Insulation materials, thermal expanded polystyrene

Nearly all the expanded polystyrene that is not used for thermal insulation is used for packaging. Uses range from individually designed box interiors for packing delicate equipment such as cameras and electronic equipment, thermoformed egg-boxes to individual beads (which may be up to 5 cm long and about 1 cm in diameter) for use as a loose fill material. There is also some use of thin-wall containers for short-term packaging and conveying of hot food from... 

Polystyrene can be moulded, cast or extruded in sheets, rods and tubes. It can be easily pigmented. It finds wide, application in making household goods, lenses, plastic moulds, toys, wood laminates, films, battery boxes and electrical components. Expanded polystyrene is used as thermal insulating material and packaging. It is also used in lifejackets and floats. 

The PBDEs (decaBDE, octaBDE, and pentaBDE) and are used as flame retardants in plastics, electronic equipment, printed circuit boards, vehicles, furniture, textiles, carpets, and building materials. Global demand has increased rapidly since the 1970s with 70,000 tonnes produced in 2001. Their flame retardant activity relies on decomposition at high temperatures, leading to the release of bromine atoms. This slows the chemical reactions that drive 02-dependent fires. HBCDs are a flame retardant added to extruded and expanded polystyrene that is used as thermal insulation in buildings. 

Expanded polystyrene products have widely increased the market for polystyrene resin (see the section on polystyrene foams in Chapter 2). With as light a weight as 2 Ib/ft (0.032 g/cm ), the thermal conductivity of expanded polystyrene is very low, and its cushioning value is high. It is an ideal insulation and packaging material. Common applications include ice buckets, water coolers, wall panels, and general thermal insulation applications. 

Expanded polystyrene foam (EPS) has different applications, because of its physical form (beads) and properties (higher permeability to water and less effective adhesion to facing materials than polyurethane). The expansion gases, pentane and steam, escape fairly rapidly from the foam, so the thermal conductivity of the foam filled with air is about twice that of the best polyurethane foam—a 50 mm thick slab of foam has a U-value of 0.5-0.6 Wm K . EPS mouldings can be used as shutters (formwork) for pouring concrete in a composite wall. The two EPS layers are connected at intervals to fix the thickness of the concrete. Extruded polystyrene foam (XPS) is used in plank form for insulation imder the concrete floor of houses, and in roofing panels. 

Polystyrene is an aromatic polymer made from styrene, an aromatic monomer which is commercially manufactured from petroleum. Polystyrene is commonly injection moulded or extruded while expanded polystyrene is either extruded or moulded in a special process. Solid polystyrene is used in disposable cutlery, plastic models, CD and DVD cases, etc. Foamed polystyrene is mainly used for packing materials, insulation, foam drink cups, etc. Polystyrene foams are good thermal insulators and therefore used as building insulation materials such as in structural insulated panel building systems. They are also used for non-weight-bearing architectural structures. The information on OPF-polystyrene composites is limited. 

Styrofoam (Dow Chemical Co.) is the tradename for expanded polystyrene foam. It is made by a process similar to the one described for foamed polyethylene. The materials have a closed-cell structure with very low thermal conductivity and low moisture absorption. One of the serious limitations of polystyrene foam is its rather low maximum operating temperature of approximately SO C. It is used mainly as thermal insulation in buildings, flotation apparatus, decorations, and packaging. 

Expanded polystyrene foam is used for thermal insulation and as a packaging material. It is often used for food trays. Polystyrene can also be crosslinked. Cross-linked polystyrene parts are often used in low-loss electrical and electronic applications requiring moderate resistance to temperature. 

Expandable polystyrene (EPS) is a specialized form of plastics, which usually includes a pentane blowing agent, used to make low densities of 0.75 to 10 Ib./ft. of foam shapes and blocks. Different-sized pellets provide changes in density. These materials are well suited for thermal insulation and energy absorption. Various different formulations exist such as ones with improved heat tolerance, solvent resistance, and cushioning abilities. 

Applications of expanded polystyrene Insulation Polystyrene foam at densities below llOkg/m exhibits a thermal conductivity X (u) of 0.037 W/m.K (k = 0.26 Btu.in/ft h°F). As a general rule, therefore, polystyrene foam insulation must be 70% thicker than a urethane foam to provide equivalent heat loss characteristics, but since material costs are substantially lower for polystyrene both foams are used depending upon requirements. 

Expanded polystyrene has become very important as a thermal insulating material and to a lesser extent as a packaging material. 

Thermal Insulation. Foamed plastics (qv) are used as thermal insulation for aU types of constmction because of their low heat- and moisture-transmission values. Polystyrene is used either as foamed board or expandable beads. The foam may be faced with a stmctural surfacing material, eg, a kraft liner-board, to form a panel for insulating mobile homes. These foams can dupHcate the appearance of wood and be used as trim. Foams can also be used as backing, for example, on aluminum siding, to provide heat and sound insulation. Foamed beads can be incorporated in concrete to reduce its density and provide some thermal insulation. 

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