| Trimellitic anhydride is an excellent epoxy resin curing agent,mainly used for plasticizers,insulating paint,resin coatings and epoxy resin curing agent at present,which can curve epoxy resin in a short period of time.The cured epoxy resin system has excellent heat resistance,mechanical properties and corrosion resistance Due to the introduction of rigid benzene ring,while the anhydride and epoxy reaction to produce flexible ether bond.However,trimellitic anhydride due to its high melting point(168 ?),resulting in more stringent curing conditions,while the higher curing temperature of some resin material also adversely affected the performance.In recent years,the trimellitic anhydride has been modified by chemical or physical means to reduce its melting point,so as to overcome some of its deficiencies in performance,resulting in a higher activity and a new acid anhydride curing of the resin at a lower temperature or room temperature Agents has been a hot topic in this field.In this paper,the butane chain is introduced into the trimellitic anhydride's No.4 substitution site by selective esterification,while the acid anhydride groups used to cure the epoxy resin can be retained.This method can improve the flexibility of the modified epoxy resin,improving its flexibility and reducing the melting point,which can reduce the curing temperature and the negative effects of high temperature on the resin.It perivide a new method for the modification of acid anhydride curing agent.Specific work as follows:Using thionyl chloride as Acid chlorination reagent on the raw materials trimellitic anhydride(TMA)for acyl chloride reaction to obtain the intermediate product.trimellitic anhydride chloride(TMAC),which has strong reactivity.The final product trimellitic anhydride n-butyl ester(TMNB)was prepared by the reaction of TMAC and n-butyl under the condition of ice salt bath with pyridine as catalyst.The reaction conditions were as follows:by L9(33)orthogonal test,reaction temperature of 0 ?,reaction time of 5h and the ratio of I:2:1.2.The yield of the product was 91.5%,and the melting point of the product was 87.2?87.9?;The structure of the product was confirmed by FT-IR and 1HNMR.Quantitative analysis of n-butyl trimellitate was carried out,indicating that the TMNB geometry was a planar asymmetric structure.TMNB was able to ring-open at lower temperature,and shortened the carbon-oxygen bond length by 0.49%and 0.64%.A conclusion was got from comparing TMNB/epoxy resin and TMA/epoxy resin in the the mechanical properties and heat resistance.TMNB/epoxy system tensile strength increased by 3.08%,reaching 29.9MPa;bending strength increased by 1.0%,reaching 47.2 MPa;impact strength increased by 22.3%,reaching 2.03kJ/mol.The curing process is 75?lh,100 ? 3h,130 ? 2h.The Thermogravimetric temperature of TMNB/epoxy system is lower than the TMA/epoxy system when the weight loss is 5%.The curing kinetics of TMNB/epoxy resin system was studied by non-isothermal DSC method.The results show that the autocatalytic model is suitable for describing the curing behavior of the resin system and the curing process is obtained by extrapolation.The kinetic equation of TMNB/E51 resin curing system was obtained by calculating the parameters:da/dt=2.106 x 104 exp(37510/RT)a0.5163(1-a)0.366... |
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