Polystyrene is a synthetic aromatic polymer made from the monomer styrene. Polystyrene can be solid or foamed. Expanded polystyrene (EPS) is a rigid and tough, closed-cell foam. It is usually white and made of pre-expanded polystyrene beads. Polystyrene is one of the most widely used plastics, the scale of its production being several billion kilograms per year.
Polystyrene foams are produced using blowing agents that form bubbles and expand the foam. In expanded polystyrene, these are usually hydrocarbons such as pentane
Extruded polystyrene (XPS)
Extruded polystyrene foam (XPS) consists of closed cells, offers improved surface roughness and higher stiffness and reduced thermal conductivity. It is slightly denser and therefore slightly stronger than EPS.
Water vapour diffusion resistance (μ) of XPS is very low - making it suitable for application in wetter environments.
Phenolic foam insulation is made from a resole resin in the presence of an acid catalyst, blowing agents (such as pentane) and surfactants.
Polyisocyanurate/ Polyurethane foam (PIR/PUR)
Polyurethane (PUR and PU) is a polymer composed of organic units joined by carbamate (urethane) links. Polyurethane can be made in a variety of densities and hardnesses by varying the isocyanate, polyol or additives.
Polyisocyanurate, also referred to as PIR, is a thermoset plastic typically produced as a foam and used as rigid thermal insulation. Its chemistry is similar to polyurethane (PUR) except that the proportion of methylene diphenyl diisocyanate (MDI) is higher and a polyester-derived polyol is used in the reaction instead of a polyether polyol. Catalysts and additives used in PIR formulations also differ from those used in PUR.
Glass mineral wool
Made from molten glass, usually with 20% to 30% recycled industrial waste and post-consumer content. The material is formed from fibres of glass arranged using a binder into a texture similar to wool. The process traps many small pockets of air between the glass, and these small air pockets result in high thermal insulation properties. The density of the material can be varied through pressure and binder content.
Rock mineral wool
Rock (Stone) mineral wool is a furnace product of molten rock at a temperature of about 1600 °C, through which a stream of air or steam is blown. More advanced production techniques are based on spinning molten rock in high-speed spinning heads somewhat like the process used to produce candy floss. The final product is a mass of fine, intertwined fibres with a typical diameter of 2 to 6 micrometers. Mineral wool may contain a binder, often a Ter-polymer, and an oil to reduce dusting
Largely manufactured from recycled glass (e.g. windscreens) and mineral base materials such as sand and without the use of binding agents. The ingredients are melted into molten glass, which is cooled and crushed into a fine powder. The powdered glass is poured into molds and heated (below the melting point) in a "sintering" process that causes the particles to adhere to one another. Next, a small amount of finely ground carbon-black is added and the material is heated in a "cellulation" process. Here, the carbon reacts with oxygen, creating carbon dioxide, which creates the insulating bubbles in the (material). CO2 accounts for more than 99% of the gas in the cellular spaces.
Wool insulation is made from sheep wool fibres that are either mechanically held together or bonded using between 5% and 15% recycled polyester adhesive to form insulating batts and rolls. Sheep are no longer farmed primarily for their wool; however, they need to be clipped annually to protect the health of the animal. The wool used to manufacture insulation is the wool discarded as waste by other industries due to its colour or grade
Cellulose insulation is a material made from recycled newspaper. The paper is shredded and inorganic salts, such as boric acid, are added for resistance to fire, mould, insects and vermin. The insulation is installed either blown or damp-sprayed depending on application.
The success of wood fibre insulation derives from an attractive environmental profile combined with a whole bag of functions including rigid insulation, sheathing and sarking for timber frames, roofs and flooring as well as flexible insulation for studs and rafters.
Wood of course is renewable, it sequesters carbon during its growth and product production is relatively free from pollution. The insulation value of wood fibre boards is not as dimensionally efficient as some of the orthodox petro-chemical materials - but it's no slouch either - typically coming in with a 'k value' range of between 0.038-0.043 W/mK depending on format.
Hemp fibres are produced from hemp straw of the hemp plant. Most hemp is imported, but an increasing amount of home-grown crop is becoming available. Hemp grows up to a height of nearly 4 metres within a period of 100-120 days. Because the plants shade the soil, no chemical protection or toxic additives are required for hemp cultivation. The product is composed of, usually, 85% hemp fibre with the ballance made up of polyester binding and 3-5% soda added for fire proofing.
Straw is an agricultural by-product, the dry stalks of cereal plants, after the grain and chaff have been removed. Straw makes up about half of the yield of cereal crops such asbarley, oats, rice, rye and wheat.