Effect of kappa-carrageenan on the properties of poly(vinyl alcohol) hydrogel prepared by application of gamma radiation

Abstract

Synthesis of hydrogels from aqueous solution of poly(vinyl alcohol) (PVA) and kappa-carrageenan (KC) has been performed with radiation processing technology using Co-60 gamma source. As investigation on the influence of radiation dose and concentration of KC on gel content, swelling properties, and thermal behaviors of hydrogel has been performed. Gel content obtains a maximum value at 25 kGy radiation dose. Equilibrium water content of hydrogel decreases with increased radiation dose but it increases with increased concentration of KC. The water absorption of hydrogel is fast up to 5 hours and it becomes a maximum value at 24 hours. It increases with increased concentration of KC in the feed solution. The water absorption of hydrogel increases from 210 to 410% for the increment of KC content from 0 to 2.0% at the radiation dose 25 kGy. Thermo-gravimetric analysis (TGA) and dynamic mechanical analysis (DMA) showed that thermal degradation reduces with increased concentration of KC in PVA hydrogel. Scanning electron microscopy (SEM) was used to investigate the surface morphology of PVA/KC blend hydrogel. The hydrogel was applied to absorb dye (methyl violet) from aqueous solution. Langmuir and Freundlich models were applied to study the dye adsorption pattern.