Synthesis and properties of carrageenan grafted copolymer with poly(vinyl alcohol)

The aim of this work was to prepare a carrageenan-g-poly(vinyl alcohol) (CG-g-PVA) polymer using potassium persulphate as an initiator. The effect of different ratios of the polymer blends on the parameters of the grafted polymer was investigated. The grafting ratio decreased with an increase of the CG content in the graft copolymer. The resulting CG-g-PVA was characterized by ATR-FTIR, tensile strength, elongation at break, swelling ratio, contact angle and biodegradation in soil. From the ATR-FTIR the 3,6-anhydride-galactose of the CG showed a peak at 927 cm−1 that was absent in the CG-g-PVA and the ether linkage of PVA-g-CG between the hydroxyl group of PVA and the 3,6-anhydride-galactose of CG showed a peak at 1089 cm−1 in the graft copolymer. The tensile strength and elongation at break decreased with an increase of the CG due to its phase separation. The highest tensile strength was observed at 2:8 CG/PVA. In addition, the swelling ratio decreased and the contact angle increased as a function of the increase of the CG in the grafted copolymer. The best ratio of CG-g-PVA was 2:8 CG/PVA. This graft copolymer was easily biodegraded in natural soil.