Impact of Reduced Graphene Oxide on structure and properties of polyethylene rich binary systems for performance-based applications

Interfacially compatibilized PI/PDMS blends with reduced octadecylamine-functionalized graphene oxide: morphological and rheological properties

We investigate the interfacial compatibilization effect of reduced octadecylamine-functionalized graphene oxide (ODA-GO) on the morphological and rheological properties of immiscible homopolymer blends of polydimethylsiloxane (PDMS) and polyisoprene (PI). We prepared droplet-matrix blends with a PI : PDMS ratio of 30 : 70 or 70 : 30 and interfacially localized ODA-GO stabilizer loadings from 0.1% to 1%. Blends were examined by optical microscopy and rheometry. Both blends show typical droplet-matrix morphology with stabilized round drops that do not stick together. With the addition of ODA-GO, smaller drops were observed in PI-continuous blends as compared to the PDMS-continuous blends suggesting that the effects of particles are not symmetric in the two cases. At sufficiently high ODA-GO loadings, flow-induced coalescence is suppressed almost completely. Dynamic oscillatory rheology broadly confirms the morphological observations. Specifically, all the blends show an interfacial relaxation process that is distinct from the bulk viscoelasticity, and the dependence of this process on GO content and flow conditions confirms the compatibilizing effect of the ODA-GO. This work provides a strategy for interfacially-compatibilizated polymer blends with specific properties for practical applications.

Non-Isothermal Crystallization Behavior and Thermal Properties of Polyethylene Tuned by Polypropylene and Reinforced with Reduced Graphene Oxide

This research work is the first to report thermal stability, heat deformation resistance, and crystallization behavior of a Polyethylene (PE)-based biphasic polyolefin system reinforced with Reduced Graphene Oxide (RGO), which was obtained through Graphene Oxide (GO) chemical reduction. Polypropylene (PP) represented the polymeric dispersed phase. A strategic PE/PP/RGO manufacturing procedure was employed to thermodynamically localize RGO at the PE/PP interface, as confirmed by Transmission Electron Microscopy (TEM), bringing a uniform micro phase dispersion into the macro phase. In addition, studies of PE non-isothermal crystallization kinetics indicated that the morphology tunable micro phase and the nanolayered RGO promoted a nucleation-controlled PE crystallization, which was supported by Polarized Light Optical Microscopy (PLOM). This, together with fine morphology, justified the remarkable enhancement registered for the ternary system’s thermal stability and heat deformation resistance. Different filler loads were employed, with weight fractions of 2% and 4%. It was observed that the former, being better exfoliated and more homogeneously distributed at the PE/PP interface than the latter, led to a more improved PE crystallization, alongside a greater ternary system’s thermal properties. Moreover, the thermal stability of PE/PP reinforced with 2% of RGO was even higher than that of virgin PP, while their heat deformation resistance values were found to be similar. Therefore, this unique outcome provides industries, such as the energy and automotive sectors, with the opportunity to substitute PP-rich products with those mostly comprised of a cheaper, more abundant, yet performant PE.