Extruded polystyrene thermal insulation

Table 10.1 Physical properties of commercial extruded polystyrene foams ASTM C578 - Standard for Rigid, Cellular Polystyrene Thermal Insulation... 

Polyurethane, PVC, and extruded polystyrene provide the bulk of the cellular plastics used for low and cryogenic temperature appHcations. In some cases, eg, the insulation of Hquid hydrogen tanks on space systems, foams have been reinforced with continuous glass fibers throughout the matrix. This improves strength without affecting thermal performance significantly. 

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. 

In modem PMR construction, thermal insulation that is unaffected by water or that can be kept dry in some manner is required. Extruded polystyrene (XEPS) foam insulation boards are commonly employed (see Insulation, THERMAL). They are placed on top of the waterproofing roof membrane, which is next to the deck. The insulation should not be adhered to the membrane. Ballast at the rate of >48.8 kg/m2 (1000 lb/100 ft2) holds the insulation in place and offers protection from the sun. The insulation joints are open and drainage must be provided. Various other materials, eg, patio blocks and concrete slabs, are also used as surfacings and ballast. The extra weight imposes more exacting requirements on construction. 

HBCD Extruded and expanded polystyrene for thermal insulation of buildings... 

In plastic roof insulations under controlled thermal gradients, the moisture gains found in polyurethane are greater than those of bead polystyrene, and much greater than those of extruded polystyrene [9]. 

We conclude from findings on moisture absorption and freeze-thaw resistance of various insulations, and the effect of moisture on thermal performance, that in protected-membrane roofing applications the order of resisting moisture pickup is extruded polystyrene > polyurethane > molded polystyrene [57]. Water absorption values for insulation in use for 5 years were 0.2vol% for extruded polystyrene, 5vol% for polyurethane without skins, and 8-30 vol%... 

This type of foam is available in two forms, extruded-polystyrene foam and expanded polystyrene for molded foams. Polystyrene foams are light, closed-cell foams with low thermal conductivities and excellent water resistance. They meet the requirements for low-temperature insulation and buoyancy media (6). 

Styrodur . [BASF AG] Extruded rigid polystyrene foam fin thermal insulation of roofi, fioors, walls, as frost protection of subsoils below roads, aircraft runways. 

Non-insulating foam products typically utilize hydrocarbons, such as isobutane, pentane, isopentane, and hexane. The use of CO2 (either water-based or liquid) is a major identified option to reduce the emission of non-HCFC blowing agents from polyurethane foam and extruded polystyrene boardstock applications. However, the thermal insulation properties of C02-blown foam are significantly compromised when compared to halocarbon-blown foam. Halocarbons (i.e., HCFCs, HFCs) are thus expected to be used in insulation foam manufacture for several years into the future. The primary HCFC replacements in these sectors are expected to be the liquid HFCs, which may see extensive use once HCFCs can no longer be used. 

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. 

Moistnre pickup and freeze-thaw resistance of various insulations and the effect of moistnre on the thermal performance of these insulations has been reported (215). In protected membrane roofing apphcations the order of preference for minimizing moisture pickup is extruded polystyrene polyurethane > molded polystyrene (215). 

Water pickup values for insulation in nse for 5 years were, extruded polystyrene, 0.2 vol% polynrethane withont skins, 5 vol% and molded polystyrene 8-30 vol%. These correspond to increases in k of 5-265%. For below-grade applications extrnded polystyrene was better than molded polystyrene or polyurethane withont skins in terms of moistnre-absorption resistance and retention of thermal resistance. Increased water content has been related with increased thermal condnctivity of the insnlations (216-220). 

Polystyrene foam is widely used for floatation and thermal insulation, and this product is produced in a unique way. Polystyrene beads are first produced by co-extruding polystyrene and liquid heptane (CyH ) in... 

HBCDs are primarily used as additives in expandable polystyrene (EPS) and extruded polystyrene (XPS) foam used to thermally insulate buildings. HBCDs also are added to the back-coating of textiles of upholstered furniture as well as in HIPS housing of electrical and electronic equipment and appliances (Alaee et al. 2003). Although y-HBCD is predominant in the commercial HBCD formulations... 

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