| With the development of the automotive industry,the automotive filter industry is also constantly updated in response to market demand,and as environmental requirements become higher and higher,production and environmental protection are also increasingly valued.At present,the main reinforcement method of automobile filter paper is to use phenolic resin for reinforcement,and alcohol-soluble phenolic resin uses a large amount of organic solvent in the production process,which involves solvent recovery process and increases the cos,flammable and explosive characteristics will increase the risk in the production process.Water-soluble phenolic resins have been the focus of research in recent years,but water-soluble phenolic resins are low-molecular-weight and A-stage thermosetting resins,the material is brittle after curing,and the strength and toughness are insufficient.It is necessary to improve the current shortcomings.Silicon is a general term for a class of polymers composed of long chains of Si—O.There are many types of organosilicon and its secondary processing,which involve various fields of the national economy and all aspects of people's production and life.They are the main organosilicon chemicals Categories.However,due to the hydrophobic nature of organosiloxane,it cannot be effectively dispersed in water to form a stable dispersion,and the blending stability with most organic polymer resins is poor,and it cannot form a good interfacial bond,making it difficult to prepare composite materials with excellent comprehensive performance.In this thesis,the hydrophilic modification of hydrogen-containing silicone oil is used to change the polarity of the silicone and improve the compatibility of the silicone and the phenolic resin.At the same time,further reactive groups are introduced to modify the chemical copolymerization with the phenolic resin.First,modified silicone was prepared by"one-pot method"and sequential feeding method,and the optimal reaction conditions were determined.Allyl glycidyl ether(AGE)and allyl polyoxyethylene ether(PEO)are co-grafted onto hydrogen-containing silicone oil(PHMS).PEO imparts the dispersibility of silicone oil in water,and AGE provides the activity of the resin for further reaction.The results show that the highest conversion rate of the modified silicone prepared by the"one-pot method"is 63.1%,and as the reaction time and the molar ratio n(C=C):n(Si—H)increase,the synthesis process appears the gel phenomenon which is not suitable for actual production and application.In the sequential method,under the condition of n(C=C):n(Si—H)=1.2:1,n(PEO):n(AGE)=3:1,PEO with low reactivity is added in advance,and the reaction time is 135?3 h,then add AGE for the reaction time at 85?is 3 h.At this time,the yield of modified silicone is as high as 90.5%.With the adjustment of the ratio of n(PEO)/n(AGE),the modified silicone showed an insoluble-emulsion-solution change trend.The results of FT-IR and ~1H-NMR indicated that the product had the expected structure,and AGE and PEO were successfully grafted onto the silicone molecular chain.The self-made modified silicone is compounded with the water-soluble phenolic resin by physical blending.When the modified silicone resin is added in 5%and 10%(mass ratio with the phenolic resin),the two have good blending stability of the blend,after the blend is cured at high temperature,the epoxy group in the modified silicone will undergo a ring-opening reaction and participate in the crosslinking and curing of the phenolic resin.DSC shows that the molecular chains of the two types of resin are entangled with each other,forming a structure similar to an interpenetrating network.The TGA results show that the heat resistance of the water-soluble phenolic resin modified by silicone has been significantly improved,and the epitaxial onset temperature of thermal decomposition has increased by 20.7%.The water-soluble phenolic resin modified with silicone is used as a reinforcing resin on automotive filter paper.Compared with the filter paper impregnated with pure phenolic resin,after adding the modified silicone,the mechanical properties of the automotive filter paper have been obtained significantly improved.First,the addition of the modified silicone resin reacts with the methylol or phenolic hydroxyl group of the phenolic resin through the ring opening of the epoxy group,thereby affecting the crosslinking reaction of the phenolic resin itself and changing the crosslinking of the final resin structure.Among them,the modified silicone(PHMS-750)/phenolic resin(PF)(w/w5%)impregnated paper has the best comprehensive mechanical properties,the bending stiffness is increased by 32%,the bursting resistance is increased by 21%,the tensile strength strength increased by 28%and elongation increased by 24%.At the same time,PHMS-750/PF(5%)impregnated enhanced filter paper has excellent oil resistance and water resistance.Compared with pure phenolic impregnated filter paper,the water-based phenolic resin modified by silicon,after impregnating the filter paper in fuel and engine oil for a period of time,the retention rate of burst resistance,stiffness and tensile strength are higher than filter paper impregnated with unmodified pure phenolic resin;after immersed in water and saturated,its bursting strength and stiffness also have a relatively high retention rate,indicating that the silicone-modified phenolic resin forms a dense three-dimensional network structure after high temperature curing,and has good oil resistance and water resistance.Finally,the laser confocal microscope(CLSM)and scanning electron microscope with energy spectrum(SEM-EDS)were used to microscopically characterize the blended system.The fluorescence spectrometer was used to determine the experimental conditions of CLSM under liquid and solid phase conditions,respectively.Observation of the blending system showed that the modified silicone resin was dispersed in water-soluble phenolic resin in the form of small droplets with a size of 1?m-30?m under the liquid phase conditions during the initial blending period;The ring opening of the oxygen group occurs and the fluorescent properties of the modified silicone disappear.The modified silicone is evenly dispersed in the phenolic resin and participates in the crosslinking reaction of the phenolic resin itself.However,when the amount of silicone added reaches 10%,there will be agglomeration of modified silicone in a small area.This modified silicone still retains fluorescent properties after high-temperature curing,indicating that there are a small number of silicone which failed to open the epoxy ring,just play the role of physical blending.Further using SEM-EDS to observe the microscopic morphology of the impregnated filter paper,it can be seen from the atomic distribution diagram that when the amount of modified silicone resin is 5%,the silicone is evenly distributed in the phenolic resin,when the silicone is added reaches 10%,a small area of aggregation will occur.This part of the silicone resin,which retains the epoxy group,is compounded with phenol formaldehyde by force blending.The results show that it is not conducive to the improvement of the mechanical properties of the paper sheet. |
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