Synthesis And Properties Of COPNA Resin From Aromatic-enriched Feedstocks

As byproduct of oil refining and ethylene production,fluid catalytic cracking?FCC?slurry,vacuum residue and ethylene tar are in large quanlity,while their added-value applications are in low level.With a large number of bicyclic or polycyclic aromatic hydrocarbons that with high substitution reaction activity,theoretically,FCC slurry,vacuum residue and ethylene tar can react with cross-linking agent to prepare condensed poly-nuclear aromatic?COPNA?resin.COPNA resin is a kind of carbon material with good cohensiveness,which can be usedas binder to prepare carbon brush and other products used in the field of electric carbon,thus a new technique to realize the high added-value application of heavy aromatic oil is forwarded.In this paper,FCC slurry,vacuum residue and ethylene tar were used as raw materials to prepare COPNA resin.The pretreating methods,such as solvent extraction and heat treatment,were used according to the property of materials.The composition and structural changes of raw materials before and after pretreatment were investigated via the analyses of the group composition,FT-IR,¹H-NMR and elemental analysis.The average molecule structure and molecular model of raw materials before and after pretreatment were calculated by improved Brown-Ladner method.COPNA resins were then successfully synthesized from above aromatic-enriched oil at relatively low temperature,during which 1,4-benzenedimethanol?PXG?,trioxymethylene and benzaldehyde were used as cross-linking agent,p-toluene sulfuric acid was used as catalyst.Properties of the abtained COPNA resin,such as softening point,carbon residue and content of?resin,were systematically characterized.The effect of crosslinking agent on the adhesivity and heat resistance of COPNA resins was studied.To achieve a definitive insight into the condensation mechanism,the critical characteristics of the resultant COPNA resin and raw material were purposely explored via FT-IR,¹H-NMR,vapor pressure osmometer?VPO?,and elemental analysis.Cured COPNA resin was obtained through heat curing process,and the curing mechanism and behavior were investigated by FT-IR,¹H-NMR,SEM,XRD and thermogravimetric analyses.The curing kinetics of COPNA resin synthetized from phenanthrene was studied by differential scanning calorimeter?DSC?.The pyrolysis kinetics of as-made COPNA resins were studied by the method of Miura integral,and the chemical changes in the pyrolysis process of the resin were also studied.In order to increase the heat resistance and adhesivity of COPNA resin,modified COPNA resin was synthesized through copolymerization by phenolic resin and epoxy resin,and the influence of modifier content on the properties of the modified resin was investigated.By analyzing the changes on the molecular structure and functional groups of COPNA resin before and after modification,the modification mechanism was discussed.COPNA resin/graphite composites were made,and the effects of preparation conditions on the properties of the flexural strength,Shore hardness,resistivity and bulk density were investigated,and the feasibility of COPNA resin as a binder for carbon brush was discussed.The results show that the aromatics content and condensation activity of FCC slurry and vacuum residue can be significantly increased via pretreatment.The synthetic mechanism of COPNA resins from aromatic-enriched feedstocks is based on the acid-catalized positive ion condensation polymerization.The cured COPNA resin has a good streamline structure,smooth surface,better molecular alignment and more excellent heat resistance than those of the uncured resin.The curing reaction of COPNA resin from phenanthrene,takes place between 150²00°C,and the activation energy obtained by Kissinger method is basically consistent with that by Ozawa method,which are 71.90 and 75.49 kJ/mol,respectively.Due to the wide distribution of polycyclic aromatic,the activation energy of COPNA resins synthesized from three kinds of aromatic-riched materials are not concentrated,and the curing exothermic peak are not obvious.Thermogravimetric analyses indicate that the weight losses of the uncured and the cured COPNA resins both can be divided into three stages.The temperatures of T_i,T_f and T_max of the cured COPNA resins are found to be higher than those of the uncured resins.The three kinds of resins derived from the aromatic-riched materials,have two activation energy distribution peaks,which are mainly caused by the volatilization of small molecules and the intermolecular condensation and dehydrogenation reaction of COPNA resin.Phenolic resin and epoxy resin have significant effect on the residual carbon,toluene insoluble,quinoline insoluble and beta resin content of COPNA resin.The heat resistance of COPNA resin has been significantly improved as the contents of phenolic resin and epoxy resin are 8 wt%and 5 wt%respectively.The properties of COPNA resin based carbon brushs,such as flexural strength,Shore hardness,resistivity and bulk density,are close to the best foreign products,and COPNA resins are expected to be used as commercial carbon brush binder in the near future.