UV/thermal dual curing of tung oil-based polymers induced by cationic photoinitiator

With the increasing shortage of petroleum-based resources, the exploitation and application of the polymers derived from the renewable resources has becomes increasingly important for the industrial development. In this work, in order to promote the direct application of tung oil in the coating field, the tung oil-based polymers with the excellent mechanical properties by using cationic photoinitiator as the green initiator were prepared. The cationic polymerization mechanism and the optimal polymerization conditions of methyl eleostearate (ME) induced by triarylsulfonium salt (TAS) are characterized via the nuclear magnetic resonance spectroscopy. The effects of different monomers on the properties of tung oil-based polymers and the post curing behaviors of the polymers are studied by dynamic mechanical test and microtensile test. The results display that the heating treatment after UV irradiation is necessary and favorable for the cationic polymerization of ME induced by TAS. And the optimal reaction condition is 500 W of irradiation energy, 5 wt% of initiator concentration, 60 min of irradiation time, 100 degrees C of heating temperature and 3 h of heating time. Moreover, tung oil-based polymers with good hydrophobicity can be obtained under the optimal reaction condition. In addition, adding 20 wt% divinylbenzene and 10 wt% styrene to the tung oil can effectively increase the mechanical properties and glass transition temperatures (T-g) of tong oil-based polymers.