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 ℃.FR-IR and1 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 Tm0 is evaluated to be 251.8 ℃ for the copolymers with5 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.

MXD6/PA6共混物的结晶与熔融行为

采用熔融挤出工艺制备了不同配比的MXD6/PA6尼龙共混物,研究了MXD6与PA6的相容性及其在结晶与熔融性能方面的相互影响。玻璃化转变温度测试结果表明MXD6与PA6具有相容性。结晶与熔融行为研究表明,PA6的加入使共混物的熔点降低,且随共混物组成的变化呈渐变走向;淬冷条件下,当PA6用量不超过30%时共混物可以形成共晶,PA6用量大于等于40%时则各自结晶;PA6的加入可以提高MXD6的结晶速率,MXD6对PA6则起到了异相成核的作用。对晶体结构的观察显示共混物晶粒细化。