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Glass transition of thermotropic polymers based upon vanillic acid, p ‐hydroxybenzoic acid, and poly(ethylene terephthalate)
Author(s) -
Li XinGui,
Huang MeiRong,
Guan GuiHe,
Sun Tong
Publication year - 1996
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/(sici)1097-4628(19960103)59:1<1::aid-app1>3.0.co;2-y
Subject(s) - thermotropic crystal , polyester , differential scanning calorimetry , glass transition , materials science , polymer chemistry , ethylene , condensation polymer , monomer , polymer , organic chemistry , chemistry , composite material , thermodynamics , liquid crystalline , catalysis , physics
Differential scanning calorimetry (DSC) and dynamic and thermomechanical analyses are used to study the glass transition temperature (T g ) 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 T g 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 T g decreases slightly. The experimental T g values are compared with the T g 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.