Studies on sequential interpenetrating polymer network (IPN) based on nitrile rubber and poly(vinyl acetate)

Abstract

AbstractSeveral elastomeric sequential interpenetrating polymer networks (IPNs) based on nitrile rubber (NBR) and poly(vinyl acetate) (PVA) have been synthesized. Cross‐linked NBR was swollen in vinyl acetate monomer containing benzoyl peroxide (BPO) as initiator and tetraethylene glycol dimethacrylate (TEGDM) as cross‐linker and then the swollen mass was polymerized. The composition of the IPNs could be varied by varying the swelling time and concentration of BPO and TEGDM. The properties of these IPNs were investigated by tensile test, differential scanning calorimetry (DSC), dynamic mechanical analysis, and swelling measurement. On increasing the PVA content as well as cross‐linking level, the tensile strength increased because of better mixing. DSC showed a single Tg value for all the individual IPNs, the Tg values changing regularly with composition. The tan δ peak for IPNs appeared at higher temperature compared to NBR and was found to be dependent on both the composition of IPNs as well as cross‐linking level. IPNs having 2 and 5% cross‐linker (TEGDM) showed splitting in the tan δ peak. On increasing the cross‐linker concentration to 9% and beyond, the splitting disappeared. The damping capability of the IPNs has been explained in terms of the magnitude of tan δ, area under the tan δ curve, and ½ peak width. The IPNs also showed better solvent‐resistance properties. © 1993 John Wiley & Sons, Inc.