Biodegradation of starch–graft–polystyrene and starch–graft–poly(methacrylic acid) copolymers in model river water

Abstract

In this paper the biodegradation study of grafted copolymers of polystyrene (PS) and corn starch and poly(methacrylic acid) and corn starch in model river water is described. These copolymers were obtained in the presence of different amine activators. The synthesized copolymers and products of degradation were characterized by Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). Biodegradation was monitored by mass decrease and number of microorganisms by Koch’s method. Biodegradation of both copolymers advanced with time, poly(methacrylic acid)-graft-starch copolymers completely degraded after 21 day, and polystyrene-graft-starch partially degraded (45.78-93.09 % of total mass) after 27 days. Differences in the degree of biodegradation are consequences of different structure of the samples, and there is a significant negative correlation between the share of polystyrene in copolymer and degree of biodegradation. The grafting degree of PS necessary to prevent biodegradation was 54 %. Based on experimental evidence, mechanisms of both biodegradation processes are proposed, and influence of degree of starch and synthetic component of copolymers on degradation were established. [Projekat Ministarstva nauke Republike Srbije, br. 172001 i br. 172062]

Keywords

• graft copolymers
• model river water
• degradation study
• statistical analysis