Entropy Barrier Mitigation and Harnessing Localized Upcycled Graphene Nanoplatelets in Polypropylene/High-Density Polyethylene Nanoblends

Abstract

In pursuit of a sustainable future, the focus on thermoplastic compounding emerges as a transformative avenue. Strategically blending and compounding thermoplastics unlock the potential for eco-friendly materials, addressing pressing environmental concerns. Polymer blending is a widely utilized technique that offers significant advantages in terms of cost-effectiveness and the development of materials with diverse properties. However, achieving compatibility between polymers remains a challenge due to their non-negligible entropy, particularly in the case of immiscible polymers like Polypropylene (PP) and High-Density Polyethylene (HDPE). The success of such systems heavily depends on optimizing factors such as additive selection, mixing methodology, composition, and processing conditions. Despite the extensive industrial usage of polymers like PP and HDPE, there is still limited understanding regarding the impact of blending these polymers, especially when graphene is introduced. This study addresses these challenges by overcoming the entropy barrier between PP and HDPE using a high shear rate thermo-kinetic mixer and employing upcycled graphene nanoplatelets (GNP) as a type of low-cost graphene material through interface engineering. The GNP content in the blends ranged from 0 to 1 wt%, and through meticulous selection of the polymer weight fraction and the use of minimal GNP content, GNP was strategically localized at the blend interface. This resulted in remarkable mechanical performance achieved through the optimized manufacturing technique. Incorporating 0.1 wt% GNP resulted in a significant 38% increase in tensile modulus, while flexural modulus and flexural strength saw respective increments of 39% and 22% compared to neat PP. Further enhancements were observed with higher GNP contents. This study illuminates the transformative potential of thermoplastic compounding as a key driver toward a sustainable future. Graphical Abstract