| Unsaturated polyester resin(UPR)has been widely used in transportation,chemical industry,construction and electronics because its advantages such as easy to get raw materials,excellent strength and simple processing technology.However,its performance still has some defects,due to its brittleness,weak impact resistance,flammability and so on.The researchers usually modified by blending resin and adding adjuncts,but the modified effect was limited and the durability was poor.C36 dimer fatty acid modified unsaturated polyester resin(DFA/UPR)was prepared by modifying the main chain.Among them,phthalic anhydride was partially substituted with C36 dimer fatty acid.Then DFA/UPR was secondary reinforcement modified by in-situ polymerization and mechanical blending with different structures of montmorillonite,silica and carbon nanotubes respectively.Moreover,a variety of resin materials with different structures were designed and prepared.In the end,the reaction mechanism and enhancement mechanism of the montmorillonite,silica,carbon nanotubes and DFA/UPR were preliminarily explored respectively.The main research as follow:(1)Using C36 dimer fatty acid,phthalic anhydride,maleic anhydride and 1,2-propylene glycol as the raw materials,p-toluenesulfonic acid as the catalyst,styrene and acrylic acid as the crosslinking agents,and methyl ethyl ketone peroxide as the initiator,C36 dimer fatty acid modified unsaturated polyester resin was prepared.It was found that when the ratio of acid to alcohol was 1:1.3,the dosage of catalyst p-toluenesulfonic acid was 1.9 mol%,the reaction temperature was 170 ?,the reaction time was 4 h,the amount of C36 dimer fatty acid was 6 mol%,the crosslinking agent was styrene and acrylic acid with the molar ratio of 1:1,and the dosage of initiator methyl ethyl ketone peroxide was 2.0 wt%,the DFA/UPR materials showed the optimum performance.The elongation at break and the initial thermal decomposition temperature of DFA/UPR were 32.44 times and 1.04 times of ordinary UPR,respectively,which solved the problem of high brittleness of ordinary UPR to some extent.At the same time,the thermal stability and solvent resistance of UPR were improved.(2)Using in-situ polymerization,the tensile strength and elongation at break of the material increased by 16.13%and 30.57%respectively when added 0.6 wt%hydroxyl group of montmorillonite(DK-2).In addition,montmorillonite was dissected in the hybrid material and dispersed uniformly in the resin.However,montmorillonite(DK-4)with larger interlayer spacing can only improve the toughness of DFA/UPR properly,and improve the other performance of the material weakly,and even decreased the strength of the material.The above results showed that modifying the main chain and adding inorganic particles with reactive groups,the performance of the material was improved better after modifying.(3)The nano SiO2(RNS-E)containing epoxy group enhance toughening of DFA/UPR.As a reactive monomer,the mechanical properties and thermal stability of DFA/UPR can be improved significantly,but the performance of DFA/UPR did not show any significant differences after adding as additives to the system.In addition,by mechanical blending,0.6 wt%SiO2(RNS-D)with double bond was added in the process of crosslinking monomer copolymerization,the elongation at break and elasticity modulus of the material were increased by 19.63%and 41.23%,respectively.The results showed that the addition of appropriate additives can also improved the performance of the material.(4)The strength and toughness of DFA/UPR can be significantly improved by adding carbon nanotubes containing carboxyl(MWCNT-COOH)or hydroxyl(MWCNT-OH),and the material performance prepared by in-situ polymerization were better than that of mechanical blending.Among them,the tensile strength and elasticity modulus of the material increased by 70.32%and 156.32%respectively by using in-situ polymerization and adding 0.5 wt%MWCNT-COOH.In addition,the elasticity modulus and the initial thermal decomposition temperature of the material were increased by 187.58%and 25.13%respectively by adding 0.5 wt%MWCNT-OH.The above results showed that the modification of the main chain was better than that of the external addition method,and the better the performance of the nanoparticles,the greater the improvement of the performance of the materials. |
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