Preparation And Properties Of Polyfunctional Pendant Polysiloxane

Polysiloxane has the characteristics of both inorganic materials and organic materials.It has been applied in wide fields like aviation,spaceflight,electronics,mechanics,medical treatment and chemical industry for withstanding extreme temperatures,moisture-proof,corrosion resistance and chemical stability,and so forth.Functional side group polysiloxane is one of the important varieties of silicone resins.In addition to the above advantages,it can be formulated into a one-component sealant,which can undergo a curing reaction at room temperature,which is suitable for large-scale field operation,thus having a broad application future.For different applications of polysiloxane,different functional groups can be introduced on the linear polysiloxane side groups to modify it to obtain a wider range of applications.In order to expand the application of polysiloxane,this paper mainly uses polymethyl hydrogen siloxane as a raw material,and uses different mechanisms of hydrosilylation and hydrosilylation reaction to introduce different content of methoxy groups on the polysiloxane side groups.And epoxy groups,using infrared spectroscopy and nuclear magnetic hydrogen spectroscopy to characterize and confirm the structure of the synthesized product,and to study its applications in flame retardant,adhesion and ceramicization.The details are as follows:1.Designed the pendant methoxypolysiloxane(PMOS)with pendant groups containing different methoxy groups,using polymethyl hydrogen siloxane and methanol as raw materials and a solvent-free system under alkaline conditions in the reaction,PMOS was prepared,and the remaining methanol can be recovered and then fed.The reaction process is energy-saving and environmentally friendly.The curing reaction and the basic properties of the cured product were studied.It was found that when the total catalyst amount was 5 ‰ and the mass ratio of stannous octoate and polyetheramine(D230)was 4:1,Its surface drying time is short,and the curing depth is large;as the methoxyl content increases,the heat resistance of the pendant oxypolysiloxane increases,when the methoxyl content is 1.07mol/100g,it is under nitrogen The initial thermal decomposition temperature in the atmosphere is 425℃,the weight loss at 1000℃ is only 12.97%,the initial thermal decomposition temperature in the air atmosphere is 336℃,and the weight loss at 1000℃ is 17.95%.2.The Poly(methoxy epoxy)siloxane(PMOSA)with methoxy and epoxy groups in the pendant group was designed.Polymethyl hydrogen siloxane was combined with methanol and allyl glycidyl ether.The compounding of the catalyst can effectively promote its curing.With the increase of methoxy ratio,its flame retardancy and thermal stability are improved.When the proportion of epoxy groups introduced is 5%,its thermal decomposition temperature is 381℃,800℃ residual weight is 78.63%,and when the introduction of epoxy groups accounted for 50%,the initial thermal decomposition temperature is only 246℃,800℃ residual weight is less than 50%.It is applied to the study of glass adhesion and coating adhesion,when the epoxy group accounts for 20-30%,PMSOA has good adhesion on the glass surface,the shear strength is greater than 1.86MPa,and after the glass surface is treated,the adhesion can reach level 0.As a compatibilizer,PMOSA improves the compatibility of PMOS and epoxy resin.The addition of polysiloxane improves the flame retardancy of epoxy resin composites,limit oxygen index increased by 3.1.3.The ceramizable silicone resin with PMOS as the substrate is designed,and the active filler added can effectively improve the mass loss rate.In the air atmosphere,significant weight loss of ceramic silicone before 600℃.At 600℃ or higher,boron carbide is oxidized and the mass of the system is increased.Active fillers also have a beneficial effect on the compactness of the ceramic body.The ceramization mechanism of the ceramicized silicone resin was analyzed by SEM,XRD,etc.The polymer was pyrolyzed at 400℃ to 600℃,and then the flux began to melt to form a liquid phase at 800℃ to 1000℃,and the pyrolysis products and inorganic fillers were formed.A eutectic reaction occurs,and a new crystal form is formed after cooling,thereby preparing a ceramic body.When the calcination temperature is 1000℃,its compressive strength reaches 54.8 MPa,which is 2.9 times that before calcined,and its three-point bending strength is 66.8 MPa,which is 6.4 times that before calcined.When calcined at high temperature,the ceramic body has obvious linear shrinkage.