TY - JOUR
T1 - Deformation and failure kinetics of iPP polymorphs
AU - Caelers, H.J.M.
AU - Parodi, E.
AU - Cavallo, D.
AU - Peters, G.W.M.
AU - Govaert, L.E.
PY - 2017/5/1
Y1 - 2017/5/1
N2 - In this study, the mechanical performance of thedifferent polymorphs of isotactic polypropylene, typically pre-sent in iPP crystallized under industrial processing conditions,is assessed. Different preparation strategies were used toobtain samples consisting of almost solely alpha, beta, or gamma crystals. X-Ray measurements were used to validate that the desired phase was obtained. The intrinsic true stress - true strain response of all individual phases was measured in uniaxial compression at several strain rates (deformation kinetics). Moreover, measurements were performed over a wide temperature range, covering the window in between the glass transition and the melting temperature. The relation between obtained yield stress and the strain rate is described with a modification of the Ree-Eyring model. Differences and similarities in the deformation kinetics of the different phases are presented and discussed. Furthermore, the presence of three deformation processes, acting in parallel, is revealed. The Ree-Eyring equation enables lifetime prediction for given thermal and mechanical conditions. These predictions were experimentally validated using constant load tests in uniaxial compres-sion.
AB - In this study, the mechanical performance of thedifferent polymorphs of isotactic polypropylene, typically pre-sent in iPP crystallized under industrial processing conditions,is assessed. Different preparation strategies were used toobtain samples consisting of almost solely alpha, beta, or gamma crystals. X-Ray measurements were used to validate that the desired phase was obtained. The intrinsic true stress - true strain response of all individual phases was measured in uniaxial compression at several strain rates (deformation kinetics). Moreover, measurements were performed over a wide temperature range, covering the window in between the glass transition and the melting temperature. The relation between obtained yield stress and the strain rate is described with a modification of the Ree-Eyring model. Differences and similarities in the deformation kinetics of the different phases are presented and discussed. Furthermore, the presence of three deformation processes, acting in parallel, is revealed. The Ree-Eyring equation enables lifetime prediction for given thermal and mechanical conditions. These predictions were experimentally validated using constant load tests in uniaxial compres-sion.
KW - Failure kinetics
KW - Intrinsic properties
KW - Lifetime predictions
KW - Mechanical behavior
KW - Yield kinetics
KW - iPP-polymorphism
KW - α-, β- and γ-iPP
UR - http://www.scopus.com/inward/record.url?scp=85014603360&partnerID=8YFLogxK
U2 - 10.1002/polb.24325
DO - 10.1002/polb.24325
M3 - Article
SN - 0887-6266
VL - 55
SP - 729
EP - 747
JO - Journal of Polymer Science, Part B: Polymer Physics
JF - Journal of Polymer Science, Part B: Polymer Physics
IS - 9
ER -