Sorption and thermal polymerization of vinyl monomers in low density polyethylene-iron (III) oxide composite

Abstract

The nature of the species produced after sorption and thermal polymerization of acrylic acid, methyl methacrylate and 4-vinylpyridine in low density polyethylene-iron (III) oxide composite was investigated by Mossbauer and IR spectroscopies. The values of the Mossbauer parameters indicate no change in the oxidation state of iron (III) in the LDPE-Fe2O3 composite before and after sorption and thermal polymerization of the monomers. Acrylic acid interacts with iron (III) oxide particles yielding acrylates, hydroacrylates, polyacrylates and polyhydroacrylates. The iron (III) oxide particles remained unchanged after sorption and thermal polymerization of methyl methacrylate although some thermal polymerization is observed in the presence of Fe2O3-doped LDPE. Iron (III) oxide acts as catalyst for the radical polymerization of methyl methacrylate on LDPE-Fe2O3. The interaction of iron (III) oxide and 4-vinylpyridine after its sorption and thermal polymerization in LDPE-Fe2O3 is mainly by coordination bonding of the pyridine ring of the polymer to the iron of Fe2O3.