熔融结晶过程中热历史对尼龙6多晶现象的影响

Effect of Thermal History on Polymorphism During Melt Crystallization of Nylon 6

用差示扫描量热仪考察了熔融结晶过程中晶核的残留对尼龙6多晶形成的影响。在熔融成型过程中尼龙6易形成较稳定的α和γ晶型。实验结果表明,在此过程中,尼龙6的α和γ晶核都对尼龙6的结晶有诱导性能,当尼龙6的熔体中存在其中一种晶型的晶核时,在结晶过程中则优先形成这种晶型。γ晶型在γ晶核不被熔融消失的情况下会向更稳定的α晶型转变,而这种转变不具有可逆性。

The influence of residual crystal nucleus on the polymorphism during the melt crystallization of nylon 6was investigated. In the melt crystallization,it is very easy to form two types of stable crystal forms( α-form and γ-form)for nylon 6. The results show that the extents of residual α-form and γ-form nuclei left in the molten nylon 6 strongly affect the subsequent crystallization,the residual α-or γ-nuclei left in the molten state lead to packing into α-or γ-crystals preferentially at the melt crystallization stage. The γ-form crystal of nylon 6 can be transformed into more stable α-form when traces of γ-form crystal are present and not erased,while this shift is not reversible.