A STUDY ON GRAFT COPOLYMERIZATION OF ACRYLIC ACID ONTO COCONUT FIBRE INITIATED BY (NH4)2S2O8

Abstract

Coconut fibre was taken from Tam Quan - Hoainhơn – Binhdinh. The sample of the coconut fibre with the size of the particles ≤ 0,05mm and humidity at 8,73% was used as an graft material. Graft copolymerization of acrylic acid (AA) onto coconut fibre initiated by (NH₄)₂S₂O₈ in aqueous solution and in the nitrogen atmosphere has been studied. The reaction was stopped by the addition of hydroquinone. The remaining monomer was determined by ICl 0,1N titration. The mixtures were filtrated and washed to remove the remaining monomer and residual additive. To remove homopolymer, the graft product was extracted with etanol in a soxhlet apparatus for 24 hours and dried at 60⁰C until it reached the constant weight. The optimal conditions for graft copolymerization were: time = 180 minutes; temperature = 70⁰C; volume H₂O = 50ml; [(NH₄)₂S₂O₈] = 0,08M; pH = 3; rate acrylic acid /coco fibre = 2,5ml/1,0g. The necessary parameters attained  are :  the percentage of graft yield (%GY) = 24,46%; graft efficiency (%GE) = 10,56% and the percentage of total convercion (%TC) = 92,64%. The chemical and physical characteristics of the coconut fibre and graft copolymer were shown in the IR spectrum, SEM image and differential thermal analysis DTA/TG.