Oil-Extended Rubbers

Abstract

One hesitates to close this review by adding a paragraph of conclusions. The term “oil-extension principle” introduced a new concept to the manufacturer of synthetic rubbers. The principle (if it may be identified by such a word) and the application of the products it generated do not involve any novel or unfamiliar approaches to the art of rubber compounding. Indeed, it would be rendering a disservice to the progress of their adoption by industry to suggest that it required a revision in the viewpoint of the rubber compounder. The use of softeners in compounding was almost coincidental with the discovery of rubberlike substances by the explorers of the 16th century. The development of carbon blacks having more useful characteristics in rubber came after the compounder had become familiar with the application of innumerable inorganic fillers in rubber and, indeed, soots and lampblacks. The tailor-made synthetic rubbers were developed by the chemical industry in the second-quarter of the 20th century and it is scarcely likely that higher molecular weight types would not be produced nor that any inherent processing problems would not be solved when there existed an economic and raw material incentive to do so. These are the contributions of the polymerization chemists and the synthetic rubber industry. Where it is more economically-attractive and technically-desirable to add softener and filler to the synthetic rubber in the manufacturing process, oil-extended rubbers and filler masterbatches will be provided as raw materials for the rubber industry. If on the other hand, these ingredients may be added quite readily during factory mixing operations, without any detrimental effects on the polymer quality, the synthetic rubber producer would be quite unwise to attempt to usurp the functions of the rubber manufacturer. The income of the rubber manufacturer, depends upon the skill and economy that he applies to the operation of mixing rubber with liquid and solid materials and this is the prime occupation of a rubber compounder. It would avail the synthetic rubber producer nothing to try and convince the compounder that he is doing something novel and unusual by preparing softener-filler masterbatches. However, the compounder will be receptive to a pre-blended product that enables him to produce rubber mixes of better or different quality at an equal, or lower, cost. This is the aim and accomplishment of oil-extended rubbers.

Sources of fine organic aerosol. 3. Road dust, tire debris, and organometallic brake lining dust: roads as sources and sinks

“…Pigments such as carbon black are used as filling and reinforcing agents, providing the necessary stability of the tire. About 20-30 % of the tire stock formula is made up of carbon black particles having average diameters ranging from 10 to 500 nm (11,16,17). In order to adjust the materials' viscosity to the degree necessary for the dispersion of fillers and to ensure lubrication during molding, softeners are commonly added.…”

“…Waxes, consisting of higher n-alkanes (sunproof waxes) are used in quantities ranging from 0.5 to 1.0% of the rubber material and serve both as softeners and as UVand ozoneprotecting agents (11,14,15). Together with the aromatic and naphthenic-type compounds added as extenders, additional n-alkanes are introduced into the rubber stock (16).…”

Butadiene

“…Typical emulsion polymerization processes incorporate about 75% butadiene. The initiators are based on persulfate in conjunction with mercaptans (197), or organic hydroperoxide in conjunction with ferrous ion (198). The rest of SBR is produced by anionic solution polymerization.…”

Health aspects of the curing of synthetic rubbers.

“…Since vapor pressure data for most technical compounding ingredients are unava'lable, it is impossible to predict exact emissions at process temperatures. However, the literature reviewed indicates that losses occur primarily among ingredients which are either liquids at room temperature or solids with melting points at or below curing temperatures (1)(2)(3)(4)(5)(6)(7)(8)(9)(10). Polymer or Blend Volatiles.…”