Starch-g-poly(benzyl methacrylate) copolymers

Marta Worzakowska

doi:10.1007/s10973-016-5328-7

Abstract

The physicochemical properties such as swelling in polar and non-polar solvents, moisture resistance, chemical resistance, ability for gelatinization and the thermal properties along with the evolution of volatile decomposition products of some starch-g-copolymers obtained through the grafting of benzyl methacrylate monomer onto potato starch have been studied. The chemical structure of copolymers was confirmed using ATR–FTIR analysis. The prepared materials were characterized by completely different properties than unmodified potato starch due to the covalent bonding of poly(benzyl methacrylate) chains onto starch backbone. The copolymers were not able to gelate; however, they exhibited higher swelling in non-polar solvents, lower swelling in polar solvents and higher resistance toward moisture, acid and base conditions than unmodified potato starch. In addition, DSC analysis showed that T g of copolymers was shifted to a little higher values as compared to T g of poly(benzyl methacrylate). The thermal stabilities of copolymers and potato starch were comparable. Their decomposition took place in two main stages connected with the emission of various volatile decomposition products (CO2, CO, H2O, CH4, aldehydes, alcohols, furan derivatives, acids, benzyl methacrylate) in inert atmosphere as it was confirmed based on the simultaneous TG/DSC/FTIR analysis.

Highlights

The modification of biopolymers is one of the most active fields of research which allows preparing novel, cheap and more environmentally friendly materials based on renewable resources
The present paper focuses on the physicochemical and thermal properties of some starch-g-copolymers obtained under grafting process of benzyl methacrylate monomer onto potato starch backbone
The starch-g-poly(benzyl methacrylate) copolymers were obtained under free-radical copolymerization of different potato starch-to-benzyl methacrylate ratio, Table 1

Summary

Introduction

The modification of biopolymers is one of the most active fields of research which allows preparing novel, cheap and more environmentally friendly materials based on renewable resources. The present paper focuses on the physicochemical and thermal properties of some starch-g-copolymers obtained under grafting process of benzyl methacrylate monomer onto potato starch backbone. The grafting process was carried out in optimum temperature and time conditions (80 °C, 2 h) and different starch-to-monomer ratio in the presence of potassium persulfate as a radical initiator. The effect of grafting percent on the swelling properties, moisture and chemical resistance, gelatinization properties, glass transition temperature, thermal stability, thermal decomposition pathways and the type of volatile decomposition products emitted under heating of copolymers in inert conditions has been evaluated. The purified copolymers were washed with methanol and dried to a constant mass at 60 °C [28] The grafting parameters such as the grafting efficiency (GE/%) and the grafting percent (G/%) were evaluated using the following equations according [29, 30]: GE/% 1⁄4. The gas FTIR spectra were recorded from 600 to 4000 cm-1

Results and discussion

* Results for potato starch

Conclusions