Effect of different plasticisers on the mechanical and barrier properties of extruded cast PHBV films

PHAs are gaining interest as biobased and biodegradable thermoplastics as an alternative for conventional polymers. However applications still struggle with the high brittleness of these polymers. In this study PHBV was plasticised by different types and concentrations of plasticisers in order to improve flexibility and elongation. Thereby an evaluation of the effectiveness of the selected plasticisers, which differ in their molecular weight and functional groups, is enabled. Those are propylene glycol, glycerol, triethyl citrate, castor oil, epoxidised soybean oil and polyethylene glycol. The results of an increasing plasticiser concentration show a decreasing melting temperature, increasing crystallinity, a decreasing Young's Modulus and tensile strength as well as an increasing elongation at break. The water vapour and oxygen permeability is increased by all plasticisers but to a different extent. Overall the effectiveness of triethyl citrate and polyethylene glycol in PHBV showed the most promising results within thermal, mechanical and permeative characterisation. (C) 2015 Elsevier Ltd. All rights reserved.