| Polyurethane (PU) is a class of polymers which contains repeated carbamate (-NHCOO-) in its main molecular chain. Polyurethane has excellent flexibility, low temperature resistance, wear resistance and good adhesion to the substrate and so on, and diversity of raw materials, a large degree of freedom adjustment formula, so it is widely used in foam plastics, elastomers, coatings, adhesives and other fields.In this paper curing behavior analysis, mechanical properties and adhesion properties of one-component polyurethane adhesives were researched, and these established a complete evaluation system. In the course of the study the reaction between polyurethane prepolymer and inorganic silicate was found, and then a new kind foam system was prepared. The main research contents were as fellowed:The structure characterization, curing behavior analysis, storage stability, adhesion and mechanical properties of one-component polyurethane adhesives (PU) and silylated polyurethane adhesive (SPU) were researched. The FI-IR of PU and SPU showed that there were differences isocyanate (NCO) absorption at 2265cm-1 and Si-CH3 absorption at 1485cm-1.This was because the different end-group structure. When the relative humidity was set at 95% and the curing temperature was 23℃,30℃,35℃and 40℃, the tack-free time of PU adhesives (Sikaflex-256,Sikaflex-265,SikaTack-Drive,SikaTack-Ultrafast) and SPU adhesive (Sikaflex-555) decreased from 20min,29min,11min,12min and 13min to 7min,8min,4min,4min and 4min. And the curing rate increased from 5.22mm/24h,5.34mm/24h,5.62mm/24h,5.60mm/24h and 5.44mm/24h to 6.32mm/24h,7.78mm/24h,>10.00mm/24h,>10.00mm/24h and7.27mm/24h. When the curing temperature was set at 23℃and the relative humidity was 50%,65%,80% and 95%, the tack-free time of five kinds of adhesives decreased form 43min,48min,15min,12min and 24min to 20min,29min,7min,9min and 13min. And the curing rate increased from 3.98mm/24h,4.00mm/24h,3.82mm/24h,4.06mm/24h and 4.08mm/24h to 5.22mm/24h,5.34mm/24h,5.62mm/24h,5.60mm/24h and 5.44mm/24h. These showed that PU and SPU had similar curing behavior. The adhesives were stored at room temperature, the tack-free time and cure rate remained unchanged during 12 months, indicating five kinds of adhesives had good stability. The curing behavior in different seasons in Beijing revealed that the curing rate was slower in winter while fast in summer. The tensile strength and tear strength of four types of PU adhesives (Sikaflex-256, Sikaflex-265, SikaTack-Drive and SikaTack-Ultrafast) were 8.2MPa,6.8 MPa,9.3 MPa,6.6 MPa and 19N/mm,20 N/mm,19 N/mm,19 N/mm. The tensile strength and tear strength of SPU (Sikaflex-555) were 5.8 MPa and 13 N/mm. The mechanical properties of PU were better than SPU. Under standard conditions and Beijing weather conditions, with increase curing time, the tensile strength and tear strength of PU and SPU increasesd rapidly firstly and then remain unchanged. The elongation decreased rapidly firstly and then remain unchanged. The substrate treated by cleaner and activator had good adhesion with PU adhesive. The peel strength of adhesives to treated substrates in order was activated glass, activated galvanized steel and activated steel plate. But the adhesion properties of SPU were good to untreated and treated substrates. The similar adhesives were evaluated with the evaluation system. The results displayed the adhesives of Sika were better than other products in solid content, tack-free time, curing rate and mechanical properties.In the course of the study the reaction between polyurethane prepolymer and inorganic silicate was found. The reaction mechanism was proposed and a new kind foam system was prepared. It could be from foam when the temperature was at 10℃, the ratio of water glass and PAPI mass was 5:4, added the physical blowing agents-pentane, foam stableilizer-silicon oil and stannous octoate.
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