Surface segregation and blooming of crystallisable melt-processing additives

Melt processing additives are used to facilitate processing and deliver bespoke properties to polymer surfaces. At present the process by which they migrate to surfaces or interfaces is poorly understood and often inefficient. We propose to use NR to study the surface and interfacial segregation of two melt processing additives in polyethylene; one which has a melting point slightly above that of PE and the other which melts lower temperatures than PE. We wish to understand how the sequence of cooling and crystallisation may manipulate surface or interfacial segregation and particularly to resolve this on the nanometre scale with NR in the melt state. Results will complement our room temperature studies of crystalline PE with the same additives by ion beam analysis and contact angle analysis to provide a complete picture of the role of additive and matrix crystallinity in segregation.

熔体加工助剂（Melt processing additives）可助力聚合物加工，并为其表面赋予定制化性能。目前，这类助剂向表面或界面迁移的具体机制尚不明确，且迁移效率往往偏低。本研究拟采用中子反射法（NR），探究两种熔体加工助剂在聚乙烯（PE）中的表面与界面偏析行为：其中一种助剂的熔点略高于聚乙烯，另一种则低于聚乙烯的熔点。我们旨在明确冷却与结晶的时序如何调控表面或界面偏析，尤其希望借助中子反射法在熔体状态下实现纳米尺度的机制解析。本研究结果将与我们此前采用离子束分析与接触角分析，针对添加相同助剂的结晶态聚乙烯开展的室温研究形成互补，从而全面阐明助剂与基体结晶度在偏析过程中的作用机制。