Properties of different chitosan/low-density polyethylene antibacterial plastics

HDPE/Chitosan Composites Modified with PE-g-MA. Thermal, Morphological and Antibacterial Analysis

In this work, composites of high density polyethylene (HDPE) with chitosan were prepared by melt compounding in a laboratory internal mixer. Maleic anhydride grafted HDPE (PE-g-MA) in a concentration up to 25 phr was used as a compatibilizer to enhance the dispersing effect of chitosan in the HDPE matrix. The degree of crystallinity was investigated by X-ray diffraction (XRD) and the thermal properties were analyzed by differential scanning calorimetry (DSC) and thermogravimetry (TG). The morphology was investigated by optical microscopy (OM) and scanning electron microscopy (SEM). The integrity of composites was evaluated by mechanical properties and antibacterial properties were assessed against Escherichia coli (DH5a). Neither crystallinity nor HDPE's melting parameters changed upon addition of chitosan and PE-g-MA. Chitosan aggregates were observed, which were dispersed upon addition of PE-g-MA, which also provided improved mechanical performance. Chitosan significantly improved the bacteriostatic effect of HDPE compounds preventing bacteria to colonize thus reducing the number of viable colony-forming units (CFU). This study revealed that HDPE/chitosan composites could be obtained by melt compounding, at lower cost and additionally having antibacterial properties, which might provide a new formulation option for developing antimicrobial film for food packaging.

HDPE/Chitosan Blends Modified with Organobentonite Synthesized with Quaternary Ammonium Salt Impregnated Chitosan

In this study, blends based on a high density polyethylene (HDPE) and chitosan (CS) were successfully prepared by melt processing, in a laboratory internal mixer. The CS biopolymer content effect (up to maximum of 40%), and, the addition of bentonite clay modified with quaternary ammonium salt (CTAB) impregnated chitosan as a compatibilizing agent, on the properties of the blends was analyzed by Fourier transform-infrared spectroscopy (FT-IR), wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermogravimetric analyses (TG), tensile strength, and scanning electron microscopy (SEM). The use of clay modified with CTAB impregnated chitosan, employing a method developed here, improved the compatibility of HDPE with chitosan, and therefore the thermal and some of the mechanical properties were enhanced, making HDPE/chitosan blends suitable candidates for food packaging. It was possible to obtain products of synthetic polymer, HDPE, with natural polymer, chitosan, using a method very used industrially, with acceptable and more friendly properties to the environment, when compared to conventional synthetic polymers. In addition, due to the possibility of impregnated chitosan with quaternary ammonium salt exhibit higher antibacterial activity than neat chitosan, the HDPE/chitosan/organobentonite blends may be potentially applied in food containers to favor the preservation of food for a longer time in comparison to conventional materials.