Analytical prediction of creep behavior in polymeric-based nanocomposites

A micromechanical model using properties of both polymer and filler is proposed to address creep response in case of nanocomposites consisting of graphite nanoparticles embedded in a polymer matrix. Empirical creep models like Burgers and Findley models have been frequently used for creep simulation of polymeric-based nanocomposites. An elastic stiffness model has been established first to simulate stiffness property of nanocomposites with emphasis on filler distribution conditions. Creep stiffness is then predicted from the outstanding stiffness model based on the linear elastic–viscoelastic principle. In the model development, a parameter termed as additional constraint stiffness factor has been defined in the model to account for the constraining effect played by nanoparticles on the polymer chains. Magnitude of constraint factor indicates performance of nanoparticles in preventing polymer chains motion under creep loading of the nanocomposite. Creep predictions of the model with and without effect of the additional constraint stiffness factor are compared with experimental results obtained for vinyl ester reinforced nanocomposites. Predictions of the model disregarding the additional constraint stiffness factor overestimate the experimental results and do not provide good agreement. For each of the studied nanocomposites, the present model was able to provide creep response according to different filler percentage and different temperature along with the same stiffness function and similar constraint factors, in each case.