Understanding process-structure-property relation for elastoplastic behavior of polymer nanocomposites with agglomeration anomalies and gradient interphase percolation

Abstract

For polymer nanocomposites, disordered microstructural nature makes processing control and tailoring properties to desired values a challenge. Understanding process-structure-property relation can provide guidelines for process and constituents design. Our work explores nuances of PSP relation for polymer nanocomposites with attractive pairing between particles and polymer bulk. In the absence of any nano or micro-scale local property measurement, we develop a material model that can represent decay for small strain elastoplastic properties in interfacial regions and simulate representative or statistical volume element behavior. This interfacial model is further combined with a microstructural design of experiments for agglomerated nanocomposite systems. Agglomerations are particle aggregations that are microstructural defects resulting from lack of processing control. Twin screw extrusion process can reduce extent of aggregation in hot pressed samples via erosion or rupture depending on screw rpms and toque. We connect this process-structure relation to structure-property relation that emerges from our study. We discover that balancing between local stress concentration zone and interfacial property decay governs how fast yield stress can improve if we break down agglomeration via erosion. Rupture is relatively less effective in helping improve nanocomposite yield strength. Additionally, we allude to yield initiation and progression in these multiphase materials. We have come up with a field quantity called local yield resistance that indicates balance stress concentration zones and interfacial effects. Yield resistance map from linear regime acts as a predictor of local yielding process and can be a useful tool for interface design for plastic deformation behavior.