Novel Functional Graphene and its Thermodynamic Interfacial Localization in Biphasic Polyolefin Systems for Advanced Lightweight Applications
Implementation of multiple polymers represents a fast and cost-efficient method to bring additional functional attributes that are practically impossible without a highly capital-intensive synthesis of the product from a monomer. However, most polymer groups are thermodynamically immiscible, resulting in the material to devalue in performance. The purpose of this research is to study the impact of a novel nanostructured carbon co-factor on the compatibility between Polyethylene (PE) and Polypropylene (PP), in a macro-micro biphasic polyolefin system, with PE representing the macro phase. An alternative and inexpensive Graphene Oxide (GO) modification is performed for synthesizing a novel functional graphene. Then, a thermodynamically driven mixing mechanism of the three components is proposed for selectively localizing the additive at the PE/PP interface. The focus is on improving the structural attributes of PE, increasing its industrial value, through the combined effect of micro phase PP and interface localized novel functional graphene. The experimental results highlight the effectiveness of the GO modification process in recovering pure graphene structure and properties, in a cost-effective way. Moreover, the preferential localization of the highly exfoliated novel functional graphene at the biphasic system interface lowers PE/PP interfacial tension and viscosity mismatch. This increases phase compatibility and promotes a remarkably fine dispersion of the micro phase into the macro phase. Consequently, a significant thermo-mechanical performance enhancement is seen, with stiffness and toughness being greater than the ones of virgin PP, and strength and heat deformation resistance almost matching the neat PP ones. Lastly, PE non-isothermal crystallization kinetics are investigated to validate the experimental data. It is shown that the increase in material’s performance is in direct correlation with nucleation-controlled PE crystallization, induced by the synergistic combination of micro phase and novel functional graphene. These findings will allow industries to replace their PP based materials with one that has a more abundant, simpler, cheaper, and yet performant PE as the major component, bringing a paradigm shift in the manufacturing of advanced lightweight polyolefin materials with tuned functionalities, suitable for emerging engineering applications.
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