Alkali treated coir/pineapple leaf fibres reinforced PLA hybrid composites: Evaluation of mechanical, morphological, thermal and physical properties

The present study deals with the incorporation of different ratios of alkali-treated coir fibres (CF) and pineapple leaf fibres (PALF) in polylactic acid (PLA) hybrid composites. Developed hybrid composites are characterized in terms of mechanical, morphological, thermal and physical properties. Mechanical characterization revealed that alkali-treated C3P7 hybrid composites (CF:PALF = 3:7) showed highest tensile strength (30.29 MPa) and young’s modulus (5.16 GPa) among all hybrids composites, whereas C1P1 (CF:PALF = 1:1) showed highest impact properties. Scanning electron microscopy (SEM) justified the consequence of alkali treatment on fibre-matrix adhesion. Thermal analysis revealed that C1P1 and C7P3 (CF:PALF = 7:3) having a higher thermal stability and char content due to the higher content of lignin in CF. Remarkably, the coefficient of thermal expansion (CTE) of treated hybrid composites displayed lesser values than untreated hybrid composites. The physical tests revealed that C3P7 showed highest water absorption (WA) and thickness swelling (TS) though after treatment the WA and TS values get reduced. Overall results indicated that treated CF/PALF/PLA hybrid composites possess enhanced mechanical, thermal and physical properties with lowered CTE over untreated CF/PALF/PLA hybrid composites. The success of these findings results sustainable and degradable hybrid composites for different outdoor and food packaging-based applications.