Modeling and prediction of compressive creep of silane-treated TiO2/high-density polyethylene

Abstract

Silane-treated TiO2/high-density polyethylene (silane-TiO2/HDPE) is a potential bone substitute material with good bioactivity and mechanical properties. In this composite, 40 vol.% TiO2 particles were connected chemically with HDPE (high-density polyethylene) by silane-coupling agent. The intensive silane connection was believed to play very important role in compressive creep behavior of silane-TiO2/HDPE in our previous study. In order to deeply understand the relationship between the special structure and creep behavior, both a viscoelastic creep model named Burgers, and an empirical model called Findley power law were applied to simulate and predict the creep curves obtained in both air and saline solution. The results showed that Burgers model succeeded in simulating the creep curves but failed in long-term prediction for all dry samples, while Findley power law failed in simulating the creep curves in air but succeeded in saline solution. By analyzing the parameters obtained from Burgers model, it was believed that the structure of intense connection by silane chains resulted in the very big and gradually increased permanent viscous flow of this material with creep time. The big permanent viscous flow brought on the failure in simulating creep curves using Findley power law, and the improved permanent viscous flow during creep conduced to the positive deviation between the prediction and practical creep curve using Burgers model. The effect of saline solution around sample could not only decrease the permanent viscous flow but also stabilize it gradually, which resulted in the success in the prediction and simulation of creep curve in saline solution by the two models.