摘要:

AbstractLiquid crystalline polymers containing sodium sulfonate groups pendant to the polymer backbone were synthesized by an interfacial condensation reaction of brilliant yellow, a sulfonate‐containing monomer, with 4,4′‐dihydroxy‐α,α′‐dimethyl benzalazine and a 50/50 mixture of sebacoyl and dodecanedioyl dichlorides. Polymers containing up to ca. 4 mol% brilliant yellow were characterized by elemental analysis and ultraviolet spectroscopy. The polymers were thermally stable to about 300°C, and they exhibited a broad nematic mesophase region of 70–100°C. The solution viscosity behavior in chloroform suggested thatintramolecular associations of the sulfonate groups occurred at low polymer concentrations andintermolecular associations predominated at high

ISSN:0887-624X    

DOI:10.1002/pola.1992.080300111

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractNucleophilic substitution of PVC with sodium thiophenate was carried out in cyclohexanone solution at 5, 25, 40, 60, and 70°C. The initial rate obeys an Arrhenius law from 25 to 60°C, with an activation energy of 70 kJ/mol. Conversion limits are observed which strongly depend on the temperature. The stereoselectivity of the reaction with respect to the configurational triads does not depend on the temperature: the distribution of configurations is only dependent on the conversion. Assuming an SN2 substitution mechanism governed by steric factors, the Monte Carlo simulation procedure described in a prior study is shown to give a good account for all temperatures above 40°C assuming for the mm, mr or rm, and rr triads a reactivity such asRmm= 2RmrandRrrnil at low temperature and very low at temperatures ≥ 40°C. The low conversion limits observed at 5 and 25°C cannot be explained by a limited accessibility of a part of the polymer. Finally, it is shown that the elimination reaction, which remains limited, does not interfere with the substitution p

ISSN:0887-624X    

DOI:10.1002/pola.1992.080300112

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractA rigid rod polyimide derived from biphenyldianhydride (BPDA) andp‐phenylenediamine (PDA) was modified by the incorporation of diamines containing performed phenylquinoxaline and aryl ether linkages, and the morphology and mechanical properties of the resulting imide‐aryl ether phenylquinoxaline copolymers were investigated. These phenylquinoxaline containing diamines, 1, 4‐bis[6‐(3‐aminophenoxy)‐3‐phenyl‐2‐quinoxalinyl] benzene and 1, 4‐bis[6‐(4‐aminophenoxy)‐3‐phenyl‐2‐quinoxalinyl]benzene, were prepared by a novel nucleophilic aromatic substitution reaction of 1,4‐(6‐fluoro‐3‐phenyl‐2‐quinoxalinyl) benzene with either 1, 3‐ or 1, 4‐aminophenol in the presence of K2CO3, respectively. The diamines were utilized as co‐monomers with BPDA and PDA to synthesize poly(amicacids.) Films were cast and cured (350°C) to effect imidization, affording films which showed high elongations and moduli. The copolymers with high phenylquinoxaline compositions displayedTg's in the 300°C range, and the thermal stability of the copolymers was comparable to that of the parent polyimide. The copolymers also showed improved auto‐ or self‐adhesion, particularly those which showed aTg,

ISSN:0887-624X    

DOI:10.1002/pola.1992.080300113

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractSolution and solid‐state proton decoupled13C‐NMR spectra were determined on two diimides derived from 4, 4′‐oxydiphthalic anhydride. Comparison of the individual diimide spectra to that of a mixture of the two diimides indicates that ordering of these materials occurs in the solid state via charge transfer complex formation. A similar study was conducted using two isomeric dianhydrides, 4, 4′‐isophthaloyldiphthalic anhydride (IDPA) and 4, 4′‐terephthaloyldiphthalic anhydride (TDPA). The solution spectra of these compounds are similar and are those which would be expected for these compounds. However, their solid state spectra differ from each other. The solid‐state spectrum of TDPA resembles its solution spectrum, whereas, that of IDPA differs greatly from its solution spectrum and indicates charge transfer complex formation occurs with this molecule. This difference is explained in terms of the stereochemistry of the two isom

ISSN:0887-624X    

DOI:10.1002/pola.1992.080300114

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractBinary condensation copolymers of 1,2‐ethane dithiol and 1,3‐propane dibromide, 1,4‐butane dibromide, and 1,6‐hexane dibromide were prepared. Yields ranged from 55 to 89% with molecular weights of 1–2 × 104Daltons. The polymers were synthesized via an SN2 process with and without the presence of water. The polymers were characterized by DSC, viscosity, FT‐IR, and1H‐and1

ISSN:0887-624X    

DOI:10.1002/pola.1992.080300115

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe reactions of monomaleamic acid derived from an aromatic diamine with furfural afforded a novel class of furfurylidene‐substituted maleamic acids2a–2d. The latter were cyclodehydrated to yield maleimides3a–3dwhich are AB‐monomers for a Diels–Alder polymerization. In addition,N‐furfurylmaleamic acid (4) was synthesized by reacting furfurylamine with maleic anhydride at ambient temperature. Cyclodehydration of4affordedN‐furfurylmaleimide (5). The polymer precursors were characterized by IR and1H‐NMR spectroscopy. Their curing behavior was investigated by DTA and correlated with chemical structures. Diels–Alder polymerization of monomers occurred at the temperature range of 113–210°C. Thermal stability of monomers was evaluated by TGA and isothermal gravimetric analysis (IGA). It was shown that thermal stability of the polymer derived from maleamic acid4was dramatically improved upon curing at high temperatures due to the formation by dehydration of a stabl

ISSN:0887-624X    

DOI:10.1002/pola.1992.080300116

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractGlass beads pretreated with equal amounts of either natural abundance‐or selectively13C‐enriched (3‐13C)‐3‐aminopropyltriethoxysilane were used as filler for the preparation of polyamide‐6 model composites. After isolation of the glass beads from the composite by dissolving the polymer matrix in trifluoroethanol, the glass beads were investigated by pyrolysis capillary gas chromatography–mass spectrometry. The identification of the aldimine derivatives1and2, respectively, containing the13C‐label at C3 next to the imine nitrogen atom provides compelling evidence for amide formation between carboxylic end‐groups of the polyamide‐6 and amine groups of the surface‐bound poly(3‐aminopropyltrisiloxane) in the interphase region durin

ISSN:0887-624X    

DOI:10.1002/pola.1992.080300117

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractMonodisperse polymethacrylate beads of varied size and crosslink density are prepared by emulsion copolymerization of methacrylate and divinyl monomers in the absence of emulsifiers. The sizes of polybutyl and polyethyl methacrylate beads decreased with increasing polymerization temperature, while polymethyl methacrylate beads were largely unchanged in size. The molar mass of polymer in polymethyl metnacrylate beads markedly exceeded that in polystyrene beads. The rate of polymerization increased, and bead size decreased, with increasing initiator concentration or decreasing monomer concentration. The polymethacrylate beads are used as filler particles in polymer composites.

ISSN:0887-624X    

DOI:10.1002/pola.1992.080300118

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

ISSN:0887-624X    

DOI:10.1002/pola.1992.080300119

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

ISSN:0887-624X    

DOI:10.1002/pola.1992.080300120

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY