Study On High Flexibility Epoxy Resin System At Room Temperature Curing

Epoxy resin has a high bonding strength,excellent physical and mechanical properties,in the engineering adhesives and aerospace structural adhesive has been an important position.Although epoxy resin have many advantages,but after curing there is a problem of brittleness and poor toughness,so that the scope of application in today's life has been a certain limit.Especially in the civil,construction or low temperature environment,due to the external conditions,so that the construction is difficulties,Search the room temperature curing,low toxicity and high flexibility of epoxy curing system is of concern.Room temperature curing epoxy adhesive not only easy to use,after curing the performance is relatively good,it's able to satisfy the requirements of a number of areas,so widely used today.However,the research on the room temperature curing high flexibility epoxy system is still not perfect.Based on the above,it is the focus of this paper to develop room temperature curing high flexibility epoxy resin curing system.The main work is as follows:Low molecular weight polyamide is not only less toxic,the molecule contains a flexible segment,can be cured at room temperature,So that the epoxy resin has a better flexibility.In this paper,diethylene glycol bis(3-aminopropyl)ether and dimer acid YD-29A were used as raw materials to synthesize high flexibility and low molecular weight polyamide.The effects of raw material ratio and reaction conditions on the amine value and viscosity The optimum reaction conditions were determined,that is,when the ratio of amino group to carboxyl group was 3.0,the reaction was carried out at 200 ?for 5h,and the low molecular weight polyamide with viscosity of 966mPa.s and amine value of 232 mgKOH · g could be obtained.And the structure of the product was characterized by infrared spectroscopy.The mechanical and thermal properties of low molecular weight polyamides were studied.When the ratio of low molecular weight polyamide P-5 to epoxy resin is 100:80,the tensile strength is 25.1MPa,the elongation at break is 51%,and the thermal stability of the system is better.The results of DMTA and DSC showed that the Tg of the synthesized low molecular weight polyamide/E-51 curing system was between 42 ? and 55 ?,which confirmed that the system could be cured at room temperature.The room temperature curing high flexibility epoxy formula system was studied.The results show that the performance of self-made low molecular weight polyamide curing agent is superior to the commercially available curing agent,And the residual carbon ratio of E-51/polyamide P-5 and E-51/XH-95 system at 600 ? was higher than that of E-51/910 system.Epoxy resin polymers modified with terminal carboxy liquid fluororubber(CTLF)were prepared by introducing functional terminal carboxyl liquid fluoroelen segments into epoxy resin molecules.This improves the chemical resistance of epoxy resin and heat resistance properties to a certain extent.The results show that when the content of CTLF in the epoxy resin is 25 phr,the synthetic modified prepolymer has better heat resistance.The molecular weight of the prepolymer is about 5000,And the hardness and tensile strength of the system after curing are reduced,but the elongation at break is greatly increased.