Premium
Elasticity at large deformations and high strain rates in injection molded polypropylene
Author(s) -
Dijkstra P. T. S.,
Gaymans R. J.,
Van Dijk D. J.,
Huétink J.
Publication year - 2003
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.10135
Subject(s) - materials science , composite material , strain rate , elasticity (physics) , creep , brittleness , deformation (meteorology) , ultimate tensile strength , crystallinity , thermoplastic elastomer , polymer , copolymer
The deformation behavior of isotactic polypropylene (PP) as a function of strain rate was investigated at 50°C in uniaxial tension. Injection molded dogbone specimens were tested at high strain rates, ε = 10 −1 – 10 2 s −1 , and the local deformation in the neck was studied using fast tensile videometry. A strong elastic recoil was observed after fracture in this strain rate range with local elastic strains as high as ϵ e = 2.0 – 3.2. The recoil is very fast and takes place within 1 ms. The elastic fraction of the strain at break was found to increase with the local strain rate. The elasticity further depends on strain and temperature. The elastic deformation behavior is part of the known transition from ductile cold drawing behavior to brittle fracture that occurs with strain rate or temperature. The elasticity in PP is thought to be due to a decrease in crystallinity, resulting in a discontinuous crystalline structure comparable to that of thermoplastic elastomers.