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Medical tubing used in minimally invasive devices presents a number of design considerations depending on the material used, design requirements (such as sufficient stiffness, flexibility and biocompatibility) and processing conditions. Currently, manufacturing industries adopt co-extrusion systems to meet design specifications, by using multilayer configuration leading to higher cost per device and increased complexity. This paper investigates the mechanical performance of nanocomposites using supercritical carbon dioxide assisted polymer processing technique. The use of innovative medical compounds such as PEBAX graphene nanocomposites have resulted in measurable improvements in mechanical properties. This study also presents the effect of supercritical carbon dioxide on the mechanical and physical properties of the polymer matrix. The mechanical properties have been investigated using dynamic mechanical analysis (DMA) and mechanical tensile test, where sufficient reinforcement was observed depending on the composition of graphene within PEBAX matrix. ATR-FTIR was used to further analyze the effect of supercritical carbon dioxide and interactions within the polymer composite matrix.

The paper presents an in-depth analysis on the crystallisation kinetics of Pebax-Graphene composites when processed with and without supercritical fluid carbon dioxide (scCO 2) assisted extrusion at various graphene loading concentrations. Crystallisation behaviour was understood using the Avrami model for isothermal conditions and the Avrami, Ozawa and Combined Avrami-Ozawa model for non-isothermal conditions. The results from crystallisation kinetics suggest that the crystal structure transformed from 2D to 3D when processed with scCO 2. The overall crystallisation rate decreases when the composite matrix was processed with scCO 2 under both isothermal and non-isothermal conditions promoting possible exfoliation and crystal rearrangement resulting in homogenisation of the composite matrix. The Arrhenius and Kissinger's activation energy was calculated which is indicative of restriction opposed by graphene exfoliation to nucleation and crystal growth when processed with scCO 2. Crystallite size was calculated from the X-ray diffraction (XRD) pattern using Scherrer's equation, where the crystallite size tends to decrease when processed with scCO 2 favouring the production of a homogenous composite matrix due to crystal rearrangement and graphene exfoliation.

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