On the Correlation of Lignocellulosic Filler Composition with the Performance Properties of Poly(ε-Caprolactone) Based Biocomposites

In this work, three types of agricultural waste: olive stones (OS), date seed (DS) and wheat bran (WB) were applied as potential lignocellulosic fillers in poly(ε-caprolactone) (PCL) based biocomposites. Differences in composites’ performance were related to the higher content of proteins, noted for WB comparing to other fillers applied, which enhanced plasticization of PCL matrix. The mechanical properties of biocomposites were significantly affected by the agricultural waste fillers. Use of WB caused an obvious, even 25% decrease of tensile strength and hardness, which could be explained on account of glass transition temperature depletion and weaker matrix–filler interfacial interactions. Such phenomenon also increased water uptake of PCL/WB composites by more than 100%, while for PCL/OS and PCL/DS systems only for about 50%. Thermogravimetric analysis revealed that all investigated composites can be effectively processed without thermal decomposition. Generally, the outcome of this work demonstrated that OS, DS, and WB could be applied as promising lignocellulosic fillers used in manufacturing of high-performance polymer biocomposites.