The effects of molecular weight and thermal history on the partial melting of polyethylene (PE) were investigated by in-situ small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) techniques. In the partial melting process, both surface melting and melting of small lamellae were found to play prominent roles. However, in some cases that could not be explained by these mechanisms, the concept of “non-lamellar crystalline” (NLC) was proposed. We argue that melting of the NLC domains can also contribute to the partial melting, especially at low temperatures. The event would decrease the crystallinity but does not perturb the lamellar structure, which are not seen in surface melting and melting of small lamellae. Upon further heating, structural changes, including the extension of lamellar length and reduction of lamellar width, were also observed. The experimental results in the temperature range dominated by the surface melting mechanism could be described by the model proposed by Albrecht and Strobl.

通过原位研究了分子量和热历史对聚乙烯（PE）部分熔融的影响小角度X射线散射（SAXS）和广角X射线衍射（WAXD）技术。在部分熔化过程中，发现表面熔化和小薄片的熔化都起着重要作用。但是，在某些情况下，这些机制无法解释，提出了“非层状晶体”（NLC）的概念。我们认为，NLC域的熔化也可能导致部分熔化，特别是在低温下。该事件将降低结晶度，但不会干扰层状结构，这在表面熔融和小薄片的熔融中看不到。进一步加热后，还观察到结构变化，包括层状长度的延长和层状宽度的减小。