摘要:

AbstractLiquid crystalline main chain polymers have outstanding properties concerning their modulus, thermal expansion, shear viscosity, and flame retardant behavior. It is of interest to introduce these properties into other polymers by the synthesis of block copolymers.

ISSN:0258-0322    

DOI:10.1002/masy.19890260103

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

ISSN:0258-0322    

DOI:10.1002/masy.19890260104

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractCopolyesters of 4‐hydroxybenzoic acid were prepared by thermal polycondensation of 4‐acetoxybenzoic acid with various acetylated comonomers, such as 4‐mercaptobenzoic acid, 3‐hydroxybenzoic acid, N‐(4‐carboxyphenyl)4‐hydroxyphthalimide or hydroquinone in combination with 1,12‐dodecane bistrimellitimide. The copolyesters were characterized by elemental analyses, inherent viscosities,1H‐ or13C NMR spectroscopy, DSC‐measurements, WAXS‐measurements at temperatures between 25 and 425°C, microscopic observation, thermomechanical and thermogravimetrical analyses. Copolyesters containing 4‐mercaptobenzoic acid or N‐(4‐carboxyphenyl)4‐hydroxyphthalimide possess a reversible first order phase transition which represent a change of modifications and not a melting process. Both classes of copolyesters adopt the same kind of high temperature modification as poly(4‐hydroxybenzoate), namely a pseudo‐hexagonal chain packing. In contrast, copolyesters of 3‐hydroxybenzoic acid or copoly(ester imide)s with aliphatic spacer containing more than 50% 4‐hydroxybenzoic acid form a nematic phase over a broad temperature range. However, in the case of copolyesters derived from 3‐ and 4‐hydroxybenzoic acid the homogeneous nematic melt is thermodynamically unstable and gradually turns into a heterogeneous more or less crystalline mater

ISSN:0258-0322    

DOI:10.1002/masy.19890260105

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractStructure ‐ property relations of substituted para‐linked aromatic homopolyesters are reported. Thermotropic liquid‐crystalline substituted poly (1,4‐phenylene terephthalate)s with phase transition temperatures less than 230 °C and good solubility in common organic solvents have been synthesized. If a noncoplanar 2,2′‐disubstituted biphenylene moietyis combined with a monosubstituted phenylene moiety with sufficient bulky substituent, polyester with similar properties were obtained. Although these polyesters are soluble up to high concentrations, no lyotropic liquid‐crystalline behavior

ISSN:0258-0322    

DOI:10.1002/masy.19890260106

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractThe phase behavior of a number of rigid‐chain polyesters and polyamides is reviewed and compared to the result obtained from low‐molecular‐weight model systems. The dilution of the steric forces by flexible side chains appended to the rigid main chains is discussed. It is shown that even stiff‐chain polyamides may be transformed to a thermotropic mesophase and an isotropic melt if the number and length of side chains per repeating unit is high

ISSN:0258-0322    

DOI:10.1002/masy.19890260107

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

ISSN:0258-0322    

DOI:10.1002/masy.19890260108

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractA structure of polyethylene (PE) and poly[bis(2, 2,2‐trifluoroethoxy)phosphazene] (PPh) has been studied by means of the X‐ray diffraction technique, scanning electron microscopy and differential scanning calorimetry. The polymers under investigation are examples of the organic and inorganic mesophase flexible‐chain polymers not containing the mesogenic groups. When heated above the melting point both polymers form the condis crystal mesophase state which is stable in a wide temperature range. The PE mesophase reveals the pseudohexagonal structure, while the structure of mesophase PPh has some peculiarities arising from the sharp increase in the chain stiffness within a certain temperature range. The PPh mesophase structure is characterized by the perfect one‐dimensional long‐range order of the monomolecular layers and by the short‐range order only along the two other directions within the layer. This structure may be due to the difference between the interactions of the inorganic backbones and regularly alternating side trifluoro‐

ISSN:0258-0322    

DOI:10.1002/masy.19890260109

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractThe paper summarizes the recent achievements concerning the influence of the chemical structure and rigidity of cyclolinear polyorganosiloxane chains on the glassy, crystalline and mesophase behaviour with a special emphasis on the temperature range of mesophase stability and some thermal, X‐ray and optical characteristics of their mesophase state. The packing of macromolecules in the mesophase state is suggeste

ISSN:0258-0322    

DOI:10.1002/masy.19890260110

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

ISSN:0258-0322    

DOI:10.1002/masy.19890260111

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

ISSN:0258-0322    

DOI:10.1002/masy.19890260112

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY