Solvent-Free Solid-State-Processed Tapes of Ultrahigh-Molecular-Weight Polyethylene: Influence of Molar Mass and Molar Mass Distribution on the Tensile Properties
Solvent-Free Solid-State-Processed Tapes of Ultrahigh-Molecular-Weight Polyethylene: Influence of Molar Mass and Molar Mass Distribution on the Tensile Properties
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DOI：
10.1021/acs.iecr.5b01469
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发表时间：
2015-08-05
影响因子：
4.2
通讯作者：
Rastogi, Sanjay
中科院分区：
文献类型：
--
作者：
Ronca, Sara;Forte, Giuseppe;Rastogi, Sanjay
在通常的实践中，加工的容易性以机械性能的降低为代价。在这里，我们表明，通过控制合成是可能的，合成范围广泛的线性超高分子量聚乙烯，可以单轴拉伸成带。在这些单轴拉伸带中，纤维束以优选的晶面取向排列，从而导致非常高的拉伸模量。拉伸过程在固态下完成，不需要任何溶剂。固态加工的简易性为跟踪摩尔质量对拉伸性能的影响提供了独特的机会。单轴拉伸带与溶剂纺成的纤维类似，证实了货车Krevelen在1976年提出的拉伸强度和拉伸模量之间的经验关系，该关系随后得到Smith和Lemstra对溶液纺成纤维的实验结果的支持。然而，固态处理的带没有实现从该关系预期的高拉伸强度值，其中200GPa的模量将对应于5GPa的拉伸强度。在单轴拉伸带中观察到的200GPa的非常高的模量的相对较低的4GPa的拉伸强度归因于缺陷的存在，因为带可以被认为是纤维的复合材料。带材的高模量与拉伸强度相结合，有可能在复合材料中提供独特的物理性能。
In normal practice, ease in processing conies at the expense of a reduction in mechanical properties. Here we show that by controlled synthesis it is possible to,synthesize a Wide range of linear ultrahigh-molecular-weight polyethylenes that can be stretched uniaxially into tapes. In these uniaxially drawn tapes, the bundles of fibers align themselves in a preferred crystal plane orientation, accounting for an extraordinarily high tensile modulus. The stretching process is accomplished in the solid state with no need for any solvent. The ease of solid-state processing provides A unique opportunity to follow the influence of the molar mass on the tensile properties. The uniaxially drawn tapes, similar to the fibers spun from solvent, confirm the empirical relationship between tensile strength and tensile modulus proposed by van Krevelen in 1976 and Subsequently supported by experimental findings on solution-spun fibers by Smith and Lemstra. However, the solid-state-processed tapes do not achieve the high values of tensile strength expected from this relationship, where a modulus of 200 GPa would correspond to a tensile strength of 5 GPa. The relatively lower tensile strength of 4 GPa for the extraordinarily high modulus of 200 GPa observed in the uniaxially stretched tapes is attributed to the presence of defects, as tapes can be considered composites of fibers. The high modulus in combination with the tensile strength in tapes has the potential to provide unique physical properties in composites.