Resistivity, commercial solutions

Soon after vinyl BR s were first introduced commercially, it was recognized that the vinyl structure imparted non-typical dynamic properties. In particular, their vulcanizates showed improved resistance to heat build-up when compared to emulsion SBR. j O Before relating the special contribution of the vinyl structure to properties, it is informative to first determine the influence of styrene content (at constant vinyl) on the two fundamental properties of interest Tg and tan 6, as shown in Figure 14. As expected, both Tg and tan 6 increase almost linearly with styrene content. Thus like a conventional tire tread rubber, the rolling resistance of solution SBR s prepared using lower amounts of styrene is accompanied by a decrease in the wet traction of the rubber. 

High Water-Base Fluids. These water-base fluids have very high fire resistance because as Httle as 5% of the fluid is combustible. Water alone, however, lacks several important quaUties as a hydrauHc fluid. The viscosity is so low that it has Httle value as a sealing fluid water has Httle or no abiHty to prevent wear or reduce friction under boundary-lubrication conditions and water cannot prevent mst. These shortcomings can be alleviated in part by use of suitable additives. Several types of high water-based fluids commercially available are soluble oils, ie, od-in-water emulsions microemulsions tme water solutions, called synthetics and thickened microemulsions. These last have viscosity and performance characteristics similar to other types of hydrauHc fluids. 

Atmospheric corrosion is electrochemical ia nature and depends on the flow of current between anodic and cathodic areas. The resulting attack is generally localized to particular features of the metallurgical stmcture. Features that contribute to differences ia potential iaclude the iatermetaUic particles and the electrode potentials of the matrix. The electrode potentials of some soHd solutions and iatermetaUic particles are shown ia Table 26. Iron and sUicon impurities ia commercially pure aluminum form iatermetaUic coastitueat particles that are cathodic to alumiaum. Because the oxide film over these coastitueats may be weak, they can promote electrochemical attack of the surrounding aluminum matrix. The superior resistance to corrosion of high purity aluminum is attributed to the small number of these constituents. 

Ethoxylated andSulfatedAlkylphenols. Because these aLkylphenols degrade less readily than the sulfated alcohol ethoxylates, their anticipated expansion failed to materialize, although by 1965 they were widely used in retail detergent products. Sulfated alkylphenol ethoxylates are used in hospital cleaning products, textile processing, and emulsion polymerization. Sulfated alkyphenol ethoxylates are sold as colorless, odorless aqueous solutions at concentrations of >30%. The presence of ethylene oxide in the molecule increases resistance to hardness ions and reduces skin irritation. Representative commercial sulfated alkylphenol ethoxylates are given in Table 12. 

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