Fe2+‐thioureadioxide‐H2O2 induced polymerization of various vinyl monomers with flax fibres

Fe2+‐thioureadioxide‐H2O2‐redox system induced polymerization of various vinyl monomers with flax, alkali‐treated flax, and partially carboxymethylated flax was investigated. Monomers used included glycidyl methacrylate (GMA), methyl methacrylate (MMA), 2‐hydroxy ethylmethacrylate (2‐HEMA), and acrylonitrile (AN). The polymerization reaction was carried out under a wide range of conditions including temperature (50–90°C), H2O2 concentration (0.01–1%), monomer concentration (20–200%, based on sample weight), and time (5–120 min). Results obtained led to the following conclusions: Raising the polymerization temperature from 50 to 60°C increases the percent polymer add‐on while the latter decreases by further increase in temperature, irrespective of the substrate and monomer used. The percent polymer add‐on increases by increasing monomer concentration from 20 to 200% and by increasing H2O2 concentration up to 0.1%, then decreases upon using higher H2O2 concentrations due to faster rate of termination. For a given polymerization condition, the percent polymer add‐on follows the order partially carboxymethylated flax > alkali treated flax > flax. Monomer reactivity follows the order: GMA > 2‐HEMA > MMA > AN. Poly(GMA)‐containing flax retains its free epoxy rings practically intact, provided that the add‐on is low (ca. 10%). Involvement of these functional groups in reactions with the functional groups of flax occurs at higher percent add‐on (ca. 50–100%).