Thermoplastic Copoly(Ester Imide)s Derived from PBT, Trimellitic Anhydride, and 1,4-Diaminobutane

Abstract Starting from 1,4-diaminobutane and trimellitic anhydride, α,ω-diaminobutanebis(trimellitimide) was synthesized and subsequently esterified with methanol. Thermal polycondensation with dimethyl tereph-thalate in mol ratios from 0 to 100% and 1,4-butanediol yielded the corresponding series of random copoly(ester imide)s based on poly(butylene terephthalate) (PBT). Differential scanning calorimetry and wide-angle x-ray scattering showed that all poly(ester imide)s are semicrystal-line with degrees of crystallinity up to 50% (depending on the comonomer content). Compared to pure PBT, the rate of crystallization, however, is strongly decreased if the content of the comonomer is higher than 20%. Annealing is necessary to crystallize these materials. The melting temperatures (T ms) of the copoly(ester imide)s display the usual melting point depression of copolymers: by increasing the content of the comonomer, the melting temperatures initially decrease but increase when the content of the comonomer is ...