In this paper, we present the use of metathesis catalysts in solutions of nitrile butadiene rubbers (NBR). In general, metathetic degradation induces chain scission along a polymer backbone having unsaturated bonds. More specifi cally, the reaction is used to obtain tailored Mooney viscosities of nitrile rubbers with optimal molecular weight and molecular weight distribution for a given application. When metathesis is applied to the rubber which is then subjected to hydrogenation, hydrogenated nitrile rubbers (HNBR) with Mooney viscosities of 60 MU and even below can be obtained. We optimized the reaction conditions of various commercially available catalysts with different chemical structures to achieve high efficiency and found out that the optimum condition varied surprisingly between the types of catalyst. The influence of the nature of NBR feedstock and reaction temperature on the progression of the reaction are also described. The most noteworthy effect occurs when adding additives, such as salts and Lewis acids, because they can be both beneficial and detrimental to the efficiency of the catalyst.

Conjugate substitution reaction of α-(halomethyl) acrylates that proceeds in addition-elimination (S_N2’) mechanism is attractive for polymer chemists, because it undergoes under ambient conditions in quantitative yields to afford α-(substituted methyl) acrylates. In this report, the conjugate substitution reaction is applied to elemental reactions in polymer chemistry, including termination of stereospecific living anionic polymerization, polycondensation, and main chain scission.

Polyurethanes are synthesized by reaction of polymer glycols, diisocyanates and active hydrogen compounds as chain extenders (curing agents). Chain extenders are low molecular glycol and diamine. Elucidation of the reaction mechanism of isocyanate with active hydrogen compound is indispensable to expand the dream to create new polyurethane. Recent advances in computer chemistry has greatly contributed to understand the reaction mechanism of active hydrogen-containing compound and isocyanate. This article, at first, reviewed the progress of the reaction mechanism of isocyanate, and then described the features of the new diisocyanates, polyol, curing agent, and catalyst.

Glass transition temperatures of raw and filled rubbers can be measured not only statically with dilatometry or differential scanning calorimetry but also dynamically with dynamic viscoelastometry. Introduction of interchain crosslinking shows clear effect to increase the glass transition temperature. This is because chain motion is constrained with crosslinked network. However, mixing of various filler into raw rubber leads to no change in the glass transition temperature irrespective of kind of filler or amount of filler, unless interaction between polymer chain and filler particle is not so strong or amount of filler loaded is not so large. No change in T_g with filler loading may be due to much larger dimension of filler particles in comparison with chain segment size.