Synthesis Of Microcellular Polyurethane Elastomers Based On Poly(Propylene Carbonate) And Study On Its Properties

Poly(propylene carbonate) (PPC) polyols is a new kind of promising material which can be prepared by the copolymerization of carbon dioxide and propylene oxide in the presence of double metal cyanate catalyst. It has great industrial value for its excellent propertiy in polyurethane synthesis and cheap raw material. PPC with narrow molecular weight distribution, low residual catalyst content, is prepared by the copolymerization of propylene oxide and CO2 using a new kind of double metal cyanate catalyst developed by us.In this paper microcellular polyurethane elastomers (MPUE) based on this PPC were synthesized and characterized. Influence of isocyanate idex, chain extender, and foaming agent on the properties of MPUE was explored in this paper. Influence of polymer polyols, which was used as modifier, on MPUE was also studied in this paper.The results were listed as follows:1. Mechanical properites were studied in this paper. Results showed that hardness and strength of MPUE increased with the increasing of isocyanate index (R), and the increasing rate became slower after R exceeding 1.05.2. Chain extender had great influence on mechanical properties of MPUE. Hardness and mechanical strength of MPUE increased with the dosage of chain extender increasing and in the same time elongation decreased, and the lower molecular weight of chain extender, the better mechanical properties of MPUE.3. Dosage of foaming agent aslo had great influence on the density and mechanical strength of MPUE and pore structure. The density and mechanical strength decreased with the increasing of foaming agent and pore structure became larger and pore distribution became wider.4. MPUE based on polypropylene glycol (PPG) and polyester polyol (PBA) were prepared and comparison with PPC base MPUE was made in this paper. Results showed that PPC based MPUE exhibit much more excellent mechanical property comparing with PBA and PPG based MPUE. PPC based MPUE has excellent hydrolysis resistance as well as PPG based MPUE, and the best damping performance at room temperature.5. Structure and molecular weight had great influence on the properties of PPC based MPUE. Mechanical properties of MPUE increased with the increase of the molecular weight and COO segment content and in the same time thermal stability property and elongation at break decreased.6. The properties of MPUE has not changed after PPC and PPC based prepolymer being kept at 80℃ for 24h, which showed PPC had excellent storage stability.7. Polymer polyols was used as nucleating agent to modify PPC based MPUE. The results showed that polymer polyols could improve comprehensive properties of MPUE. It could improve hardness, mechanical strength, damping property, pore structure, which made pore structure much more uniform, skin quality and high temperature resistant property, but reduce elongation at break. The best comprehensive performance was obtained when the dosage of polymer polyols was 40%.