Study On Synthesis And Properties Of Crosslinked Polyamide By Bulk Michael Addition And D-A Reaction

Cross-linked polyamide material(cPA)is a widely used engineering plastic with excellent mechanical properties and large development space.However,the synthesis process of cPA is high in temperature and complicated in process.And it is generally required to use a solvent for dissolution,which is difficult to purify.Like traditional cross-linking materials,cPA is cracked inside due to the external environment,which affects its service life.Therefore,the synthesis method of the conventional cPA is simplified.In order to have a self-healing function,a reversible D-A chemical bond is introduced.The specific research contents are as follows:1.Methyl acrylate(MA)and 1,6-hexanediamine(HDA)are synthesized by a "one-pot method" of bulk Michael addition and polycondensation to synthesize a crosslinked polyamide material HDA-MA-cPAs,which is simple in preparation and excellent in mechanical properties.We investigated the effect of changes in MA content on the content of each component of the Michael addition product and the performance of HDA-MA-cPAs.The structural tests show that HDA-MA-cPAs contain a significant Tg,and with the increase of MA content,both Tg and tensile strength increase first and then decrease;HDA-MA-cPAs have no melting and crystallization peaks and are amorphous;The initial decomposition temperature of HDA-MA-cPAs is higher than 180?,and the maximum tensile strength is 45 MPa,which has good thermal stability and mechanical properties.2.In order to provide a self-healing function for the crosslinked polyamide material,a D-A bond is introduced.First,the Michael addition reaction introduces a pendant furan group,which is then polycondensed with a diamine compound(hexamethylenediamine HDA,isophoronediamine IPDA)and finally cross-linked with 1,5-bismaleimido-2-methylpentane(MPDBMI).We investigated the effect of changes in IPDA content on the properties of the self-healing polyamide material D-cPA-DA-n-a/b.Tests show that with the increase of IPDA,the tensile strength decreases gradually,and the repair efficiency increases gradually;the tensile strength is up to 13.36 MPa,the maximum repair efficiency is 89%,and it can be repaired multiple times.3.In order to improve the previous chapter,a more flexible polyetheramine D230 and a polyetheramine T440 were introduced.Not only increases the length of the fatty chain,but also increases the molecular weight of the prepolymer PA-x%-t-(HDA).We changed the content of polyetheramine T440 to study the effects on the mechanical properties and repair efficiency of self-healing crosslinked polyamide materials(cPA-DA-x%-t-(HDA)).It was found that with the increase of T440 content,the tensile strength gradually increased and the repair efficiency decreased gradually;the addition of hexamethylenediamine enhanced the tensile strength of the material and weakened its repair efficiency;the highest tensile strength was 45MPa,and the highest repair efficiency was 92.2%and can be fixed multiple times.