Tuning PBT vitrimer properties by controlling the dynamics of the adaptable network

Vitrimers, which form a bridge between thermosets and thermoplastics, are a class of materials with promising opportunities for modern material innovations. Poly(butylene terephthalate) (PBT) vitrimers that combine the properties of neat PBT and those of adaptable networks are expected to greatly extend the potential applications of this industrially important engineering plastic. The current study aims at building up a tailor-made semi-crystalline vitrimer through understanding the effect of the dynamics and density of the adaptable network on the physical properties of PBT vitrimers. We show that the rubber plateau modulus of PBT vitrimers is almost exclusively governed by the cross-linker (glycerol) content, whereas the ratio of the glycerol to the Zn(ii) catalyst content strongly influences both the elastic and stress relaxation properties. This enables independent tuning of the tensile storage modulus (E′) and rubber plateau modulus. The PBT vitrimer exhibits a better creep resistance than neat PBT at service temperature while a similar crystallinity is maintained.