EMULSION POLYMERIZATION OF BUTYL ACRYLATE .4. EFFECT OF INITIATOR TYPE AND CONCENTRATION

The free radical emulsion polymerizations of butyl acrylate initiated by a water-soluble (ammonium peroxodisulfate, AP) and an oil-soluble (2,2'-azobisisobutyronitrile, AIBN) initiator in the presence of an anionic emulsifier at 60-degrees-C were kinetically investigated. Polymerization with AP is faster than that with AIBN. The effect of the initiator type, blend and concentration on the kinetic and colloidal parameters was investigated. The rate of polymerization was found to be proportional to 0.46th or 0.5th power of AP or AIBN concentration at [initiator] less-than-or-equal-to 1 x 10(-4) mol dm-3 and 0.33rd or 0.16th power of AP or AIBN concentration at [initiator] greater-than-or-equal-to 5 x 10(-3) mol dm-3. The polymerization proceeded quantitatively with AP whereas with AIBN reached limiting conversion. The rate of polymerization with an initiator blend (AP and AIBN) was smaller than the sum of appropriate individual rates. AIBN saturated monomer/polymer particle acts as a radical trapper.