| In order to improve the high temperature applied range of low-density cement slurry technology developed by lab,this paper studies the factor that restrict low-density cement slurry technology applied in high temperature,it is found that the key problem is the poor temperature resistance of new lightening material.In the paper,through the analysis of the factors that affect the temperature resistance of new lightening material,we conducted a design of molecular structure and material selection.The epoxy resin and curing agent with good temperature resistance were selected to prepare a good heat resistance epoxy curing system,as a basis for the synthesis of high temperature resistant material,finally design a set of high early strength and low-density cement slurry.(1)Through the design and screening of molecular structure,three kinds of epoxy resins(H-2,S-1,S-2)and two kinds of curing agents(GH1,GH2)were selected as materials to basic synthesis for the synthesis of high temperature resistant materials.The thermal stability of cured epoxy resin was studied by means of(DSC)and simultaneous thermal analyzer,it is found that the degree of polymerization,the amount of epoxy groups involved in crosslinking,and the structure of the curing agent all affect the glass transition temperature of the curing system,and the glass transition temperature(Tg)of HYJ-6 reached 131?.The relationship between the cross linking density and the glass transition temperature(Tg)was investigated by nuclear magnetic resonance(NMR):For the same curing system,when the curing conditions changed,the crosslinking density of the cured material network changed,which has a direct effects on the glass transition temperature(Tg),That is,the higher the crosslinking density of the cured material,the higher the glass transition temperature(Tg)of the cured material,and the two showed a positive correlation;and to a certain extent,the degree of polymerization of epoxy resin also influences the crosslinking density of the curing system,and finally affects the Tg of the system.Infrared characterization found that for the same system,after higher temperature curing,curing epoxy groups disappeared completely,which indicates a more complete response,this is in accordance with the results of differential scanning calorimetry(DSC)and synchronous thermal analyzer:After the reaction is more completely,the system exhibits higher glass transition temperature(After HYJ-6 reacted 12h under 160?,its,glass transition temperature was increased to 138?,and the thermal stability of the material was improved).(2)The active filler was modified by interfacial bridging agent.Infrared characterization showed that filler not only has its own characteristic absorption peaks,but also exhibits a stretching vibration peak of interface bridging agent,moreover,with the increase of the amount of interface bridging agent,the stretching vibration peak becomes stronger,which indicates that the interface bridging agent is successful in modifying the filler.With the activation index as the index,the ratio of interface bridging agent to inorganic active filler was determined to be 1:11.Through the selection of active filler and the effect of dosage on the compressive strength of cement stone,the micro silicon was selected as the filler for the synthesis of active material,and the dosage is 20%of resin base material.The compressive strength of cement paste with HJG-1(13.2MPa)was significantly improved compared with that of HYJ-6 cement paste(8.6MPa),and the cement slurry of HJG-1 system is stable,compared with HYJ-6,the hydrophilicity of HJG-1 is obviously improved,the contact angle between distilled water and distilled water is 34.7°.(3)Using HJG-1 as the lightening material to prepare low density cement slurry,through the combination of micro silicon,superfine fly ash and additives,designed cement slurry formula with density of 1.3?1.5g/cm3,the results show that the slurry has good basic performance,high compressive strength. |
PDF Full Text Request