Ultrasound enhanced radical graft polymerization of starch and butyl acrylate

• Graft polymerizations based on starch were performed under ultrasound irradiation.
• Ultrasound irradiation can enhance the graft reaction drastically.
• Initiator plays an important role in propelling the graft polymerization.
• Feeding mode can influence the graft ratio of graft copolymer.

The graft polymerizations of starch and butyl acrylate were performed with and without ultrasound irradiation. Potassium persulfate was used as radical initiator. During the process of graft polymerization with ultrasound of 40 kHz, the effects of reaction time, temperature, initiator dosage and feeding mode on graft ratio, graft efficiency and monomer conversion were investigated. The results demonstrated that ultrasound had a strong enhanced influence on the graft reaction. Compared to the conventional graft polymerization without ultrasound, the graft ratio, graft efficiency and monomer conversion increased significantly in ultrasound fields. The radicals produced by the decomposition of initiator played an important role in propelling the graft polymerization. Furthermore, the graft ratio and graft efficiency increased when starch and initiator were pre-treated with ultrasound for a short time prior to the addition of monomer.