Anaerobic biodegradation of urea cross-linked starch: Effect of lignin on tensile properties

Abstract

Lignin was used as a natural filler to improve the recalcitrance of environmentally friendly biocomposites made from starch. The tensile properties of lignin-starch biocomposites prepared by lignin reinforcing of urea cross-linked starch (UcS) were investigated in this study. The amount of lignin loaded into UcS was from 5 to 20%. These various compositions were buried in a microcosm of anaerobic soil. After 7 days of burial, biodegraded biocomposites were tested for changes in tensile characteristics. Changes in biodegradation were measured by comparing them to pristine samples, which were utilised as a benchmark for estimating. Through reinforcing polymeric starch in UcS, lignin was discovered to slow down the rate of loss in tensile characteristics of composites. With increasing lignin loadings from 5 to 20%, biodegraded biocomposites showed a constant reduction in elongation at break, Young’s modulus, and tensile strength. As a result, the biodegraded biocomposites’ metrics exhibited a substantially slower decrease than the control biodegraded film. The reduction in tensile properties of biodegraded biocomposites was explained by a significant difference (p < 0.05) using a paired t-test. This study found that lignin increased the strength of UcS and reduced the loss of tensile characteristics, probably as a result of soil microorganisms’ biodegradation activity being inhibited.