Injection-moulded biocomposites from polylactic acid (PLA) and recycled carbon fibre: Evaluation of mechanical and thermal properties

The properties of injection-moulded polylactic acid (PLA) and recycled carbon fibre composites are examined in this study. Measurement of tensile, flexural, and impact resistance properties quantify the mechanical properties of the composites with increased fibre loading. Tensile strength and modulus of PLA and 30 wt% carbon fibre composite were found to increase by 73% and 438%, while flexural strength and modulus of carbon fibre composite increased by 53% and 400% compared to neat PLA. Consequently, storage modulus measured by dynamic mechanical analysis also improved with the addition of carbon fibre. Mechanical properties were correlated with the Hirsch model. Composite morphological study through scanning electron microscopy (SEM) showed pullout and partial wetting of fibre by matrix along with agglomeration. Differential scanning calorimetry study of the composites showed minor increase in relative crystallinity and crystallization temperature, while melting and cold crystallization temperatures were found to decrease due to the high-thermal conductivity of carbon fibre.