Double Yielding in Deformation of Semicrystalline Polymers
Double Yielding in Deformation of Semicrystalline Polymers
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DOI：
10.1002/macp.202000151
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发表时间：
2020-09
影响因子：
2.5
通讯作者：
M. Razavi;Shi‐Qing Wang
中科院分区：
文献类型：
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作者：
M. Razavi;Shi‐Qing Wang
研究了聚L-乳酸、聚对苯二甲酸乙二酯、间规聚苯乙烯和聚酰胺12等不同的半结晶聚合物对单轴压缩变形的力学响应。在玻璃化转变温度附近的应力-应变曲线上，非晶相和晶相屈服的明显解耦被识别为单独的峰。预拉伸半结晶聚对苯二甲酸乙二酯的单轴拉伸也具有相同的特征。结果表明，在没有强非晶相的情况下，半结晶聚合物不能屈服并发生塑性变形，在单轴压缩下呈脆性破坏。将半结晶聚合物视为非晶态和晶态相的复合体，强调了非晶态相在晶区之间起连接点的重要作用，指出非晶态相的屈服是晶态相屈服的前提条件，从而在分子水平上更好地理解了半结晶聚合物的力学性质。
Different semicrystalline polymers including poly(l‐lactic acid), poly(ethylene terephthalate), syndiotactic polystyrene, and polyamide 12 are studied in terms of their mechanical response to uniaxial compression deformation. Apparent decoupling of yielding of amorphous and crystalline phases is identified as separate peaks in the stress–strain curve in the vicinity of the glass transition temperature. The same feature is also observed for the uniaxial extension of predrawn semicrystalline poly(ethylene terephthalate). It is indicated that in absence of a strong amorphous phase a semicrystalline polymer is unable to yield and undergo plastic deformation and it fails in a brittle manner in the uniaxial compression. Treating a semicrystalline polymer as a composite of amorphous and crystalline phases, putting emphasis on the crucial role of amorphous phase in acting as connectors between crystalline domains and indicating that the yielding of amorphous phase is a prerequisite for yielding of crystalline phase, work toward a better understanding of the mechanical properties of semicrystalline polymers at the molecular level is done.