The Structure And Properties Of Low Temperature Resistant Epoxy Adhesive And Its Application In Energy Transportation

Epoxy adhesives are widely used in energy transportation and construction fields due to their excellent bonding properties,mechanical properties,weather resistance and acid and alkali corrosion resistance.Epoxy adhesives are usually hard and brittle,which will damage the bonding structural layer in the cold and thermal shock environment,and are prone to creep deformation under long-term load.The low-temperature environments will aggravate the damage,which limits its application in low-temperature engineering.In this thesis,the low temperature resistant epoxy adhesives were prepared after designing of epoxy/curing agent molecular structure and crosslinking density.The effects of the molecular structure of amine curing agent,equivalence ratio(R),amine hydrogen equivalent weight(AHEW)of polyamide(PA),polyetheramine D-2000(PEA D-2000)content and other factors on the mechanical,bonding and thermal properties of epoxy adhesives at room temperature(RT)and low temperature(77 K)were investigated.The main contents are as follows:(1)The effects of molecular structure on the mechanical properties and bonding properties of epoxy adhesives at room temperature were studied by changing the types of raw materials and the equivalent ratio.It was found that when the epoxy matrix and R are constant,the Tg of the bisphenol A epoxy resin/triethylenetetramine(BPA /TETA)system is the highest,which is strong and brittle;the second is the bisphenol A epoxy resin/polyamide(BPA/PA)system,and the rigidity and toughness are between the two;the lowest is the bisphenol A epoxy resin/polyetheramine(BPA/PEA)system,the lowest Tg,is soft and tough.Tg is related to the structure,density and segment mobility of the cured cross-linked network.With the increase of R,the tensile strength of BPA/TETA cured products gradually decreased,the adhesive strength first increased and then decreased,and Tg(86.9～125.8oC)increased first and then decreased.The tensile strength and adhesive strength first increased and then decreased,and Tg(22.2～74.3oC)gradually increased;the tensile strength and adhesive strength of BPA/PEA cured products increased first and then decreased,and Tg(-17.1～13.9oC)gradually increased.(2)The effects of PA and PEA D-2000 contents of different AHEW on the mechanical and bonding properties of epoxy adhesives at RT and 77 K were investigated.It was found that with the increase of the AHEW,the tensile strength and elongation at break of the BPA/PA system first decreased and then increased at RT and 77 K,the shear strength increased first and then decreased,and the Tg increased from high to low and then bigger.With the gradual increase of PEA D-2000 content,the tensile strength of BPA/PA3 at RT and 77 K gradually decreased,the elongation at break increased gradually,the shear strength decreased first,then increased and lastly decreased,and the Tg gradually decreased;When 10% PEA D-2000 was added,the elongation at break of the modified BPA/PA3 cured product increased by 44.6% and 55.1%,respectively,and its toughening effect was remarkable at RT and 77 K,and the low temperature cracking was improved.(3)The application of epoxy adhesive in the field of energy transportation.An epoxy adhesive with low temperature resistance,high thixotropy,load bearing and no cracking was prepared,which had good mechanics,bonding,compressive creep,high modulus and sag resistance,and suitable open time.Its various properties meet the M4004 industry standard and can be widely used in the field of energy transportation.