Polyesteramides based on PET and nylon 2,T

The properties of polyesteramides based on PET and nylon 2,T (PETA) using DMT, the bis(esterdiamide) T2T-dimethyl (N,N′-bis(p-carbo-methoxybenzoyl)ethanediamine) and 1,2-ethanediol as starting materials has been studied. A PETA series with an increasing T2T content (0.1–30 mol%) has been synthesised and studied. It was observed by dynamic mechanical analysis, that the Tg, flow temperature (Tfl) and modulus of the rubbery plateau of PETA increased with increasing T2T content, implying a considerable improvement in the dimensional stability. The increase in Tg was approximately linear with T2T content. The Tm and Tfl were also increased with increasing diamide content. The increase in Tfl was non-linear, indicating that random co-crystallisation of the ester and amide segments did not occur. The amide segments are expected to self-assemble in the melt, and preferentially order with other amide segments. The crystallisation rate of PET was considerably improved by the incorporation of a small amount of T2T (0.1 mol%). By using higher concentrations of T2T, the crystallisation rate of PETA was improved even further. The crystallisation of PETA from the melt was studied using time-resolved WAXD measurements. It was observed that for PETA25, crystalline amide segments were present at 310°C, this being well above the Tm measured by DSC (280°C). The hypothesis is that at high amide concentrations, small alternating segments are formed (amide–ester–amide), these have a much higher melting temperature and are present in their crystalline form above the melting temperature of the polymer. Upon cooling, these segments form the nucleation sites for PETA