A preliminary study of the mechanical effects of polymer crystallization in the vicinity of a rigid cylindrical inclusion: Homogeneous crystallization under plane strain

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:175152

Ma, R; Negahban, M ^[1]

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1. Univ. of Nebraska, Lincoln, NE (United States)

The objective of this study is to investigate the effect of crystallization on the mechanical response of a polymer containing a rigid cylindrical inclusion under different loading conditions and under the plane strain restriction. As will be shown, external loading and crystallization can both induce an inhomogeneous distribution of stress and deformation in the vicinity of a cylindrical inclusion and can also interact with each other. Crystallization is a process of transition of the polymer`s microstructure from disordered state to an ordered one. This transition occurs in many polymers, such as polyethylene, polypropylene, nylon, and natural rubber. The process of crystallization gives rise to a macroscopic deformation, reducing the macroscopic volume, and it can increase the toughness and rigidity of a polymer. For example, for natural rubber crystallization causes a two order of magnitude increase in the elastic moduli. Moreover, crystallization can result in stress relaxation under constant uniaxial extension and creep under constant load. These effects have been captured in a constitutive model developed by Negahban, Wineman and Ma, which has been shown to be in good agreement with experimental results. This presentation provides (1) a theoretical evaluation of the effect of crystallization on the distribution of stress and mechanical moduli under axisymmetric loading and an estimation of the idual stress resulting from crystallization in the vicinity of a cylindrical inclusion; and (2) a numerical simulation of the stress distribution in the vicinity of an inclusion due to crystallization under both constant displacement loading and constant traction loading. All results are for plane strain conditions. Results show that an inhomogeneous distribution of stress and deformation is developed in the vicinity of the inclusion due to the external loading and/or due to crystallization.

• OSTI ID: 175152
• Report Number(s): CONF-950686--
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CREEP
CRYSTALLIZATION
DEFORMATION
MICROSTRUCTURE
NATURAL RUBBER
NYLON
POLYMERS
POLYPROPYLENE
SHEAR
STRESS RELAXATION