Modulus prediction of binary phase polymeric blends using symmetrical approximation systems as a new approach

Abstract

In this study, a symmetrical approximation system (SAS) is proposed in order to predict Young’s modulus of polymer blend based on new geometrical approaches. The dominant morphologies of the blend (droplet-matrix and co-continuous) were simulated using comprehensive geometrical structures across the volume fraction range of dispersed phase. These morphologies were considered to be the dominant internal structures of the blend under percolation threshold and phase inversion point, respectively. However, between phase inversion point and percolation threshold a combination of both morphologies was assumed to form the dominant internal structure. This assumption led to dividing the volume fraction range of dispersed phase into four intervals and one phase inversion point. The co-continuous structure representative parameter (r) was calculated using R(D) factor which indicated the portion of co-continuous morphology in the blend structure resulted by increasing the volume fraction of dispersed phase after percolation threshold. Model parameter R representing droplet-matrix structure was evaluated using two different approaches to represent the best calculation procedure with best prediction of Young’s modulus. The geometrical structures of SAS model were designed to represent the most acceptable simulation of a blend system. Unlike other proposed models, SAS model provided the most compatible hypothetical structures with blend morphologies using appropriate and comprehensive geometrical foundations. Samples based on isotactic polypropylene and polyamide 6 were prepared in order to check the accuracy of SAS model. Furthermore, direct and independent approximation model and some other elicited data were also used in order to investigate the validity of SAS model.