Poly(lactic acid)/Polyethylenimine Functionalized Mesoporous Silica Biocomposite Films for Food Packaging

The environmental pollution issues associated with petrochemical-derived plastics have urged the search for a new class of sustainable plastics. The utilization of bioplastics in the packaging field has been increasing due to the exhaustion of fuel resources. Poly(lactic acid) (PLA) is a hastily industrialized candidate among the biobased plastics family. The disadvantages of PLA like poor ductility and poor gas barrier characteristics limit its end use as food packaging material. Therefore, the present study attempts to overcome these limitations by fabrication of PLA/polyethylenimine-modified mesoporous silica (PEI-MS) composites via solution casting method. The influence of PEI content in MS and wt % loadings of optimized PEI content in MS on the structural, thermomechanical, and oxygen permeability properties of PLA is investigated in detail. The reduction in pore volume and surface area after modification of MS with PEI is demonstrated by BET analysis. Thermogravimetric analysis revealed that the presence of PEI-MS aided in significantly improving the thermal stability of PLA biocomposite films. DSC analysis results revealed the faster crystallization process for PLA composites due to the nucleating effect induced by the PEI-MS reinforcement. The SEM micrographs confirmed that the PEI-MS is uniformly dispersed in the PLA matrix. Contact angle analysis revealed the increased hydrophobicity for PLA/PEI-MS composite films upon reinforcement. Mechanical studies demonstrated that the elongation-at-break (%) for PLA/PEI-MS composite films improved due to the plasticizing effect exhibited by PEI-MS. Interestingly, a decrease in oxygen transmission rate is observed for PLA composites in the presence of filler.