Tensile Deformation of Oriented Poly(ε-caprolactone) and Its Miscible Blends with Poly(vinyl methyl ether)
Tensile Deformation of Oriented Poly(ε-caprolactone) and Its Miscible Blends with Poly(vinyl methyl ether)
复制标题
取向聚己内酯及其与聚乙烯基甲基醚的混溶共混物的拉伸变形
DOI：
10.1021/ma401052x
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发表时间：
2013-09-10
期刊：
影响因子：
5.5
通讯作者：
Men, Yongfeng
中科院分区：
文献类型：
--
作者：
Jiang, Zhiyong;Wang, Yaotao;Men, Yongfeng
利用同步辐射小角X射线散射（SAXS）和扫描SAXS技术研究了微模塑聚己内酯（PCL）及其与非结晶聚乙烯基甲基醚（PVME）纳米级共混物的结构演变与形变比和共混物组成的关系。结果发现，取向样品的变形机制示出了拉伸变形过程的一般方案：在小的变形，然后沿拉伸方向在一个临界应变下的应力诱导的碎裂和再结晶过程沿着拉伸方向的结晶片层的平均厚度在拉伸过程中保持基本上恒定的发生在片层内的晶块滑移。临界应变的值取决于掺入共混物中的无定形组分的量，这可以追溯到缠结的无定形相的较低模量，因此，在加入PVME后作用于微晶的网络应力降低。当拉伸超过临界应变时，发生原纤维（新形成的层片的堆叠）彼此之间的滑移，导致拉伸的层间无定形链的松弛。由于变形诱导的引入的无定形PVME到在高度取向的共混物中的原纤间区域，原纤之间的相互作用变得更强，进一步变形，从而在一定程度上阻止原纤的滑动，最终导致较少的收缩层间的无定形层相比，纯PCL。
The structural evolution of micromolded poly(e-caprolactone) (PCL) and its miscible blends with noncrystallizable poly(vinyl methyl ether) (PVME) at the nanoscale was investigated as a function of deformation ratio and blend composition using in situ synchrotron small-angle X-ray scattering (SAXS) and scanning SAXS techniques. It was found that the deformation mechanism of the oriented samples shows a general scheme for the process of tensile deformation: crystal block slips within the lamellae occur at small deformations followed by a stress-induced fragmentation and recrystallization process along the drawing direction at a critical strain where the average thickness of the crystalline lamellae remains essentially constant during stretching. The value of the critical strain depends on the amount of the amorphous component incorporated in the blends, which could be traced back to the lower modulus of the entangled amorphous phase and, therefore, the reduced network stress acting on the crystallites upon addition of PVME. When stretching beyond the critical strain the slippage of the fibrils (stacks of newly formed lamellae) past each other takes place resulting in a relaxation of stretched interlamellar amorphous chains. Because of deformation-induced introduction of the amorphous PVME into the interfibrillar regions in the highly oriented blends, the interactions between fibrils becomes stronger upon further deformation and thus impeding sliding of the fibrils to some extent leading finally to less contraction of the interlamellar amorphous layers compared to the pure PCL.