Diffusion versus Cocrystallization of Very Long Polymer Chains at Interfaces: Experimental Study of Sintering of UHMWPE Nascent Powder

Ultrahigh-molecular-weight polyethylene (UHMWPE) has been processed by means of sintering of a nascent powder. Particular attention was paid to the precompaction of the powder just below the melting point (T m) under vacuum. The particle welding was subsequently carried out under pressure at various...

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Bibliographic Details
Published in:Macromolecules 2014-01, Vol.47 (1), p.197-207
Main Authors: Deplancke, T, Lame, O, Rousset, F, Aguili, I, Seguela, R, Vigier, G
Format: Article
Language:English
Subjects:
Applied sciences
Engineering Sciences
Exact sciences and technology
Machinery and processing
Materials
Miscellaneous
Plastics
Polymer industry, paints, wood
Technology of polymers
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Summary:Ultrahigh-molecular-weight polyethylene (UHMWPE) has been processed by means of sintering of a nascent powder. Particular attention was paid to the precompaction of the powder just below the melting point (T m) under vacuum. The particle welding was subsequently carried out under pressure at various temperatures above T m for various durations. Tensile drawing experiments performed on sintered samples either at room temperature or above T m were specifically aimed at discriminating the role of chain interdiffusion through the particle interfaces from that of cocrystallization in the mechanism of particle welding. It turned out that efficient welding occurred within a very short time. One of the novel results of the work is the much weaker influence of sintering time as compared with temperature, giving evidence that chain interdiffusion is not governed by a reptation process. The entropy-driven melting explosion over distances much larger than the chain length between entanglements is suggested to be the main mechanism of the fast chain re-entanglement and particle welding in the present case of a nascent powder consisting of nonequilibrium chain-disentangled crystals. Another major aspect of this study is the demonstration of the huge cocrystallization efficiency in the interface consolidation in the solid state that significantly hides the kinetics of chain intertwining occurring in the melt.
ISSN:0024-9297
1520-5835
DOI:10.1021/ma402012f