Improvement of physical and mechanical properties on bio-polymer matrix composites using morphed graphene

Abstract

Chitosan is a natural-occurring biopolymer found commonly in the exoskeleton of crustaceans, vegetables, fungi and plants. Due to its relatively high mechanical properties, chitosan, is attractive for structural applications. Here, we show the benefits of morphed graphene as reinforcement for chitosan composites. Morphed graphene is incorporated into the chitosan matrix via thermomechanical process to produce composites with tunable mechanical performances that are ideal for applications where impact resistant (toughness) and elasticity are required. Optimum sintering conditions were determined by means of thermogravimetry and calorimetry. The characterization results show a clear homogeneity of the microstructure between chitosan and the reinforcement material. The characterization of the composite was carried using X-ray diffraction (XRD), Raman and infrared spectroscopies, optical microscopy, scanning and transmission electron microscopy. The mechanical properties were evaluated by nanoindentation and microhardness tests. The composite sintered at 180 °C for 3 h with 5 wt% of morphed graphene demonstrated to provide the best performance with 33% higher density, 78% less porosity, 133% higher maximum penetration depth, 25% superior hardness, and 73% higher elastic energy ratio. The combination of the reinforcement, morphed graphene, and the technology presented herein are ideal to produced fully dispersed/highly homogeneous composites with up to 5 wt% C. Therefore, morphed graphene additions have unique benefits as chitosan reinforcement material can be used for structural applications such as packaging with environmental advantages over polymers such as Polyethylene Terephthalate. The manufacturing methodology has potential for industrial scalability and presumably the composite is recyclable and compostable.