Experimental Study On The Recycling Residue Of Waste Silicone Rubbers In Acid-catalyzed Depolymerization

With the increasing of silicone rubber consumption currently, the recycling of waste rubber has become very urgent and important, but the technology of recycling of waste rubber in our country is still at an early stage, and the focus of the study revolve around how to improve the recovery rate of DMC.Because of the technical defects of current recovery, the recovery residue of depolymerization have the problem of components complexity and exist residual silicone oil, limit the recycling of residues. Not only cause a huge waste, pollute the environment of factory and affect workers health, but also serious pollute the environment outside the factory, endangering the safety of the surrounding environment.By the researched of the status of recycle waste silicone rubber at home and abroad,and the depolymerization mechanism of silicone rubber recycle, analysised the composition of residue and the property of depolymerization. Comparison on the relevant experimental methods, this paper selected the method of constant temperature electric heating-jacket heating, to qualitative and quantitative analysis of pyrolysis residues.Through the analysis of thermogravimetric experiment, found that the weight reducing of pyrolysis residue had no regularity, and by heating from 22℃to high temperature 600℃, residue mass loss rate was 30.4%. There were some complex chemical changes under high temperature, exsited several endothermic peaks and exothermic peaks, exothermic reaction and endothermic reaction coexisted, which the contained silane polymer oxidation and pyrolysis were complex change.Through experimental research, identify the best secondary recovery process state of pyrolysis residue as follows: heating temperature is 300℃, constant heating time is 60min, and the largest amount of recycling silicone oil was 25.73%. As the temperature increased, the property of recycling silicone oil were constantly changed, from the colorless, odorless, transparent liquid in 140℃, to the pungent odour, milky liquid in 200℃, andunder the pungent odour, yellow liquid in 340℃.By analysis of recycling silicone oil in GC-MS analysis technogy showed that, recycling silicone oil in 180℃mainly had D₃, D₄, D₆, linoleic acid and other substances, products relatively single and no significant chemical changes. Recycling silicone oil in 340℃mainly had D₃, D₄, D₅, D₆, phenol, oil methyl ester, hexadecanoic acid methyl ester, linoleic acid and other substances.Products were complexity, not only had the products of silicone oil oxidation, pyrolysis reaction,but also had the products of oxidation and pyrolysis reaction of additives and curing agent.The recycling silicone oil reuse difficult.In the last,by analysis the nature of experimental residue showed that, the density and particle size of second residue decreased significantly, the content of 80 mesh～120 mesh residue reached to 38.2%.Though determination the DBP of residue in different conditions known, DBP increased significantly, by 0.72ml/g of material, increased to maximum 1.24ml/g of 340℃. Recycled residue had a certain reusable, by a follow-up treatment, they can be reused as filler of rubber,and made into sound-absorbing materials used in highway terms.