Study On Structural Characterization And Synthesis Mechanism Of Water-soluble SMF Resins

The effects of different sucrose contents and synthesis process on the structure and thermal stability of Sucrose-Melamine-Formaldehyde (SMF) resins were discussed in this paper. The structures of resins were characterized by methods of FT-IR,1H-NMR,13C-NMR and MALDI TOF MS. The curing properties were measured by DSC and TG. And the synthesis kinetic and reaction mechanism of SMF resins were studied. The main research contents and results are listed as following:(1) The conclusions that there are two different synthesis mechanisms of Mannish reactions between Sucrose, Melamine and Formaldehyde and dehydration condensation of methylol groups were discovered according to the results of FT-IR,1H-NMR,13C-NMR and MALDI TOF MS. It was also found that the bonding strength of SMF resins which compared with MF resin decreased, but it would be good for SMF resins with free sucrose to get a much better storage stability than MF resin at room temperature.(2) The first-order to formaldehyde in the reaction of the system of Sucrose, Melamine and Formaldehyde were achieved by solitary method in alkaline condition and systems with excessive Melamine and Sucrose. Meanwhile, it was reasonable for the assumptive mechanism of SMF system because the results of them coincided with the experimental results. The activation energy of MF resin was 49.01kJ/mol, and of SMF resin was 43.51kJ/mol, and it was better for Sucrose to reduce the reactive abilities of SMF which were good for the storage stability of SMF resins.(3) The results of TG and DSC showed that there is ternary polymerization with Sucrose, Melamine and Formaldehyde and binding systems with Sucrose and MF resin and SMF resins in the structure of SMF resins. And it would be also good for SMF resins with free Sucrose to develop heat resistance beside the storage stability of SMF resins.