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首页> 外文期刊>Journal of Applied Polymer Science >Plastic behavior of monoclinic polypropylene under hydrostatic pressure in compressive testing
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Plastic behavior of monoclinic polypropylene under hydrostatic pressure in compressive testing

机译：单斜聚丙烯在静水压力下的压缩性能

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摘要

The plastic deformation of monoclinic isotactic polypropylene is studied in compressive testing with particular attention to the effect of hydrostatic pressure up to 300 MPa, in the temperature range 20-60 °C. The coefficients of the Coulomb criterion are fairly consistent with those assessed from the comparison of the tensile and compressive yield stresses at atmospheric pressure, in the same temperature range. The high friction coefficient of polypropylene is ascribed to a strain-induced order-to-disorder transition from the monoclinic to the smectic form accompanied by an increase of specific volume. This local and transient phase change is assumed to result from the mobile conformational chain defects that govern the elementary mechanism of plasticity in the crystalline phase of polypropylene consisting of 3/1 helix chains. A comparative discussion is made with polyethylene that displays a much lower friction coefficient. The dislocation-based approach that is proposed in relation to the viscoelastic relaxation processes provides a new insight into the molecular grounds of the elementary mechanism of plasticity of polypropylene.
机译：在压缩测试中研究了单斜全同立构聚丙烯的塑性变形，尤其要注意在20至60°C的温度范围内高达300 MPa的静水压力的影响。库仑标准的系数与通过比较在相同温度范围内大气压下的拉伸和压缩屈服应力所评估的系数相当一致。聚丙烯的高摩擦系数归因于应变引起的从单斜晶向近晶形的有序到无序的转变，同时伴随着比体积的增加。假定这种局部和瞬时相变是由可移动的构象链缺陷引起的，该缺陷控制着由3/1螺旋链组成的聚丙烯结晶相中塑性的基本机理。对显示出低得多的摩擦系数的聚乙烯进行了比较讨论。与粘弹性松弛过程有关的基于位错的方法为聚丙烯可塑性基本机理的分子基础提供了新的见识。

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