Application of microbial levan as a new component for production of graft copolymer with polystyrene

Abstract

Polysaccharides based on fructose, also called fructans, are synthetized from sucrose by some plant species and many bacteria, fungi and Archaea. Levan is an exopolysaccharide composed of fructose units and has numerous applications in personal care and cosmetics, medicine and food industry. Polystyrene is the most widespread polymer for plastic production due to its low costing and easy production. Degradation of polystyrene is longterm process, therefore incorporating natural polymers is the desirable approach. In the present study, levan-polystyrene graft copolymer (L-g-PS) was synthetized, characterized and influence of reaction time on grafting reaction at two temperatures was investigated. Levan was isolated after cultivation Bacillus licheniformis NS032. Syntheses of L-g-PS were performed by the free radical reaction using K2S2O8 as initiator. Grafting reactions proceeded in nitrogen atmosphere, at 55ºC and 70ºC and reaction time ranged between 15 and 210 min. FTIR spectra and XRD patterns were recorded using a Thermo Nicolet 6700 Spectrophotometer and Philips PW-1710 automated diffractometer, respectively. The formation of L-d-g-PS was confirmed by FTIR spectra which displayed the presence of all characteristic peaks for both component and X-ray diffractograms which showed amorphous nature of copolymer. Compared to other reaction parameters, the temperature of 70ºC and time of 45 min was more optimal showing higher percentage of grafting.