Properties and Morphologies of Elastomer Blends Modified with EPDM-g-Poly[2-dimethylamino ethylmethacrylate]

The graft copolymerization of 2-dimethylamino ethylmethacrylate (DMAEMA) onto ethylene propylene diene mononer rubber (EPDM) was carried out in toluene via solution polymerization technique at 70 degrees C, using dibenzoyl peroxide as initiator. The synthesized EPDM rubber grafted with poly[DMAEMA] (EPDM-g-PDMAEMA) was characterized with (1)H-NMR spectroscopy, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). The EPDM-g-PDMAEMA was incorporated into EPDM/butadiene acrylonitrile rubber (EPDM/NBR) blend with different blend ratios, where the homogeneity of such blends was examined with scanning electron microscopy and DSC. The scanning electron micrographs illustrate improvement of the morphology of EPDM/NBR rubber blends as a result of incorporation of EPDM-g-PDMAEMA onto that blend. The DSC trace exhibits one glass transition temperature (T(g)) for EPDM/NBR blend containing EPDM-g-PDMAEMA, indicating improvement of homogeneity. The physico-mechanical properties after and before accelerated thermal aging of the homogeneous, and inhomogeneous EPDM/NBR vulcanizates with different blend ratios were investigated. The physico-mechanical properties of all blend vulcanizates were improved after and before accelerated thermal aging, in presence of EPDM-g-PDMAEMA. Of all blend ratios under investigation EPDM/NBR (75/25) blend possesses the best physico-mechanical properties together with the best (least) swelling (%) in brake fluid. Swelling behavior of the rubber blend vulcanizates in motor oil and toluene was also investigated. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114:2547-2554,2009