Design, Synthesis And Application Of Modifier For Epoxy Resins

In this dissertation, a series of novel modifier for epoxy resins were synthesized to meet the need in high-tech applications which required higher toughness, flame retardance and better degradability. The structure-propeties relationships of the resulting epoxy thermosets were investigated.1. An epoxy-terminated carbosiloxane has been designed and synthesized as a modifier for to improve toughness and stiffness of epoxy resins simultaneously. The modifier was rubbery in nature and possessed several epoxy groups. When co-curing with a conventional epoxy precursor, diglycidyl ether of bisphenol-A (DGEBA), it would phase separated as individual domains and thus acted as a toughener. Through participating curing reaction with its multiple epoxy groups, the crosslinking density of the system was increased and thus resulting in reinforcing. The modifier was synthesized via hydrosilylation and cohydrolysis reactions. The chemical structures of the carbosiloxane were confirmed by FTIR and 1H NMR spectra. The cured epoxy products were characterized with dynamic mechanical thermal analysis (DMTA), thermogravimetric analysis (TGA), impact strength testing, and atomic force microscopy (AFM).2. Polymethyl (3-glycidyloxypropyl) siloxane (PMGS) was synthesized as flame retardant additive, which were co-cured with diglycidyl ether of bisphenol-A (DGEBA) using 4,4-diaminodiphenylsulfone (DDS) as a curing agent. The structure of PMGS was confirmed through FTIR and 1H NMR spectra. The cured products were characterized with dynamic mechanical (DMTA), thermogravimetric analysis (TGA), and oxygen index analyzer. With PMGS incorporated, the cured epoxy resin showed better thermal stability, higher limited oxygen index (LOI), and higher char yield. At moderate loading of PMGS, the storage modulus and glass transition temperature of the cured epoxy resin based on neat DGEBA were obviously improved.3. An epoxy monomer, hexa (3-triglycidyloxysilylpropyl) triphosphazene (HGPP) was synthesized and used as a flame retardant component in epoxy resins. The obtained HGPP was introduced into epoxy systems by co-curing with diglycidyl ether of bisphenol-A (DGEBA) using 4,4-diaminodiphenylsulfone (DDS) as a curing agent. The structure of HGPP was confirmed through FTIR and NMR characterizations. The physical and mechanical properties of the cured products were evaluated with dynamic mechanical analysis (DMTA) and thermogravimetric analysis (TGA). With HGPP incorporated, the thermal stability, limited oxygen index (LOI), and char yield of the epoxy resin were increased. At moderate loading of HGPP, the storage modulus and glass transition temperature of the cured epoxy resin were higher than those based on neat DGEBA.4. A series ofβ-cyclodextrin-based epoxy resins were synthesized with different epoxy equivalent weight. Their chemical structures were characterized with FTIR and NMR examination. These epoxy resins were cured using L-agrinine as a curing agent and the degradation behavior of the cured resins was evaluated under different acidic buffer solutions at 37℃. The degradable behavior of such epoxy resins suggested potential applications as environment friendly materials.