Glass transition temperature aramids

However, the opposite effects are also known, as for example, in blends of polyethersulfone (PES) with polyaramid (PARA) prepared by polycondensation of bis (4-aminophenyl)ether with isopthaloyl chloride [Nakata et al, 1990]. The PARA had been thought to be an amorphous polymer, whereas it did crystallize in the blend. The results suggest that the crystallization of PARA was induced by the presence of PES, i.e., this is an example of the blend-induced crystallization. The aramid seems to be a dormant crystalline polymer. In other words, the crystallizability is latent but crystallization in neat PARA was not possible even when annealing - it did take place in the presence of PES. This may be due to an increase of chain mobility by decreasing the glass transition temperature (T ) on blending PARA with PES that has lower T. ... 

Also, analysis of the kinetics and the glass transition temperature suggested greater interaction between aramid fibres and elastomer matrix. In particular, the degradation of PU or PU composites reinforced with aromatic PA or short carbon fibres followed first-order kinetics. 

Table 1 lists the thermal properties of a series of type II aramid elastomers. Differential scanning calorimetry (DSC) measurements revealed that the aramid elastomers exhibited three transition points a glass transition, Tg, below room temperature (RT), and melting transitions, T , below RT and around 200 C. The DSC thermograms are typical of block copolymers consisting of crystalline... 

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