Reactions of vinyl trimethoxysilane grafting onto low-density polyethylene ( LDPE ) were investigated using Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermal gravimetric analysis. The silane grafting reactions were induced by a fixed amount of dicumyl peroxide at 0.2 part of reagent per hundred parts with respect to LDPE. Fourier transform infrared data demonstrated that the extent of the silane grafting reaction was increased as the amount of silane used, the reaction time, or the reaction temperature was increased. The apparent activation energy of the silane grafting reaction was 9.7 kJ mol 01 . Differential scanning calorimetry was used to follow the silane grafting reactions in situ at a heating rate of 20ΠC per minute. The silane grafting reaction was exothermic starting at about 150ΠC and ending at about 230ΠC, indicating a completion of the reaction in 4 min. The grafting reaction heat has linear relations to the amount of silane used. The grafting reaction heat of about 1 J / g of sample was generated during reaction per part of reagent per hundred parts of silane used. The reaction heat of silane grafting onto LDPE per mol of silane used was 14.5 kJ mol 01 silane, and the reaction heat of peroxide that reacted with LDPE was 012 kJ mol 01 peroxide.