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 solid at room temperature and melting point above approximately ,[ Raw materials and candles production processes , AECM] dyed paraffin wax can be made into .
Un-dyed, unscented paraffin candles are odorless and bluish-white. Paraffin wax was first created by Carl Reichenbach in Germany in 1830 and marked a major advancement in candlemaking technology, as it burned more cleanly and reliably than tallow candles and was cheaper to produce.
In chemistry, paraffin is used synonymously with alkane, indicating hydrocarbons with the general formula C nH2 n+2. The name is derived from Latin parum ("very little") + affinis, meaning "lacking affinity" or "lacking reactivity", referring to paraffin's unreactive nature.
Properties
Paraffin
wax is mostly found as a white, odorless, flavourless, waxy solid, with a typical melting point between about ,
[ This can vary widely, even outside the quoted range, according to such factors as oil content and crystalline structure.] and a density of around 900 kg/m
3.
It is insoluble in water, but soluble in
diethyl ether,
benzene, and certain
. Paraffin is unaffected by most common chemical
but
combustion readily.
Its heat of combustion is 42 MJ/kg.
- is a typical component of paraffin wax.]]
Paraffin wax is an excellent electrical insulator, with a resistivity of between 1013 and 1017 Resistivity.
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.[ Wax-pellet thermostat United States Patent 4948043]
If pure paraffin wax is heated in a partially open glass vessel until it nears the flash point and then rapidly cooled, its vapors may autoignite as result of reaching boiling liquid pressure.
History
Paraffin wax was first created in 1830 by German chemist
Carl Reichenbach when he attempted to develop a method to efficiently separate and refine waxy substances naturally occurring in petroleum. Paraffin represented a major advance in the candle-making industry because it burned cleanly and was cheaper to manufacture than other candle fuels such as
beeswax and
tallow. Paraffin wax initially suffered from a low melting point. This was remedied by adding
stearic acid. The production of paraffin wax enjoyed a boom in the early 20th century due to the growth of the oil and meatpacking industries, which created paraffin and stearic acid as byproducts.
Manufacturing
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 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 to be (semi-refined versus fully refined).
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.
Other uses
-
Anti-caking agent, moisture repellent, and dustbinding coatings for fertilizers
-
Antiozonant agents: blends of paraffin and micro waxes are used in rubber compounds to prevent Ozone cracking of the rubber; the admixture of wax migrates to the surface of the product and forms a protective layer. The layer can also act as a release agent, helping the product separate from its mould.
-
Bicycle chain lubrication
-
Bullet lubricant – with other ingredients, such as olive oil and beeswax
-
Candle-making
-
Coatings for waxed paper or waxed cotton
-
Component of surfboard wax, ski wax, and skateboard wax
-
-
Food-grade paraffin wax:
-
Shiny coating used in candy-making; although edible, it is nondigestible, passing through the body without being broken down
-
Coating for many kinds of hard cheese, like Edam cheese
-
Sealant for jars, cans, and bottles
-
Chewing gum additive
-
Forensic investigations: the nitrate test uses paraffin wax to detect nitrates and nitrites on the hand of a shooting suspect
-
Fuel for fire breathing
-
Investment casting
-
Lava Lamps
-
Manufacture of boiled leather armor and books
-
Mechanical thermostats and actuators, as an expansion medium for activating such devices
-
Microwax:
-
Moisturiser in toiletries and cosmetics such as Vaseline.
-
Neutron radiation shielding
-
Phase change material for thermal energy storage
-
Used by MESSENGER (Mercury spacecraft), when the spacecraft was unable to radiate excessive heat.
-
Phlegmatized agent, commonly used to stabilise/desensitize such as RDX
-
Potting material to encapsulate electronic components such as guitar pickups, , and , to prevent moisture ingress and to reduce electromagnetically induced acoustic noise and Microphonics
-
Prevents Redox on the surface of Steel and iron
[
]
Occupational safety
People can be exposed to paraffin in the workplace by breathing it in, skin contact, and eye contact. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) for paraffin wax fume exposure of 2 mg/m
3 over an 8-hour workday.
See also
External links
