High-performance polylactic acid compressed strawboard using pre-treated and functionalised wheat straw

An eco-friendly pre-treatment coupled with surface functionalisation were developed to enhance the quality of wheat straw particles to be used for development of high-performance polylactic acid (PLA) compressed strawboard. Eco-friendly hybrid pre-treatment (i.e., hot water followed by steam, H+S) and surface functionalisation processes employing attapulgite nanoclay (AT) and graphene nanoplatelets (G) were used to obtain an appropriate wheat straw surface quality while increasing its compatibility with the PLA matrix. The successful pre-treatment and surface functionalisation of wheat straw particles was verified through characterisation techniques, including SEM, FTIR, XRD, Raman spectroscopy, and TGA. Tensile strength and water absorption properties of compressed strawboards were examined to investigate the influence of pre-treatment and surface functionalisation of wheat straws. The maximum tensile strengths of 28 MPa and 27 MPa were recorded for 10 H+S-AT and 10 H+S-G samples, respectively, which are considerably higher than the value (i.e., 9.7 MPa) registered for the sample without pre-treatment and surface functionalisation (i.e., 10UN). The lowest water absorption after 24 h of immersion was registered for 10UN-G (i.e., 1.6%), which is 11% and 31% lower than the 10UN and 10 H+S samples, respectively. The effect is attributed to an improved interfacial bond between wheat straw and PLA matrix due to the graphene surface functionalisation, as evidenced by the SEM.