Research On The Oxidative Modification Of Naphthenic Vacuum Residue

Oxidative modification of vacuum residue can significantly change the composition and structure to extend the scope of residue application.In this study,the naphthenic vacuum residue was modified through air-blowing oxidation,and the effect of reaction conditions on residue oxidation were studied.The composition and structural changes of oxidized residue were determined to investigate the mechanism of air-blowing oxidation,as well as the polycondensation performance.Furthermore,the applications of oxidized residue as compatible agent of high aromatic for SBR were studied.Residue oxidation reaction is mainly affected by the combined effects of temperature,time and air flow,and the impact of which on softening point could complement each other.While the optimal amount of air flow is 120 m3·t-1·h-1.Oxidized residue with a specific softening point synthesized at high temperature for a short time also could be synthesized at low temperature for a long time.Air-blowing was very effective in raising the molecular weight,softening point and coking values.Oxidation of residue carried out at 280℃ shows the maximum ΔCV/ΔSP ratio,the oxidized product of which are considered to be a good matrix precursor for the preparation of C-C composites.The composition and structure of oxidized products were significantly changed during the oxidation process.From the chemical composition perspective,the feedstock was occurred a series of tandem reaction to produce the so-called “component migration” phenomenon: saturates were converted to aromatics,while aromatics were condensed with bridge-bond into resin,or together with resin deeply condensed into asphaltene.And the relative molecular mass of each component tended to the polymer-movement direction.Elemental analysis showed a progressive increase of C/H ratio,oxygen content and the average molecular formula.All these results reinforce the view that oxygen was incorporated into asphalt molecules and the reactions of dehydrogenation polymerization and crossing-linking with biphenyl-type of oligomers occurred severely.From the structure change of view,oxygen groups were formed,exited as hydroxyl firstly.Along with the oxidation time,the carbonyl functional groups gradually emerged.Under the action of thermal,naphthenic rings were open and alkyl side-chains were cleavage.Air-blowing created oxy-radicals,which promoted oxidative dehydrogenation,aromatization of naphthenic structures and aromatic ring condensation,which leads to oligomeric cross-linked structures and highly condensed aromatic molecules.The iodine adsorption index shows that with the prolongation of the reaction time,the increased content of cross-linked structure,which in the form of a three-dimensional state,destroyed the order of vacuum oil structure.When oxidized residue were high-temperature poly-condensed,the yield and coking value increased significantly with the softening point of oxidized product.The optical structure of parent and oxidized asphalt is completely isotropic,whereas those from the thermally treatment at 410 C for 8 h contained mesophase.The oxidation reaction is the combination of cross-linking and condensation,which lead to the formation of cross-linked olygomers inhibiting the development of anisotropy unit and structure.The environmental oxidized asphalt(OMVR)with high CA value could be used as additive for the production of tire rubber.In this study,the application of OMVR partly replacing commercial environmental aromatic oil by equal weight in tire rubber was investigated.Experimental results revealed that the mooney viscosity,flexing resistance,tearing resistance,aging properties and abrasive resistance of vulcanized rubber were improved by OMVR,while the rolling resistance of vulcanized rubber was minimized.Therefore,OMVR used as rubber additive can meet the demands of tire rubber processing and performance behavior under the similar processing technic of rubber processing.