| Phenolic resins are one of the three major thermosetting resins. They are well known for their excellent heat resistance, fire, smoke toxicity properties and cheaper characteristics, and wide application, and the development of a long history, but the cured have byproduct and the shortcoming of brittle. Epoxy resins have a large amount application in thermosetting resins. It is with small shrinkage, excellent adhesion and mechanical performance characteristics, but is not with flame retardant. Using epoxy resin modified phenolic resin which have excellent adhesion of epoxy resin and excellent heat resistance of phenolic resin can be widely used in building materials, pipe insulation material or transportation and so on. The phenolic-epoxy resin which of modified by the two methods of physical and chemical methods are applied to the pultrusion process. It will meet the requirements of fast pultrusion process which of less byproducts, fast curing and small shrinkage. The main contents are as follows:(1) By blending the different ratio of the low viscosity of bisphenol A type epoxy resin with low viscosity ammonia catalytic phenolic resin, the performance of the resin systems were investigated by the gel time, viscosity, mechanical properties, heat resistance, flame retardance. When the phenolic resin was mixed with 5% epoxy resin, the results were as follow: the gel time of 121 s at 150℃, viscosity of 7760 m Pa·s at 30℃, flexural strength of 83.3 MPa, impact strength of 6.9 k J/m2, tensile strength of 20 MPa, heat deflection temperature of 148.5℃, oxygen index of 34.5% and the apparent cure activation energy of 94.2k J/mol. The resin systems had higher service temperature, low viscosity, excellent mechanical properties and service characteristics, and it could meet the requirements of fast pultrusion process. The weightless rate of 5% phenolic-epoxy-phenolic resin is 27.56% in the first stage, and was 30.12% in the second stage;(2) Through the analysis of the nonisothermal method, we can calculate that 5% phenolic-epoxy curing kinetics equation is6 0.925d?/ dt ?5.33?10 exp(-94.2 / RT)(1-?), and the apparent activation energy(Ea) is 94.2k J/mol, and the reaction order is 0.925, and the pre-exponential factor(A) is 5.33×106s-1; we can calculate that 30% phenolic-epoxy curing kinetics equation is 7 0.928d?/ dt ?2.73?10 exp(-99.9 / RT)(1-?), and the apparent activation energy(Ea) is 99.9k J/mol, and the reaction order is 0.928, the pre-exponential factor(A) is 2.73 × 107s-1;(3) Through the experimental process of the reaction temperature, time, ratios and their effects on the epoxy value, we could obtain the optimum synthetic technology conditions of 3-aryloxy-1,2-epoxypropanes in epoxidation stage. With phenol and epichlorohydrin as raw materials, and potassium hydroxide as catalyst, we can obtain that the reaction molar ratios is 1:1.6, and the etherification reaction temperature is 75℃, and etherification reaction time is 3h, and the cyclization temperature is 85℃, and the cyclization time is 2h. The epoxy value of 3-aryloxy-1,2-epoxypropanes is 0.7mol/100g; With 3-aryloxy-1,2-epoxypropanes, phenol and formaldehyde as raw materials, and ammonia as catalyst, the molar ratios of phenol and formaldehyde is 1:1.1, and the molar ratio of 3-aryloxy-1,2-epoxypropanes and phenol is 0.6:1, and the content of catalyst is 2%, and reaction temperature is 90 ℃. The flexural strength of phenolic-epoxy is 42.8MPa. |
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