Preparation And Performance Of Vinyl-terminated Hyperbranched Polyester And Its Influence On UV-curing Reaction Of Thiol-ene

UV curing technology has many advantages, including short curing time, low temperature, high efficiency, saving energy and resources, and it has become an environmentally friendly and important curing technology. But the traditional UV curing is also susceptible to oxygen polymerization and poor curing surface. For these key issues, we studied performance of vinyl terminated hyperbranched polymer by thiol-ene click UV curing reaction. Detailed research and results have been followed:(1) Vinyl-terminated hyperbranched polyester(VTDP) was synthesized via Micheal addition between trimethylolpropane triacrylate(TMPTA) and ethylenediamine(EDA) with a high yield of 98.42%. The structure of VTDP was characterized by FT-IR, 1H-NMR. The resultant VTDP was cured by UV light, and the formed film with the pencil hardness of 3H and adhesion class of level 2 was investigated, indicating their good comprehensive properties. The glass transition temperature and the apparent thermal decomposition temperature of the cured VTDP were 84.4? and 268.1?, respectively, obtained from their differential scanning calorimeter(DSC) and thermogravimetric analysis(TGA) curves of cured VTDP. UV curing kinetics of the VTDP with a reaction order of 2 was confirmed.(2) BDDA was crosslinked with TMPMP and TTPA by UV curing reaction, and the properties of cured TMPMP-BDDA and TTPA-BDDA were also measured. The photopolymerization kinetics and thermal properties were investigated by FI-IR, TG and DSC technologies. Result showed that the hardness(4H) of cured TTPA-BDDA film was better than that(H) of the cured TMPMP-BDDA film. Glass transition temperature of cured TMPMP-BDDA and TTPA-BDDA were 54.5 ? and 54.8 ?, and their apparent thermal decomposition temperature were 345.0 ? and 340.98 ?,respectively. The reaction order of 2 about thiol-ene UV-curing was confirmed by researching their UV curing kinetics.(3) Effect of VTDP content on performance of two thiol-ene systems(TMPMP-BDDA and TTPA-BDDA) was studied. Result showed that the pencil hardness and abrasive resistance of cured film increased first and then decreased with the increase of VTDP content, but their flexibility with about 7-class and adhesion with about 1-class changed a little. When the content of VTDP was 70%, cured TMPMP-BDDA films had highest pencil hardness(4H) and the best abrasive resistance. When the content of VTDP was 50%, cured TTPA-BDDA films had highest pencil hardness(4H) and the best abrasive resistance. The glass transition temperature of two thiol-ene systems increased slightly with the increase of VTDP content, but the corresponding apparent decomposition temperature of two thiol-ene systems decreased.