No abstract

In this study, the different effects of nanoparticle aggregates and agglomerates on the mechanical properties of polymer nanocomposites are comprehensively investigated. To this end, a specific strategy, based on the equilibrium between the dispersion and cohesion energies in the mixing stage, is proposed using which the content and size of aggregates/agglomerates can be defined. The aggregated/agglomerated networks are considered to place in constrained volumes (CVs), having co‐continuous morphology. An equivalent box model (EBM), corresponding to the system, is used to predict the tensile modulus of the nanocomposite. Different test results of HDPE nanocomposite samples, containing 1–3 wt.% of surface‐modified silica nanoparticles, prepared by a semi‐industrial single screw extruder, are applied to validate the model. Moreover, other data from the literature are also used to further evaluate the accuracy and capability of the proposed analytical method.

The formation of polymer/particle interphase region besides affecting most of the mechanical characteristics of polymer nanocomposites also alters some of their physical properties. The physical/mechanical properties inside the interphase may change based on a specific pattern (e.g., linear, exponential, etc.). De Gennes's self‐similar carpet theory represents a unique definition for the concentration variation of the adsorbed polymer chains. Accordingly, this specific pattern was developed to predict the tensile strength of the polymer/particle interphase region based on the molecular characteristics of the matrix and polymer/particle compatibility. In addition, Pukanszky's model was developed to define the characteristics of the aggregates/agglomerates using the results of De Gennes's theory. Different high‐density polyethylene (HDPE) nanocomposite samples, containing compatibilized silica nanoparticles, were prepared and subjected to the tensile and field emission scanning electron microscopy (FE‐SEM) tests. Moreover, other data from the literature were used to further investigate the accuracy of the proposed model. It was revealed that considering the gyration radius of the polymer chains as the maximum interphase thickness and the scaling parameter as 0.49 provides accurate predictions. On the other hand, the obtained data regarding the average content and size of nanoparticle aggregates/agglomerates also were in good agreement with the actual results.

No abstract