ABSTRACT The study focused on experimental and classical data to establish some mechanical properties
for optimum design of new polypropylene components to serve under creep environment. The
creep studies recorded stress limits that never exceeded 24.19MPa and maximum creep modulus
that never exceeded 1.49GPa as against the predictions of classical equations that gave 2.0GPa
for PPC0 and 2.46GPa for PPC2 at ambient conditions. The shear modulus and shear strength
of the PPC0 and the PPC2 are predicted as 0.75GPa and 120MPa respectively and 0.92GPa
and 150MPa respectively while the yield strengths found to be about 13.19MPa and 13.20MPa
respectively for PPC0 and PPC2 at elastic strains 0.008 and 0.009 respectively. Further found
are that as the material deforms the stiffness or modulus decrease, at low strains there is an
elastic region, as temperature and applied stress increase the material becomes more flexible
characterized with reduction in moduli. Plastic deformation at strains above 0.01 resulted to
strain- hardening or strain-strengthening that manifested as the increasing area ratios and
associated creep cold work. Also established by this study is a computational model for
evaluating the elastic modulus of polypropylene matrix based material as expressed in equation
(6). Both the Halphin-Tsai and the Birintrup equations for elastic modulus of unidirectional fibre
composites were confirmed to be appropriate for prediction of elastic modulus of nanofiller
composites with polymer matrix.
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