Lignin Effect on Tensile Properties of Biodegradable Urea-Crosslinked Starch in Aerobic Soil Microcosm

Abstract

Lignin has proved its potential role as biodegradable filler for reinforcement of composite materials derived from renewable resources. Slow release fertilizer (SRF) based on starch was tested with different lignin weight percentages (5, 10, 15, 20 wt%) to analyze its effect on mechanical properties of non-biodegraded (NB) samples before and biodegraded (BD) samples after the incubation in the aerobic soil microcosm. In all NB samples, elongation at break (EB), young’s modulus (YM) and tensile strength (TS) was improved with increasing lignin from 5 to 20 wt%. However, in all BD samples, percent change in EB, YM was increased towards higher values as the lignin percentage increases. It was also observed a significant difference (pair t-test, p < 0.05) between each composition before and after biodegradation. In BD samples with 5-15 wt% lignin, percent change in mechanical properties was non-significant (pair t-test, p > 0.05). It was further noticed that percent change in mechanical properties was low in BD samples with lignin compared to the BD samples without lignin. From the present work, it is concluded that lignin strengthens the lignin-starch matrix in NB samples and it also reduced the impact of mechanical properties loss in BD samples.