Proton spin-spin relaxation and n.m.r. imaging of peroxide/coagent crosslinked cis-1,4-polyisoprene

Proton T-2 relaxation and n.m.r. imaging experiments were utilized to study the molecular mobility and heterogeneity of cis-1,4-poly isoprene crosslin ked with dicumyl peroxide in the presence of triallyl cyanurate (TAC) and z inc diacrylate (ZDA) as coagents. It was observed that the long T-2 relaxat ion times of the rubber protons in peroxide/TAC or peroxide/ZDA crosslinked elastomers decrease with the increase in the crosslink density resulting f rom the addition of peroxide or coagent. The T-2 relaxation times of protic solvent in swollen rubber are also affected by the physical property chang es of the networks induced by peroxide and coagent addition. It was conclud ed that the solvent T-2 relaxation times depend on solvent-polymer interact ions as well as the crosslink density of the networks. (C) 1999 Elsevier Sc ience Ltd. All rights reserved.