Preparation And Properties Of Polycarbonate Diols-Castor Oil Polyurethane Elastomers

In this dissertation, a series of research have taken on the synthetic process ofpolycarbonate diol, then the preparation and properties of polyurethane elastomersbased on polycarbonate diols and castor oil mixture were studied, finally the structureand properties of castor oil elastomer composites were studied. The dissertationconsists of four parts as follows.The first part，Poly(1,4-Butanediol) carbonate diols (PCDL) was synthesized. Theinfluences of molar ratio of DEC/BDO, vacuum reaction time and temperature, andplate number were investigated. The experimental results showed that the fraction ofstandard atmosphere stage is ethanol, and it has no influence on the molar ratio ofDEC/BDO; DEC can form azeotrope with ethanol and they will be steamed togetherwhen molar ratio of DEC/BDO less then1.0. The molecular weight of PCDL can bestable on2000g·mol-1when molar ratio of DEC/BDO greater than or equal to1.0. Themolecular weight of PCDL increases with the increase of vacuum polymerization timeand temperature. Meanwhile, the hydroxyl value decreases.The second part, a serial polyurethanes were synthesized from the soft segmentmixture of renewable castor oil and polycarbonate diols. The results indicated that withan increase in the NCO group content, the hardness, modulus and strength enhancedrapidly. It was also observed that with the increase of polycarbonate diols, both thetensile and tear strength increased first and then decreased, and the permanent set andelongation at break were gradually increased. The TGA result showed that thermalperformance of the polycarbonate diols/castor oil polyurethane was better than castoroil polyurethane.The third part, with ultrasonic wave assistant mixing way, a mixture of PUU/HGBwas pretreated. The structure of elastomers was characterized by FT-IR, the thermalproperty of materials were characterized by TGA. The results show that when the HGB content is5%, the PUU/HGB composites perform the super mechanical properties.The TGA result showed that thermal performance of the PUU/HGB composites wasbetter than castor oil polyurethane. The toughening mechanism was mainly the crackgrowth prevention of the HGB and “island structure” of PU.The forth part, the paper took castor oil PUU as the research object, thecorrelation among structure, properties and temperature of polyurethane-ureas wasinvestigated by means of temperature-dependent FT-IR spectroscopy. The resultsshowed that with temperature increased, the absorption of vibration of NH hydrogenbonded gradually decrease and the NH free bond increased slightly; the band site ofNH hydrogen bonded shifted from low wave number to higher wave numbers, whilethat of NH free bond keeps constant. The band site of C=O free urethane shift from1738cm-1to1744cm-1, and that of C=O hydrogen urethane also shift slightly from1695cm-1to1696cm-1, while the band could not be detected near80℃. The C=C inaromatic ring shifted to lower wave numbers. With the temperature increased, thedegree of micro-phase separation decreased. At the same time, the hard domain ofPUU was dissociated under heating, and tensile strength of material was decreasedquickly with the temperature improving；but decreasing tendency of tensile strengthbecame gently beyond100℃. The mechanical properties under high-temperatureenvironment mainly depended on the physicochemical reaction of soft domain ofPUU.