Synthesis Of Heat-resistant And Wear-resistant PBOZ-BMI Resin And The Research Of Its Modification

Bismaleimide(BMI)is a kind of polymer derived from polyimide system,which exhibit excellent comprehensive performance,and has been drawn widely attention from scholars.However,it also possess the some defects,such as brittleness of curing,poor solubility in common solvents,bad flame retardant,and high molding temperature.Thus,it is necessary of the BMI to be further modified for its practical application.As a new kind of phenolic resin,benzoxane(BOZ)overcomes the defects of the traditional phenolic resin.Furthermore,the BOZ exhibits very low volume shrinkage.Studies have showed that,the introduction of phosphorus in BOZ monomer can greatly improve the thermal stability and flame retardancy of its cured resin.Thus,this paper is proposed to introduce the phosphoru element into the structure of BOZ monomer,which is aiming to design and controll the synthetic process of BOZ.After high symmetry of phosphorus-contained BOZ monomer synthesised,it can be used to co-cure with BMI resin.Meanwhile,HNSs treated by KH-560 and HBPSi surface-grafted of CNTs(HBPSi-CNTs)were used as modifiers to prepare the HNSs/HBPSi-CNTs/PBOZ-BMI composite,which is expected to possess the excellent dispersive and high bonding-strength of interface,high heat resistant and super wear resistance.The main research contents of this dissertation were as follows:1.To prepare phosphorus-contained benzoxazine monomer(PBOZ),the compound10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide(ODOPB)was chosen as amine resource,while the O-phenylenediamine and paraformaldehyde were chosen as raw materials,and the solvent process was chosen to synthesis PBOZ monomer.The novel monomer PBOZ was then used to blend with bismaleimides(PBOZ-BMI),while the thermal properties,mechanical properties and the tribological properties were all researched.The results showed that the optional addition is 10.0 wt%,with this reasonable content of PBOZ,the overall properties of PBOZ-BMI resin reached the optimal.The main reason is that,as the structure of PBOZ contains the P element and N element simultaneously,thus the P-N synergistic effect can further promote the formation of thermal-protective coating during the burning process,thus the fire resistant of the thermal resistant of PBOZ-BMI can be enhanced.Meanwhile,the PBOZ monomer can reacted with BMI resin,which can form the dense crosslinked structure,thus the mechanical properties can be further increased.In addition,the enhancement of mechanical properties and thermal properties can also prevent the heat damage effected on the materials during the wear process.2.The silane coupling agent KH-560 was grafted on the surface of hydroxyl silicate nano-films(HNSs)during a hydrolysis process.The HNSs were then added into the PBOZ-BMI resin,and its effect on the mechanical properties and tribological properties of PBOZ-BMI were also researched.The results showed that,with the 0.8 wt% content of HNSs,the mechanical properties and tribological properties of HNSs/PBOZ-BMI composites both reached the optimal.The special layer structure of HNSs determined that its layer can easily slide when by a force,which can not only decrease the impact force,but also decrease the actual wear area,thus both the mechanical properties and tribological properties were enhanced.Especially,the Si-O bond of silane coupling agent KH-560 is a kind of soft segment,thus the toughness of PBOZ-BMI resin can be increased.3.The hyperbranched polysiloxane(HBPSi)was grafted on the surface of carbon nanotubes(CNTs)during a hydrosilylation process,and HBPSi-CNTs was finally synthesis,and its dispersibility and thermal properties were researched,and its grafting percentage were also estimated by TGA.The HBPSi-CNTs were then chosen as the modifiers to fabricate the HBPSi-CNTs/PBOZ-BMI composites,the thermal properties,mechanical properties while the tribological properties of the composites were also researched.The results showed that when the addition of HBPSi-CNTs monomer was 0.8 wt%,the overall properties of HBPSi-CNTs/PBOZ-BMI resin were the best.The main reason can be attributed to the special tubular structure of HBPSi-CNTs,which exhibits high surface areas and excellent mechanical properties.Secondly,the HBPSi on the surface of HBPSi-CNTs possess lots of active groups,these groups can reacted with PBOZ-BMI resin,and the strong chemical bonds can enhance the interface bonding force of between HBPSi-CNTs and PBOZ-BMI,which can improve the stress transfer efficiency,thus the mechanical properties of the composites were also increased.4.When the HNSs and HBPSi-CNTs were added into the PBOZ-BMI resin at the same time to prepare the HNSs/HBPSi-CNTs/PBOZ-BM composites,the composites can exhibit better mechanical properties and tribological properties than both the HNSs/PBOZ-BMI and HBPSi-CNTs/PBOZ-BMI composites,indicating that the synergistic effect of the modifiers HNSs and HBPSi-CNTs is excellent.The main reason can be attributed to the outstanding performance of HNSs and HBPSi-CNTs,respectively.Furthermore,when HNSs and HBPSi-CNTs coexistence,a part of HBPSi-CNTs get into the interlayers of HNSs,which can promote the sliding of each HNSs layers,thus the actual wear area can be further decreased efficiently,while the mechanical properties and the tribological properties were also highly increased.