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Analysis of zone‐drawing process in preoriented polypropylene
Author(s) -
Yamada K.,
Takayanagi M.
Publication year - 1982
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1982.070270621
Subject(s) - materials science , tacticity , composite material , necking , modulus , deformation (meteorology) , polypropylene , activation energy , amorphous solid , elastic modulus , flexural modulus , ultimate tensile strength , polymer , crystallography , chemistry , organic chemistry , polymerization
Preoriented isotactic polypropylene was used to clarify the molecular process in zone‐drawing with which the necking part is confined in a thin heating zone during uniaxial drawing. The process was analyzed on the basis of rate process, the mechanical properties of zone‐drawn samples, and the superstructural change during zone‐drawing. The values of activation energy for deformation, Δ H * , and the activation volume, Δ V * , were affected by the deformation mechanisms preferentially taking place during the zone‐drawing. The attainable maximum modulus of zone‐drawn sample at θ = 45° was larger than those at θ = 0° and 90°. The highest strength was also obtained at θ = 45°. The values of modulus and strength strongly depended on both the orientation function of the crystal c ‐axis and the orientation function of amorphous chains. In the region of a very high zone‐drawing rate, in which microcracks are preferentially formed, both modulus and strength decreased, whereas they increased with increasing the zone‐drawing rate below this region, giving the optimum condition for achieving the maxima in the modulus and strength.