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  • 1
    Electronic Resource
    Electronic Resource
    Transition kinetics of smectic liquid-crystalline polyesters (1992)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 193 (1992), S. 2477-2486 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Two smectic main-chain liquid-crystalline polyesters containing biphenyl as mesogen and spacers with 8 and 18 methylene carbon atoms were prepared, and their transition kinetics were investigated by means of differential scanning calorimetry (DSC). The isothermal liquid-crystallization was analyzed using the Avrami equation. The Avrami exponent n was found to be 2 to 4 indicating that the liquid-crystallization of these two smectic polyesters would be a process of two-to three-dimensional growth rather than of one-dimensional growth as for nematic liquid-crystalline polymers. The nonisothermal liquid-crystallization and crystallization were also analyzed by means of DSC. The crystallization from the smectic phase was found to be a very fast process and the supercooling of crystallization was small. Thus, the smectic phase might nucleate crystallization. The transition kinetics of these two smectic polyesters are considerably different from those of nematic liquid-crystalline polymers due to the different orders of the liquid-crystalline phases.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1992.021930930
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  • 2
    Electronic Resource
    Electronic Resource
    Polyimides, 1. Studies on the thermal curing of imide model compound with tricyclic structure by nuclear magnetic resonance and mass spectraRevised Manuscript of October 15, 1991. (1992)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 193 (1992), S. 1521-1535 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A model imide with a tricyclic structure was synthesized by reacting 3-phenyltricyclo[6.2.2.02,7]-2,11-dodecadiene-5,6 : 9,10-tetracarboxylic dianhydride with aniline. The thermogravimetry curve showed that it degraded at about 300°C, and its differential scanning calorimetry curve was found to be similar to that of its corresponding polyimides. The thermal curing of this model imide was studied in detail. A curing mechanism was proposed based on the analysis of the cured product using NMR and mass spectroscopy. The results show that the curing mechanism started with a reverse Diels-Alder reaction, forming an intermediate which either dehydrogenated or further decomposed into 1,1-diphenylethylene, and N-phenylsuccinimide. The 1,1-diphenylethylene and N-phenylsuccinimide would either polymerize or become hydrogenated to form 1,1-diphenylethane and N-phenylsuccinimide, respectively.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1992.021930628
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  • 3
    Electronic Resource
    Electronic Resource
    Polymides, 2Part 1: cf. ref.22. Curing characterization and thermally induced polymerization of polyimides based on reverse Diels-Alder reaction (1992)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 193 (1992), S. 1537-1550 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polyimides were prepared by the condensation of 3-phenyltricyclo[6.2.2.02,7]-2,11-dodecadienne-5,6:9,10-tetracarboxylic dianhydride with diamines. Thermal curing of these polyimides was studied using thermogravimetry, infrared spectroscopy, nuclear magnetic resonance spectroscopy, mass spectroscopy and elemental analyses. The results were compared with those of a model imide compound and a neat dimaleimide. It is proposed that the thermal curing mechanism is controlled by a reverse Diels-Alder reaction, a three-dimensional polymer network being formed following the degradation of the polymer. Based on these studies, a three-dimensional structure is proposed if the curing temperature was over 330°C. The weight loss of isothermal thermogravimetry studies was tentatively used to determine the composition of the crosslinked structure and elemental analyses confirmed the results.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1992.021930629
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  • 4
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of polyimides based on novel tricyclo[6,2,2,02,7] dianhydride (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 3347-3362 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 3-Phenyl-tricyclo [6,2,2,02,7]dodeca-2,11-ene-5,6,9,10-tetracarboxylic dianhydride was prepared from 1,1-diphenyl ethylene and maleic anhydride in 1 : 2 mole ratio by [4 + 2]π Diels-Alder cycloaddition. The structure of the dianhydride was determined by mass spectroscopy, IR, 1H-NMR, elemental analyses, and single crystal x-ray diffraction. The monomer was condensed with several diamines in N-methyl pyrrolidone or m-cresol. The polyamic acids and the polyimides synthesized had inherent viscosities in the range of 0.19-0.31 and 0.17-0.25 dL/g, respectively, measured in N-methyl pyrrolidone at 30°C. Both the polyamic acids and the polyimides were found to be soluble in m-cresol, N-methyl pyrrolidone, dimethylacetamide, dimethyl formamide, and dimethyl sulfoxide. The polymides showed a low degree of crystallinity from wide angle x-ray diffraction. Thermal analysis of these polyimides revealed that their glass transition temperatures (Tg) were in the 215-237°C range and they decomposed in two stages. The first-stage decomposition temperatures were almost the same in O2 or N2 atmospheres, but the polymers showed a better thermal stability in O2 rather than in N2 in the second stage. The mechanism of thermal degradation is discussed.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1990.080281214
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  • 5
    Electronic Resource
    Electronic Resource
    Molecular composite. I. Novel block copolymers of liquid-crystalline polyamide and amorphous polyimide: Synthesis and characterization (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 2775-2784 
    Details
    ISSN: 0887-624X
    Keywords: molecular composite ; liquid-crystalline polymer ; block copolymer ; lyotropic polyamide ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two series of PA/PI block copolymers have been prepared from a two-pot polycondensation reaction. Acid-terminated poly-p-benzamide (PBA) prepolymer, composed of a rigid-rod structure and lyotropic character, was synthesized by applying the phosphorylation reaction of Yamazaki. On the other hand, two amine-terminated polyimide prepolymers with an amorphous structure were prepared by a typical low-temperature condensation reaction from 4,4′-(hexafluoroisopropylidene)-bis(phthalic anhydride) (6FDA)/2,2′-bis-(4-aminophenyl)-hexafluoropropane (BAAF) and 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA)/2,3,5,6-tetramethyl-p-phenylene diamine (TMPD). The molecular weight of these prepolymers was determined by intrinsic viscosity or GPC. The copolymerization was carried out by mixing two prepolymer solutions. The products were analyzed by extraction, IR, and ηinh so as to confirm that the copolymerization reaction was precisely accomplished. Thermal analysis and lyotropic behavior were studied for these block copolymers and the critical concentration in NMP-LiCl was found to be 6.0% for one among those block copolymers. The copolymers were observed to form anisotropic liquid-crystalline domains under polarized light once the solutions had been prepared at (and beyond) the critical concentration. © 1993 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1993.080311114
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  • 6
    Electronic Resource
    Electronic Resource
    Molecular composite. II. Novel block copolymer and semi-interpenetrating polymer network of rigid polyamide and flexible polyimide (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 2629-2639 
    Details
    ISSN: 0887-624X
    Keywords: molecular composite ; liquid-crystalline polymer ; lyotropic polyamide ; polyimide ; semi-interpenetrating polymer network ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2,2'-Dimethyl-4,4'-diamino-biphenyl was used to prepare a lyotropic amine-terminated polyamide (PBTA) prepolymer with terephthaloyl dichloride, and an amide oligomer with reactive endcaps of maleimide, respectively. The former was employed in an attempt to increase the solubility of PA/PI block copolymers, and the latter to produce a three-dimensional (isotropic) reinforced molecular composite through the technology of a semiinterpenetrating polymer network (semi-IPN). PBTA prepolymer was copolymerized with an amine-terminated polyimide via a coupling reaction using terephthaloyl dichloride. The resultant block copolymers were characterized by IR, NMR, ηinh and GPC to confirm that the copolymerization reaction was precisely accomplished, as well as to determine their composition and molecular weight. Thermal analysis and lyotropic behavior were also studied for these copolymers. Rigid-rod amide oligomer was crosslinked in the presence of another flexible polyimide. Five sets of semi-IPN films were prepared under varying compositions. The curing conditions were investigated by DSC; in addition, the cured semi-IPNs exhibited a single phase (1 Tg) according to examination by an instrument for thermally stimulated current (TSC). No large-scale phase separation was observed in SEM images of the fractured surfaces. © 1994 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1994.080321404
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  • 7
    Electronic Resource
    Electronic Resource
    Thermal degradation of polymethacrylic acid (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 2389-2397 
    Details
    ISSN: 0887-624X
    Keywords: polymethacrylic acid ; thermal degradation ; kinetics ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal degradation of polymethacrylic acid was found to have two separate decomposition regions. The first decomposition region, due to anhydride formation primarily, was caused by the conversion of polymethacrylic acid to polymethacrylic anhydride. This reaction followed first-order kinetics and had an activation energy of 40.5 kcal/mol. The second decomposition region was the thermal degradation for the corresponding polymethacrylic anhydride. In this region, the fragmentation of anhydride rings structure in polymethacrylic anhydride constitutes the major decomposition reaction with an activation energy of 37.4 kcal/mol. © 1992 John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1992.080301113
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  • 8
    Electronic Resource
    Electronic Resource
    The preparation and properties of polyarylate block copolymers by interfacial polycondensation (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 41 (1990), S. 1651-1658 
    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: Block copolymers of bisphenol A isophthalate and sebacate were prepared by a two-step interfacial polycondensation. The copolymers had sebacate contents of 1 : 5 and 1 : 3 molar with block lengths (DP) of 4,9, and 19. Thermal analysis of the copolymers by DSC showed the Tm of PBI. The crystallizability of PBI chain segments in the block copolymers was confirmed by X-ray diffraction. The Tm of the copolymers was primarily influenced by the DP of the chain segments rather than the sebacate content. The Tg of the copolymers was mainly affected by the sebacate content rather than the DP of chain segments. The independent Tg of sebacate in the copolymers was not detected by DSC, i.e., the two polymer chains were compatible without phase separation. Phase separation was only observed in the rheometric spectrum of a 1 : 1 blend of the two homopolymers. The sebacate, being compatible with the isophthalate, had a plasticizing effect upon the polyarylate, which resulted in an improvement in toughness of the copolymers.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070410724
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  • 9
    Electronic Resource
    Electronic Resource
    Synthesis and characteristics of organic soluble photoactive polyimides (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 53 (1994), S. 1513-1524 
    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: Soluble aromatic polyimides with inherent viscosities of 0.23-0.50 dL/g have been synthesized from 2,2-bis(3-amino-4-hydroxyphenyl) hexafluoropropane (BAPAF) and various aromatic tetracarboxylic dianhydrides. Almost all polyimides were soluble in a wide range of organic solvents, i.e., acetone, m-cresol, N,N-dimethylacetamide, N,N-dimethylformamide, N,N-dimethylsulfoxide, N-methyl-2-pyrolidone, methyl ethyl ketone, and tetrahydrofuran (except that polyimide deriven from 3,3′,4,4′-biphenyl tetracarboxylic dianhydride). Synthesized polyimides have a glass transition temperature in a range of 293 to 355°C, showing no appreciable weight loss up to 400°C in both air and nitrogen. These soluble polyimides exhibit high transparency in the UV visible region, with water absorption being between 3.6 to 5.7 wt %. They provide an aqueous base developable positive photoresist system when formulated with diazonaphthoquinone sensitizer. On the other hand, negative photoactive polyimides which are soluble in common organic solvents and optically transparent at a light of 365 nm wavelength, being obtained by reacting these soluble polyimides with methacryloyl chloride. Properties and characteristics of both positive and negative photoactive polyimides have been studied here. © 1994 John Wiley & Sons, Inc.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070531113
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  • 10
    Electronic Resource
    Electronic Resource
    Studies of addition type polyimidesulfones and their composites (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 41 (1990), S. 2177-2187 
    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: Addition type polyimidesulfone oligomers have been synthesized from 3,3′,4,4′-benzophenone tetracarboxylic dianhydride and 3,3′-bis(aminophenyl) sulfone using three latent crosslinking groups as endcappers. The prepolymers were isolated and characterized for infrared spectra analysis, solubility test in various type solvents, melt flow, and cure properties. The crosslinked polyimides were characterized for thermal stability in a nitrogen atmosphere. The most promising systems, nadimide and maleimide prepolymers, were selected for the detailed study as the matrix for graphite woven cloth reinforced composites for which mechanical and other properties were tested. The differences due to various end-capped agents, including processibility, the extent of crosslinking of prepolymers, and thermal and mechanical properties of their composites, were compared.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070410922
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