Bio-based D-limonene/chitosan surface coating for enhanced performance and degradability properties of natural rubber films

Natural rubber is a good physical barrier against bacteria penetration. However, it could not refrain the bacteria to adhere and proliferate on its surface. This poses the risk of cross-contamination through contact, especially in medical and food handling processes. Prolonged degradation for disposal rubber shall be impacted on the landfill capacity as vulcanized natural rubber products are resistance towards biodegradation. Developing an environmentally benign rubber with controlled degradation while imparting antimicrobial protection is therefore essential for specific rubber products’ application. In this study, a bio-based coating system composed of D -limonene and chitosan was formulated to enhance antibacterial performance of natural rubber films. The coating solution was prepared by emulsifying D -limonene with Tween 80 and incorporating chitosan. Systematic evaluation across different D -limonene loadings showed that ratio 4:6 D -limonene-chitosan coating solution produced the most consistent enhancement. The coated films exhibited a marked increase in elongation and tensile strength, reaching improvements of approximately 67.08% and 71.27%, respectively, compared to uncoated NR films. Thermal stability significantly improved, with the onset temperature rising from 293.4 °C to 302.4 °C when coating is applied. The coatings also displayed notable antibacterial activity, particularly against Bacillus subtilis, and accelerated soil degradation, showing a 56.06% reduction in final mass. These findings demonstrate that the D -limonene-chitosan system provides an effective green-coating approach for strengthening NR films while enhancing the green product’s antimicrobial and environmental performance.