Thermal and Chemical Studies of Hibiscus sabdariffa-graft-(Vinyl Monomers)

Abstract

In this paper, the thermal and chemical changes in Hibiscus sabdariffa stem fiber on graft copolymerization with methyl acrylate (MA) and acrylonitrile (AN) monomer, using a ceric ammonium nitrate – nitric acid initiator system, has been reported. Different reaction parameters such as temperature, time, initiator concentration, monomer concentration, and pH were optimized to get the maximum graft yield. The graft copolymer thus formed was characterized by FTIR, SEM, TGA, DTA, and XRD techniques. The swelling behavior of graft copolymers in methanol, n-butanol, water and di methyl formamide was studied and screened for dye uptake behavior in 0.1% gentian violet dye for seven hours. With increase in percentage grafting the percentage crystallinity, crystallinity index, and moisture absorbance were found to decrease whereas chemical resistance (against 1 N HCl and 1 N NaOH) and thermal resistance were found to increase for its various advanced applications.

Keywords:

• monomer
• chemical resistance
• graft copolymerization
• Hibiscus sabdariffa
• thermal resistance

Notes

where CAN = ceric ammonium nitrate, Pg = % grafting, SD = standard deviation, SE = standard error.

where I_15.0, I_22.68 = Peak intensities at 2θ-Scale.

where IDT = initial decomposition temperature, FDT = final decomposition temperature.