FTIR analysis of silane grafted high density polyethylene

Vinyltrimethoxysilane (VTMOS) monomer was grafted onto high density polyethylene by reactive processing in a twin screw extruder in the temperature range of 180-240°C. The effect of VTMOS and 1,3-bis (tert-butylperoxyisopropyl) benzene peroxide (BTBB) on the extent of grafting was studied using qualitative and quantitative Fourier transform infrared spectroscopy. The grafting reactions were confirmed via infrared absorption bands present in the 800 cm-1 region which are characteristic wavenumbers for the vibration modes of the Si-CH group from VTMOS (CH2=CH-Si-(OCH3)3). The percentage of reacted and unreacted VTMOS was calculated by a novel Fourier transform infrared spectroscopy quantitative method developed through measurements of infrared absorbance bands at peaks 795 and 814 cm-1 that are influenced by both reacted and unreacted silane. The effect of silane and peroxide concentrations on the concentration of reacted and unreacted silane present in the material was determined. The change in unsaturation content measured at absorbance 1009 cm-1 supported these findings.