Synthesis and Characterization of Epoxidized Acrylated Natural Rubber Cross-linked by Star-shaped Polystyrene

Polyacrylamide (PAM) and its copolymers are of important polymeric materials inpetroleum industry, for example in drilling fluids and enhanced oil recovery. Highmolecular weights of these polymers are needed to have optimum efficiency inthe above given applications. High molecular weight polyacrylamide nanoparticleswere prepared by inverse-emulsion polymerization of aqueous acrylamide solution inxylene as a continuous phase under various conditions in the presence of a mixture ofnon-ionic emulsifiers (Tween 85 and Span 80). Monomer conversion, particle size andits distribution in the final emulsion and molecular weight of the polymer product wereanalyzed appropriately by gravimetry, dynamic light scattering (DLS) and capillaryviscometry techniques. The effect of variables such as stirrer speed, temperature,initiator concentration and type, emulsifier concentration and hydrophilic-lipophilicbalance (HLB) value of the emulsifier system on the viscosity-average molecularweight, particle size and its distribution and reaction kinetics were investigated.Depending on the reaction conditions, PAM particles with average particle sizesgenerally smaller than 200 nm in diameter and particle size distribution in the range of50-400 nm and viscosity-average molecular weights as high as 8×106 g.mol-1 wereobtained.