Synthesis of Poly(methacrylic Acid)-Cellulose Composites Using Different Cellulosic Materials in the Presence of Potassium Permanganate and Activator

Abstract

Polymerisation of methacrylic acid (MAA) in the presence of cellulose pulps prepared from bagasse, rice, straw and cotton stalk was carried out under a variety of conditions. Potassium permanganate (KMnO₄) was used as initiator, along with either citric acid or sodium thiosulphate (Na₂S₂O₃) as activator. The polymerisation products, including grafted cellulose, homopolymer, ungrafted cellulose and oxidised cellulose in a polyblended form, is called “composite”. Major factors affecting the polymerisation reaction were studied. These encompass initiator, activator and monomer concentrations, duration and temperature of polymerisation as well as the nature of the cellulose substrate. Results for the percent polymer yield of the composite and those of the total conversion of monomer to polymer suggest appropriate conditions for the synthesis of poly (MAA)-cellulose composite as: [KMnO₄], 0 08%; [Na₂S₂O₃], 2.5 m.mole L; [MAA], 100% based on weight of sample; material to liquor ratio, 1:30; temperature, 70°C and time, 60 minutes. The effect of the nature of the cellulose on the properties and characteristics of the composite could be realised from the following orders:

(1) for the polymer yield, graft yield and swellability: bagasse > rice straw > cotton stalk;

(2) for carboxyl content: bagasse > cotton stalk > rice straw; (3) for solubility: rice straw > cotton stalk > bagasse.