An EBM based multi-stage mechanical model to predict the time-dependent creep behavior of semi-crystalline polymer nanocomposites

In this study, a multi-stage model is proposed to predict the creep behavior of semi-crystalline polymer nano-composites considering the impact of nanoparticle aggregation/agglomeration, polymer/particle interphase re-gion and self/induced crystallization phenomenon. A specific equivalent box model (EBM) was designed, based on excluded volume concept, to evaluate the different roles of dispersed or aggregated/agglomerated nano-particle domains in the system. The tensile modulus of these domains was defined using mechanical and cohesive energy-based parameters in the melt-mixing stage. In the next stage, the physical/mechanical characteristics of the polymer/particle interphase were indicated using an analytical model and mechanical properties of the system. Another EBM was developed using standard linear viscoelastic (SLV) model components to study the time-dependent creep behavior of the matrix and polymer/particle interphase region. The impact of polymer/ particle compatibility on the creep behavior of the samples was also experimentally evaluated by applying different amounts of compatibilized and un-compatible silica nanoparticles to the high-density polyethylene (HDPE) matrix. Different experimental tests were used to provide the required data or verify the obtained theoretical results. Both model predictions and experimental results showed that increasing the nanoparticle content and polymer/particle compatibility increases the resistance of the semi-crystalline nanocomposite sys-tem against the time-dependent creep.

Automated summary

A multi-stage model was proposed to predict the creep behavior of semi-crystalline polymer nano-composites, taking into account the impact of nanoparticle aggregation/agglomeration, polymer/particle interphase region, and self/induced crystallization phenomenon. The model involved a specific equivalent box model (EBM) to evaluate the roles of dispersed or aggregated/agglomerated nanoparticle domains, an analytical model to study the characteristics of the polymer/particle interphase, and a standard linear viscoelastic (SLV) model to examine the time-dependent creep behavior. Experimental tests were conducted to verify the theoretical results, showing that increasing nanoparticle content and polymer/particle compatibility enhances the resistance against time-dependent creep.