Mechanisms of Chain Reentanglement during the Sintering of UHMWPE Nascent Powder: Effect of Molecular Weight
Mechanisms of Chain Reentanglement during the Sintering of UHMWPE Nascent Powder: Effect of Molecular Weight
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DOI：
10.1021/acs.macromol.5b00618
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发表时间：
2015-08-11
期刊：
影响因子：
5.5
通讯作者：
Vigier, Gerard
中科院分区：
文献类型：
--
作者：
Deplancke, Tiana;Lame, Olivier;Vigier, Gerard
不同分子量范围为 0.6 < M-v < 1050 万克/摩尔的超高分子量聚乙烯 (UHMWPE) 初生粉末已通过烧结加工而成。界面固结或颗粒焊接是在压力下、在高于熔点的不同温度下和不同持续时间下进行的。在熔点以上进行的拉伸拉伸实验能够研究通过颗粒界面的链相互扩散的作用。证明每个分子量都会发生熔化爆炸现象。 M-v 越高，该现象的效率就越大。但这不允许烧结样品的纠缠网络均质化。事实上，在高于熔化温度的拉伸测试中，晶粒和界面之间变形的不均匀性明显出现。熔融状态下分子量之间机械行为的差异似乎因张力下的结晶而加剧。熔化爆炸后，端链扩散以及侧向运动可能参与长链聚合物界面的修复，以达到足够高的缠结密度。后一种现象似乎是热激活的。
Nascent powders of ultrahigh molecular weight polyethylene (UHMWPE) with different molecular weights in the range 0.6 < M-v < 10.5 million g/mol have been processed by means of sintering. The interface consolidation or particle welding was carried out under pressure at various temperatures above the melting point and for various durations. Tensile drawing experiments performed above the melting point enabled to study the role of chain interdiffusion through the particle interface. The melting explosion phenomenon was demonstrated to occur for each molecular weight. The higher is M-v, the greater is the efficiency of the phenomenon. But this does not allow a homogenization of the entanglement network of the sintered sample. Indeed, heterogeneity of deformation between the grain and the interface clearly appears during tensile tests above the melting temperature. The differences in mechanical behavior in the molten state between the molecular weights seem exacerbated by crystallization under tension. After melting explosion, end-chain diffusion as well as sideways motions are probably involved in the healing of very long chains polymer interfaces to reach a sufficiently high entanglement density. This latter phenomenon seems thermally activated.