Abstract
The reaction parameters for the graft co-polymerization of efficient Butyl acrylate (BA) monomer onto Hibiscus sabdariffa (Roselle) stem fiber were optimized and used to further explore the additive effect of methyl acrylate (MA), vinyl acetate (VA) and styrene (Sty) on percentage grafting, properties and the behavior of the fiber, in binary vinyl monomeric mixtures. The graft co-polymers were characterized by XRD, TGA, DTA, SEM and FTIR techniques and evaluated for physico-chemical changes like moisture absorption, swelling behavior, dye uptake studies and chemical resistance against 1N NaOH and 1N HCl. With increase in percentage grafting the percentage crystallinity, crystallinity index, and hydrophylicity were reduced whereas there was an increase in physico-chemico-thermal resistance, hydrophobicity, miscibility with organic solvents as a result of morphological transformation in these fibers. These modified graft copolymers were then used as reinforcement in phenol-formaldehyde polymer matrix as reinforcement and evaluated mechanically for modulus of elasticity, modulus of rupture, stress at the limit of proportionality and hardness. The composites reinforced with grafted fiber had better strength than raw fiber reinforced composites and phenoplast.