SAXS study on deformation behavior of isotactic polypropylene under pressurized CO2
SAXS study on deformation behavior of isotactic polypropylene under pressurized CO2
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DOI：
10.1002/app.37669
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发表时间：
2013-01
影响因子：
3
通讯作者：
N. Osaka;Fumiya Kono;H. Saito
中科院分区：
文献类型：
--
作者：
N. Osaka;Fumiya Kono;H. Saito
采用原位拉伸变形仪和小角x射线散射（SAXS）测量技术，研究了等规聚丙烯（iPP）在加压CO2作用下的拉伸变形行为和结构变化。抗拉强度包括屈服应力、平台应力和拉伸模量随着CO2压力的增加而降低，这表明吸收CO2使非晶态区域膨胀，使晶片容易变形，而缠结较少。在CO2作用下，试样在屈服点以上变得不透明，在二维SAXS图中出现强烈的赤道条纹。通过使用Ruland的条纹法，它们被归因于形成的纳米尺寸的空隙大于晶片的周期距离。加压CO2条件下片层峰的方位角比常压条件下更明显。这意味着CO2容易使晶片旋转，导致晶片的优先取向，从而导致在片层堆叠之间的聚合物基质间隙形成纳米尺寸的空隙。在减压后的第二阶段拉伸中，拉伸iPP的伸长率得到了提高，这是因为形成了纳米尺度的空隙。©2012 Wiley期刊公司j:。变异较大。科学。, 2013年
Tensile-deformation behavior and structure change of isotactic polypropylene (iPP) under pressurized CO2 were investigated by using in situ tensile-deformation instruments and small-angle X-ray scattering (SAXS) measurements. Tensile strength including yield stress, plateau stress, and tensile modulus decreased with increase of CO2 pressure, suggesting that expansion of amorphous regions by absorbing CO2 allows crystalline lamellae to deform easily with less entanglement. Under CO2, the specimens became opaque beyond yield point and strong equatorial streaks appeared in two-dimensional SAXS patterns. By using Ruland's streak method, they are attributed to formation of nanometer-sized voids larger than the periodic distance of crystalline lamellae. An azimuthal profile of the lamellar peak was sharper under pressurized CO2 than that under ambient pressure. This meant that the easy rotation of the crystalline lamellae by CO2 results in the preferred orientation of the crystalline lamellae, which caused formation of the nanometer-sized voids at the interspace in the polymer matrix between lamellar stacks. Owing to the formation of the nanometer-sized voids, the elongation was enhanced in the second stage stretching of the stretched iPP at ambient pressure after depressurization. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013