In this investigation, solution grafting of acrylic acid (AA) in presence of benzoyl peroxide (BPO) was carried out onto metallocene-based "poly(ethylene-octene) elastomers" (POE) as well as "poly(ethylene-butene) elastomers" (PBE), to impart polarity on the non-polar rubbery matrix and also to study the effects of crystallinity and pendant chain length on the "grafting percentage" and "percent gel yield" at optimized conditions for all the POE and PBE systems. Reaction parameters were optimized on the basis of the relative proportions of graft and gel formations obtained through %weight gain, Fourier Transform infrared spectroscopy and elemental analysis. The effect of grafting at its maximum level on various physico-mechanical properties was also thoroughly investigated by using X-ray diffraction (XRD), differential scanning calorimetry (DSC), mechanical, dynamic mechanical (DMTA), and thermogravimetric analysis (TGA) and the properties were correlated with the structure of the modified polymers. (c) 2007 Wiley Periodicals, Inc.