PEROXIDE-INITIATED GRAFTING OF ACRYLAMIDE ON TO POLYETHYLENE SURFACES

Acrylamide has been grafted onto the surface of a polyethylene film with the aid of a peroxide initiator (tert-butyl peroxyneodecanoate). The peroxide was first swollen into the film from cyclohexane solution; the film was then dried under reduced pressure at room temperature. Excess initiator, adsorbed on the surface, was washed off with acetone. The grafting reaction was carried out by placing the film in a boiling solution of the monomer in water. After grafting, the film was extracted with water to remove monomers and homopolymer. The grafted films were characterized by infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), gravimetric measurements, and contact angle measurements. The graft yield was found to increase with reaction time up to about 5-15 min and thereafter level off. The presence of air was found to retard the grafting reaction. Increase in monomer concentration gave an almost continuous increase in graft yield, but high concentrations were not necessary to cover the surface of the film with polyacrylamide. This grafting has been found to function, but the process requires further development to reduce the total grafting time before it can be used commercially.