Development of biopolymer nanocomposites for gas barrier aplications

In recent years, the plastics industry has started to look for alternative raw material sources to solve the environmental the problems created by petroleum-based products, and natural, renewable solutions have attracted attention at this point. This trend has contributed greatly to the reduction of environmental pollution as well as to the reduction of dependence on fossil fuels. Many research groups are trying to improve the properties of bioplastic because of the great benefits of recyclable eco-friendly materials and a wide range of applications. As bio-polymers are obtained from renewable sources, they have many advantages over petroleum-based polymers used in packaging, agriculture, medical applications. Biopolymer nanocomposites, a new class of nano-structured materials consisting of bio-polymers and nano-filling materials, have emerged to improve the industrial use of these polymers. The primary application targets of the produced bio-nanocomposites are to incorporate the petrochemical polymers used for packaging and coating applications. In this study, polyhydroxybutyrate-co-valerate (PHBV) based nanobiocomposites (PHBV/BN) were prepared with the incorporation of the various percentage of hexagonal boron nitride (h-BN) by using melt blending method. Three boron nitride particles of different shapes,sizes and surface area were used to improve the gas barrier properties of PHBV. It is the objective of this study to identify and characterize the effects of the exfoliated boron nitride nanoplatelets on gas barrier properties of PHBV/BN nanocomposites. Several methods were performed to exfoliate h-BN prior to composite production, and the powders were characterized by SEM, NanoS and particle size analysis. It was found that the most appropriate method for producing 2D boron nitride nanosheets was liquid phase exfoliation by using isoproponal-water mixture. The silane coupling agent was used to improve the bonding of PHBV with BN. The prepared bio-nanocomposites were characterized by XRD, FTIR, SEM. The gas permeability and mechanical properties of the prepared composites were measured. The results demonstrate that barrier properties of the composites were found to increase more for the silanized exfoliated flake type BN (PHPP325B) compared to silanized hexagonal disk type BN (Bortek). The best barrier properties are obtained for the nanocomposite sample containing 0.5% wt, PHPP325B, for which a reduction of oxygen permeability up to 28.3% was observed in comparison to the neat PHBV. Key words: Bio-polymer, polyhydroxyalkanoate (PHA), PHBV, h-BN (hexagonal boron nitride), gas barrier properties.