Analysis and numerical investigations on the temperature-dependent creep behavior of polypropylene matrix composite used for coating of offshore pipeline

Abstract

In this paper, the effect of temperature on the creep-recovery behavior of a polypropylene matrix syntactic foam material under low stresses is analyzed. Previous dynamic mechanical analyses have shown that the mechanical response of the composite material is strongly time dependent with the polymeric nature of its matrix despite a high volume fraction of hollow glass microspheres. The permanent deformations are more pronounced at the higher temperatures. With the low level of the applied stress, the results lead to the assumption that the microcracks can be generated in the matrix of the composite material. Under the effect of temperature gradients in the offshore environment, the response of the material could evolve from a linear viscoelastic behavior to a behavior of which one part could be associated with the viscoelasticity of the matrix and a second with its viscoplasticity. We propose to use hooke, spectral triangular, and Zapas-Crissmann models to predict the overall creep response of a polypropylene matrix syntactic foam at the different temperatures. The results showed that the creep deformation at the higher temperatures conforms well to the global model including a power law that takes into account the permanent deformations of the polypropylene matrix composite of syntactic foam material type.