Polyethylene wax (also known as PE wax) is a low molecular weight polyethylene polymer. Because of it’s low molecular weight Polyethylene Wax has wax like physical characteristics that include properties such as low viscosity, high hardness (brittleness) and relatively high melt point.
There are a variety of methods for producing Polyethylene wax. Polyethylene wax can be made by direct polymerization of ethylene under special conditions that control molecular weight and chain branching of the final polymer. Another method involves thermal and/or mechanical decomposition of high molecular weight polyethylene resin to create lower molecular weight fractions. A third method involves separation of the low molecular weight fraction from a production stream of high molecular weight polymer. These last two methods produce very low molecular weight fractions that should be removed to avoid a product with low flash point that can result in flammability, migration and other safety issues.
There are three major characteristics that differentiate one polyethylene wax from another. They are I) Molecular weight, II) Degree and length of polymer branching, III) Monomer / polymer composition. Changing any of these factors will alter the physical characteristics of the polyethylene wax, such as viscosity, hardness, melt point, reactivity etc.
Homopolymer polyethylene wax can also be functionalized by means of oxidation that adds acid and ester functional groups to the polyethylene wax. Oxidized polyethylene wax is polar and has different compatibility properties that polyethylene homopolymer. This functionality allows for emulsification of oxidized polyethylene wax and also increases compatibility with polar materials such as PVC.
Paraffin wax is usually produced as a by-product of oil refining. It has a molecular weight which is usually less than half that of most polyethylene waxes. Because of this and other differences, paraffin wax usually has a much lower melt point and is softer than most polyethylene waxes.
FT waxes are another class of waxes that are only produced by a limited number of suppliers (i.e. Shell and Sasol) due to the large capital requirements involved in constructing these plants. FT waxes are produced in the process of making synfuels. Variations in properties of FT waxes are generally limited to modifying melt point.
Polyethylene waxes can be supplied in many forms. The can be supplied in bulk with the use of specialty bulk trailers that are heated. Polyethylene wax can be finished as a prill, or atomized powder. Polyethylene waxes can also be ground into various particle sizes. Harder waxes are usually easier and less costly to grind than are softer waxes.
Polyethylene waxes have very unique polymer properties that make them useful in many applications. The major functions of polyethylene wax in many formulations are to either provide lubrication and/or provide physical modification of a formula by changing viscosity and / or melt point.
Raw polyethylene wax is derived from extracting low molecular weight fractions from high density polyethylene resin streams. These streams contain contaminants and non – wax fractions such as catalyst, volatile fractions and water. Refined polyethylene wax derived from high density polyethylene resin manufacturing processes undergo an extensive refining process that removes catalyst, volatile fractions and water. The final product is usually finished by prilling into 1 to 3 mm free flowing prills.
Raw polyethylene wax is usually found in flake form. Upon inspection of the flakes, water from processing can be exposed or trapped inside the flakes. Catalyst residue in raw polyethylene wax can be found when the wax is sintered. Also upon processing at elevated temperatures the raw polyethylene can cause smoking or even fires due to the volatiles being vaporized/ignited. The volatiles, water and catalyst present in raw polyethylene can lead to significant yield loss vs fully refined polyethylene wax. For over 40 years Marcus has offered only fully refined polyethylene waxes.
Paraffin wax is usually produced as a by-product of oil refining. It has a molecular weight which is usually less than half that of most polyethylene waxes. Because of this and other differences, paraffin wax usually has a much lower melt point and is softer than most polyethylene waxes.
FT waxes are another class of waxes that are only produced by a limited number of suppliers (i.e. Shell and Sasol) due to the large capital requirements involved in constructing these plants. FT waxes are produced in the process of making synfuels. Variations in properties of FT waxes are generally limited to modifying melt point.
Be sure to visit Dr Wax to get any other wax questions answered!