Preparation And Properties Of Novel Flame-retardant Cyclotriphosphazene-containing Epoxy Resins

Epoxy resins have been widely applied as microelectronics encapsulating materials due to their good thermal and dimensional stability, excellent chemical and corrosion resistance, superior electrical and mechanical properties. However, the fire risk and hydrophilicity are major hazards of these materials. Cyclotriphosphazene (CPZ), a ring compound consisting of alternating phosphorus and nitrogen atoms with two substituents, exhibits remarkable resistance to heat, super flame retardancy and low surface energy. Besides, it is possible to obtain multifunctional initiators or terminators through incorporating types of moieties to the molecules to meet particular needs because CPZ leaves phosphorus with two available sites for pendant groups. Therefore, CPZ-based epoxy resin is attractive and promising to achieve good comprehensive performance. Based on lots of published papers either domestic or overseas, two novel CPZ-based epoxy resins were prepared.In the study, two novel CPZ-based epoxy resins with two functional groups have been successfully prepared, and what's more, the thermal stability, flame retardant property, mechanical property, hydrophobicity and electrical property of the cured epoxy resins were studied. The main contents were listed below:1. A novel flame-retardant cyclotriphosphazene-based epoxy resin (CPEP) was successfully prepared and it was characterized by 1H NMR, FTIR and GPC. Then the blends of CPEP and diglycidyl ether of bisphenol A (E51) with different mass ratios were cured using 4,4'-diaminodiphenylmethane (DDM) as a curing agent. The curing behaviors and the glass transition temperature of the resulting thermosets were studied by differential scanning calorimetry (DSC). The thermal stabilities and flame retardant properties of the cured resins were studied by thermogravimetric analysis (TGA) and UL94 tests respectively. In addition, mechanical properties, hydrophobic properties and electrical properties were also observed. Compared to the corresponding E51-based thermosets, the cured resins with a mixture of CPEP and E51 showed better thermal stabilities, higher char yields and greatly improved flame retardant properties. Furthermore, relatively good mechanical properties, hydrophobicity and electric resistance were maintained. The cured resins of CPEP/E51 (mass ratio 1:1) achieved UL94 V-0 rating, indicating that CPEP prepared in this study could be used as a flame retardant material.2. Based on CPEP, another novel fluoride cyclotriphosphazene-based epoxy resin (CPFEP) was successfully prepared and its structure was also characterized by 1H NMR, FTIR and GPC. Then CPFEP was blended with diglycidyl ether of bisphenol A (E51) at different mass ratios, and the blends were cured by DDM. Related properties tesing results showed that the cured resins with a mixture of CPFEP and E51 had better thermal stabilities, greatly improved flame retardant and hydrophobic properties. Relatively good mechanical properties and electric resistance were also maintained. The cured resins of CPFEP /E51 (mass ratio 1:1) achieved UL94 V-0 ratings and the contact angle was 105°, indicating that CPFEP prepared in this study could be used as a flame retardant and hydrophobic coating material.