Plastic Surface Materials

Basic info is found in Chapter 9.

One of the principle advantages of plastics is that they can be made to almost any consistency, durability or shape. Plastic surface materials can be sheets, panels, plaster, terrazzo, soft roof and floor coverings, carpets and wallpapers. The two latter uses are discussed in separate sections at the end of the chapter.

Sheets and panels are usually composite products consisting of cellulose paper combined with plastics, usually a thermosetting plastic containing phenol or melamine (about 25% by weight), pressed together under high pressure and heated. These products are mainly used for internal cladding and flooring. Sheets for exterior use are often of polyester with a mixture of stone particles reinforced with fibreglass.

Synthetic plaster is most often based on acrylic copolymer mixed with crushed limestone, sand, colour pigments and water. Synthetic plasters have a low diffusivity to humidity and should be used with caution on external surfaces.

Traditional terrazzo flooring consists of marble or other stone aggregates set in cement mortar. The mortar can be substituted with synthetic glue, usually epoxy resins, making thinner dimensions possible, but introducing environmental disadvantages.

Seamless plastic flooring is applied as liquid and consists of a polymer with fillers of sand, ground stone, colour pigments and often plasticizers like dibutylphthalate (DBP). The recipe can also include nonylphenol. The polymer is most often epoxy, but polymethyl meta-crylate and polyurethane are also used.

Soft plastic coverings are widely used flooring materials and are usually produced from polyvinyl chloride (vinyl flooring), polyolephines and synthetic rubbers. Among the latter, the most frequently used is styrene-butadiene rubber (SBR) but also products of butyl rubber (IIR) and ethylene-propylene rubber (EPDM) are available. In the production of vinyl flooring the polyvinyl chloride is mixed with fillers such as sand, chalk, kaolin, wood flour, zinc oxide, lime or powdered stone and recycled glass. Colour pigments, softeners and stabilizers, which can contain lead and cadmium, are also added. The softeners are usually added in quantities between 10 and 20% and most important are dietylhexylphthalate (DEHP), diisononylphthalate (DINP) and benzylbu-tylphthalate (BBzP). Chlorinated paraffins are also used as so-called secondary plasticizers and at the same time serve as flame retardants. The material is often glued to an underlay of jute, polyester, cork, foamed polyvinyl chloride or fibreglass. Several of the same additives are also a part of products based on styrene-butadiene rubber (SBR)

and polyolephines which also quite often include fire retardants. Softeners are, however, not needed in these products. Soft plastic coverings are most often glued to a subfloor of concrete, chipboard, gypsum, etc., usually with an acrylate adhesive or polyvinyl-acetate (PVAC).

Products for roofing are mostly based on polyvinyl chloride, chlorinated polyethylene, ethylene-propylene rubber (EPDM) and polyolephines. The products are composed with much of the same ingredients as in floor coverings and include fire retardants that are often brominated hydrocarbons. Additional treatments for ultraviolet stabilization are necessary. Softeners are needed only in products of polyvinyl chloride.

The main raw material for all plastic products is fossil oils. However, some products are, to a growing extent, based on recycled plastics. The energy use in the production of plastics is high and it entails substantial emissions of carbon dioxide, organic solvents and various other environmental toxins.

In the indoor climate, a wide range of chemical irritants can be emitted (Ehmsperger etal., 2006). Very high emissions have been detected from vinyl flooring on concrete because of alkali reactions. The most critical emission from vinyl products, however, will be the phthalates (DEHP, BBzP and DINP) which are emitted as long as the building is used. Each year around 1% of the total amount contained in the product is emitted. There is a clear relationship between the occurrence of DEHP and asthma in children (0ye, 1998; Jaakkola et al., 2000). DINP is regarded as less damaging. SBR flooring has been known to emit styrene and butadiene. From products containing polyurethane, emissions of unreacted isocyanates is a significant risk.

Floor coverings of polyvinyl chloride and SBR will shrink somewhat as the softeners evaporate, and damage can occur in the joints which makes them dirt traps and an attractive breeding ground forfungi. On all interior plastic surfaces, the production of bacteria is generally several times greater than on mineral or wooden surfaces with moisture regulating properties.

Glued plastic products are difficult to disassemble in the demolition phase, and re-use is probably not an option for most products. A few of the products can be down-cycled, whilst incineration for energy recovery probably will be preferred for most of them. However, when burning plastics, the emission of carbon dioxide will be the same as when oil is fired. Dioxins are emitted from the burning of polyvinyl chloride. Ash and waste will contain a wide range of pollutants and must be deposited at controlled tips.

15.9

Wood-plastic composite used for cladding, outdoor deck floors, railings and fences.

15.9

Wood-plastic composite used for cladding, outdoor deck floors, railings and fences.

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