Polyester diol PCL and PBA, polyether diol PTMG and polycarbonate diol PCDL were used as components of WPU soft segment, respectively. Polyether PTMG-WPU has the worst hydrolytic property and the highest thermal stability. The maximum degradation rate temperature Tmax is 407.8 °C, the water contact angle reaches 89.5 °. Traditional polyester PCL-WPU shows the strongest hydrolysis performance, the smallest water contact angle, only 71.7 °, the water absorption rate of 72 h at room temperature is as high as 26.7%. However, the thermal stability of PCL-WPU is lower, the soft segment Tg is −52.3 °C, and Tmax is only 333.7 °C, but the mechanical property of which is the best, the tensile strength is 58.3 MPa, and the elongation at break reaches 857.9%. The most important thing is that the structure of polyester PCL-WPU is more easily destroyed by lipase and water molecules. The acidic products produced after hydrolysis will further promote the degradation of polyester. Therefore, compared with other WPUs, PCL-WPU has the best biodegradability and the most obvious degradation effect under the same conditions. The degradation rate of PTMG-WPU after 30 days of degradation in 0.6% lipase PBS buffer solution and soil was only 4.2% and 2.3%, while the highest degradation rate of traditional polyester PCL-WPU reached 41.7% and 32.0%, respectively. In addition, polycarbonate PCDL-WPU has the highest hardness, reaching 95.5 HD. But its other performances are lower than PCL-WPU.
Liu Shunjie,Qin Yusheng,Guo Hongchen,Wang Xianhong,Wang Fosong
Synthesis of polyols from carbon dioxide (CO 2 ) is attractive from the viewpoint of sustainable development of polyurethane industry; it is also interesting to adjust the structure of the CO 2 -polyols for versatile requirement of polyurethane. However, when renewable malonic acid was used as a starter, the copolymerization reaction of CO 2 and propylene oxide (PO) was uncontrollable, since it proceeded slowly (13 h) and produced 40.4 wt% of byproduct propylene carbonate (PC) with a low productivity of 0.34 kg/g. A careful analysis disclosed that the acid value of the copolymerization medium was the key factor for controlling the copolymerization reaction. Therefore, a preactivation approach was developed to dramatically reduce the acid value to ~0.6 mg(KOH)/g by homopolymerization of PO into oligo-ether-diol under the initiation of malonic acid, which ensured the controllable copolymerization, where the copolymerization time could be shortened by 77% from 13 to 3 h, the PC content was reduced by 76% from 40.4 wt% to 9.4 wt%, and the productivity increased by 61% from 0.34 to 0.55 kg/g. Moreover, by means of preactivation approach, the molecular weight as well as the carbonate unit content in the CO 2 -diol was also controllable.
Fluorinated polyurethane (FPU) with a different fluorine content was prepared using perfluoropolyether glycols, poly(propylene glycol), and isophorone diisocyanate as starting materials, and 1,4-butanediol as a chain extender. The structure and molecular weight of FPU were characterized by Fourier transform infrared spectroscopy and gel permeation chromatography. A solution of FPU in xylene and cresol was then coated on copper wires using an enameled machine to prepare enameled wires. The friction coefficient and adhesion performance of the enameled wires were tested. The friction coefficient of the as-prepared enameled wires reached 0.095, which was much lower than 0.149 of the polyurethane without fluorine. FPU-based enameled wires also showed good mechanical performances and increased breakdown voltages. In addition, FPU exhibited good hydrophobic and oleophobic characterization.
危险品化学品经营许可证（带存储）