Graphene-based nano-functional materials for surface modification of wheat straw to enhance the performance of bio-based polylactic acid composites

To enhance wheat straw compatibility with the polylactic acid (PLA) matrix, several graphene-based materials (GBMs) derivatives, including graphene nanoplatelets, graphene oxide, and nano graphite particles with a constant fraction of 0.1 wt.-%, were employed for the surface functionalisation of wheat straw. Wheat straw surface quality was assessed by comparing PLA bio-based composites' mechanical and thermal performance with and without GBM surface functionalisation. All the resulting composites with surface functionalised straw particles exhibited higher thermal stability, flexural strength, tensile strength, and tensile toughness than those with pristine straw. This could be associated with the improved straw/PLA matrix interfacial bonding induced by the existence of GBMs on the surface of straw particles which was confirmed through morphology assessments. The mechanical properties investigations revealed maximum enhancements of 27%, 66%, and 322% for flexural strength, tensile strength, and tensile toughness, respectively, for bio-based composites consisting of graphene oxide-functionalised straw particles compared to control samples.