Synthesis And Study Of Low Unsaturated Polyether And Special Polyether

Firstly, in this experiment, ethylene oxide (EO), propylene oxide (PO) were mainly catalyzed using potassium hydroxide (KOH) as catalyst and using 1,2-propylene glycol as initiator by ring opening atactic copolymerization and block copolymeration, respectively. A series of polyether with straight chain or branched chain structure was prepared and the influences of reaction conditions were studied on the ring opening polymerization. Then, in this paper, the hydroxy terminated polyether as raw material, such as PTMG3500, PG1000, PE3500, etc were performed by solution polymerization reaction process with MDI and DMF, respectively. They were conducted by the prepolymer synthesis process, and prepared polyurethane elastomer was proceeded by the chain extension reaction of ethylene glycol. The synthesis methods of polyether polyol and points for attention were discussed in detail. The technical conditions were determined for the synthesis of the optimum polyether polyol. The effects of reaction temperature and catalyst concentration were discussed on the average relative molecular weight and degree of unsaturation of polyether. The main conclusions of the experimental research were showed as following:1. With the increase of the polymerization temperature, the reaction speed increases. And higher reaction temperature results in polyethers with higher unsaturation level and darker color and reduces the average molecular weight of the polyether. With the increase of catalyst concentration, the reaction rate increases. Meanwhile, the unsaturation level of polyether also increases slightly. With the increase of catalytic agent concentration, but the average molecular weight of polyether decreases slightly.2. The block polyether was synthesized using 1,2-propylene glycol as initiator and the monomer was continuously fed. The optimal condition for the synthesis of polyether is obtained:the concentration of catalyst is 0.2% of the quality of the product, the reaction temperature is 110℃, and reaction pressure is less than 0.3MPa. The relative molecular mass distribution of the product is narrow. This product is colorless and transparent.3. The structure of polyether polyols were characterized using nuclear magnetic resonance (NMR), infrared spectroscopy and other methods. It is proved that the design structure of the polyether is obtained indeed. And the thermal stability, viscosity and other performance indicators were determined. The relationship between structure and properties of copolyether was analyzed.4. PTMG type polyurethane elastomer is better than PPG and PE type polyurethane elastomer in tensile strength, yield strength,100% tensile force. But the elongation at break of the former is smaller than the latter two.5. At the same creeping time, the strain value of PPG type polyurethane elastomer is always greater than that of PTMG type polyurethane elastomer. Eventually the deformation of PTMG type polyurethane elastomer is significantly less than that of PPG type polyurethane elastomer by creeping. When the deformation reaches 100%, the decay rate of stress of PTMG type polyurethane elastomer is greater than PPG type polyurethane elastomer after the same relaxation time. But the residual stress of PTMG type polyurethane elastomer is significantly higher than PPG type polyurethane elastomer.6. PTMG type polyether polyol polymerized and mixed into propylene oxide. The glass transition temperature (Tg) increases. When the chain extender ethylene glycol content is 60, the glass transition temperature (Tg) of PTMG type polyurethane material reduces from -28.09℃ to -35.23℃. Finally, in this paper, the thermal properties of polyurethane elastomer were discussed. The results show that the thermal stability of the prepared polyurethane elastomer is good. The thermal degradation does not occur before 200℃.