Agricultural Wastes as a Base for Synthesis of Vinyl Polymer-Cellulose Composites

Abstract

Cellulose pulps prepared from bagasse, rice straw, cotton stalk and wood sawdust were polymerized in the presence of acrylic acid(AA) and acrylonitrile(AN) with binary mixtures. Potassium persulphate was used as the initiating system. The treatment was carried out under different conditions including concentration of AA and AN, composition of AA/AN binary mixture, potassium persulphate concentration, material to liquor ratio, time and temperature of polymerization. Based on the results obtained, appropriate conditions for the preparation of vinyl polymer-cellulose composites were established. The maximum total conversion occurred at 0.5% K2S2O8 along with 5% AA and 5% AN at 70°C for 60 minutes using a material-to-liquor ratio of 1:20. The treated samples were monitored for polymer yield, carboxyl and nitrogen contents as well as swellability and solubility. Results indicated that the total conversion (grafting and homopolymerization) increased by increasing K2S2O8 concentration irrespective of the land of cellulose pulp used. Nevertheless the percent polymer yield and percent graft yield follow the order: > Bagasse > rice straw > cotton stalk ≥ wood sawdust. The nitrogen content is higher the higher the concentration of AN in the AA/AN binary mixtures regardless of the kind of agricultural waste. Carboxyl content is higher, the higher the concentration of AA in the AA/AN binary mixture. The swellability of the composite is governed by the composition of the AA/AN binary mixture and it is higher, the higher the concentration of AN in the AA/AN binary mixture irrespective of the kind of cellulose source, but with the certainty that swellability of the composites follows the order: Bagasse > rice straw > cotton stalk > wood sawdust. The solubility of the composite is also governed by the composition of AA/AN binary mixture and it is higher the higher the concentration of the AA in the mixture and follow the order: Rice straw ≥ wood sawdust > cotton stalk ≥ bagasse