Studies in polymer composites based on carbon containing pulverized rubber materials

Pulverized rubber/thermoplastic IPNs (interpenetrating polymer networks) were synthesized using AIBN or BPO initiated polymerization in order to make high value-added materials from scrap tire. Catalytic polymerization in the presence of pulverized rubber using BPO as initiator was observed and found the catalytic activity was associated with the presence of carbon black in the rubber formulation.;A comprehensive kinetic study of catalytic polymerization of some vinyl acrylate monomers in the presence of pulverized rubber and carbon black was conducted. Overall, the kinetics was influenced by carbon content, carbon surface chemistry, reaction temperature, initiator concentration and type, dispersion of carbon, rubber formulation, etc. Catalytic mechanism of carbon black was proposed as carbon black nanoparticles were involved in the redox decomposition of BPO on their surfaces after it was adsorbed through pi-pi interaction. The unpaired pi electron on the basal plane of carbon black was suggested to be the main electron donor. Besides, it noted that the magnitude of the catalytic effect was higher in the presence of pulverized rubber than when carbon black was used. Experimental results revealed it was from the synergetic coupling between the catalytic effect of carbon and diffusional limitation effect.;A heterogeneous model considering the adsorption of BPO, redox and thermal decomposition and inhibition effect of carbon was developed and showed good predications with the experimental data at low carbon content while at high carbon content, the model prediction appears some deviation which would be the result of attaining maximum adsorption condition and/or possible re-agglomeration of carbon particles. Proper modification of the model is needed to describe these phenomena.;Carbon/PMMA nanocomposite and rubber/PMMA semi-IPNs were prepared by this catalytic polymerization and characterized DSC, TGA, SEM, three point bending flexural test and nanoindentation. The IPNs exhibited improved degree of phase compatibility and good mechanical properties at low rubber content. When rubber composition increased, modulus and hardness of the IPNs decreased but the elasticity increased. Besides, the IPNs made from smaller rubber particles were observed to have higher modulus and increased toughness. Finally, the pulverized rubber/PAA full-IPNs were prepared. The kinetics and swelling capacities of the IPNs were investigated.