Hexadiene Research Articles

Hydrogenation of phenylacetylene and 3-phenylpropyne using Rh(diene) complexes under homogeneous and heterogeneous conditions

Hydrogenation of phenylacetylene (PA) and 3-phenylpropyne (PP) was carried out using [Rh(diene)Cl] 2 complexes (diene is hexadiene (HD), cycloocta-1,5-diene (COD), norborna-2,5-diene (NBD)) in their immobilized forms and compared with hydrogenation in homogeneous arrangement. Immobilization brings significant increase of the catalytic activity and product selectivity in the step-wise hydrogenation to corresponding vinyl-resp. allyl-benzenes. Diene-ligand effect was apparent in PA hydrogenation; the product selectivity decreased in order Rh(HD) > Rh(NBD) > Rh(COD) and catalytic activity decreased in order Rh(HD) > Rh(COD) > Rh(NBD).

Studies on ethylene‐propylene‐diene rubber modification by N‐chlorothio‐N‐butyl‐benzenesulfonamide

AbstractN‐Chlorothiosulfonamides have been used to modify ethylene‐propylene‐diene rubber (EPDM) to enhance the compatibility of EPDM in, e.g., natural rubber (NR)/butadiene rubber (BR)/EPDM blends for ozone resistance. N‐Chlorothio‐N‐butyl‐benzenesulfonamide (CTBBS) was selected as a representative for N‐chlorothiosulfonamides. In this study, we found that CTBBS behaves differently with various types of EPDM. Three types of EPDM were selected: ethylidene norbornene (ENB)‐EPDM, hexadiene (HD)‐EPDM, and dicyclopentadiene (DCPD)‐EPDM. HD‐EPDM showed the greatest effectiveness toward CTBBS‐modification. However, this EPDM is not commercially available anymore. On the opposite side, DCPD‐EPDM showed the lowest reactivity so that almost no modification could be realized. The result with ENB‐EPDM was, that upon application of CTBBS to ENB‐EPDM, gelation occurred and, therefore, a low amount of modification was achieved. With the limited modification efficiency for ENB‐EPDM, there is no significant improvement when applying the modified ENB‐EPDM into NR/BR/EPDM blends. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Carbon accumulation on Pt black from hydrocarbons of different structure

Pt black was subjected to deactivating treatments with 3 hydrocarbons: hexadiene (HD), hexane (nH) and neohexane (neoH) followed by measurements of XPS and UPS spectra. The binding energy of the Pt 4f peak remained unchanged after treatments. The carbon accumulation after HD treatment was greater than that after contact with nH or neoH. The carbon content and its chemical state was close to each other after both alkanes. The graphitic component was higher after HD treatment while slightly more ℌdisordered Cℍ was present after deactivation with nH, indicating no pronounced ℌ1 routeℍ of carbonization during neoH treatment.

Effect of Hexadiene and Vinyl Acetate Content on the EPDM and EVA Blends

Melt mixed blends of EPDM rubber and thermoplastic/elastomeric EVA copolymer in the presence of dicumyl peroxide have been studied over the entire composi tion range with special reference to the effect of hexadiene (HD) content of EPDM and vinyl acetate (VA) content of EVA copolymer. Viscosity of the blends decreases as the EPDM/EVA ratio decreases with more pronounced effect associated with VA content of EVA for high HD containing EPDM. For low HD content, VA has no effect up to 20% of EVA in the blend. Lower VA and higher HD are associated with lowering of scorch safety of the compound. For higher HD containing EPDM, state of cure drastically decreases as EVA percentage in the blend increases. With lower HD containing EPDM, there is an in flexion around 50:50 blend ratio irrespective of the VA content of EVA. Initially, rate con stant decreases rapidly for higher HD containing EPDM up to 55 % of EVA in the blend, whereas high VA containing EVA gives rise to flat minimum extending up to 55 % of EVA. A s...