Completely biodegradable composites reinforced by the cellulose nanofibers of pineapple leaves modified by eco-friendly methods

Abstract

In this study, cellulose nanofibers (CNF) derived from waste pineapple leaves (PALF) were incorporated into poly (lactic acid) (PLA) with the aim of developing completely biodegradable and sustainable composites. CNF was first prepared by the 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) method, and then, different surface modifications of the eco-friendly method were carried out for better dispersion in the PLA matrix. Then, a series of eco-friendly modified CNF/PLA composites were prepared by melt-blending. According to the contact angle experiment, the values of eco-friendly modified CNFs increased from 12.02° to 61.49 and 57.45°, respectively. DSC thermograms show that eco-friendly modified CNFs have a significant nucleating effect for the crystallization of PLA compared to the original CNF. Mechanical testing reveals that the tensile and impact strengths of eco-friendly modified CNF containing composites are improved by 5.4~22.7% and 17.5~56.1%, respectively, through the addition of only 1~3 wt% of modified CNF, and are all higher than that of the original CNF containing composite. Moreover, eco-friendly modified CNF containing composites can allow good light transmittance due to better dispersity of the modified CNF. Consequently, the addition of modified CNFs to the PLA matrix results in increased mechanical and thermal properties of the composites, as well as transparency. Moreover, the addition of CNFs extracted from pineapple leaves by eco-friendly methods can not only reduce the amount of agriculture waste but also avoid the usage of an organic solvent and meet the requirements of environmental protection.