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  • Chemistry  (13)
  • 1
    Electronic Resource
    Electronic Resource
    Solution-induced changes in the properties of polyethylenes (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 30 (1985), S. 731-740 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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 chain entanglement states in high density, linear low density, and low density polyethylenes (HDPE, LLDPE, and LDPE) have been modified by recovering the polymers from solutions in trichlorobenzene (TCB) and p-xylene. In the thermodynamically good solvent, TCB, the entanglement density is assumed to be sharply reduced, a condition which is carried over to the corresponding solids. These display transient, but large increments in tensile moduli, slight changes in stress at rupture, and decreases in dynamic mechanical parameters and in elongation at rupture. Scanning calorimetry also shows these solids to have reduced crystallinity. Much smaller property modifications are noted in corresponding samples recovered from p-xylene. This liquid is a poorer solvent, particularly for HDPE and LLDPE. The results indicate that property modifications due to deliberate changes in the entanglement states of the polymers are a general phenomenon in the polyethylenes, and the magnitude of property changes depends on parameters of the molecular weight distribution. Chain branching does not seem to be a leading factor in the sensitivity of properties to modifications in the entanglement states. The property modifications produced by the present solution treatments are viewed as guides to the magnitude and duration of shear refining effects to be expected in HDPE, LLDPE, and LDPE polymers.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1985.070300221
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  • 2
    Electronic Resource
    Electronic Resource
    Properties and morphology of polystyrene and linear low density polyethylene polyblend and polyalloy (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 1033-1042 
    Details
    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 co-rotating twin screw extruder was employed in melt mixing and reactive extrusion of polystyrene/linear low density polyethylene (PS/PE) blends. Blends of PS/PE in the ratio of 9: 1 were prepared under different conditions of shear mixing and with different concentrations of dicurnlyl peroxide (DP) and triallyl isocyanurate (TALC) coupling agent. The Charpy impact strength of unnotched samples of melt blends was found to be lower than that of the polystyrene and was not affected much by the different conditions of melt mixing at different rates of extrusion, screw speeds, and screw configurations. In the case of reaction-extruded blends, the impact strength initially deteriorated with small addition of TAIC/DP, but improved with further increase in the level of TAIC/DP, exceeding that of polystyrene at an optimum concentration. With even further increase in TAIC/DP concentration, the impact strength again decreased. This was attributed to the different extents of coupling reactions of PE-TAIC-PE, PE-TAIC-PS, and PS-TAIC-PS with different levels of TAIC/DP. The interfacial adhesion of the incompatible PS-PE was postulated to be improved by the graft copolymers formed during reactive extrusion. This observation was supported by melt rheology, thermal characterization, molecular weight, and fracture surface morphology studies.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760311407
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  • 3
    Electronic Resource
    Electronic Resource
    Compatibilization of a polystyrene-polyethylene blend through reactive processing in a twin screw extruder (1992)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 32 (1992), S. 1678-1686 
    Details
    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: Direct grafting of polystyrene onto polyethylene has been carried out in a twin screw extruder with an organic peroxide and a crosslinking co-agent. The reaction extruded blends exhibited enhancement in impact properties at an optimum level of peroxide and co-agent. Further improvement was achieved by introducing styrene monomer into the system during reactive extrusion. The structure and morphology of the blends were studied using differential scanning calorimetry, scanning electron microscopy, infrared spectroscopy, and size exclusion chromatography.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760322205
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of resole phenol adhesives on the crystallinity of cellulose (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 39 (1990), S. 531-538 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: Resole phenolic resins are widely used for gluing wood structures. Solid state 13C-NMR and wide angle X-ray scattering experiments show that a typical resole adhesive disrupts some of the crystallinity of the cellulose. Several explanations are offered for this observation. It is possible that this effect is connected with the adhesive action of the phenolic polymer. If this is so, then measurements of the type described here could be used to understand the adhesion better and to develop better wood glues.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070390304
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  • 5
    Electronic Resource
    Electronic Resource
    iPP/HDPE blends: Interactions at lower HDPE contents (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 58 (1995), S. 995-1006 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: Mechanical and rheological properties of blends of polypropylene (PP) and linear polyethylene (PE) were studied, with particular attention to the effects of aging of such mixtures. These two olefin polymers are basically incompatible. In PP-rich blends, addition of highdensity PE (HDPE) causes only a slight decrease in tensile properties and impact resistance of injection-molded specimens. In all cases, annealed specimens have higher moduli and lower impact strength than as-molded products. While none of these changes are very drastic, the addition of small amounts of HDPE was observed to result in a serious decrease of gate-region impact resistance of thin-walled moldings. Blends with 10-20% HDPE exhibited an unexpected interaction in tensile, thermal, and melt-flow properties as well as in crystallization behavior. © 1995 John Wiley & Sons, Inc.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070580605
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  • 6
    Electronic Resource
    Electronic Resource
    i-PP/HDPE blends. III. Characterization and compatibilization at lower i-PP contents (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 61 (1996), S. 959-968 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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 mechanical properties of high-density polyethylene (HDPE)-rich i-PP/HDPE blends were studied. Two grades of HDPE were investigated, one with a melt viscosity close to that of the polypropylene (PP) and the other having a much lower melt viscosity. Compatibilization of the 10/90 i-PP/HDPE blend with three copolymers (an ethylene/propylene/diene [EPDM] copolymer and two ethylene/vinylacetate [EVA] copolymers, differing in their VA content) was also investigated. Blends of PP with the low melt viscosity HDPE displayed poor mechanical properties. It was not possible to improve these properties sufficiently with EPDM or EVA. In the case where viscosity matching was achieved between PP and HDPE, addition of i-PP (up to 30%) to HDPE resulted in a large drop in the impact strength of the blends, compared to that of the neat HDPE. A large drop (〉50%) was also observed in the ultimate tensile elongation. However, the flexural modulus, yield stress, and ultimate tensile strength all increased with the introduction of i-PP into HDPE. Modification of these blends with an EPDM resulted in the return of all properties to values very close to those of the neat HDPE. The ultimate tensile elongation of the EPDM-modified i-PP/HDPE blend even exceeded that of the virgin HDPE. It was also found that although EVAs can be used to compatibilize these blends these additives were not as effective as was the EPDM. © 1996 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    iPP/HDPE blends. II. Modification with EPDM and EVA (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 60 (1996), S. 1405-1417 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: Past work has shown that addition of high-density polyethylene (HDPE) to polypropylene (PP) resulted in a significant reduction in the elongation at break and in the gate-region impact strength of injection molded articles. In this study, we report on the compatibilization of these blends with ethylene/propylene/diene monomer (EPDM) or ethylene/vinyl acetate (EVA) copolymers. EPDM is effective at improving the impact strength and gate puncture resistance of a 90/10 PP/HDPE blend. EVA, on the other hand, is effective at improving the impact strength and the elongation at break of this material. It was also found that EVA is a better impact modifier for PP than is EPDM. DSC analysis indicated that EPDM, when blended with PP, caused a significant reduction in the degree of crystallinity of the PP. This was not observed in the case of EVA/PP blends. Further, our results indicate that care must be taken in designating a particular material as a better compatibilizer than some other material. It is crucial that conditions be attached to the label compatibilizer, indicating in particular the desired mechanical properties of the blend. © 1996 John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Structure and properties of polyethylene-polypropylene blend (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 28 (1983), S. 605-618 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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 structure and mechanical properties of blends of low-density polyethylene and isotactic polypropylene were studied. The blends behaved like a simple composite obeying the rule of mixture for the modulus dependence on composition. Tensile strength of the LDPE was enhanced with the addition of PP but elongation at break was drastically reduced for all blend compositions. Studies with WAXD, hot-stage microscope, and DSC indicated lack of interaction between the LDPE and the PP. The crystallographic structure of LDPE and PP remained unchanged. However, the spherulite size of the PP was found to be reduced in the presence of LDPE, possibly due to an increase in nucleation density.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1983.070280216
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  • 9
    Electronic Resource
    Electronic Resource
    Shear modification of low density polyethylene (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 30 (1985), S. 1345-1357 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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 single screw extruder was used to impose different shear histories on a low density polyethylene with broad molecular weight distribution and high molecular weight tail that had very little long chain branching. This polymer exhibits relatively high melt elasticity and the viscoelastic properties of its melt are strongly affected by preshearing. Such changes are accomplished without significant changes in molecular weight distribution or chemical structure. Measured viscous and elastic properties of the melt are different from piston-driven and screw extruder capillary rheometers. Shear modification effects in single screw extruders are enhanced by decreasing melt temperature, increased screw rotation speeds, and higher screw compression ratios. Melt elasticity can be cycled between high and relatively low values, for the particular polymer, by annealing or shearing the polymer melt.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1985.070300402
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  • 10
    Electronic Resource
    Electronic Resource
    DSC analysis of fusion level of rigid PVC revisited: Filler effects on thermal analysis data (1992)
    Brookfield, Conn. : Wiley-Blackwell
    Journal of Vinyl and Additive Technology 14 (1992), S. 156-160 
    Details
    ISSN: 0193-7197
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A DSC method for assessing degree of fusion of rigid PVC compounds has been improved, so as to make the technique more precise and objective. Analysis of conventional pipe samples provides assessments of gelation level that accord with solvent resistance and practical experience. However, thermal analysis techniques prove to be unreliable for compounds that contain no filler or more than about 13% filler. At least about 1% filler appears to be necessary for the phenomena that are the basis of this technique. Filler may affect crystallization of PVC compounds.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/vnl.730140309
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