| Recently, Epoxy resins (EP) have attracted growing attention because of their outstanding advantages on strength, modulus, thermal stability, and heat, moisture and chemical resistance, making them widely used in many applications as resins matrixs. However, Epoxy resins suffer from their high joint density and brittleness of the cured resins, which limited them applications in many high-tech fields. Thus, it is necessary to investigate the toughening EP for their theoretical and practical researches. In this dissertation, the methods and mechanisms of toughening EP have been reviewed, and a view to toughen epoxy resins by poly(ether ether ketone) (PEEK) which was modified by chemical method had been proposed based on experimental results. Main contents and conclusions of this dissertation are as follows:(1) SPEEK with different degree of sulfonation was synthesized by using sulfonation reactions of PEEK and concentrated sulfuric acid. The results indicated SPEEK exhibit excellent thermal stability, displaying less than 3 wt% weight loss at 400℃. The degree of sulfonation of SPEEK increases with the enhancement of the reaction temperature and time. Compared with PEEK, the crystallinity of SPEEK was identified to decrease. It was found that the modified-PEEK with -SO3H and -CH2N(CH3)2 groups could be obtained by the chlorinemethylation and the amination modification.According to the experimental data, the dynamics parameters of PEEK sulfonation reaction was calculated. The activation energy of sulfonation reaction Ea was 35.48 kJ/mol, and constant k was 2266.5 exp (4267.5/T).(2) By using DSC, the processing of the curing for the modified PEEK/EP system was ascertained to be 80℃/2h＋125℃/2h＋180℃/3h. The activation energy E of the solidification reactions of modified-PEEK/EP system is 63.82 kJ/mol, and the order of reaction n and the dynamic equation of the solidification reaction dα/dt are 0.964 and 1.792×107 exp(-7676.2/T )( 1-α)0.964, respectively. Furthermore, the curing reaction mechanism of was the modified PEEK/EP system discussed.(3)The mechanical properties of modified-PEEK/EP system were examined. The modified-PEEK/EP system exhibits superior stability with less change of viscosity and longer gelation time at the room temperature, and sensitive to temperature with better high temperature reaction activity at the high temperature. All these properties of modified-PEEK/EP system can satisfy the requirement of practical applications. The modified-PEEK/EP solidification system displays higher toughness, tensile strength, bending strength, elasticity coefficient and fracture elongation ratio compared wtih EP. The maximum of tensile strength, bending strength, impact intensity and fracture elongation ratio get about 71 MPa, 142.3 MPa, 23.1 kJ/m2 and 4.13%, respectively. Compared with the pure epoxy resin, modified-PEEK/EP system displays superior mechanical properties. The maximum of fracture toughness KIC is up to 2.169 MPa.m1/2, which is 2.1 times of pure EP solidification system.(4)The results of DMA analysis indicated that modified PEEK improved the thermal properties of the resin system. The glass transition temperature Tg and the onset temperature Tonset of resin system increased with the enhancement of modified-PEEK content, and storage modulus E' elevated with the increase of modified PEEK content below Tg. The long-term application temperature of the modified resins was up to 186.7℃.(5) According to the results of DMA, SEM and FT-IR, the toughening mechanism of PEEK and modified-PEEK toughening EP were discussed initially. The toughening of PEEK and modified-PEEK toughening EP rely on the cooperation effect of bridge-link anchor of the dispersed phase, piaying the leading role and the effect of shearing-bending of the matrix in the secondary position. The toughening effect of modified PEEK exhibit more effective, which are ascribed to the contribution of the polar groups of modified-PEEK. Entrance of the polar groups of modified-PEEK into the solidification joint network, becoming the network points, played an important role of dispersing and enduring stress.
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