Published: Jan 2010
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WAXES CAN BE DEFINED AS HYDROCARBONS OR hydrocarbon derivatives that are solid at room temperature, but are low-viscosity liquids at moderate temperatures. Waxes are thermoplastic materials but, due to their low molecular weight, they are normally not considered to be plastics or polymers. Common wax properties are water repellency, smooth texture, low toxicity, low odor, combustibility, solubility in most organic solvents, insolubility in water, and low reactivity. By far the most important waxes in terms of volume produced and economic impact are petroleum waxes. Petroleum waxes are derived from crude oil. Other types of wax include hydrogenated triglycerides made from tallow or plant oils; animal waxes, such as beeswax; plant waxes such as carnauba and candelilla; mineral waxes such as montan; and synthetic waxes such as Fischer- Tropsch and polyethylene. Although this chapter deals only with petroleum waxes, much of the information and many of the test procedures can be applied to other types of wax as well. In the early years of petroleum processing, the waxy materials that were separated were regarded as having no commercial value. Ultimately, however, wax products were recovered that, with the benefit of additional refining, were found to be useful in many applications. A variety of grades of petroleum wax evolved that covered a broad range of physical properties. Now the petroleum wax product lines are in demand for a wide variety of uses. Modern refining methods have made available select grades of wax of controllable and reproducible quality, and some have unique properties for specialized applications.
Case, Alan R.
Technical Director, Sasol Wax North America, Richmond, CA