Feasibility of the use of different types of enzymatically treated cellulosic fibres for polylactic acid (PLA) recycling.

In the present study, the potential use of cellulosic microfibers (CMFs) extracted from hemp fiber (HF) and pulp and paper solid waste (mixed sludge (MS), deinked sludge (DS)) as a reinforcing agent in novel bio composite materials produced from recycled Polylactic acid (rPLA) was investigated. CMFs were extracted and treated using physicochemical method followed by enzymatic treatment with laccase and cellulase. The effects of CMFs concentrations (1.5, 3 and 6% w/w) and fiber size (75 μm-1.7 mm) on the mechanical properties (impact and tensile) and biodegradability of the biocomposite samples were investigated. A modified interfacial adhesion between rPLA matrix and the three fibers used, was clearly observed through mechanical tests due to alkali and enzymatic treatments. The use of different types of enzymatically treated cellulosic fibers for polylactic acid (PLA) recycling was assessed by Scaning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The combined physicochemical and enzymatic treatments led to a considerable size reduction of the cellulosic fibers (HF, MS and DS) resulting in the enhanced interfacial adhesion between rPLA matrix and fibers. The biocomposite obtained with rPLA with HF gave the most favorable values for Young's modulus (324.53 ± 3.10 MPa, p-value 0.03), impact strength (27.61 ± 2.94 kJ/m2, p-value 0.01) and biodegradation rate (1.97%).