Synthesis and characterization of copolymers of poly(m-xylylene adipamide) and poly(ethylene terephthalate) oligomers by melt copolycondensation

Poly( m -xylylene adipamide)/poly(ethylene terephthalate) (MXD6/PET) copolymers are synthesized by melt copolycondensation with 1–5   wt% low molecular weight PET oligomers into the MXD6 oligomers at 260   °C. FR-IR and 1 H NMR analysis results indicate that the interchange reaction has occurred between MXD6 oligomers and PET oligomers. The thermal behavior of copolymers shows that the melting temperature of MXD6/PET copolymers decreases with the increasing of amount of PET oligomers, while the crystallization temperature accordingly increases. And the equilibrium temperature T m 0 is evaluated to be 251.8   °C for the copolymers with 5   wt% PET oligomer adding, which is very close to that of neat MXD6. The tensile and impact strength of MXD6/PET copolymers are significantly improved than that of pure MXD6 by mechanical properties test, and the microfibril structure in the impact fracture sample's surface reveals the feature of ductile fracture.