以氢氟酸为催化剂,环氧氯丙烷(ECH)、相对分子质量为400的聚丙二醇(PPG)为基体,采用两步法合成低黏度聚丙二醇缩水甘油醚。通过对产物环氧值和产率分析,研究了开环原料配比、催化剂用量、温度、时间以及闭环原料比、温度、时间对合成的影响。实验结果表明:催化剂、原料配比、开环反应、闭环反应均对产物环氧值和产率有较大影响。最优反应条件为m(催化剂):m(PPG)=0.15%、m(PPG):m(ECH)=1:2.4、开环温度60~65℃、闭环温度50~55℃,此时环氧值为3.23 mmol/g,收率为95.49%,旋转黏度为36~60 m Pa·s。 相似文献
A series of methacrylated poly(propylene oxide)/reduced styrene content/dimethacrylate resin systems have been prepared. These modified vinyl esters may be ideal for coatings, toughened matrix resins for fiber-reinforced composites, bridge deck wear surface resins, and structural adhesive applications. Network systems cured with room-temperature and elevated-temperature cure methods have been studied. The network morphologies were investigated by DMA and TEM analyses. The K1c values of the adhesives increases when systems were cured with the room-temperature cure package. The lap-shear strength of these systems were investigated for structures including composite-to-composite, composite-to-steel, and composite-to-concrete following ASTM D1002. Lap-shear adhesive strengths of all of the adhesives, which had appropriate viscosities on composite substrates, were in the structural regime with values of ～13.8 MPa. Room-temperature cure schedules (with and without a postcure) resulted in good adhesive strength on the composite and aluminum substrates, displaying values up to 15.2 MPa. 相似文献
A series of methacrylated poly(propylene oxide)/reduced styrene content/dimethacrylate resin systems have been prepared. These modified vinyl esters may be ideal for coatings, toughened matrix resins for fiber-reinforced composites, bridge deck wear surface resins, and structural adhesive applications. Network systems cured with room-temperature and elevated-temperature cure methods have been studied. The network morphologies were investigated by DMA and TEM analyses. The K1c values of the adhesives increases when systems were cured with the room-temperature cure package. The lap-shear strength of these systems were investigated for structures including composite-to-composite, composite-to-steel, and composite-to-concrete following ASTM D1002. Lap-shear adhesive strengths of all of the adhesives, which had appropriate viscosities on composite substrates, were in the structural regime with values of ∼13.8 MPa. Room-temperature cure schedules (with and without a postcure) resulted in good adhesive strength on the composite and aluminum substrates, displaying values up to 15.2 MPa. 相似文献
This paper analyzes the thermal and thermo‐oxidative degradation behavior, phase separation, melting, and crystallization of blends consisting of isotactic poly(propylene) (IPP) and poly(propylene) grafted with maleic anhydride (PP‐g‐MA). It has been established that, depending on the blend composition and crystallization/preparation procedure, the blends of IPP and PP‐g‐MA can either co‐crystallize or evidence phase separation. This conclusion has been attained by comparing the DSC results of crystallization under dynamic and isothermal conditions with X‐ray diffraction results. On the basis of the obtained results, the optimum mixing ratios have been established as 95–85 wt.‐% IPP/5–15 wt.‐% PP‐g‐MA. Thermo‐oxidative behavior has been studied by thermogravimetry and differential thermal analysis.
Summary The synthesis and characterization of 4-[poly(propyleneoxy)propyloxy]-4'-bis[4-decyloxycarbonylbiphenyl-4'-biphenylcarboxylate] with poly(propylene oxide) coil of seven (dimer-7), twelve (dimer-12), seventeen (dimer-17), twenty one (dimer-21) are described. Dimer-7 with short length of poly(propylene oxide) coil exhibits successively smectic C, smectic A and nematic mesophases, while dimer-12 and dimer-17 with longer lengths of coils exhibit a bicontinuous cubic mesophase with Ia3d symmetry. Further increasing the length of coil, as in the case of dimer-21, suppresses liquid crystallinity. Received: 22 February 2000/Revised version: 21 March 2000/Accepted: 29 March 2000 相似文献
