Infrared study on in situ polymerization of zinc dimethacrylate in poly(α-octylene-co-ethylene) elastomer

An infrared spectroscopic method was used to follow the course of in situ polymerization of zinc dimethacrylate (ZDMA) in poly(α-octylene-co-ethylene) elastomer (POE). The integral intensity of the 831 cm^-1 band, ie the out-of-plane deformation mode of =CH, was used to determine the residual amount of ZDMA in composites cured at 165°C for different times, through which the course of in situ polymerization of ZDMA in POE was traced and the dynamic curve determined. The curing course of the ZDMA/POE/peroxide system at 165°C was examined with a rheometer and compared with the course of in situ polymerization. The results surprisingly show that the in situ polymerization of ZDMA is almost complete at the beginning stage of curing, and that substantial crosslinking starts subsequently. Scanning electron microscopy and transmission electron microscopy observations on morphologies of ZDMA/POE composites cured at 165°C for different times were carried out and confirmed the results of infrared experiments. Combining all the investigations, it was deduced that a competition exists between in situ polymerization and crosslinking in the composites. Covalent crosslinking rather than ionic bond crosslinks are the major types of crosslinks structures in ZDMA/POE composites, and its total density is lower than that of carbon-black-reinforced POE.