Effect of hydrazine monomers on the curing kinetics and degradation kinetics of polyurethane-polyacrylate latex films

The waterborne polyurethane-acrylate emulsions were prepared by in-situ polymerization and modified by ketone hydrazine crosslinking reaction,using methyl methacrylate acetoxy( AAEM) as ketone monomer,adipic dihydrazide,carbodihydrazide,oxalylhydrazide and succinohydrazide as hydrazine monomers. Effects of hydrazine monomers on the curing kinetics and degradation kinetics of polyurethane-polyacrylate latex films were studied by non-isothermal differential scanning calorimetry( DSC) and thermal gravimetric analysis( TGA). The temperatures of the curing process were obtained by T-β extrapolation method,the curing reaction activation energy,reaction order and frequency factor were calculated by Kissinger-Ozawa and Crane equation,and the thermal degradation kinetics of latex films were analyzed by Kissinger method. The results showed that the apparent activation energy of latex film with oxalylhydrazide was the highest,which was 3. 153 k J / mol,the reaction order was 1. 148 and the frequency factor is 57. 943. While the apparent activation energy of latex film with carbodihydrazide is the lowest,which was 1. 639 k J / mol,the reaction order was 1.317 and the frequency factor was 1. 917. In addition,the polyurethane-acrylate latex film with carbodihydrazide exhibited the highest thermal stability,while with adipic dihydrazide showed the poor thermal stability.