| Materials play an important role in modern large aircraft manufacturing.The interior materials used in a modern wide-body aircraft account for 15%of the gross weight of aircraft.Moreover the area of members manufactured by composite materials such as cover plates,ceilings,partitions and wallboards in cabin exceeds more than 1000 m~2.It is of great significance to prepare materials which can meet the requirements of strength,rigidity with beautiful design.It can thus can greatly reduce aircraft weight,improve safety and comfort of the flight and cut down aircraft operating costs.At present,the panel materials used in the cockpit and cargo hold in Chinese civil aviation are mainly made by cured phenolic resin composites with reinforced glass fiber at relative medium temperature.The production and manufacturing of phenolic resins composites mainly depends on non-renewable petroleum resource.During the production of phenolic resins composites,not only energy consumption is high,the utilization rate of raw materials is low,but also a large amount of industrial waste are discharged,which leads to serious environmental damage.In addition,phenolic resins and its derivative industrial products are difficult to degrade and recover.They have to be disposed of by incineration or burial,which further deepens their harm to the environment and runs counter to the new era aviation concept of pursuing green and sustainable development.It is apparently contrary to the concept of green and sustainable development in new generation of civil aviation.At the same time,the phenomena such as pitting,cracking,over-burning and decarburization oxidation during the curing process of phenolic resins also affect the comprehensive performance of materials.Therefore,it is imperative to pursue the development of green,environmental-friendly and degradable new materials.In this study,acrylated epoxy soybean oil,a natural green vegetable oil derivative,was used to blend with silicone resins to prepare silicone prepolymer and epoxy-soybean oil acrylate prepolymer,and a green environment-friendly epoxy-soybean oil-based hybrid resins with good comprehensive performance and certain natural degradation performance was prepared by mixed copolymerization.The main research contents and results are as follows:(1)The ring-opening prepolymerization of acrylate epoxy soybean oil(AP),the dehydration polycondensation of silicone resins(SP)and the copolymerization of the two prepolymers were studied.AP,SP and APSP hybrid resins were prepared under relative different reaction conditions,mass ratio or environment.The rheological properties of the prepolymers and hybrid resins were studied by rotary rheometer.There are significant differences in composite viscosity between samples,which ruled out the possibility of only physical blending and proved the occurrence of the above three polymerization processes;The chemical structure changes of prepolymers and hybrid resins during polymerization were studied by FTIR and XPS.The microscopic morphology of APSP hybrid resins was studied by SEM.The results showed that the"snowflake"structure was evenly distributed on the samples with different light and dark degrees,which was the first discovery in relevant research.Combined with the chemical structure changes of prepolymer and hybrid resin in the spectral experiment and the study of relevant literature,the possible conjecture of its"snowflake"structure was put forward.(2)The properties of the APSP hybrid resins were determined.The mechanical,thermal,rheological properties and natural degradability of APSP hybrid resins were studied by means of mechanical test,TGA and rheometer.The results of tensile and bending tests show that the elastic modulus of the hybrid resins is 231.05 MPa,and the bending modulus reaches 26.16MPa.The thermogravimetric test shows that the mass retention rate of the hybrid resins increases significantly under high temperature after modification with silicon resins.The quality decline of the hybrid resins was restrained,indicating its good thermal performance.The rheological test results show that the composite viscosity of hybrid resins is higher than that of AESO,and its composite viscosity reaches 4.87×10~4Pa·s.The rheological behavior of hybrid resins is also better in the low frequency range.In addition,the natural degradation of APSP hybrid resin was carried out for one year.The mass degradation rate of APSP hybrid resins was 5.61%without external degradation power,which means good degradation performance.(3)The curing behavior and curing kinetics of APSP hybrid resins were studied.The Time-Temperature-Transformation of hybrid resin at different heating rates was studied by DSC.Its reaction activation energy E_αand reaction frequency factor A was calculated based on Kissinger method and Owaza method.The classical non-isothermal conversion method,Malek method,was used to determine that the curing model of the hybrid resins.The results show that it is an autocatalytic model.The curing kinetic parameters and its equation of the reaction system were obtained by fitting and calculating the Sesthk-Berggren(m,n)model.The obtained curing kinetic equation is in good agreement with the experimental data.Finally,the optimum curing temperature of the curing system was extrapolated and the curing process was optimized,which provided a theoretical basis for exploring and preparing high-performance soybean oil-based composites. |
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