Cotton stalk-enhanced LDPE composites: a sustainable approach to improved food preservation and packaging

Abstract

In this study, cotton stalk (CS) was incorporated into low-density polyethylene (LDPE) to fabricate biodegradable composites for food packaging applications. LDPE-CS composites with varying CS contents (5–30%) were prepared via melt blending and compression molding. Mechanical testing demonstrated that the addition of 15% CS enhanced the tensile strength by approximately 5.1% compared to neat LDPE, attributed to the uniform dispersion of CS fibers and the formation of an effective reinforcing network. X-ray diffraction analysis revealed that CS incorporation disrupted the crystallinity of LDPE, with the most stable crystalline structure observed at 15% CS content. Differential scanning calorimetry confirmed that moderate CS loading only slightly reduced the crystallinity, while thermogravimetric analysis showed that excessive CS addition lowered thermal stability, with 15% CS exhibiting better stability than 5% CS Due to improved dispersion. Contact angle measurements indicated that moderate CS addition could improve surface compactness, whereas excessive CS loading led to increased hydrophilicity and structural defects. Water absorption and moisture content tests showed that higher CS contents compromised the moisture resistance of the composites. Water vapor permeability and oxygen permeability tests demonstrated that a 10% CS loading yielded the best overall barrier performance, attributed to the tortuous diffusion path created by well-dispersed fibers, whereas higher CS contents reduced barrier efficiency. Vegetable preservation tests confirmed that LDPE-CS (15%) films exhibited superior preservation performance, achieving the lowest weight loss compared to neat LDPE and the control group after four days of storage. Overall, this study provides valuable insights into the development of sustainable LDPE composites reinforced with cotton stalks, balancing mechanical strength, moisture/gas barrier performance, thermal stability, and practical applicability for eco-friendly food packaging solutions.