Starch-graft-poly((2-Dodecen-1-yl)succinic anhydride): studies of microwave-assisted synthesis, characterizations, and its potential as bioplastic materials Natalia Devita Purnama and Rachmawati Rachmawati
Inorganic and Physical Chemistry Division, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jalan Ganesha 10, Bandung 40132, West Java, Indonesia
Abstract
Starch is a natural polymer which can be applied as a potential bioplastic material. However, due to its low plasticity and mechanical properties, starch needs to be modified chemically, such as involving a graft copolymerization method. In this research, microwave-assisted synthesis of graft copolymer of starch was conducted via free radical polymerization. For this reaction, (2-Dodecen-1-yl)succinic anhydride (DDSA) was used as a monomer and cerium(IV) ammonium nitrate (CAN) as an initiator. Several factor were varied, such as the ratio of DDSA and CAN, polymerization time, and microwave power, to study their effects on the values of grafting percentage (%G) and grating efficiency (%E). The resulting starch-g-poly(DDSA) was characterized using Fourier-Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and Thermogravimetric analysis (TGA). The optimum grafting condition resulted in a graft copolymer with %G of 42% and %E of 86%. This was obtained for a theoretical degree of polymerization of 5, starch and CAN mass ratio of 3:1, 200 W power, and 25 minutes polymerization time. The FTIR spectra of the copolymer products showed characteristic peaks at 2847-2914 cm-1 and 1313-1421 cm-1 which corresponded to C-H methyl and methylene groups, and 1686 cm-1 from the C=O groups from DDSA. XRD diffractograms showed that there were broad peaks at 2 theta of 19.8 and 27.9 degrees, while TGA thermograms showed that the higher the %G, the lower the onset temperature of the thermal degradation. The copolymer products were further mixed with poly(vinyl alcohol), and casted as films using glycerol as a plasticizer. The highest elongation and tensile strength obtained for starch-g-poly(DDSA)/PVA film was 216.5% and 3.91 MPa respectively, which used starch-g-poly(DDSA) with %G of 42%.
