| With the development of the industrialization, urbanization and continuous upgrade of consumptive structure, energy demand in China tends to grow rapidly. Because of constrains from domestic resources and environmental capacity, and the effect from global energy security and climate change, the restriction of resource and environment increases gradually. It is scientific researchers and enterprise employees’responsibility to accelerate the construction of a resource-saving, environment-friendly society. The technical bottleneck of increasing the monomer conversation rate in emusion polymerization of styrene butadiene rubber (SBR) and the green terminator was respectively focused on, technical innovation has been carried out for the process of SBR in emulsion polymerization which was introduced in80s of last century, increasing the monomer conversion rate of Styrene Butadiene Rubber in emulsion polymerization and environmental performance of new technology has been investigated.Firstly, Effect of prolonging the reaction time to icreasing the monomer conversion on the performances of (SBR) in emulsion polymerization was investigated with the industrial original formula. The results showed that the monomer conversion was increased by prolonging the reaction time, the SBR properties of production such as combination of the styrene content, organic acid content, soap content can meet up with the requirement of the national standard GB8655-88. But the Mooney viscosity of the rubber exceeded the standard slope, which is the technical bottleneck of increasing the monomer conversion. The latex viscosity, properties and molecular weight distribution of rubber synthesized by increasing the monomer conversion was also studied. It indicates that the latex viscosity, the number averge molecular weight and weight average molecular weight of rubber increased with increasing the monomer conversion, the relative molecular mass distribution width index is larger. That is to say, the molecular weight distribution broadens. It revealed that the exceeding of Mooney viscosity of SBR is caused by the latex number of nucleation, polymer molecules of molecular weight and its distribution.Secondly, one molecular chain propagation progress and the neacleation stage in emulsion polymerization for SBR was simulated by Monte Carlo method respetively with original formula. The influences of formulation conditions on the micro structure of the emulsion polymerization of SBR were researched. The results showed that in the later reaction stage the instantaneous combination styrene content increases and the average combination styrene content increased rapidly. The average combination styrene content ranged from22.5%to24.5%with the monomer coversion ranged between38%and74%. The Np is in proportion to [S]0.6062[I]0.4055for SBR emulsion polymerization what agrees well with the Smith-Ewart theory. If the target is to rate the monomer conversion up to70%only by changing the original formula of the emulsifier and the initiator concentration, and the product of latex particles and the polymer chains should be in keeping with what is in the62%of the monomer conversion of the original formula, the simulation results showed that the amount of initiator should be increased by13%-35%, and the amount of emulsifier should be increased by13%-22.2%. The established model gives the guidance of adjusting formula to increase the monomer conversion rate in emulsion polymerization of SBR.On this basis, effects of the amount of initiator, emulsifier, molecular weight regulator and its feeding method on the emulsion polymerization for SBR were studied in experiments. The results indicated that the reaction time of monomer conversion reaching up to70%can be shorten obviously by increasing the amount of initiator and emulsifier. The Mooney viscosity of rubber syntheised by the monomer conversion of70%meets the requirement of national standard range with the additional molecular weight regulator. The latex viscosity problem can be solved by properly increasing the amount of electrolyte solution. In the adjustment formula based on the original one, the amount of oxidant and reduction agent in the initiator is120%, the amount of reduction agent keeps the same, and the initialization amount of emulsifier and molecular weight regulator is100%, the additional amount is20%with the polymerization reaction time of2hours, the amount of electrolyte solution is110%. The monomer conversion rate reaches up to70%with the polymerization reaction time of8.5hours. The rubber performances meet the requirement of national standard. It is formed a new technology for SBR emulsion polymerization with short reaction time and high monomer conversion rate. And it also investigates the conversion rate with the changes of reaction time and the performance changes of intermediate product in laboratory polymerization reactor. It indicated that the new formula can effectively improve the latex number of nucleation, the latex particle size distribution, and polymer molecules of molecular weight and its distribution.Next, the back-propagation neural network was trained by the original formula and adjustment formula. The average combination styrene content and the Mooney viscosity of SBR can be effectively predicted by the BP neural network model. The application of basic theory for adjustment recipe and prediction the performance of SBR was enriched.Then, the termination mechanism and the nitrosamine source of the original terminator were studied based on the anlysis of initiator role and the trigger mechanism of the reduced oxidation initiator system. The results showed that the main resource of nitrosamine in SBR is the production reacted secondary amines, which was easily formed by diethyl hydroxylamine, dimethyl dithiocarbamate sodium formate under acidic conditions in the gel, with sodium nitrite or nitrogen oxides in the air. It screened the terminator without forming secondary amines and with the termination of free radical fuction. The results showed that the environment-friendly terminator was composition of the main agent, which was the mixture of N-isopropyl hydroxylamine and monomethyl dithiocarbamate sodium formate, with the auxiliary agent, which was the tensile stress intensifier. With the amounts of main agent0.6%o and the tensile stress intensifier between the amounts of1.5‰-2.5‰. The rubber performances can meet up with the requirements of the superior SBR product, the reproducible preparation was fairly well. The nitrosamine compounds of SBR were not detected by German Rubber Industry Institute (DIK). The environmental friendly terminator can be used for environmental friendly SBRLastly, the transformation of the existing SBR industrial devices based on the laboratory results, the industrial experiment with increasing the monomer conversion to70%and increasing the monomer conversion to70%of environmental friendly SBR was done respectively. The results showed that the control indexes of the experiments were stable with the similarity of the original monomer conversion of62%, the properties of synthesis rubber and compound rubber can meet up with the requirements of the superior SBR product.The performances of environmental friendly SBR by industrial experiment and the original SBR was tested, the properties of two type rubber meet up with the requirements of the superior SBR product. The Mooney scorch time of environmental rubber was longer than original rubber, that is to say, the environmental friendly had a better processing security. The nitrosamine compounds of environmental friendly were not detected by European authorities inspection departments of German Rubber Industry Institute (DIK), the performances of the original SBR can be completely replaced environmental friendly by the product user of technology development department of Fuxin Huanyu Rubber (Group) Co., Ltd.The results enhanced a new cognition of the introduction technology of SBR in emulsion polymerization. A new technology in emulsion polymerization for SBR was formed by a short reaction time and high monomer conversion rate. The application of basic theory of SBR in emulsion polymerization was enriched. |
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