Uncatalysed photografting of poly(methyl methacrylate) from photofunctionalised sisal fibre

Graft copolymerisation of PMMA on sisal fibre has been the subject of prime investigation in this report. Sisal fibre was carboxy functionalised on photoexposure with an aqueous solution of oxalic acid in a method previously reported. Varying the concentration of oxalic acid during the functionalisation resulted in variation of the level of incorporated acid groups in the fibres. The functionalisation hence performed rendered the substrates photoactive and in the resulting fibres (after removal of the adhered acid by proper washing and drying), when photoexposed with aqueous dispersion of MMA for the required time in N2 atmosphere, graft copolymerisation took place without further addition of any initiator from outside. The degree of grafting was found to depend on the monomer concentration as well as on the acid content of the functionalised fibres. The resulting graft copolymers, after proper removal of homopolymer, were characterised with respect to their structural and textile related properties. FTIR study revealed the presence of the ester moiety on the fibre backbone and SEM pictures also showed the deposition of grafted-on polymer on the surface of the fibres. Some important modifications in the thermal properties of sisal fibre after PMMA grafting were revealed by the DSC thermograms. Mechanical strength as well as the stiffness of the resulting fibres increased on grafting as reflected in the tensile values, while the moisture regain property was hampered to some extent.