Annealing of Oriented PP/PE Double-layer Film within the Melting Range of PE: the Role of Partial Melting and Self-nucleation
Annealing of Oriented PP/PE Double-layer Film within the Melting Range of PE: the Role of Partial Melting and Self-nucleation
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DOI：
10.1007/s10118-022-2681-9
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发表时间：
2022-02
影响因子：
4.3
通讯作者：
Jia-Yi Xie-;Yong-Shi Wu;Ze-Feng Yin;Liang Yin;R. Xu;C. Lei
中科院分区：
文献类型：
--
作者：
Jia-Yi Xie-;Yong-Shi Wu;Ze-Feng Yin;Liang Yin;R. Xu;C. Lei
由于PP层的机械稳定性，具有行晶结构的取向PP/PE双层膜可以在比PE单层膜更高的温度下进行热处理。本文研究了PE熔融范围内的退火温度对PP/PE双层膜结晶结构和性能的影响。在低于PE熔点的100~130℃温度范围内，由于薄片的熔融和部分熔融熔体的自成核作用，PE层中片晶的结晶度、长周期、横向尺寸和取向随退火温度的升高而增大。随着退火温度进一步提高到138℃，在PE熔融终点附近，由于片晶完全熔融，熔体记忆变弱，在样品中形成了球晶结构，导致取向降低。相反，退火只会导致PP层出现低温吸热平台。PE层片层结构尺寸和取向的改善增加了拉伸PP/PE微孔膜的孔排列和孔隙率。本研究成功地将部分熔融聚合物熔体的自成核效应应用于实际的退火工艺中，对高性能PP/PE/PP锂电池隔板的生产和其他多层膜产品的退火工艺具有一定的指导意义。
Due to the mechanical stability of the PP layer, the oriented PP/PE double-layer film with a row-nucleated crystalline structure can be annealed at a higher temperature than the PE monolayer film. In this work, the effects of annealing temperature within the melting range of PE on the crystalline structure and properties of PP/PE double-layer films were studied. When the annealing temperature is between 100 and 130 °C, below the melting point of PE, the crystallinity, the long period, lateral dimension and orientation of the lamellae in the PE layer increase with the annealing temperature due to the melting of thin lamellae and the self-nucleated effect of partially-melted melts during annealing. With the annealing temperature further increasing to 138 °C, near the melting ending point of PE, since the lamellae melt completely and the melt memory becomes weak during annealing, some spherulite structures are formed in the annealed sample, resulting in a decrease of orientation. In contrast, the annealing only causes the appearance of a low-temperature endothermic plateau in the PP layer. The improved size and orientation of lamellar structure in the PE layer increase the pore arrangement and porosity of the stretched PP/PE microporous membrane. This study successfully applies the self-nucleation effect of partially-melted polymer melt into the practical annealing process, which is helpful to guide the production of high-performance PP/PE/PP lithium batteries separator and the annealing process of other multilayer products.