and on the temperature. The order-disorder transition temperature of the block copolymer is also affected by the added homopolymer. At the other extreme of concentration, spherical micelles of block copolymer are formed when a small amount of the copolymer is added in the bulk homopolymer, and the critical micelle concentration again depends on the relative lengths of the molecules and blocks involved and on the temperature. Measurements were made with light scattering and small-angle X-ray scattering techniques to determine the phase behavior of mixtures containing a styrene-butadiene block copolymer and either a polystyrene or a polybutadiene. The resulting phase diagram exhibits a fascinating complexity. Comparison with recent theories treating these phenomena shows that a good agreement is generally obtained on a qualitative or semi-quantitative level, but a quantitative agreement is often not attained.
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  • 152
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    Polymer Engineering and Science 25 (1985), S. 1110-1117 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polymers are often formulated into detergent products in order to confer properties which facilitate processing and/or storage of the product, or to yield desirable attributes for the end-user. Carbopol resin which consists essentially of polyacrylic acid, is one such polymer. Carbopol resin systems exhibit Bingham-Body-type rheology with measurable yield-value and pronounced shear-thinning at shear stresses above the yield value. These properties render Carbopol resins useful as a thickener and a suspending agent. Interaction with other components in a formulation, however, can radically alter the thickening and suspending properties of Carbopol resins. Phase diagrams of Carbopol resins with other major components of the system can guide the formulator away from areas where undesirable interactions, such as coacervate formation, can occur, and when presented in the form of contour diagrams they quantitatively map the physical properties of interest, enabling the formulator to be guided directly into the composition region which will best satisfy his requirements. The phase diagrams can also predict when different desirable properties cannot be simultaneously achieved and they can define the extent of compromise which may be necessary in formulation of the final product.
    Additional Material: 17 Ill.
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  • 153
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    Polymer Engineering and Science 25 (1985), S. 1145-1147 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Poly(butylene terephthalate)PBT or Poly-1, 4-butanediyl 1, 4-diearboxylate. polycondenses readily in the presence of small amounts of organo-titanium compounds to form progressively higher molecular weight polymers, The reaction is reversible in the presence of the condensation byproduct, 1,4-butanediol. Usually this reaction is carried out in the melt phase, but the viscosity is soon limiting. In the current work the polymerization is carried out in the solid phase just below the melting point of 227°C. The equilibrium constant for this reaction is measured by subjecting the polymer to a nitrogen stream saturated with a controlled quantity of butanediol. The reaction is followed by measuring the change in the number of alcoholic end-groups by infrared spectroscopy. At about 220°C the equilibrium constant is 0.31 (σ = 0.08).
    Additional Material: 3 Ill.
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  • 154
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    Polymer Engineering and Science 25 (1985), S. 1171-1178 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Unprimed sapphire/nylon 6 peel joints (2.13 ± 0.27 Kg/cm) are found to be stronger than sapphire/polyethylene joints (0.06 ± 0.02 Kg/cm). Priming the sapphire with γ-aminopropyl triethoxy silane (γ-APS) improves the strength significantly resulting in adherend failure in the nylon. The rate and extent of degradation is lower with priming. The optimal silane thickness is about 1900 Å, obtained with a 0.3 percent γ-APS solution, for a five day exposure to water at 25°C. Peel joints made with 0.3 percent γ-APS film, both dried at 25°C (standard conditions) and dehydrated at 110°C under vacuum, fail cohesively when exposed at 25°C. Increasing the exposure to 55°C in a second step results in strength degradation only with dehydrated films. Lower joint strengths are obtained with five days exposure as compared to one day exposure. However, if the temperature is raised to 65°C the joints primed with standard dried films now begin to degrade and lose 90 percent of their strength in five days. Further, the nylon 6 peel joints made with a 0.3 percent γ-APS film, dehydrated for three days prior to lamination, show 10 times greater wet strengths than the corresponding PE joints. Failure surface analyses by ESCA and SEM suggest that failure locus due to water degradation is within the γ-APS layer and the failure mode is cohesive. Failure mechanics during testing the wet peel joints may also cause a partial interfacial failure mode. The effects of the silane film thickness, dehydration condition, time, and temperature dependence of the peel strength degradation indicates that the structure of the γ-APS layer plays an important role in the promotion and retention of adhesion with a thermoplastic polymer system capable of limited primary interactions through possible interdiffusion with the silane layer.
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  • 155
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    Polymer Engineering and Science 25 (1985) 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 156
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    Polymer Engineering and Science 25 (1985), S. 36-36 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 157
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    Polymer Engineering and Science 25 (1985), S. 32-36 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Interesting phenomena were observed in the polymerization of styrene and ethylene oxide into PEO-PSt-PEO triblock copolymers using potassium naphthalene as initiator and tolusene as a solvent. The relationship between the phenomena and molecular weight of the blocks was studied. The purified and characterized triblock copolymer showed mesomorphic behavior in toluene solution which depolarized polarized light increasingly as the concentration was increased. The structure of the triblock copolymer was also studied by small-angle laser light scattering and by electron microscopy.
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  • 158
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    Polymer Engineering and Science 25 (1985), S. 57-63 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A detailed mathematical model for absolute particle-size distribution in continuous emulsion polymerization of styrene monomer is proposed on the basis of the modified population-balance theory. The computer simulation is then performed for styrene polymerization as an example of a nondesorption system. The effects of emulsifier and initiator concentrations as well as mean residence time on the absolute particle-size-distribution function, total concentration of polymer particles, conversion, average number and weight radii, average number of radicals per polymer particle, and polydispersity of radius are simulated by the model proposed.
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  • 159
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    Polymer Engineering and Science 25 (1985) 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 160
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    Polymer Engineering and Science 25 (1985), S. 157-163 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Dynamic mechanical properties have been investigated for interpenetrating-network systems based on polyol-cured polyurethanes (PU) and 2 to 1 n-butyl acrylate-n-butyl methacrylate (Ac) networks. The systems were formed simultaneously (SIN) from all of the precursors and reactants for both networks in the same vessel, and sequentially (SIPN) by swelling a precured PU with the reactants that will form the Ac network. If the Ac network is formed after gelation of the PU, the IPNs are transparent and appear to have single T (tan δmax) between those of the homonetworks; visible-phase separation occurs if the Ac is intentionally polymerized prior to PU gelation. Damping curves were lower and broader and the T (tan δmax) and rubber moduli were higher for the SIN than for the SIPN systems. Up to 65 percent Ac, the T (tan δmax) data for both SIN and SIPN fit the Gordon-Taylor equation if a T (tan δmax) for the Ac homonetwork 7°C higher than observed is used, suggesting a higher crosslink density for the Ac network under these conditions. The differences in properties of the SIN and SIPN are assumed to be dependent on sample homogeneity and upon the presence of a tin catalyst in the SIN preparation. This can result in limited Ac-network formation and consequent phase separation before PU gelation has occurred, and the catalyst may also increase the extent of interaction, such as grafting or hydrogen-bond formation between the networks.
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  • 161
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    Polymer Engineering and Science 25 (1985), S. 170-177 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The fatigue behavior of pure poly (vinylchloride) (PVC) and a PVC pipe compound has been investigated. Unnotched S-N lifetime, fatigue-crack growth, and craze/crack-initiation data are presented. The data trends, coupled with direct-microscopic observation, suggest that the unnotched-specimen lifetime in fatigue is dominated by the craze/crack-initiation process. This differs from the observed consistency of crack propagation and specimen-lifetime trends in several other polymers, whose failure can be traced to the initiation and growth to instability of a single dominant craze/crack.
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  • 162
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    Polymer Engineering and Science 25 (1985), S. 182-187 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Single Kevlar-29 fibers have been subjected to creep loading over a temperature range of 23 to 400°C for which the applied load was 50 percent that of tensile strength at each temperature considered and also subjected to a range of loads at 23°C. It has been shown that strain expressed as a logarithmic function of time describes the experimental results obtained. Up to 70 percent of breaking load, a primary creep mechanism dominates and at higher loads a secondary creep process becomes increasingly important.
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  • 163
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    Polymer Engineering and Science 25 (1985), S. 206-206 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 164
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    Polymer Engineering and Science 25 (1985), S. 494-496 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Ultra-high molecular weight polyethylene films prepared by melt flow crystallization under torsional flow conditions were characterized by wide angle (WAXS) and small angle (SAXS) diffraction techniques and scanning electron microscopy (SEM). The films had a fibrillar morphology in which lamellae having an average fold period of 650Å were stacked with their c-axis along the circular flow lines. X-ray analysis showed that the a and b-axes were preferentially oriented along the thickness and radial directions of the sample.
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  • 165
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    Polymer Engineering and Science 25 (1985) 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 166
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    Polymer Engineering and Science 25 (1985), S. 535-540 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polycarbonate (PC), one of the leading engineering plastics, suffers from deterioration under harsh environmental conditions. It is sensitive to the effects of light (UV) radiation, to thermal degradation, and to the attack of hot water, due to hydrolysis. By exposure of various commercial PC grades - at various molecular weights and stabilization - to either natural or accelerated conditions, a maximum lifetime of three years was predicted for the best-behaving grades. The criterion for failure was mainly based on loss of ductility in tensile tests, as well as loss of optical clarity and chain scission. Hot water has a significant effect on the performance of PC samples, and this is considered to be its greatest weakness. Degradation after exposure at various temperatures (without UV or humidity) leads to estimation of a temperature-endurance index, that may serve as a practical limiting criterion for polymer life expectancy.
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  • 167
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    Polymer Engineering and Science 25 (1985), S. 548-552 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: As an engineering thermoplastic acetal homopolymer is often used in the manufacture of parts subjected to fatigue. This article presents the results of flexural fatigue tests on acetal Delrin 550 under different environmental conditions, namely ambient air, forced-air ventilation at ambient temperature, or oil kept at a constant temperature at 40°C. The fatigue tests were performed on specimens cut from extruded sheets at a constant frequency of 30 Hz. Surface temperatures of the test specimens were measured either optically or electrically, depending on the environment. The test results show that both acetal stress and surface temperature of specimen, which are somehow related, vary considerably from one type of environment to another. However, results show that the fatigue life of the specimen is mainly governed by the amplitude of the initial stress and is almost independent of the environment, Another subject examined was the effect of oil on acetal's mechanical properties. It was found that prolonged contact with oil produced slight variations in tensile properties, but no significant effect on fatigue, life.
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  • 168
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    Polymer Engineering and Science 25 (1985), S. 577-581 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The role of the size and type of residual stresses and their distribution in the interior of polycarbonate mold-injected test bars was studied, in view of the interrelationship between toughness and thermal or environmental history. The large thermal gradient during solidification of the polymer in the mold builds up compressive stresses near the wall and tensile stresses in the core. Annealing followed by slow cooling may reverse the type of stresses near the surface, while quenching augments the compressive stress. The latter stress near the wall is responsible for the extraordinarily high impact strength of polycarbonate. Exposure to the atmosphere and immersion in hot water may affect the distribution of residual stresses and thus contribute to the embrittlement of the originally tough polymer. The importance of molecular weight and polymer stabilization is elucidated.
    Additional Material: 7 Ill.
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  • 169
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    Polymer Engineering and Science 25 (1985), S. 585-588 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Deterministic mathematical models of the Maddock melting mechanism based on analytical and finite-difference solution methods are surveyed and classified according to the key assumptions involved. It has been concluded that the rigid solid bed concept coupled with a consistent non-Newtonian analysis of the melt flow pattern, including cross-channel circulation, leads to superior results. It is suggested that the development of the melting theory for the Maddock mechanism as an engineering analytical tool is virtually complete.
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  • 170
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    Polymer Engineering and Science 25 (1985), S. 620-629 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This paper extends Petrie's work on film-blowing to cover viscoelastic non-isothermal flow for both the convected Maxwell and the Leonov models. Good agreement with experimental data is shown for the former. The calculations are highly unstable, however, and it is difficult to obtain convergence with arbitrary values of the film-blowing parameters. The general effect of viscoelasticity is to stiffen the film and restrain the increase in bubble diameter. There is some difference between bubble shapes generated using the Maxwell and Leonov constitutive models but the temperature variation of properties is seen as the dominant effect, The Leonov model tends not to be stiff enough in its response to the present flow, which is purely extensional and good agreement with experiment was not obtained. For the Maxwell model the relevant mean relaxation time must be used for good agreement between experiment and calculation.
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  • 171
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    Polymer Engineering and Science 25 (1985) 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 172
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    Polymer Engineering and Science 25 (1985), S. 654-654 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 173
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    Polymer Engineering and Science 25 (1985), S. 129-156 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A singular class of polymer reactions can be caused by mechanical stress. Sufficient storage of mechanical energy to break chemical bonds in the main chain is generally possible only on deformation of polymers of high molecular weight. The corresponding appropriate conditions of high stress may occur in both polymer processing and use. This review summarizes reports of such polymer stress reactions published principally after 1980. The survey is organized by polymer type and by analysis technique.
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  • 174
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Blends of polyarylate (PA)-a copolyester of bisphenol A with a mixture of terephthalic/isophthalic acids at 50/50 proportion-and polycarbonate of bisphenol A (PC) were melt mixed into films with a Brabender Plasticorder. The processing produced transreacted mixtures that exhibited a modulus and yield stress with a maximum that is above the linear (very similar to that observed for compatible polymer blends). The elongation at yield did not show any maximum but it is also above linearity.
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  • 175
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    Polymer Engineering and Science 25 (1985), S. 1-5 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Turbulent flow in the impingement mixing head of a reactions injection molding machine produces a laminated mixture, whose striations are mostly so thick that any subsequent copolymerization would be hindered by diffusion. However, further reduction in striation thickness occurs during laminar flow through the runner. This is calculated here and is a function of the radial position in the runner and of its length/diameter ratio. So, for example, when L/D = 10, it is predicted that at least 79 percent of, the reagent striations would be thin enough to permit reaction under kinetically controlled conditions.
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  • 176
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    Polymer Engineering and Science 25 (1985), S. 19-28 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In this study the effect of processing variables upon the optical properties of an injection-molded thermoplastic polyurethane were investigated. The investigation was separated into two phases. The first phase used conventional experimental methods, the second phase used a central composite factorial design. The processing variables studied were: melt temperatures, tool temperature, injection speed, injection pressure, back pressure, screw speed, cushion size, and cycle time. The optical responses used to evaluate the processing variables were: percent haze, percent luminous transmittance, and line of sight deviation. Each of the significant parameters used was found to have some effect on at least one optical property. Statistical analysis showed interaction among the processing parameters, indicating that simultaneous control of the parameters was required. Empirical models were derived to predict responses for a given set of processing conditions. There was good agreement between the models and experiments.
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  • 177
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    Polymer Engineering and Science 25 (1985), S. 778-781 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This paper reports the effect of humidity and temperature on the adhesive strength of a pressure sensitive adhesive (Flexbond 150) used to bond Mylar films. It has been found that, ill general, the adhesive strength decreases significantly with an increase in temperature. The effect of humidity on the bonding strength, however, was found to be process dependent. The sample preparation conditions, e.g., press weight for the bonding and the press time, are important in determining the humidity effect. The water sorption isotherm A 24°C for the adhesive was also determined. The amount of water sorbed by the adhesive at 95 percent relative pressure was found to be less than one weight percent.
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  • 178
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    Polymer Engineering and Science 25 (1985), S. 54-56 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Unsaturated polyesters were prepared by one-stage melt condensation of maleic anhydride, phthalic anhydride, propylene glycol, and poly(ethylene glycol)s with different molecular weight, and the properties of their castings from styrenated resins were investigated. Tensile and flexural properties decrease with the increase of molecular weight of poly(ethylene glycol), but impact strength, elongation, and water absorption have an inverse effect. This study improves the understanding of the effect of chain length of poly(ethylene glycol) in unsaturated polyester on the properties of its castings.
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  • 179
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    Polymer Engineering and Science 25 (1985), S. 70-74 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Thermal conductivity measurements with a modified Couette flow cell were obtained as a function of shear rate for two linear polyethylene melts of weight-average molecular weights 27,300 and 56,700, respectively. The lower-molecular-weight polyethylene revealed a maximum decrease in thermal conductivity of 55 percent at 150 s-1. After shearing at 400 s-1, approximately 90 minutes was required to recover the value corresponding to the zero shear condition. This was considered consistent with molecular orientation into the flow direction during shear with a subsequent relaxation upon the removal of stress. The higher-molecular-weight polyethylene gave a similar decrease in thermal conductivity at 50 s-1. Unlike the lower-molecular-weight melt, an increase was observed at higher shear rates. Enhancement of energy transport via cluster flow mechanism was presented as a possible interpretation of these results. A theory of molecular orientation of liquid poly(dimethylsiloxane) (PDMS) under shear flow was previously developed from thermal conductivity and birefringence data of this material. An attempt to clarify the difference in behavior between the two melts examined in this work, and between the polyethylene melts and the PDMS previously studied is presented.
    Additional Material: 4 Ill.
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  • 180
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: To develop polymer systems with improved lithographic resist properties, terpolymers of methyl methacrylate/methacrylonitrile/methyl α-chloroacryate (MMA/MCN/MCA), methyl methacrylate/methacrylonitrile/α-chloroacrylonitrile (MMA/MCN/ACAN), and methyl methacrylate/methacrylonitrile/vinylidene chloride (MMA/MCN/VDC) were prepared by emulsion polymerization. Also one methyl methacrylate/ methyl α-chloroacylate/α-chloroacrylonitrile (MMA/MCA/ ACAN) terpolymer was prepared. The radiation susceptibilities of these terpolymers were measured using the 60Coγ-irradiation method. Molecular weights were determined both by membrane osmometry and gel permeation chromatography. All terpolymers exhibited higher radiation-degradation susceptibilities than poly(methyl methacrylate). The Gs values did not follow the general trend, previously observed with MCN/MCA copolymers, of being directly proportional to the respective terpolymer compositions. In some cases, the addition of small quantities of α-chlorine-containing monomers caused Gx to increase. This observation greatly differs from those observed for copolymer systems such as MMA/MCA, MCN/MCA, MMA/ ACAN, etc. studied previously. Terpolymerization gives highly soluble polymers especially suitable for wet development by many solvents. This is an important consideration for polymers with high mole fractions of methacrylonitrile (MCN) or vinylidene chloride (VDC) which are rendered soluble in development solvents. The electron-beam sensitivities were obtained for samples of three classes of the terpolymers and they were higher than that of PMMA. For example, at 20Kev a 62/34/4 MMA/MCN/MCA terpolymer exhibited a sensitivity of 1.3 × 10-5 coulombs cm-2 at l/lo = 1. The introduction of ACAN narrows the working range for positive resist behavior. For example MMA/MCN/ACAN(41/40/19) has a sensitivity of 8.3 × 10-6 coulombs cm-2 at l/l0 = 0.6 but it crosslinks at 1 - 1.3 × 10- coulombs cm2. The MMA/MCN/VDC(21/76/3) polymer was about 25 times more sensitive than PMMA (7 × 10-6 C cm-2 at l/l0=1).
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  • 181
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    Polymer Engineering and Science 25 (1985), S. 118-121 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The flow of molten polymers in the calender bank has been computed using a finite-element method with stream function and vorticity. Two nonsymmetrical-recirculating regions have been obtained fully in agreement with the experimental observations on poly(vinyl chloride) melt banks. The pressure distribution along the flow axis is very close to the one obtained using the classical-lubrication approximation.
    Additional Material: 6 Ill.
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  • 182
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    Polymer Engineering and Science 25 (1985), S. 122-128 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A method is developed by which polymer molecular weight and its distribution can be accurately determined by deconvolution of dynamic melt viscoelastic properties in the terminal and plateau zones. The method is illustrated with a series of monodisperse (narrow-distribution) and polydisperse (broaddistribution) polystyrenes. The Mn, Mw, and Mn/Mw values obtained are in excellent agreement with those determined by light scattering, osmometry and gel permeation chromatography with less than 5 to 10 percent error. The differential molecular-weight distribution curves obtained coincide wall with those obtained by gel permeation chromatography. The method is applicable to insoluble as well as soluble polymers.
    Additional Material: 11 Ill.
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  • 183
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    Polymer Engineering and Science 25 (1985), S. 164-169 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Integral sorption/desorption measurements were carried out for the sulfur dioxide-glassy polyarylate polymer system at 25°C, 40°C, 55°C, and 63°C. The transport of sulfur dioxide in the glassy polyarylate polymer was governed by Fickian diffusion. The effective diffusion coefficient of sulfur dioxide increased with increasing penetrant concentration. The concentration dependence of the effective diffusion coefficient is explained on the basis of the partial-immobilization model developed by Paul and Koros. The mobility of the molecules sorbed in the Langmuir mode is shown to be significantly lower than the mobility of the molecules in Henry's law dissolution mode. The predictions of permeability values as a function of upstream gas pressure are presented. The equilibrium sorption isotherms for this system are well represented by the dualmode sorption model. The eltergetics and the temperature dependence of the dual-mode parameters are also discussed.
    Additional Material: 12 Ill.
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  • 184
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985) 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 185
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    Polymer Engineering and Science 25 (1985), S. 1120-1121 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A brief introduction to the theory of block copolymer/homopolymer mixtures is presented. All important effects, such as stretching of the polymer chains, changes in the conformational entropy at an interface, enthalpic and configurational effects, as well as connectedness of the blocks of the copolymer are included in the model.
    Additional Material: 1 Ill.
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  • 186
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    Polymer Engineering and Science 25 (1985), S. 1124-1134 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The morphology and mechanical properties of binary blends of nylon 6 (N6), as the major component, and ethylene-methacrylic acid copolymers (E/MAA), as the minor component, have been analyzed. It was found that the methacrylic acid content of the copolymer used as the second component has a profound effect upon the properties of the resulting blends. In particular, with increasing methacrylic acid content, the size of the domains of the E/MAA dispersed phase in the N6 matrix decreased in a regular fashion while the ultimate tensile properties increased regularly. This behavior has been attributed to a series of chemical and physico-chemical interactions taking place between the two components. The interactions are due to the presence of the acid functionality on the copolymer and do not occur when this functionality is absent. Chemical analysis of the blends was performed to confirm that chemical modification took place during the blending process.
    Additional Material: 9 Ill.
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  • 187
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    Polymer Engineering and Science 25 (1985), S. 1164-1170 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The copolymer resulting from the polymerization of methyl methacrylate and styrene in the aqueous phase was tested for its mechanical and thermal properties. The usual procedure to obtain such a copolymer is by radical polymerization, but it can be done also by an ionic solution polymerization and in most cases the copolymer obtained has a statistical polymer arrangement. As this polymer is made by a complex mechanism in the presence of zinc chloride and water, it has many interesting features. The polymerization itself in the presence of water has a good industrial appeal as it simplifies considerably the operations as well as eliminates the suspension phase solvent cost. Another feature is the molecular weight distribution; we have two definite nearly monodisperse groups of polymers - one of these groups has an average molecular weight of 107. The thermal properties of the polymers were studied as functions of the polymerization conditions and a mathematical expression was derived relating these factors. The mechanical properties of this, polymer compares favorably to available industrial products.
    Additional Material: 6 Ill.
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  • 188
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    Polymer Engineering and Science 25 (1985) 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 189
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The Differential Scanning Calorimeter (DSC) was used to discriminate among 25 commercial high density polyethylenes (HDPE) on the basis of their degree of crystallinity and melting temperature. The area under the melting endotherm correlated directly with density and inversely with creep and thermal expansion measurements. Since high crystallinity was related to the design required properties of density, creep, and thermal expansion, DSC studies readily identified eight of the more promising polymers from the group of 25. The overall crystallization kinetics of polyethylenes with 75 percent crystallinity were analyzed by the Avrami and Fischer-Turnbull equations. Results indicate small disk-like spherulites (Avrami n = 2) following nucleation-controlled growth kinetics. These conclusions are in reasonable agreement with polarizing microscope observations. An equilibrium melting temperature between 141 and 142°C was estimated from Hoffman-Weeks plots. Processing thick parts from highly crystalline polyethylene is difficult because of the 14 percent volume change on crystallization. Higher degrees of crystallinity are associated with moderate molecular weight, so the viscosity range of these polyethylenes is not especially suited for processing by extrusion. These caveates necessitate tradeoffs between optimal design properties and processing requirements for HDPE parts.
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  • 190
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    AIChE Journal 31 (1985), S. 842-848 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Our previous theoretical model was extended to predict the heat and mass transfer phenomena in microwave-heated porous materials. A water-filled sandstone was heated in microwaves and its drying rates and temperature profiles were measured. Predictions agree well with observations. Besides moisture loss rates and temperature profiles, the model also predicts local moisture content, gas densities, and pressure. These latter quantities were not measured in our work, but are of interest since they reveal the basic mechanisms of heat and mass transfer in internally heated porous media.
    Additional Material: 13 Ill.
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  • 191
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    AIChE Journal 31 (1985), S. 849-856 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We have measured the density of an equimolar gas mixture of C2H6-CH3Cl between 323.15 and 473.15 K at pressures to 14.0 MPa. Interaction second virial coefficients and dew-point pressures are extracted from the measurements. Intermolecular force constants for the Lennard-Jones and Stockmayer models are determined optimally for like and unlike pair interactions. Recent methods of prediction for second virial coefficients, both pure and interaction, are tested against experiment.
    Additional Material: 7 Ill.
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  • 192
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    AIChE Journal 31 (1985), S. 881-889 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper is a survey of recent published works on the dynamic and steady state modeling of emulsion homo- and copolymerization in batch, semicontinuous, and continuous latex reactors. Contributions to our understanding of diffusion-controlled termination and propagation reactions, molecular weight, long chain branching and crosslinking development, polymer particle nucleation, and of the dynamics of continuous emulsion polymerization are critically reviewed.
    Additional Material: 8 Ill.
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  • 193
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    AIChE Journal 31 (1985), S. 895-902 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: New measurements are presented for film height and pressure drop for vertical gas-liquid annular flows. Improved methods for predicting the film height and interfacial friction factor are developed for situations in which the liquid film flow rate is known.
    Additional Material: 13 Ill.
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  • 194
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The mathematical model described in Part I is applied to predict CH4 and tar yields in rapid hydropyrolysis of softening coal particles. Predicted effects of pressure and particle size agree with trends previously measured in a screen heater apparatus.
    Additional Material: 10 Ill.
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  • 195
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    AIChE Journal 31 (1985), S. 1029-1035 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A qualitative analysis is developed for the displacement of an unstable foam in a porous structure. The effects of the magnitude of the London-van der Waals forces, of the surface tension, of the surface viscosities, of the quality (volume fraction of the gas), of the bubble size, and of the viscosity of the foaming agent solution are investigated. A number of qualitative conclusions are drawn regarding three aspects of mobility control: distribution of bypassed oil, speed of displacement, and displacement efficiency.Ideally, any change in formulation should increase both the speed of displacement and the displacement efficiency. This is possible only by decreasing the surface viscosities. With all of the other variables, whenever either the speed of displacement or the displacement efficiency is increased, the other is decreased. Whether both the speed of displacement and the displacement efficiency actually increase on reducing the surface viscosities depends on whether the effects of the surface viscosities are dominant.
    Additional Material: 2 Ill.
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  • 196
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    AIChE Journal 31 (1985), S. 1044-1046 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
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  • 197
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    AIChE Journal 31 (1985), S. 1051-1051 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 198
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    AIChE Journal 31 (1985), S. 1051-1051 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 199
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    AIChE Journal 31 (1985), S. 1077-1085 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A perturbation chromatography technique using radiotracer gases has been developed to determine the adsorption equilibrium constants and diffusivities in molecular sieves. The ethane and ethylene 13X molecular sieve systems were studied in regions of high concentration. The data obtained by this technique are shown to be in agreement with equilibrium data obtained by static methods and with kinetic data obtained by adsorption uptake and chromatographic methods, but not with kinetic data obtained using NMR techniques. The tracer-pulse chromatographic technique is much more efficient for obtaining gas adsorption equilibria and intraparticle diffusivities and is considerably easier to adapt to wide pressure and temperature ranges than the conventional methods.
    Additional Material: 3 Ill.
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  • 200
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    AIChE Journal 31 (1985), S. 1187-1201 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The measurement test proposed by Mah and Tamhane (1982) allows the gross error associated with a measurement to be directly identified without a separate procedure. In this paper a comprehensive evaluation of this test was carried out based on two different definitions of its power. The influence of constraints, network configuration, position of measurement, magnitudes of gross error and standard deviations, number of measurements, and other factors were summarized as rules and guidelines for the application of this test. The simulation procedure developed in this investigation may be used to design a gross error detection scheme for any specific application.
    Additional Material: 9 Ill.
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