Comparative study of different initiation methods in the functionalization of low-density polyethylene with diethyl maleate: Gamma radiation and ultrasound

This work unfolds a comparative study of the grafting of a low-density polyethylene with diethyl maleate (DEM) using gamma irradiation and ultrasound as means of initiating the grafting reactions. The grafting degree was determined by FTIR using a reported calibration curve. The efficiency of both functionalization methodologies was calculated and the polymers were characterized by differential scanning calorimetry (DSC) and gel permeation chromatography (GPC). The results showed that the grafting degree increases with the radiation dose when the monomer is inserted by gamma radiation. When the ultrasound methodology was used, an additional initiator such as dicumyl peroxide had to be used in order for the grafting to take place. In this last case, changing the time of exposure to the ultrasound source did not induce significant changes in the obtained grafted degree. The use of ultrasonic radiation plus dicumyl peroxide as grafting initiators promoted more insertion than that when gamma radiation was employed.