Five-membered Cyclic Carbonate/Primary Amino-Basalt Fiber Synergistically Reinforced Nylon-66 Composite Materials

As the main greenhouse gas,CO₂ emissions are increasing every year,breaking the balance of energy budget.Excessive accumulation of energy will lead to global warming,severely destroy the ecological environment,and bring many bad effects to people's production and life.In the context of advocating"green chemistry"and"sustainable development",how to use effective methods to convert CO₂ into products that are practical for people has become a major research focus.The research content of this subject is to start from CO₂,synthesize a new type of surface modifier through a green chemical reaction route,and modify basalt fiber(BF)to enhance the comprehensive performance of nylon-66(PA66).The work of this thesis focuses on"green chemistry".Five-membered cyclic carbonates were prepared by the addition method of CO₂ and epoxy compounds,and the conversion rate of epoxy compounds was measured by the hydrochloric acid-acetone method.Then by controlling the reaction temperature,CO₂ pressure,reaction time and the type of catalyst,the optimal reaction conditions for the reaction are gradually determined.The experimental results show that the optimal reaction conditions for glycidyl ether under the conditions of TBAI(tetrabutylammonium iodide)as the catalyst,reaction temperature of 130^oC and reaction CO₂ pressure of 0.5 MPa are the best reaction conditions for glycidyl ether;under this reaction condition,polypropylene glycol diglycidyl ether(PPGDGE)and butyl glycidyl ether(BGE)conversion rates reached 92.7%and 97.6%.Therefore,the method of fixing CO₂ by epoxy compound is not only green,cheap and environmentally friendly,but also has a very ideal conversion rate.In this thesis,two new surface modifiers were synthesized by reacting the prepared five-membered cyclic carbonate with the primary amino group on?-aminopropyltriethoxysilane(KH-550).This reaction process avoids the use of isocyanate.Using modifiers to modify the surface of BF,two non-isocyanate polyurethane-basalt fiber hybrid materials:KBF-P and KBF-B were obtained,and they were melt-blended with PA66to prepare BF-reinforced PA66 composites,and their mechanics were investigated.Performance and water absorption,and the microstructure and thermal stability of composite materials are studied by Scanning Electron Microscope(SEM)and Synchronous Thermal Analyzer.The experimental results show that KBF-B has rough surface and good compatibility with PA66 matrix;compared with before modification,the tensile,flexural and unnotched impact strength of PA66/KBF-B are increased by 5.5%,5.9%,25.5%(fiber mass fraction is 20%);with the increase of KBF-B content,the mechanical properties of PA66/KBF-B are improved,when the mass fraction of KBF-B reaches 40%,the tensile strength of PA66/KBF-B The tensile,bending,and unnotched impact strength is 161.1%,148.7%,112.7%higher than pure PA66,and it is better than PA66/glass fiber composite with the same fiber mass fraction;the saturated water absorption rate of PA66/KBF-B is only3.8%,indicating that it has excellent water resistance;the modified composite material has a higher temperature and a smaller exothermic enthalpy at the same weight loss,indicating that it has excellent thermal stability.In this project,a cyclic carbonate/primary amino-basalt fiber synergistically reinforced nylon-66 composite material was prepared,which obtained good comprehensive performance,provided a good theoretical basis for the rational use of CO₂ and green chemical reaction pathways,and expanded the application value of cyclic carbonate.