Polymers and Carbon Black

Spin-spin relaxation dynamics were also used in the study of the kinetics of the vulcanization of polysulphide rubbers. The T2 values decrease with the course of the reaction and the time dependence of log (T2/T ), where corresponds to the time equal to zero, exhibits an inflection. The inflection point is attributed to gel formation, and the reaction rate constants for the two separate processes are determined from the T2 data. It was also observed that the addition of carbon black reduces T2 by a factor of 2 or 3, because vulcanization occurs both through the thiol groups and by the chemical reaction between the polymer and carbon black 37>. 

Powder samples of 10u average diameter were prepared by air jet micronization of polymeric or composite chunks. Composite materials were prepared by melt mixing of polymer and carbon black. Carbon black was added to the surface by milling the polymer powder and carbon black with glass beads for an hour, and subsequently heating the particles to tack the carbon black to the particle surface. Static resistivity measurements were performed on packed powders in a procedure similar to ASTM D257. 

Physical properties of various Blon elastomers with variation of crosslinker amounts In the raw polymer and carbon black levels In the compounded elastomer are summarized In Table VIII. 

Tang (134) studied the effect of the interaction between carbon black and the polymer on electrical behavior. The absorption of polymer on the carbon black surface may be physical or chemical. The latter is caused by free-radical reaction between the polymer and carbon black, and it can occur during radiation or the preparation of the composite. In carbon-black-lilled high density polyethylene, the cross-linked network of the pol5uner restricts the freedom of movement of carbon black. The free-radical reaction enhances the binding force between the polymer and carbon black. 

---