| Polyamideimide（PAI）is a polyimide engineering plastic that retains its unique properties and incorporates the excellent processability of the Polyamide material,in Aerospace,Defense Industry,naval ships and other special equipment field has broad prospects for development.PAI super engineering plastics are regulated materials,global demand for the material is basically dependent on the United States Amoco（Solvay acquisition）monopoly supply,there is currently no mature products available in our country,and the research on this material is extremely limited.PAI material also has some disadvantages,such as strong rigidity and poor symmetry of its main chain,which lead to high friction coefficient and large wear.In addition,the introduction of amide bond leads to high water absorption and size instability of PAI material.The poor wear resistance and high water absorption of PAI limit its application in harsh working conditions such as high wear resistance and high humidity.In order to improve the performance of PAI materials under the working conditions of high load bearing and high humidity,and to solve the technical problem of"neck sticking"of transmission system parts of special equipment in a certain field in China,this paper systematically studies the effects of diamine monomer containing ether bond,increasing the proportion of amide bond,trifluoromethyl group and synergistic effect on the performance of PAI materials,and prepares two high-performance PAI materials,which solves the technical problem of"neck sticking"in China.The main contents and conclusions of the study are as follows:（1）Preparation of PAI material from diamine monomer with ether bond and its performance researchThe effect of diamine monomer containing ether bond on the friction and wear properties of PAI materials was studied.The addition of ether bond to the main chain of PAI molecule could reduce the friction coefficient of the material,and moderate addition of ether bond could improve the wear amount of PAI material.The wear mechanism of PAI varied with the number of ether bonds in the main chain.M-phenylenediamine,4,4’-diaminodiphenyl ether and 1,4-bis（4-aminophenoxy）benzene contain 0,1 and 2 ether bonds in turn,and the friction coefficients of synthesized PAI（O1）,PAI（O2）and PAI（O3）were0.5445,0.4471 and 0.4216,respectively.Appropriate introduction of ether bond into the main chain of PAI molecule could improve the wear of materials,and the wear rate of PAI（O2）was 1.5 mg,which was 84.4%lower than that of PAI（O1）.The wear mechanism of PAI（O1）was adhesive wear.The wear mechanism of PAI（O2）was abrasive wear and slight adhesive wear.The wear mechanism of PAI（O3）was abrasive wear and slightly adhesive wear.（2）Increasing the proportion of amide bond to prepare PAI material and its propertiesThe effects of increasing the ratio of amide bond on the friction,wear and water absorption properties of PAI were studied.1,2,4-trimellitic anhydride acyl chloride,isophthaloyl chloride and4,4’-diaminodiphenyl ether were selected to synthesize PAI terpolymer.With the increasing amount of isophthaloyl chloride,the amide bond on PAI would gradually replace the imide bond,so as to study the influence of increasing the proportion of amide bond on the properties of PAI materials.The friction coefficient of PAI decreased from 0.4471 to 0.3264,but the wear amount increased.The wear mechanism was mainly abrasive wear.The water absorption of PAI increased from 2.79%to 3.66%by increasing the ratio of amide bond.The heat resistance of the composites decreased slightly with the increase of amide bond ratio,Tg decreased from266.5℃to 247.4℃,Td5%decreased from 476.5℃to 458.5℃.（3）Preparation and properties of PAI containing trifluoromethyl groupThe introduction of trifluoromethyl can effectively reduce the water absorption of PAI materials.Four kinds of diamine monomers with different flexibility and side chains containing trifluoromethyl were selected to synthesize PAI materials.The water absorption of the synthesized four PAI materials is relatively low,and the water contact angle is relatively large.The water contact angle of PAI（F2）synthesized by 2,2′-bis（trifluoromethyl）-4,4′-diaminophenyl ether can reach 92.28°,and the water absorption of PAI（F4）synthesized by 2,2-bis[4-（4-aminophenoxy）phenyl]hexafluoropropane can reach 1.15%.（4）Preparation of high-performance PAI materials by synergistic effect and its performance research.The synergistic effects of trifluoromethyl/methyl and ether bond/trifluoromethyl on the properties of PAI were studied by designing,synthesizing and systematically studying.At the same time,two kinds of high-performance PAI materials,PAI（F1/H1）-4 and PAI（O2/F1）-2,were prepared to solve the problem of neck-sticking of the key components of the transmission system of special equipment in China,both material properties,finite element analysis and product fatigue test could meet the technical requirements,and the self-synthesized two PAI materials had very low water absorption,which could greatly reduce the material affected by environmental humidity.PAI（O2/F1）-2 had the same mechanical properties,heat resistance and friction as the imported material,and its water absorption was 64.7%lower than the imported material.The mechanical properties,heat resistance and friction properties of PAI（F1/H1）-4 were much better than those of the imported materials.The tensile strength of PAI（F1/H1）-4 was 18.7MPa higher,the Tg was 39.7℃higher and the friction coefficient was 8.74%lower than that of the imported materials,its water absorption rate was 69.3%lower than that of imported materials.67 pictures,71 tables,187references... |
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