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:
The effect of dissymetrical units on the properties of thermotropic liquid crystalline copolyesters based on hydroxybenzoic acid (HBA), terephthalate) acid (TPA), and poly(ethylene terephthalate) (PET) units was examined. The dissymmetrical units employed included 2,7-dihydroxynaphthalene (2,7-DHN),1,4-dihydroxynaphthalene (1,4-DHN), and bromo-hydroquinone (Br-HQ). All of these polymers exhibited turbid melts. The flexible PET units lower the melting and/or stick temperature, and between 10 to 20 mol % is a critical level to achieve values in the range of 250°C or lower. The copolyesters based on 2,7-DHN have the highest glass transition temperatures and maintain stiffness to the highest temperatures. The properties of each series of copolyesters are discussed in terms of the efficiency of molecular packing. The effects of chemical and physical inhomogeneity are emphasized.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/app.1990.070410739
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