Characterization of Mango Seed Starch grafted with methacrylic acid and the determination of some physical properties of its plastic films

Abstract

This study is focused on the graft copolymerisation of mango seed starch with methacrylic acid and its characterisation. The starch was isolated from mango seed embryo and characterised in terms of its pH, moisture and ash contents, and gelatinisation temperature. Varying concentrations (i.e. 0.4; 0.6; 0.8 and 1.0 mol/dm3) of methacrylic acid was grafted onto the isolated starch using ceric ammonium nitrate (CAN) and N, N’ methylenebisacrylamide and the resulting grafted products were characterized to determine grafting parameters such as graft yield and graft efficiency. Evidence of grafting was confirmed by Fourier Transform Infra-Red (FTIR) spectroscopy. Film samples were produced by casting the ungrafted and grafted starch products on a glass slide and the corresponding hardness, solubilty of the cast films were measured. The isolated starch has a pH of 5.06; moisture and ash contents of 6.5 % and 0.12 % respectively, and a gelatinization temperature range of 70 – 80 ˚ C. The graft yield of the grafted products increased slightly with increasing monomer concentration while the graft efficiency decreased with increasing monomer concentration. The FTIR spectra of the grafted and ungrafted mango seed starch film confirmed that grafting took place. The hardness of the produced films was found to decrease from 76.33 shore A value for the ungrafted starch to 46.33 shore A value at monomer concentration of 1.0 mol/dm3. Starch based grafted products may serve as alternative material for production of single-use plastic articles for packaging and have been recommended for industrial applications such as in agricultural mulching, oilfield applications, etc.