This article discuses the meaning of paraffin wax, how it is made, the history, properties, the application and also the common uses.
What is paraffin?
Paraffin wax (or petroleum wax) is a soft colorless solid derived from petroleum, coal, or oil shale that consists of a mixture of hydrocarbon molecules containing between 20 and 40 carbon atoms.
It is a flammable waxy substance obtained from wood, coal, or petroleum and used chiefly in coating and sealing, in candles, and in drugs and cosmetics.
It comes in both liquid and solid form and is used throughout the UK in a wide range of industries. It’s an extremely versatile product, and so has a wide range of uses including heating oil, beauty products, candles and medicines.
History
Paraffin wax is acquired from petroleum by dewaxing light lubricating oil stocks. It was first produced in 1830 by Carl Reichenbach in Germany and commemorated a key advancement in candle making technology, as its burn was cleaner, more consistent than tallow candles and was cheaper to produce.
Initially, it had a low melting point, however, the addition of stearic acid later solved this. Paraffin wax production was thriving in the early 20th century from a rise in meatpacking and oil industries which generated paraffin and stearic acid as by-products.
READ: Oil and Gas Regulatory Consulting
Properties
It is mostly found as a white, odorless, tasteless, waxy solid, with a typical melting point between about 46 and 68 °C (115 and 154 °F), and a density of around 900 kg/m3. It is insoluble in water, but soluble in ether, benzene, and certain esters. Paraffin is unaffected by most common chemical reagents but burns readily. Its heat of combustion is 42 MJ/kg. The hydrocarbon C31H64 is a typical component of paraffin wax.
it is an excellent electrical insulator, with a resistivity of between 1013 and 1017 ohm-meter. This is better than nearly all other materials except some plastics (notably PTFE). It is an effective neutron moderator and was used in James Chadwick’s 1932 experiments to identify the neutron.
Paraffin wax is an excellent material for storing heat, with a specific heat capacity of 2.14–2.9 J⋅g−1⋅K−1 (joules per gram per kelvin) and a heat of fusion of 200–220 J⋅g−1. Paraffin wax phase-change cooling coupled with retractable radiators was used to cool the electronics of the Lunar Roving Vehicle during the crewed missions to the Moon in the early 1970s. Wax expands considerably when it melts and so is used in wax element thermostats for industrial, domestic and, particularly, automobile purposes.
If pure paraffin wax melted to the approximate flash point in a half open glass vessel which is then suddenly cooled down, then its vapors may auto ignite as result of reaching boiling liquid pressure.
How is paraffin wax made?
The feedstock for paraffin is slack wax, which is a mixture of oil and wax, a byproduct from the refining of lubricating oil.
The first step in making paraffin wax is to remove the oil (de-oiling or de-waxing) from the slack wax. The oil is separated by crystallization. Most commonly, the slack wax is heated, mixed with one or more solvents such as a ketone and then cooled. As it cools, wax crystallizes out of the solution, leaving only oil. This mixture is filtered into two streams: solid (wax plus some solvent) and liquid (oil and solvent). After the solvent is recovered by distillation, the resulting products are called “product wax” (or “press wax”) and “foots oil”. The lower the percentage of oil in the wax, the more refined it is considered (semi-refined versus fully refined). The product wax may be further processed to remove colors and odors. The wax may finally be blended together to give certain desired properties such as melt point and penetration. Paraffin wax is sold in either liquid or solid form.
Applications
In industrial applications, it is often useful to modify the crystal properties of the paraffin wax, typically by adding branching to the existing carbon backbone chain. The modification is usually done with additives, such as EVA copolymers, microcrystalline wax, or forms of polyethylene. The branched properties result in a modified paraffin with a higher viscosity, smaller crystalline structure, and modified functional properties. Pure paraffin wax is rarely used for carving original models for casting metal and other materials in the lost wax process, as it is relatively brittle at room temperature and presents the risks of chipping and breakage when worked. Soft and pliable waxes, like beeswax, may be preferred for such sculpture, but “investment casting waxes,” often paraffin-based, are expressly formulated for the purpose.
In a histology or pathology laboratory, paraffin wax is used to impregnate tissue prior to sectioning thin samples. Water is removed from the tissue through ascending strengths of alcohol (75% to absolute), and then the alcohol is cleared in an organic solvent such as xylene. The tissue is then placed in paraffin wax for several hours, then set in a mold with wax to cool and solidify. Sections are then cut on a microtome.
Common uses include:
- it is a white or colorless soft solid used as a lubricant, candles, crayons, electrical insulation and petroleum jelly
- Liquid paraffin (drug): a very highly refined mineral oil used in cosmetics and medicines
- Alkane: a saturated hydrocarbon used as a chemical solvent and in plastics
- Kerosene: a fuel also known as paraffin
- Mineral oil: any of various colorless, odorless, light mixtures of alkanes in the C15 – C40 range from non-vegetable (mineral) source, particularly a distillate of petroleum
- Petroleum jelly
- Tractor vaporizing oil
- for Prama-stoves or paraffin stoves, used in households in rural parts of South Africa
Liquid paraffin is a mineral oil that comes in two forms: either heavy liquid paraffin oil or light liquid paraffin oil. The terms kerosene and paraffin overlap where the latter is used as a liquid fuel. Whereas it is a waxy solid, liquid paraffin is more viscous and highly refined and can be used as a laxative.
Other uses include:
- A coolant for electrical systems
- A hydraulic fluid