Nanocomposite polyhydroxyalkanoate film synthesis for packaging application

Abstract

newline quotIn present scenario, rising environmental concerns of non-biodegradable plastic pollution and depletion of petroleum based raw materials lead to development of biopolymers. Polyhydroxyalkanoates (PHAs) are a type of biopolymers which are synthesized by microorganisms. Although, there are different substrates available in pure forms which are currently used in the production of PHA, but 40 % of production cost depends on the expensive substrate which is a major disadvantage and make it far from many applications. newlineIn the present research work, cane molasses an organic waste from a sugar industry waste stream was taken as substrate and the culture of Alcaligenes sp. NCIM 5085 and co-culture of Alcaligenes sp. NCIM 5085 and Bacillus subtilis were used in batch fermentation for conversion of organics into polymers which is an intracellular compound. Optimization of PHA synthesis conditions was performed in terms of effect of substrate concentration, pretreatment of molasses, static and shaking conditions, C/N ratio, incubation time, initial pH, inoculum volume and nutrient source. Growth kinetics of biomass was modeled by Monod and Logistic models whereas Luedeking-Piret model was used for PHA production rates. Sudan Black B staining was employed to verify the PHA synthesis initially and further TEM analysis was performed to confirm it. The structural analyses of recovered PHAs were carried out by GC-MS, FTIR, 1H NMR and 13C NMR analysis. The absorption peak at 1724.56 cm-1 revealed the presence of C=O (carbonyl) group by FTIR, which is an indicator of PHB. The thermal properties of recovered polymers were analyzed by TGA, DTG and DSC and showed thermal stability of PHB. PHB recovered was utilized to cast films. The mechanical properties of PHB film like Young s modulus, tensile strength, and elongation at the break were analyzed. The PHB film was further analyzed in terms of water vapour transmission rate (WVTR) and oxygen transmission rate (OTR). The degradation observation of synthesized PHB film was