Rubber manufacturing process

Parasiewicz, W. Analysis of chemical hazards in the rubber manufacturing process. Elastomers 5(1), 17-28 (2001). in Polish... 

Polysulfide rubber manufacturing processes are described in more detail by Bertozzi [26]. Briefly, the processes involve preparation of sodium polysulfide (S + NaOH), and reaction with bis(2-chloroethyl)formal along with 2% of a branching agent such as 1,2,3-trichloropropane to give a mercaptan terminated polymer of MW approximately 80,000 similar to that described in Preparation 2-2, Method A. 

A number of rubber manufacturing processes involve the use of solvents, which in the past were often vented to atmospheres after fulfilling their purpose in the manufacturing process. Processes involving solvents include ... 

The structure and morphology of multiphase polymers have been discussed (see Section 5.3), and the particle size and distribution have been shown to be quite important for mechanical properties and applications. In many polymers (e.g., ABS), the particle size distribution is determined during the rubber manufacturing process. The surfactant concentration during emulsion polymerization controls the size distribution of the rubber latex, and subsequent grafting increases the size further. Particle sizes can be controlled to yield a range of sizes or a monodisperse latex. Particles that are larger... 

Additional information on elastomer and SAN microstmcture is provided by C-nmr analysis (100). Rubber particle composition may be inferred from glass-transition data provided by thermal or mechanochemical analysis. Rubber particle morphology as obtained by transmission or scanning electron microscopy (101) is indicative of the ABS manufacturing process (77). (See Figs. 1 and 2.)... 

H. Long, ed., Task Compounding and Processing ofRjcbber, ACS Rubber Division, Washington, D.C., 1985. An intermediate-level textbook focusing on basic manufacturing processes for mbber articles. 

It is clear from Table 27.1 that the energy content of the car itself - that is of the steel, rubber, glass and of the manufacturing process itself - is small less than one-tenth of that required to move the car. This means that there is little point in trying to save energy here indeed (as we shall see) it may pay to use more energy to make the car (using, for instance, aluminium instead of steel) if this reduces the fuel consumption. 

Rubber manufacturing and processing giving rise to rubber process dust and rubber fume Used engine oils... 

Another common device used in the rubber industry is the thin film evaporator. This device is very often used in the manufacture of ultra-low molecular weight elastomers that are used in sealant applications or specialty coatings, and as processing aids in conventional rubber compounding processes. The thin film evaporator described earlier, has found a multitude of other industry applications, including food processing operations. 

Durihg recent years a considerable amount of re-.search has been undertaken to understand what in the makeup of a polymer affects the processability. In the late 1980s, the Rubber Manufacturers Association in the United States undertook a research project with the Department of Polymer Engineering at the University of Akron to evaluate the laboratory equipment available using specially made butadiene-acrylonitrile polymers with different acrylonitrile levels, molecular weights, and molecular weight distributions. The results from the study confirmed that, from the processing variables viewpoint, the major factors are frequency (shear rate), temperature (temperature), and deformation (strain). 

During the manufacturing process, if the grafting increases during early stages of the reaction, the phase volume will also increase, but the size of the particles will remain constant [146-148]. Furthermore, reactor choice plays a decisive role. If the continuous stirred tank reactor (CSTR) is used, little grafting takes place and the occlusion is poor and, consequently, the rubber efficiency is poor. However, in processes akin to the discontinuous system(e.g., tower/cascade reactors), the dispersed phase contains a large number of big inclusions. 

Process particulate pickup may significantly increase the risk of boiler foaming. This kind of problem happens in the crossover of hot to cold water during manufacturing processes, as in rubber tire factories, food can cookers and retorts, plastic injection molding, and the like). 

The properties of a plastic or rubber item are a combination of its intrinsic molecular properties as modified by the manufacturing process. For any given polymer there is a range of properties that can be accessed by changing the way in which it is processed. 

Thomas Hancock (1785-1865) is designated the father of the rubber industry and to him Great Britain is indebted for the honour of being the first country to manufacture rubber successfully as a large-scale project. His first major discovery, in 1819, was the process of masticating and mixing raw rubber. His subsequent claim, in his Personal Narrative published in 1857, that this was unquestionably the origin and commencement of the India-rubber manufacture, properly so called , has been amply verified since. 

The remaining latex is processed into dry rubber as sheets, crepes and bales. There is an International Standard for the Quality and Packing for Natural Rubber grades, the so-called Green Book , published by the Rubber Manufacturers Association. The following grades of NR listed in the Green Book are sold to visual inspection standards only ... 

The two-roll mill represents the earliest form of rubber processing machine, used by the rubber manufacturer being developed from the masticator of Hancock. Over the years the emphasis of the role of the two-roll mill has moved from being that of the prime means of compound preparation for the majority of the rubber industry, to that of secondary usage. In the modem factory conventional two-roll mills are used for compound blending and for sheeting off of compound mixed by other means. In addition they are used to warm-up compounds from store, and for a number of blending purposes to achieve compound uniformity for other processes. 

Workers in tire-manufacturing facilities may have a heightened potential for health hazards since the rubber vulcanization process can involve exposures to 77-hexane (Graham et al. 1995). 

Tetrachloroethane (TeCA) was the first chlorinated hydrocarbon solvent produced in large quantities before World War I [371]. It was used as a solvent for cellulose acetate, fat, waxes, greases, rubber, and sulfur. In a few cases, TeCA is used as a carrier or reaction solvent in manufacturing processes for other chemicals and as an analytical reagent for polymers [371]. TeCA was largely replaced by less toxic solvents after 1945. TeCA release in the United States varied from 44,000 pounds in 1988 to 66,000 pounds in 1991 [372]. 

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