Preparation Of Phenolic Resin Modified By Nano-ZrO₂-E And Its Applications

Phenolic resins are used for varnish,mould plastics,coatings,adhesives,ablation resistance materials due to their excellent properties such as thermal stability,flame retardancy and adhesiveness,involving transportation,construction,military,mining industries and they are closely related to human life.Polybenzoxazine is a new class of thermosetting phenolic resin which has developed rapidly in recent years.It not only have the advantages of nearly zero shrinkage upon curing,low water absorption rate and high modulus but also that its raw material is easy to obtain and the combination properties are excellent.Now,it is irreplaceable material in many industries,such as widely used in aerospace,electronic packaging materials,flame retardant materials.However,with the rapid growth of science and technology,weakness of therom-oxidation,high brittleness have been major limiting factors in their applications.Even if benzoxazine does not generate any volatiles and near zero shrinkage,the temperature is high during the polymerization.At the same time,there are many means to promoted extensive research to improve their performance.In recent years,nanomaterials provide a new way for the preparation the high performance resin,particle can react with the resin because of its reactive group,form a larger network structure after curing,it also can be used as an inorganic filler to fill the resin,improve the comprehensive performance of the resin.Nano-ZrO₂ have attracted much attention owing to its thermal stability,anti-wear,corrosion resistance,mechanical,optical and electrical.So,we prepared nano-ZrO₂by hydrothermal,and modified with silane coupling agent,then to modify of resin,to apply to impregnate of graphite and grinding wheel.The major content are as follows:1.Nano-ZrO₂ has been synthesized by hydrothermal,the diameter is about 10 nm and modified with silane coupling agent?nano-ZrO₂-E?.A benzoxazine was synthesized from 2-allylphenol,4,4 diaminodiphenylmethane and formaldehyde,the precursor was modified with nano-ZrO₂-E and bismaleimide?BMI?.The structure of monomer was confirmed by FR-IR and NMR.The curing behaviour were studied by FR-IR and DSC,BMI reduces the curing temperature of resin,from 272? to 220?.BMI solved the weakness of the high curing temperature.Thermal analysis showed that the thermal stability increases with the addition of bismaleimide,and the nano-ZrO₂-E further improves the thermal stability of the resin,the thermal stability is best when the content is 3%,whose temperature at weight loss 5%and 10%is 390.00? and 410.50? respectively,char yield ratio is 45.80%at 800? under nitrogen atmosphere.2.Nano-ZrO₂-E-PR has been synthesized in the presence of phenolic,formaldehyde and nano-ZrO₂-E via in-situ polymerization.Its structure has been examined by the FT-IR and Raman.The commercially available nano-ZrO₂-E is easy to agglomeration and the dispersion is unevenly,so the follow-up only adopted made by ourselves nano-ZrO₂-E to modified phenolic resin.Its morphology performance has been investigated by SEM.Thermo gravimetric analyzer indicate its Td10%and 800? char yield than ordinary phenolic resin increased by 57? and 8.7%,respectively when the addition amount is only 1%.3.To prepared nano-ZrO₂-E-PR for small-scale pilot test.The TGA showed that the thermal property is still very stable and nano-ZrO₂-E dispersed evenly.The industrial product was used in impregnated graphite and preparation of grinding wheel.According to the procedures,the compressive strength of graphite is improved from 18.12 MPa to 28.25 MPa.Friction test shows that the nano-ZrO₂-E increased the wear resistance of the resin,the grinding tests showed that the modified PR as binder could improve the using performance of the grinding wheel.It has reached the expected effect.