Ctivation Modification Of Carbon Black From Waete Tire And Its Application In Natural Rubber

The development of automobile industry has greatly improved people’s travel efficiency and work efficiency,however,with the increase of the number of cars,the number of waste tires has also increased sharply.A large number of discarded tires not only pollute the environment but also waste resources.Thermal cracking technology has highly-efficient and environmentally-friendly advantages.The additional products of pyrolysis technology to waste tire pyrolysis mainly include cracking gas,oil and solid residue.Solid residue after treatment can be used as secondary carbon black for rubber products,however,compared with commercial carbon black,cracked carbon black（CBP）has disadvantages of high ash content,poor activity and large particle size,so the reinforcing performance of rubber is far less than commercial carbon black.To improve the quality of cracking carbon black,the combined pickling method,heat treatment activation method and adding modifier method were proposed to modify the cracking carbon black in this dissertation.The effects of modified cracking carbon black on the processing properties,vulcanization characteristics,mechanical properties and dynamic mechanical properties of natural rubber were also investigated.The main research contents and achievements of the dissertation are as follows:（1）Based on the defects of high ash content and poor surface activity of CBP,the method of H₂SO₄（A acid）and HF（B acid）pickling was proposed to modify CBP.The structure of the modified cracked carbon black（AB-CBP）was characterized.The results show that the content of inorganic impurities such as Zn O,Zn S and Si O₂in AB-CBP are significantly reduced,and the ash content is reduced from 17%to less than 0.5%,reaching the standard of commercial carbon black N660.After pickling modification,the number of organic functional groups on the surface of AB-CBP is increased and the branched chain structure of AB-CBP is more developed.The experimental results of carbon black filling natural rubber show that the rubber filling degree of AB-CBP is increased,and the char time is prolonged.Compared with the original CBP,the tensile strength is increased by 27%,the tearing strength is increased by 25%,and the 300%fixed elongation stress is increased by 56%.In addition,the cross section morphology of AB-CBP filled rubber is more orderly and smooth,and the stress concentration point appears later in the loading process.The crosslinking density of rubber increases and the wear performance increases.Compared with the original CBP filled rubber,the dynamic mechanical properties are better,and the dispersion of the filler in the rubber is more uniform.The overall reinforcement level of AB-CBP is similar to that of N660.（2）Two heat treatment activation methods were proposed to remove the residual organic rubber hydrocarbon impurities on the surface of CBP,and the surface of CBP was activated and modified.The experimental results show that CBP activated at 500℃for 1 h has better reinforcing properties in rubber than CBP activated at 300℃,400℃and 600℃.The Payne effect and the maximum torque（MH）of CBP activated at 500℃are the weakest in rubber.Secondly,CBP was activated by high temperature transient heat treatment（increasing the heat treatment temperature to shorten the activation time）.The results show that the removal rate of organic impurities is the highest at 800℃.The tensile strength of CBP filled rubber activated at 800℃is increased to 9.25 MPa,which is 8%and 30%higher than that at 700℃and 900℃,respectively.In a word,the performance of CBP activated at 800℃as rubber filler is better than that of at 700℃and 900℃.（3）CBP was modified by silica black,silane coupling agent and accelerator.The results show that when the ratio of CBP to silica black is 40/10,the rubber vulcanization effect is the best,the mechanical property is the strongest,the tensile strength is 21.55 MPa and the 300%constant elongation stress is 11.55MPa.When the ratio of silica black is too high,the agglomeration effect is obvious and not conducive to processing and mixing.The direct modification of CBP by coupling agent KH-560 increases the cross-linking effect between carbon black and rubber,and significantly improves the reinforcing properties of rubber.The accelerant modified CBP increases the vulcanization degree of rubber and improves the network structure of rubber.The tensile strength of the rubber modified by CZ accelerator（N-cyclohexyl-2-benzothiazol-sulfamide）is increased by 10.76 MPa,the tearing strength is increased by 40.83 KN m^-1 and the hardness is increased from 55 to 62.