Functional properties of biorefined lignin microfillers for enhancing biodegradable materials

Abstract The growing demand for sustainable bioproducts in industrial applications highlights the need to utilize agricultural biomass for sustainability. This study developed green biocomposites by incorporating lignin particles (LPs), extracted from the black liquor of palm shell waste, into a poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) matrix reinforced with nonwoven kenaf bast fiber mats. The reinforced biocompatible PHBV polymer was further strengthened by adding LPs at concentrations of 0, 1, 3, 5, and 7 wt%. The biocomposites were fabricated using hot compression molding and were evaluated systematically for water‐barrier, mechanical, morphological, functional, and thermal properties. A single‐factor analysis of variance (ANOVA) was used for statistical analysis. The results demonstrated a 28% increase in tensile strength and a 15% increase in flexural strength at 5 wt% LP loading. Water absorption was reduced by 23% at the highest filler concentration, indicating enhanced water‐barrier properties. Improved interfacial bonding between LPs and the PHBV/kenaf fiber matrix was confirmed through morphological analysis, and Fourier transform infrared (FTIR) spectroscopy revealed the presence of strong interactions between the components. However, thermal stability decreased slightly with LP incorporation, and mechanical performance declined at 7 wt% due to particle agglomeration. Overall, optimal performance was achieved at 5 wt% LP loading, highlighting the potential of PHBV/kenaf/LP biocomposites as sustainable materials for environmentally friendly applications, particularly in packaging, addressing critical environmental and human health concerns.