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:
Differential scanning calorimetry (DSC) and dynamic and thermomechanical analyses are used to study the glass transition temperature (Tg) of the thermotropic liquid crystalline polyesters prepared by molten polycondensation of 4-acetoxyvanillic acid (V), 4-acetoxybenzoic acid (B), and poly(ethylene terephthalate) (E). The polyesters exhibit two glass transition ranges at 66-83 as well as 136-140°C, which are attributed to E segmental motion in the E-rich/B-rich phases of the polyesters, as well as to the local mobility of the B component in the B-rich phase. The lower Tg of the polyesters increases with an increase in the B and V unit contents or with increasing heating rate in the DSC measurements, but the higher Tg decreases slightly. The experimental Tg values are compared with the Tg values predicted from three equations on the basis of the sequence distribution and the monomer reactivity ratio of the polyesters. Uematsu's Johnston's, and Couchman's equations all give a better fit with the experimental results. © 1996 John Wiley & Sons, Inc.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
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