What are aromatics, what's their chemical composition and how are they manufactured?




See Acrylonitrile-butadiene-styrene (ABS).


Any substance that in water solution tastes sour, changes the colour of certain indicators, promotes certain chemical reactions, etc. Examples of acids include inorganic substances such as sulfuric, nitric, and phosphoric acids, and organic compounds such as citric or maleic acid.


Acrylonitrile is a chemical intermediate used in acrylic fibres, ABS (acrylonitrile-butadiene-styrene), SAN (styrene-acrylonitrile) and NBR (nitrile-butadiene-rubber).

Acrylonitrile-butadiene-styrene (ABS)

ABS is a tough, heat-resistant and impact-resistant thermoplastic, the acrylonitrile providing heat resistance, and the styrene units giving rigidity. It is widely used for appliance and telephone housings, luggage, sporting helmets, pipe fittings and automotive parts.


In many plastic products, the polymer is only one constituent. In order to arrive at a set of properties appropriate to the product, the polymer is almost always combined with other ingredients, or additives, which are mixed in during processing and fabrication. Among these additives are impact modifiers, colorants, reinforcements, plasticisers and stabilisers. See also plastics and conversion.


A chemical, such as a hormone, fungicide, or insecticide, that improves or protects the production of crops.


Alcohols are amongst the most common organic compounds. Well-known alcohols include methanol (methyl alcohol, or wood alcohol), ethanol (ethyl alcohol, or grain alcohol) and isopropyl alcohol (the common alcohol known as rubbing alcohol and used as a germicide). Alcohols are also valuable as intermediates in the synthesis of other compounds.


Any organic compound in which the main structure is a chain of carbon atoms joined to each other.

Alkyl benzene

One of the most important organic raw materials for the production of synthetic detergents.


Alkylphenol is produced using phenol as a starting material. It is mainly used as a stabiliser for rubbers and plastics, as a surfactant, as an industrial detergent, and in the mining and textile industries.


Aromatics Producers Association.


Aromatics, so called because of their distinctive perfumed smell, are a group of hydrocarbons including, mainly, benzene, toluene and the xylenes. These are basic chemicals used as starting materials for a wide range of consumer products. Almost all aromatics come from crude oil, although small quantities are made from coal.


The smallest unit into which matter can be divided without the release of electrically charged particles, and also the smallest unit of matter that cannot be decomposed into simpler substances by ordinary chemical processes. Hence the atom is the basic building block of chemistry. Atoms, also called chemical elements, can combine with one another to form compounds.

Auto Oil programme

A technical work programme launched in 1992 by the European Commission and in which the European automobile and oil industries participated. The aim of this programme was to assess the most cost-effective measures for reducing emissions from the road transport sector to a level consistent with the EU air quality standards. Several petrochemical sectors have been involved in this process. Some measures have already been implemented; a further set of restrictions will be implemented by 2005.


Benzene is the simplest aromatic compound, with a ring of six carbon atoms and six hydrogen atoms. It is a colourless liquid occurring naturally in fossil raw materials such as crude oil and coal, produced during processing of petroleum liquids and through chemical reactions. It is one of the most important feedstocks for the chemical industry, used for the manufacture of a wide range of everyday items, and is not itself used directly by consumers.


A material's biodegradability is its ability to be decomposed, or broken down, in most cases into innocuous products, by the action of living things, typically microorganisms.


Biofuels are gas or liquid fuel (alcohols, ethers, esters, and other chemicals) made from plant material, agricultural and forestry residues, and a large portion of municipal solid and industrial waste. Biofuels include material as diverse as wood, wood waste, peat, wood sludge, agricultural waste, stray, sludge waste, municipal solid waste, landfill gasesÉ Biofuels for transportation include bioethanol, biodiesel, biomethanol, and pyrolysis oils.

Bisphenol A (BPA)

An industrial chemical used to make polycarbonate plastic used for structural parts, impact-resistant glazing, street-light globes, household appliance parts, components of electrical/electronic devices, compact discs, automotive applications, reusable bottles, food and drink containers, and many other products. It is also used in the production of epoxy resins for coatings, food and beverage can linings, electrical laminates, composites and adhesives, and in other products.


See Bisphenol A


Benzene, toluene and xylenes.


One of the ingredients that are used to synthesise the most common nylon. Caprolactam is made from phenol.


An element forming a large number of compounds, many of which have important uses. Diamond and graphite are amongst the main forms of carbon. Coals are elemental carbon mixed with varying amounts of carbon compounds; coke and charcoal are nearly pure carbon. All organic compounds, such as proteins, carbohydrates, and fats, contain carbon, and all plant and animal cells consist of carbon compounds and their polymers.

Carbon dioxide (CO2)

A colourless, non-poisonous gas that is a normal part of the ambient air. Carbon dioxide is formed in combustion of fossil fuel and carbon-containing materials, in fermentation, and in respiration of animals and employed by plants in the photosynthesis of carbohydrates.


A substance which aids or promotes a chemical reaction without forming part of the final product. It enables the reaction to take place faster, remains unchanged at the end of the reaction and can provide control by increasing desirable reactions and decreasing undesirable reactions.

Catalytic cracking

The process of breaking up heavier hydrocarbon molecules into lighter hydrocarbon fractions by use of heat and catalysts. See also Cracking.


Cefic is the European Chemical Industry Council, the Brussels-based organisation representing national chemical federations and chemical companies of Europe. Cefic represents, directly or indirectly, more than 40,000 large, medium and small chemical companies in Europe, which employ about 2 million people and account for more than 30% of world chemical production.

Chemical element

See Atom.

Chemical reaction

A chemical process in which substances are changed into different substances. Chemical reactions are manifested by the disappearance of properties characteristic of the starting materials and the appearance of new properties that distinguish the products. Examples of chemical reactions include burning of wood, fermentation of crops to make alcohol, tarnishing of silver, digestion of food and the synthesis of polystyrene plastics.


A colourless, liquid organic compound used as a solvent and starting material for the manufacture of other organic compounds, such as phenol.

Clean fuels

So-called clean fuels are among the instruments introduced by EU Member States to combat air pollution problems arising from increases in road transport. See Auto-Oil Programme.


See Carbon dioxide


A black or brownish black solid, combustible carbon-rich substance formed by the partial decomposition of vegetable matter without access to air. Coal is one of the most important of the primary fossil fuels. It is indispensable to life and constitutes humankind's main source of energy.

Coal tar

Coal tar is a principal liquid product resulting from the carbonisation of coal, i.e. the heating of coal in the absence of air at temperatures ranging from about 900º to 1,200ºC (1,650º to 2,200ºF). Many commercially important compounds are derived from coal tar, such as dyestuffs and pigments.


A compound (or molecule) is a combination of two or more chemical elements (atoms) held together by chemical bonds.


The Oil Companies' European Organisation for Environment, Health and Safety


In the plastics industry, conversion is the processing of raw materials into usable forms, e.g. the conversion of plastic pellets into films or the conversion of films into food containers. The steps involved include compounding (the mixing together of various raw materials, e.g. polymers and additives), melting and extruding, shaping and solidifying.


The process of breaking down large molecules of oil into smaller ones. When this process is achieved by the application of heat only, it is known as thermal cracking. If a catalyst is used as well it is known as catalytic cracking. Cracking causes molecular decomposition and recombination to produce a range of more useful base chemicals. Cracking is the basic process taking place in crackers.

Crude oil

A mixture of comparatively volatile liquid hydrocarbons that occurs in the Earth's crust and is extracted for use as fuel and various petroleum products. Typically, crude oil contains, in various percentages, a mixture of naphtha, kerosene, middle distillates and fuel oils.


Cumene is an aromatic derived from benzene and used in turn to produce polycarbonates, phenolic resins and essential healthcare products such as aspirin and penicillin.


Cyclohexane is an aromatic derived from benzene used as an intermediate to produce nylon.


The process of boiling a liquid and condensing and collecting the vapour. This process is used to purify liquids and to separate liquid mixtures. In the oil industry, distillation is used to separate crude oil, which is a mixture of hydrocarbons with different boiling temperatures, into groups of hydrocarbons that boil between two specified boiling points.

Epoxy resins

A flexible resin made using phenols and used chiefly in coatings, adhesives, electrical laminants and composites for its excellent adhesion, strength and chemical resistance.


European Phenolic Resins Association, a sector group of the Association of Petrochemicals Producers in Europe (APPE). For more information, click here.


See Expanded polystyrene


European Solvents Industry Group, a group within the Association of Petrochemicals Producers in Europe (APPE) gathering manufacturers and users of oxygenated and hydrocarbon solvents. For more information, click here.


Any of a class of organic compounds made from the chemical reaction between an alcohol and an organic acid.


Ethylbenzene is formed by combination of ethylene and benzene, and is then dehydrogenated to styrene for use in the production of plastics and synthetic rubber.

Existing chemicals

Chemical substances, which were deemed to be on the European Community market between 1 January 1971 and 18 September 1981. An "existing" chemical substance is in the EU defined as any chemical substance listed in the European Inventory of Existing Commercial Substances (EINECS), an inventory containing 100,195 substances. The Regulation 793/93 foresees that the evaluation and control of the risks posed by existing chemicals will be carried out in four steps: data collection, priority setting, risk assessment and risk reduction. Any chemical substance marketed after 18 September 1981 is called a new chemical. For more information, visit the European Chemicals Bureau.

Expanded polystyrene (EPS)

Expanded polystyrene, manufactured from styrene, is a thermal plastic material supplied to moulders in the form of a polystyrene bead. The beads, which contain a blowing agent, are processed and moulded into low-density foam articles, such as protective packaging, foam insulation and building and construction.

Exposure assessment

The exposure assessment is the determination of the emissions in order to estimate the concentrations/doses of a substance to which human populations or environmental spheres (water, soil and air) are or may be exposed.

Extruded polystyrene (XPS)

Extruded polystyrene, manufactured from styrene, is a thermal plastic material manufactured by a variety of extrusion processes. Polystyrene foam board and extruded foam sheet have properties that make it a frequent choice for thermal insulation, sheathing, roofing and building and construction application.


Raw material used in a processing plant. The most important feedstock for the European petrochemical industry is naphtha.


Substance that adds inorganic or organic plant nutrients to soil and improves its ability to grow crops, trees, or other vegetation.


See Unsaturated polyester resins.

Fossil fuel

A general term for buried combustible geologic deposits of organic materials occurring within the Earth's crust, that can be used as a source of energy. They all contain carbon and were formed as a result of geologic processes from decayed plants and animals that have been converted to crude oil, coal, natural gas, or heavy oils hundreds of millions of years ago.


A material used to produce heat or power by burning.

Fuel oxygenate

Oxygenates are compounds containing oxygen in a chain of carbon and hydrogen atoms. Today, oxygenates are blended into gasoline in two forms: alcohols or ethers. Ethanol is the most commonly used alcohol oxygenate; methyl-tertiary-butyl-ether, or MTBE, is the most commonly used ether oxygenate. Fuel oxygenates are used in gasoline to boost the octane rating and to decrease the toxic emissions in the exhaust.


An intermediate distillate product used for diesel fuel, heating fuel and sometimes as feedstock.


Also called gas or petrol, gasoline is a mixture of volatile, flammable liquid hydrocarbons derived from petroleum, with or without small quantities of additives, and used as motor fuel. It is also used as a solvent for oils and fats.


Gross Domestic Product


The hazard associated with a chemical is its intrinsic ability to cause an adverse effect. It should be compared to risk, which is the chance that such effects will occur. Whilst a chemical may have hazardous properties, provided it is handled safely under contained conditions, any risk to human health or the environment is extremely low.

High Production Volume chemicals (HPV)

High Production Volume chemical, defined by the European Chemicals Bureau as a chemical being produced or imported in quantity of at least 1000 tonnes per year in EU by at least one Industry.


Health, Safety and Environment


Hydrocarbon Solvent Producers Association, a sector group of the Association of Petrochemicals Producers in Europe (APPE). For more information, click here.


An organic compound that consists exclusively of the elements carbon and hydrogen. Generally, the term hydrocarbon is used for the chemicals that are derived from natural gas, oil and coal.


International Council of Chemical Associations


Inorganic is said of any substance in which two or more chemical elements other than carbon are combined. Every chemical is either inorganic or organic.

Isomer / Isomeric

Two or more substances that have identical molecular formulas but different molecular structures or configurations, and hence different properties, are called isomers. Isomers differ only in the arrangement of their component atoms.


The chemical process by which a compound is transformed into any of its isomeric forms, i.e., forms with the same chemical composition but with different structure or configuration and, hence, generally with different physical and chemical properties.

Latex (pl. latices)

A water emulsion of a synthetic rubber or plastic obtained by polymerisation and used especially in coatings, paints and adhesives. Latices include a binder dispersed in the water and form films by fusion of the plastic particles as the water evaporates. Properties of these films, such as hardness, flexibility, toughness, adhesion, colour retention, and resistance to chemicals, depend on the composition of the plastic.


Large Volume Organic Chemicals


A colourless, odourless, flammable gas that occurs abundantly in nature as the chief constituent of natural gas, as a component of firedamp in coal mines, and as a product of the decomposition of organic matter. Methane is used as a fuel and as a starting material in chemical synthesis.


Metaxylene is an isomer of mixed xylene. It is used as an intermediate in the manufacture of polyesters for coatings, inks, reinforced plastics, and packaging applications.


Chemical combination of two or more atoms of the same chemical element (such as O2 - which is Oxygen) or different chemical elements (such as H2O - which is water).


A molecule that can combine with others to form a polymer.

Naphtha Petroleum

Naphtha is a petroleum distillate containing principally aliphatic hydrocarbons. It is the primary source from which petrochemicals are derived.

Natural gas

Colourless, highly flammable gaseous hydrocarbon consisting primarily of methane, ethane, and small amounts of heavier gaseous hydrocarbon compounds such as propane. Ethane and propane, also called natural gas liquids (NGL), are converted into ethylene and propylene by steam cracking. It is a type of petroleum that commonly occurs in association with crude oil.


See Nitrile-butadiene-rubber


Natural gas liquids. See Natural gas.

Nitrile-butadiene-rubber (NBR)

A synthetic rubber used in many applications, including the automotive industry.


A synthetic plastic material derived from benzene. Nylon can be used to form fibres, filaments, bristles, or sheets to be manufactured into yarn, fabric, and cordage; and it can be formed into moulded products. Nylon is tough, elastic and strong, and it has high resistance to wear, heat, and chemicals. It is generally known in the form of fine filaments in such articles as hosiery and sports equipment, e.g. parachutes; but its applications also include engineering plastics for cars, toys, healthcare products, carpets, roller-blade wheels, ship sails and parachutes.

Occupational exposure

The occupational exposure is a standard term that concerns adult workers in good health, with a possible exposure of 8 hours per day, 5 days a week, 11 months per year. See Exposure.


For a gasoline engine to work efficiently, gasoline must burn smoothly without premature detonation, or knocking. Severe knocking can dissipate power output and even cause damage to the engine. When gasoline engines became more powerful in the 1920s, it was discovered that the most extreme knocking effect was produced by a fuel composed of pure normal heptane, while the least knocking effect was produced by pure isooctane. This discovery led to the development of the octane scale for defining gasoline quality.


Occupational Exposure Limit.

Organic chemicals

Organic chemicals are based on carbon compounds and form the backbone of the petrochemicals industry, while inorganic chemicals are non-carbon chemicals, such as chlorine, alkalis or hydrogen peroxide. Every chemical is either organic or inorganic.


Orthoxylene is an isomer of mixed xylene. It is primarily used in plasticisers (primarily in flexible polyvinyl chloride – PVC – material), medicines and dyes.


Oxygenated Solvent Producers Association, a sector group of the Association of Petrochemicals Producers in Europe (APPE). For more information, click here.


A chemical reaction with oxygen.


One of the forms of xylene, paraxylene is used to make polyesters, which have applications in clothing, packaging and plastic bottles. The most widely-used polyester is polyethylene terephthalate (PET), used in lightweight, recyclable soft drinks bottles, as fibres in clothing, as a filling for anoraks and duvets, in car tyre cords and conveyor belts. It can also be made into a film that is used in video and audiotapes and x-ray films.


See Unsaturated polyester resins.


See Polyethylene Terephthalate.


An organic compound that has been derived from petroleum or natural gas. There are almost 200 chemicals that can be so described and they include many simple hydrocarbons (e.g. methane, ethane), aromatic hydrocarbons (e.g. benzene, toluene), naphthenes and several of their derivatives.


A generic term applied to oil and oil products in all forms, such as crude oil, unfinished oils, petroleum products, natural gas plant liquids, and non-hydrocarbon compounds blended into finished petroleum products. See Crude oil.


Phenol is an aromatic alcohol mainly used as an intermediate in organic synthesis. It essentially serves as a raw material for the production of bisphenol A, phenolic resins, alkylphenols and caprolactam.

Phenolic resin

Phenolic resins are manufactured from phenol. They are used in wood products and moulding powders applications, and also have a wide range of applications on the electrical, mechanical and decorative markets, in the automotive industry, in building and construction, in thermal insulation products and in foundry industry products.


Line of pipe equipped with pumps and valves and other control devices for moving liquids and gases. It is one of the main modes of transport for many chemicals.


Any of numerous synthetic materials that consist of giant molecules called polymers, with extremely long chains of repeating units derived from short molecules. Plastics can be formed into products by moulding or otherwise shaping. The two major divisions of plastics are the thermosetting resins and thermoplastic resins. Raw materials for plastics include coal and cellulose, but by far the chief source is petroleum. Because of their easy manipulation, economical manufacture, low specific gravity, and resistance to corrosion, plastics have replaced metal, wood, glass, and other materials in many applications. An immense array of plastic industrial and consumer goods is available. For more information, click here.


A plasticiser is a substance which when added to a material, usually a plastic, makes it flexible, resilient and easier to handle. Modern plasticisers are manmade organic chemicals; the majority of which are esters, such as adipates and phthalates. They are major components that determine the physical properties of polymer products. There are more than 300 different types of plasticisers.

Polycarbonate resins

Polycarbonate resins, derived from bisphenol A, are used for structural parts, impact resistant glazing, street-light bulbs, household appliance parts, components of electrical/electronic devices, automotive applications, reusable bottles, and food and drink containers. It is also a building block used to make epoxy resins for coatings, electrical laminants, composites and adhesives.


Any of a group of polymers that consist basically of repeated units of an ester and are used especially in making fibres or plastics. Polyesters can be made into woven and knitted fabrics, either alone or blended with other fibres; they also have industrial applications such as ropes, filters, conveyor belts, and tyre cords.

Polyethylene terephthalate (PET)

Polyethylene terephthalate is derived from xylene and is one of the most widely used industrial polyesters. It is used in lightweight, recyclable soft drink bottles, as fibres in clothing, as a filling for anoraks and duvets, in car tyre cords and conveyor belts. It can also be made into a film that is used in video and audio tapes and x-ray films.


When certain individual molecules (monomers) come together and link up in a chain-like fashion they form a polymer. The chemical reaction that forms a polymer is called polymerisation. There are natural polymers (often referred to as biopolymers), such as cellulose, certain rubbers and DNA, and synthetic polymers, such as polystyrene and fibreglass (see uPES). See also Plastics, Resins and Rubber.


A solid plastic made from polymerised styrene and used in a wide variety of everyday applications, from coffee cups through to CD jewel boxes.


A synthetic compound derived from foluene, belonging to the family of organic polymers. Polyurethanes are used to make the foam in furniture, mattresses, car seats, building insulation, coatings for floors and furniture and refrigerators. They are also used in artificial sports tracks, jogging shoes, and in roller blade wheels.


A preparation is a mixture or a solution composed of two or more substances. This term is used in the European legislation.

Product Stewardship

Product Stewardship is the responsible and ethical management of the health, safety and environmental aspects of a product throughout its total life cycle. Product Stewardship is Responsible Care applied to products. More...


Pygas, or pyrolysis gasoline, is a naphtha-range product with a high aromatic content, used either for gasoline blending or as a feedstock for a BTX extraction unit. Pygas is produced in an ethylene plant that processes butane, naphtha or gasoil.

Pyrolisis gasoline

See Pygas.


Conversion of crude oil into useful products, such as naphtha, the most important feedstock for the petrochemical industry. Every refinery begins with the separation of crude oil into different fractions by distillation. The fractions are further treated to convert them into mixtures of more useful products by various methods such as cracking, reforming, alkylation, polymerisation and isomerisation. These mixtures of new compounds are then separated using methods such as fractionation and solvent extraction.


The thermal or catalytic conversion of petroleum naphtha into more volatile products of higher octane number. It represents the total effect of numerous simultaneous reactions such as cracking, polymerisation, dehydrogenation, and isomerisation.


Any natural or synthetic organic compound consisting of a non-crystalline or viscous liquid substance. Natural resins are organic substances that are transparent or translucent, formed in plant secretions. Synthetic resins comprise a large class of synthetic products that have some of the physical properties of natural resins but are different chemically. Most synthetic resins are polymers. The term resin dates from the early years of the plastics industry; it originally referred to naturally occurring amorphous solids such as shellac and rosin. See also Plastics.

Responsible Care

Responsible Care is the chemical industry's commitment to continuous improvement in all aspects of health, safety and environment performance and to openness in communication about its activities and achievements. More...


Risk should be clearly distinguished from hazard. Risk is the chance that a given hazardous effect will occur. The use of fire by humans is an example of optimising the balance between hazard and risk, as fire, being extremely hazardous, must be used under carefully controlled conditions to keep risks to a minimum.

Risk Assessment

Substances on European priority lists must undergo an in-depth risk assessment covering the risks posed by the priority chemical to man (covering workers, consumers and man exposed via the environment) and the environment (covering the terrestrial, aquatic and atmospheric eco-systems and accumulation through the food chain). This risk assessment follows the framework set out in European Commission Regulation (EC) 1488/94 and implemented in the detailed Technical Guidance Documents (TGD) on Risk Assessment for New and Existing Substances. The first draft of the risk assessment reports are written by the Member States which act as "rapporteurs". The Commission mediates the meetings, which attempt to reach consensus on the conclusions of the risk assessments.


Return on Investment


Synthetic rubber, as opposed to natural rubber (obtained from the exudations of certain tropical trees), is derived from petroleum and natural gas. Because of its elasticity, resilience, and toughness, rubber is the basic constituent of the tires used in automotive vehicles, aircraft, and bicycles. Rubber is also used in electrical insulation, and because it is waterproof, it is a favoured material for shoe soles.


See Styrene-acrylonitrile


See Styrene-butadiene rubber


Safety, Health and Environment


A solvent is a liquid that has the ability to dissolve, suspend or extract other materials, without chemical change to the material or solvent. Solvents make it possible to process, apply, clean or separate materials. Water is an inorganic solvent. Organic solvents include hydrocarbon solvents, oxygenated solvents and chlorinated solvents.


A stabiliser is a substance added to another substance to prevent an alteration of its physical state. Stabilisers are added to plastics so as to allow them to have a long and useful life in any application, by keeping their properties stable.

Steam cracking/Steam cracker

Steam cracking, a further application of thermal cracking, is a petrochemical process used to produce olefinic raw materials (e.g. propylene, ethylene) from various feedstocks for petrochemicals manufacture. The feedstocks range from ethane to vacuum gas oil, with heavier feeds giving higher yields of by-products such as naphtha. The most common feeds are ethane, butane, and naphtha.


Styrene is a clear, colourless liquid that is derived from petroleum and natural gas by-products, but which also occurs naturally. Styrene is used to create plastic materials used in a wide range of strong, flexible, and lightweight products. It is used in everything from food containers and packaging materials to cars, boats, and computers.

Styrene-acrylonitrile (SAN)

SAN is a transparent, rigid styrenic plastic offering high chemical resistance, used mainly in the automotive, electrical and electronics industry, as well as in household applications and building products.

Styrene-butadiene rubber (SBR)

SBR is a rubber manufactured from styrene. Because of its excellent abrasion resistance, it is widely used in automobile and truck tyres, as well as for carpet backing and paper coating. Other applications are in belting, flooring, wire and cable insulation, and footwear.


The word "substance" is used to mean chemical elements and their compounds in the natural state or obtained by any production process, including any additive necessary to preserve the stability of the product. In the European legislation, only the word "substance" is used.


Surfactants are products used as detergents, dispersing agents, emulsifiers, wetting agents, foaming or anti-foam agents, and solubilisers. They also constitute the raw material for the formulation of household products such as fabric detergents, shampoos, housecleaning products, as well as industrial auxiliary products for facilitating work in the manufacture of textile, flotation agents for ore, metal working, etc. They are used in other sectors of industry such as food processing, metallurgy, pharmaceuticals and public works.

Sustainable development

Humanity's ability "to make development sustainable, i.e. to ensure that it meets the needs of the present without compromising the ability of future generations to meet their own needs". The European chemical industry supports this position, as defined by the World Commission on Environment and Development established by the United Nations. More...


The production of a substance by the union of chemical elements, groups, or simpler compounds, or by the degradation of a complex compound.


Toluene di-isocyanate.

Thermal cracking

Thermal cracking is a petroleum refining process used to break up heavy oil molecules into lighter, more valuable fractions (e.g. gasoline, kerosene) by the use of high temperature without the aid of catalysts. It is used to convert gas oils into naphtha.


A plastic which is solid when cold, but which may flow and be re-formed multiple times with the application of heat. Some plastics are dissolved in solvents such as water (a latex) to aid their application.


Thermosets are a type of plastic that is the reaction product of two or more chemical compounds. While reacting and while still in a liquid shape thermoset plastics are moulded to form a wide variety of parts. Once the reaction is complete, thermoset plastics form durable solid articles (they "set"). Unsaturated polyester resins that are used to make glass reinforced plastics are an example of a thermoset plastic.


Toluene, a colourless liquid, is an aromatic hydrocarbon used extensively as starting material for the manufacture of industrial chemicals. Its major end-products are polyurethanes.

Unsaturated polyester resins (PES, uPES, UPR or USPE)

Unsaturated polyester resins are durable, resinous polymers. They are used over a broad spread of industries, mainly the construction, boat building, automotive and electrical industries. In most applications they are reinforced with small glass fibres - hence these plastics are commonly referred to as GRP or Glass Reinforced Plastics.


See Unsaturated polyester resins.


See Unsaturated polyester resins.


See Volatile Organic Compound

Volatile Organic Compound (VOC)

The term "Volatile organic compounds" refers to organic compounds that readily evaporate. VOCs include pure hydrocarbons, partially oxidised hydrocarbons, and organic compounds containing chlorine, sulphur or nitrogen. They are widely used as fuels (e.g., propane and gasoline), as paint thinners and solvents, and in the production of plastics. VOC emissions have to be carefully controlled so as not to contribute to air toxicity and urban smog.


See Extruded polystyrene.


Xylene, a colourless liquid, is an aromatic hydrocarbon of which there are several forms. Xylenes are used as solvents, as components of aviation fuel, and as raw materials for the manufacture of dyes, fibres and films. Of the different forms of xylenes, paraxylene is commercially the most important.