Synthesis Of Polyurethane Material Based On Poly (Propylene Carbonate)

Aliphatic Polycarbonate Polyurethane, which owns excellent property, could be made from aliphatic polycarbonate polyols (APC) and isocyanate. The APC mostly produced by transesterification of diols with biphenyl carbonate is not be widely used because of its high cost. The APC which is synthesized by the copolymerization of CO2and epoxides is significantly reduced production cost and effectively utilize CO2, which has very important industrial value. However, due to the high catalyst residue and wide molecular distribution, polyurethane based on APC has poor mechanical property.Poly(propylene carbonate) polyols (PPC) with narrow molecular weight distribution (molecular weight distribution index1.2-1.3) and low residual catalyst content (50-100ppm) was prepared by our Lab, which made from propylene oxide and CO2in the presence of a new kind of dimetallic cyanate catalyst. In this paper, wet-curing polyurethane adhesives and polyurethane elastomers based on the PPC were synthesized and characterized. The factors that affected the performance of PUE-APC were explored. The results were listed as follows:1. The bonding performance of moisture curable poly (propylene carbonate) polyols based polyurethane adhesive was far better than the polyether type, and the reaction speed and storage stability were slightly worse;2. Poly(propylene carbonate) polyols based polyurethane elastomer (PUE-PPC) exhibited higher mechanical properties than polyether polyurethane elastomer (PUE-PPG) and higher hydrolysis resistance property than polyester polyurethane elastomer (PUE-PBA). It also exhibited better acid hydrolysis resistance and alkali hydrolysis resistance than PUE-PBA. However, poor crystallization property and heat resistance property of PUE-PPC were limited its application in some field;3. Mechanical properties of PUE-PPC was aslo tested in this article. Results showed that, as the isocyanate index (R) increasing, the mechanical strength increases and reach the maximum at R=1.05and then decreased gradually; Elongation at break increased all the time, but the hardness decreased slightly. With the increase of-NCO content of prepolymer, the mechanical strength of the elastomer and crystallite dimension increase, elongation at break decreases; Shorter chain extender has better mechanical properties and crosslinking agent is helpful to improve the mechanical strength, but elongation at break decreased greatly; With the increase of the molecular weight of soft segment, mechanical properties and hardness increase, Tg decrease;4. Structure of PPC has great influence on PUE-PPC. With-COO segment increasing, mechanical strength and Tg increases, elongation at break and heat resistance property decreases;5. Comparing with PUE-PPG, PUE-PBA and PUE-PPC exhibit better organic solvent resistance;6. As the-NCO content of prepolymer, content of-COO segment and molecular weight of soft segment increasing, gel content increases and swelling capacity decreases.7.Residue catalyst has great influence on thermal stability of PPC. Obvious degradation of PPC was found after kept at75℃for5h. Study found that thermal degradation can be inhibited by adding0.35%o-0.65%o(mass fraction)catalyst deactivator.