| Cycloaliphatic epoxy resins, as a branch of epoxy materials, have been widely employed in a variety of applications, such as microelectronic packaging, outdoor insulation, reactive diluents, plastic mould, coating and adhesives, due to their low monomer viscosity, good heat resistant, high storage modulus, superior electrical properties and excellent ultraviolet resistance. In this thesis, a series of novel silicon-and phosphorus-containing cycloaliphatic epoxy resins with enhanced properties were designed and prepared by introducing functional groups or adjusting their crosslinking density. The physical properties of epoxy monomers and cured products were investigated by various measurements, and the property-structure relationship was systematically disscussed.Endowing epoxy resin with reworkability is of theoretical and commercial significance. Two novel thermally reworkable, phosphorus-containing, di- and tri-functional epoxides (Epoxide-P1 and Epoxide-P2) were prepared from phosphoryl trichloride, phenylphosphoryl di chloride, and cyclohex-3-enyl-1-methanol. The chemical structures of the epoxides were characterized through HRMS, FTIR,1H NMR and 31P NMR spectra. The epoxides were thermally cured with hexahydro-4-methylphthalic anhydride (MHHPA), and the properties of the cured epoxides were investigated by DSC, DMA, TGA, FTIR, molecular modeling and limiting oxygen index (LOI) test. Emphasis was placed on the study of degradation behaviors and mechanism of the cured epoxides. The results showed that the cured trifunctional Epoxide-P2 had significantly increased glass transmission temperatue (227℃) due to its highest crosslinking density. Two cured phosphorus-containing epoxides exhibited rapid thermal degradation in the temperature range of 220-280℃, and lost nearly 70% weight after isothermal degradation at 260℃for 3 min and 8 min respectively. These distinctive degradation behaviors well met the requirements of degradation temperature and rate for thermally reworkable epoxy. Moreover, two cured phosphorous-containing epoxides had increased LOI by 30% compared with commercial cycloaliphatic epoxide ERL-4221.In order to meet the requirements of cycloaliphatic epoxy resins with excellent flowability and heat resistance in the application of electronic packaging, two novel silicon-containing, di- and tri-functional epoxides (Epoxide-Si1 and Epoxide-Si2) were prepared from methylphenyl dichlorosilane, methyl trichlorosilane and cyclohex-3-enyl-1-methanol. The chemical structures of the epoxides were characterized through HRMS, FTIR, H NMR and 29Si NMR spectra. The epoxides were thermally cured with MHHPA, and the curing kinetics was studied by Kissinger method. The properties the cured epoxides were investigated by DSC, DMA, TMA, TGA and water absorption test. The results showed that Epoxide-Sil and Epoxide-Si2 were colorless liquid with low viscosities (340 mPa.S and 290 mPa.S respectively) at room temperature. Compared with difunctional Epoxide-Si1, the cured trifunctional Epoxide-Si2 had increased crosslinking density (p) from 0.82×10-3 mol/cm3 to 4.08×10-3 mol/cm3 and glass transition temperature from 157℃to 228℃.To further study the effects of crosslinking density on the physical properties of cycloaliphatic epoxy resins, four novel silicon-containing epoxides (Epoxide-Si3～Si6) with tunable epoxy functionality from 2 to 4 were designed and synthesized, starting from dimethyl dichlorosilane, diphenyl dichlorosilane, phenyl trichlorosilane, tetra-chlorosilane and cyclohex-3-enyl-1-ethanol. The chemical structures of the epoxides were characterized through HRMS, FTIR,1H NMR and 29Si NMR spectra. The epoxides were thermal cured with MHHPA, and the properties of the cured epoxides were investigated by DSC, DMA, WAXD, TMA, TGA and water absorption test. The effects of epoxy microstructure on dynamic mechanical behaviors, thermal expansion, thermal stability and hygroscopic property of the cured epoxides were systematically studied. The results showed that the properties of the cured epoxides were closely related to the crosslinking density of the epoxy network. Compared to difunctional Epoxide-Si3, the cured tetrafunctional Epoxide-Si6 had remarkably increased crosslinking density (p) from 0.45×10-3mol/cm3 to 9.64×10-3 mol/cm3, glass transition temperature from 133℃to 237℃, and decreased thermal expansion coefficient (CTE) from 6.44×10-5/K to 4.83×10-5/K. |
