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  • 1
    Electronic Resource
    Electronic Resource
    Dr. Bernhard Wunderlich: An innovative educator pioneer in the physical chemistry of polymers (1992)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 32 (1992), S. 1177-1187 
    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
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760321702
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  • 2
    Electronic Resource
    Electronic Resource
    Thermodynamic properties in the liquid state of high melting polymers containing phenylene and naphthylene groupsThis work was partially done in the Dept. of Chemistry at Rensselaer Polytechnic Institute. (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 1579-1594 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: High melting polymers of three different types of crystallization behavior were analyzed as to their thermal properties. The heat capacity at constant pressure of liquid poly(butylene terephthalate) (PBT) from 490 to 540 K was measured by scanning calorimetry. Combining with prior measured liquid heat capacity data of poly(oxy-1,4-phenylene) (PO) (358 - 620 K), poly-(thio-1,4-phenylene) (PPS) (540 - 600 K), poly(ethylene 2,6-naphthalenedicarboxylate) (PEN) (400 - 450 K, 530 - 600 K), an addition scheme for liquid heat capacities was constructed. In addition, the thermodynamic functions H and S have been calculated for those five polymers. The absolute, molar, residual entropy for the glassy state at zero kelvin is estimated to be 6,6,15,2, 7,48, 5,70, and 19,9 J/(K · mol) for PPS, PEN, PPO, PO, and PBT, respectively. Another two polymers with similar structure, poly(1,4-oxybenzoic acid) (POB) and poly(2,6-oxynaphthoic acid) (PON), were also studied in their high temperature mesophase states. A test of the addition scheme has been made to predict their heat capacities.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890713
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  • 3
    Electronic Resource
    Electronic Resource
    Crystal structure and mesophase morphology of MBPE polyethers containing odd-number methylene spacers (1993)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 194 (1993), S. 3135-3148 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A series of polyethers was synthesized from 4-[2-(4-hydroxyphenyl)ethyl]-3-methylphenol and α, ω-dibromoalkenes, MBPE-n. The polymers with odd-numbered methylene spacers show a monotropic mesophase behavior during cooling from the isotropic melt before crystallization. The crystal structures of MBPE (n = odd) polyethers have been investigated through wide angle X-ray diffraction fiber patterns. Two crystallographic periods along the c-axis are found, one of which corresponds to the length of methylene spacers, and the other is close to an integral number times the length of the repeating unit. Polarized light microscopy observations of the uniaxially oriented samples obtained through mechanical shear show a banded texture, which is a typical morphology found in liquid crystal polymers. Transmission electron microscopy experiments provide morphological evidence to identify that this mesophase is a nematic liquid crystal state based on the disclination defect patterns defined by Frank. A relationship between splay elastic constant k11 and bend elastic constant k33 is discussed through lamellar decoration of disclination defects.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1993.021941117
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  • 4
    Electronic Resource
    Electronic Resource
    Thermal analysis of poly(butylene terephthalate) for heat capacity, rigid-amorphous content, and transition behaviorThe experimental work described in this paper was done at Rensselaer Polytechnic Institute as part of the 1987 Ph. D. Thesis of Robert Pan (Dept. of Chemistry).Contributed with the best wishes in honor the 65th birthday of Prof. Dr. H.-J. Cantow (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 2443-2458 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thermal analysis was performed on poly(butylene terephthalate), PBT, between 210 and 560 K. By combination of experimental heat capacities with computations with an approximate frequency spectrum of 65 group and 19 skeletal vibrations, preliminary recommended ATHAS (1988) heat capacities are proposed for the solid state from 0 to 600 K. The Tarasov parameters used for the computation of the skeletal vibrations were θ1 = 542 K and θ3 = 80 K for crystalline PBT and θ3 = 40 K for amorphous PBT. The glass transition temperature of amorphous PBT was found on efficiently quenched samples to be 248 K, much lower than for semicrystalline PBT where a 310-325 K glass transition temperature is typical. The increase in heat capacity calculated for 100% amorphous samples is 107 J/(K · mol) at 248 K and 77 J/(K · mol) at 320 K. The equilibrium melting temperature is estimated to be 518 K. The unique existence of rigid-amorphous fractions of the semicrystalline polymers is discussed with quantitative data for samples crystallized from the glass and from the melt between 275 and 490 K. The rigidamorphous fraction varies between above 0,9 for cold-crystallized samples to 0,3 for samples crystallized at 490 K. The crystallinity varied from below 0,1 to 0,5. The crystallinity could be separated into four parts, melting at high, medium, and low temperatures, and a part crystallized on cooling after isothermal crystallization. The sequence of crystallization of differently melting crystals was established.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021891022
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  • 5
    Electronic Resource
    Electronic Resource
    Thermal properties, phase transitions, and morphology of a conjugated polymer (1992)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 32 (1992), S. 1325-1332 
    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 highly conjugated polymer was synthesized from α,α′-dibromo-p-xylene, 1,4-bis(2-hydroxy-benzoyl)benzene, and benzyl bromide via a modified Williamson ether synthesis under phase transfer conditions. Based on thermal analysis, polarized light microscopy, electron diffraction, and wide angle X-ray diffraction experiments, the heat capacities in the solid and liquid states have been determined. The glass transition temperature is at 358 K with a heat capacity increase of 164 J/(K mol). Two different ordered crystal forms with different crystal unit cells were observed. The more ordered crystal shows a low transition temperature and the less ordered one a high transition temperature. This is mainly due to the effect of entropy change. These crystals exhibit various crystal morphologies with different birefringences. Transition kinetics are expressed by an Avrami equation. Two crystals show different Avrami exponents with crystallization temperature, which corrspond to the morphological change. Competition between crystal growths is also discussed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760321721
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  • 6
    Electronic Resource
    Electronic Resource
    The origin of β relaxations in segmented rigid-rod polyimide and copolyimide films (1993)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 33 (1993), S. 1373-1380 
    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: Most aromatic polyimides and copolyimides show a β relaxation process below their α relaxation processes in dynamic mechanical and dielectric measurements. The origin of this β relaxation has been under active discussion. In order to gain a better understanding of the origin of the β relaxation process, the dynamic mechanical behavior of a series of segmented rigid-rod polyimide and copolyimide films with different dianhydrides and diamines has been systematically studied. For some of the polymers, crystallinity and orientation effects on the β relaxation process were also investigated. It is found that the β relaxation process in the unoriented films can mainly be attributed to a relatively noncooperative motion in uncrystallized diamines. However, this noncooperative nature may be gradually lost by increasing the crystallinity and orientation. Molecular modeling and computation have led to a discussion of possible diamine motion in the β relaxation process.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760332102
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  • 7
    Electronic Resource
    Electronic Resource
    Heat capacities and entropies of liquid, high-melting-point polymers containing phenylene groups (PEEK, PC, and PET) (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 24 (1986), S. 1755-1765 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The heat capacity at constant pressure of liquid PEEK, poly(oxy-1,4-phenylene-oxy-1,4-phenylene-carbonyl-1,4-phenylene), has been measured by scanning calorimetry from 420 to 680 K, and that of PC, poly(4,4′-isopropylidenediphenylene carbonate), from 325 to 610 K. These new data were combined with data-bank data for PC and PET, poly(ethylene terephthalate), over wide temperature ranges. An addition scheme for liquid heat capacities of similar macromolecules has been obtained. In addition, values of absolute entropy, residual entropy for the glassy state, enthalpy, and Gibbs function are estimated for these three polymers. Both melting and glass transition temperatures have been confirmed. The heat capacity increases at the glass transition temperature have been determined by making use of previously calculated solid-state heat capacities.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1986.090240811
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  • 8
    Electronic Resource
    Electronic Resource
    Molecular segregation and nucleation of poly(ethylene oxide) crystallized from the melt. II. Kinetic study (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 24 (1986), S. 595-617 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A kinetic study of crystallization of fractions of poly(ethylene oxide)s between 3500 and 5,000,000 MW and their mixtures from the melt by differential scanning calorimetry and optical microscopy is reported. For the fractions the crystal growth rate is inversely dependent on the logarithmic molecular weight. Binary mixtures of widely different molecular weights show mixed-crystal formation at low crystallization temperature described by a single Avrami equation with exponent 3. At higher temperature, increasing segregation takes place despite higher deposition probabilities of the low molecular weight. Two consecutive Avrami equations describe the crystallization. Before the equilibrium melting temperature of the low molecular weight component is reached, complete segregation occurs. This segregation is possible up to at least 20,000 MW. Classical crystallization theory is unable to describe the process. Molecular nucleation seems a viable alternative for the description of crystallization of both fractions and mixtures. Reversibility of crystallization is on a one-molecule scale and reaches thermodynamic reversibility as the molecular length approaches monomer size.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1986.090240309
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  • 9
    Electronic Resource
    Electronic Resource
    Self-diffusion of poly (ethylene oxide) fractions and its influence on the crystalline texture (1991)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 29 (1991), S. 515-525 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Two somewhat separate issues have been delat with: the diffusion coefficients of various poly(ethylene oxide) (PEO) fractions at different temperatures; and morphological observations of spherulitic textures of a PEO mixture containing low- and high-molecular mass components at different supercooling and cooling rates. We found that simultaneous knowledge of diffusion coefficient of PEO fractions and crystal growth rate of the mixture leads to a better description of the crystal growth. As observed, the spherulitic texture of the PEO mixture comprises three texture levels: the spherulite as a whole; the crystalgrowth unit comprised of different number of lamellae in a stack; and the individual lamellar crystal. Under certain crystallization conditions, the thickness of the lamellar stack is on the same order of magnitude as the parameter δ proposed by Keith and Padden.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1991.090290501
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  • 10
    Electronic Resource
    Electronic Resource
    Time-resolved synchrotron X-ray study of crystalline phase transition in poly(aryl ether ketone ketone) containing alternated terephthalic/isophthalic moieties (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 2439-2447 
    Details
    ISSN: 0887-6266
    Keywords: morphology ; phase transition ; poly(ether ketone ketone) ; polymorphism ; SAXS ; structure ; time-resolved ; synchrotron x-rays ; WAXD ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Unique crystallization and melting behavior in poly(aryl ether ketone ketone) containing alternated terephthalic and isophthalic moieties were studied by time-resolved synchrotron x-ray methods. Recently, this material has been shown to exhibit three polymorphs (forms I, II, and III). In this work, we further investigated their distinctive thermal properties and found that form I is the dominating and the most thermally stable phase while form II is favored by fast nucleation conditions and is the least stable phase. On the other hand, form III represents a minor intermediate phase that usually coexists with form I and can be transferred from form II and to form I. Structural and morphological changes in form I have been followed by simultaneous wide-angle x-ray diffraction (WAXD)/small-angle x-ray scattering (SAXS) measurements during cold- or melt-crystallization and subsequent melting. In all cases, a larger dimensional change was found in the crystallographic a-axis than the b-axis during heating and cooling. This may be due to the greater lateral stress variation with respect to temperature along the a direction of the primary lamellae which is induced by either the formation of secondary lamellae or the preferential chain-folding direction in poly(aryl ether ketone ketone)s. During the phase transitions of form II ← III in the cold-crystallized specimen and form III ← I in the melt-crystallized samples, lamellar variables (long period, lamellar thickness, and invariant) obtained from SAXS remain almost constant. This indicates that the density distribution in the long spacing is independent of the melting in form II or III. For melt-crystallization, the corresponding changes in unit-cell dimensions and lamellar morphology during the annealing-induced low endotherm are most consistent with the argument that these changes are due to the melting of thin lamellar population. © 1995 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1995.090331715
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