摘要:

Unsaturated polyamides were among the first polymers prepared by Carothers [1]. These early polymers were easily gelled by heat and seemingly had little practical value. However, the concept of having a polyamide with latent cross-linking capability and the development of low-temperature polycondensation by interfacial techniques encouraged more recent investigators to explore further the preparation and properties of large numbers of unsaturated polyamides. Some of these polymers seem to have practical merit for such diverse uses as membranes for reverse osmosis and as unsaturated polyamide resins, the latter to serve in place of unsaturated polyester resins.

ISSN:1532-1797    

DOI:10.1080/00222357908080903

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

The assignment of the glass transition temperature of polyethylene has been a matter of heightened controversy in recent years, and has formed the basis of several reviews [la-Id] as well as numerous original contributions. The controversy in polyethylene has also focused attention on other issues: analogous questions of Tg's of other highly crystalline'polymers, a renewed interest in the molecular mechanism of frictional loss and mechanical relaxations in polymers and their relation to thermodynamic measurements, and in the origin of differences in the properties of branched and linear polyethylene and, by implication, other polymers with similar structural variations. The purpose of this paper is twofold: a) to undertake a limited discussion of some of the wider issues listed above, and b) to present the results of new heat capacity measurements for polyethylene that have bearing on the Tgcontroversy.

ISSN:1532-1797    

DOI:10.1080/00222357908080904

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

The mechanical properties of polymers are strongly influenced not only by the structure of the material but by the magnitude of the molecular orientation. Thus a great deal of interest exists in information about the molecular orientation in samples introduced by drawing or other forming processes. Several techniques of evaluation of this orientation exist such as birefringence, x-ray diffraction, sonic modulus, and fluorescence measurements [l, 2]. Vibrational analysis of oriented polymers provides a method of determining independently the molecular orientation both in the crystalline and amorphous phases of polymers. By using vibrational techniques, a number of macromolecules have been studied in the solid state for a variety of different processes. It is the purpose of this review to summarize the recent theoretical and experimental results which have occurred since the review of Zbinden [3]. Infrared and Raman measurements will be reported since they are complementary to each other in their applications and results.

ISSN:1532-1797    

DOI:10.1080/00222357908080905

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Thermotropic liquid crystals offer uniquely ordered media for intermolecular reactions such as polymerization. Unlike the recently investigated topochemical polymerizations where molecules are rigidly constrained on lattice points [l], the liquid crystalline state permits full two-dimensional (nematic and cholesteric) and one-dimensional (smectic) movement. In addition, various degrees of translational freedom are attainable depending on the class of mesogen. Such freedom of choice, plus the ability to orient nematic and cholesteric mesogens on a molecular scale in an electric or magnetic field or on certain surfaces, makes the liquid crystal state an attractive polymerization medium.

ISSN:1532-1797    

DOI:10.1080/00222357908080906

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:1532-1797    

DOI:10.1080/00222357908080902

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor