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Molecular mobility and fracture processes in ultimately drawn high-density polyethylene

 

作者: E.A. Egorov,   V.V. Zhizhenkov,   V.A. Marikhin,   L.P. Myasnikova,  

 

期刊: Journal of Macromolecular Science, Part B  (Taylor Available online 1990)
卷期: Volume 29, issue 2-3  

页码: 129-137

 

ISSN:0022-2348

 

年代: 1990

 

DOI:10.1080/00222349008245769

 

出版商: Taylor & Francis Group

 

数据来源: Taylor

 

摘要:

The reasons for cessation of drawing and for the local fracture processes occurring in linear polyethylene near ultimate draw ratios, λmax, have been studied by broad-line proton NMR and scanning electron microscopy. As λmaxwas reached during drawing, the sample whitened and kink bands similar to those observed at deformation of low molecular solids were formed. The kink bands were clearly seen in the micrographs. As evidenced by NMR, the segmental mobility of chains in the amorphous regions is almost completely suppressed because of a sharp increase of the orientation stress near λmax(though the temperature of drawing is close to the melting temperature). This phenomenon of mechanical vitrification is regarded as a fundamental reason for cessation of drawing and for transition to the “solid-state” fracture mechanism. Quantitative estimates are given for formation of submicrocracks arising at boundaries of kink bands.

 

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