Graft polymerization of methyl methacrylate on poly(ethylene terephthalate) fibers using H2O2 as initiator

The presence of poly(ethylene terephthalate) (PET) fibers during polymerization of methyl methacrylate (MMA) using H₂O₂ as initiator resulted in a substantial, constant increase in the weight of the fibers after repeated extraction with acetone. Fractional precipitation curves of the extracted PET—MMA polymerization product and a physical mixture of PET and PMMA were different, indicating that the interaction of MMA with PET involved grafting. The magnitude of the latter enhanced considerably by increasing H₂O₂ concentration up to 30 mequiv/L, then decreased by further increasing H₂O₂ concentration. There was also an optimal temperature (80°C) for grafting; below or above this temperature, lower grafting was obtained. Similarly, carrying out the polymerization reaction at different pH values revealed that pH7 constituted the optimal. On the other hand, grafting increased upon increase of the methyl methacrylate concentration within the range studied (8–20%). Incorporation of Cu²⁺ or Fe³⁺ ions in the polymerization medium caused a decrement in grafting, irrespective of the metallic ion concentrations. Using methylene chloride as a swelling agent for the fibers failed to enhance the susceptibility of the latter toward grafting. On the contrary, tetrachloroethane was quite promising in this regard. The homopolymer formed during grafting was also reported.