An Investigation on the Effect of Miscibility on the Microstructure and Mechanical Properties of Polyethylene/Chitosan Composite Films
TAN YI MIN (1)*, LIM SZU HUI CYNTHIA (2), TAY BEE YEN (2), LEE MUN WAI (3), THIAN ENG SAN (1)
(1) DEPARTMENT OF MECHANICAL ENGINEERING, NATIONAL UNIVERSITY OF SINGAPORE - SINGAPORE - Singapore, (2) FORMING TECHNOLOGY GROUP, SINGAPORE INSTITUTE OF MANUFACTURING TECHNOLOGY - SINGAPORE - Singapore, (3) FOOD INNOVATION AND RESOURCE CENTRE, SINGAPORE POLYTECHNIC - SINGAPORE - Singapore
Polyethylene (PE) is commonly used for packaging as it is low in cost, has good processability and versatility in fabrication. However, extensive use and disposal of PE has caused environmental pollution as synthetic polymers are resistant to degradation. Rising environmental awareness has led to studies on the incorporation of natural materials as a degradable component into PE, to impart biodegradable properties for the reduction of environmental footprint at the end of life. To obtain good mechanical properties, interfacial compatibility and miscibility between the hydrophobic synthetic and hydrophilic natural polymers are critical. In this study, PE/chitosan composite films were fabricated via a compression molding process. Despite studies conducted with the incorporation of compatibilisers for better interface adhesion, mixing studies involving PE/chitosan have not been investigated. Therefore, the objective of this study was to determine an optimum mixing condition through variation in compounding length as a function of L/D ratio (15:1, 30:1, 45:1, 60:1 and 75:1) for enhanced miscibility of PE/chitosan composites to achieve improvement in mechanical properties. Experimental results indicated that an increase in compounding length increased tensile strength by ~ 20 % whereas elongation at break increased by two-fold. Composite films that were fabricated from blends compounded with a L/D ratio of 60:1 had the highest tensile strength and elongation at break values, and the tensile strength was comparable to that of PE films. The morphology of the composite film revealed an improvement in dispersion and interfacial interaction within the blend, which supported the improvement in mechanical properties. Furthermore, crystallinity of the composite films increased with increasing compounding length. Thus, PE/chitosan composite films with satisfactory mechanical and structural properties have the potential to be used as environmentally-friendly packaging material.
Keywords: low density polyethylene, chitosan, composite, packaging, film