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The effects of powder morphology on the processing of auxetic polypropylene (PP of negative poisson's ratio)
Author(s) -
Pickles A. P.,
Alderson K. L.,
Evans K. E.
Publication year - 1996
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.10451
Subject(s) - auxetics , materials science , composite material , polypropylene , poisson's ratio , extrusion , morphology (biology) , polyethylene , poisson distribution , microstructure , polymer , sintering , surface roughness , statistics , mathematics , biology , genetics
With the use of a three‐stage thermal processing route, similar to that used previously for the production of ultra high molecular weight polyethylene possessing a negative Poisson's ratio (i.e. displaying auxetic behavior), an auxetic form of polyethylene has been fabricated. The polypropylene is processed by the compaction, sintering, and extrusion of a powder. The importance of powder morphology on the ability of polypropylene to achieve auxetic behavior has been examined, revealing that particle shape, size, and surface roughness are critical variables for successful processing. Negative Poisson's ratios of up to −0.22 at 1.6% strain have been obtained. The data have been successfully interpreted by use of a simple geometric model based on the polymer microstructure. These suggest that, by further optimizing the processing conditions, much larger negative Poisson's ratios should be achievable.