Pollution related to the most important building plastics

Extraction and refining crude oil and natural gas as raw materials for the plastic industry have a large impact on the environment. Depending on their type, plastics also emit a long list of damaging substances both during production and use, and when they are dumped or recycled. Important here are large emissions of greenhouse gases both as a result of chemical reactions and high energy consumption in the production process (Tables 9.9 and 9.10).

Polyethylene (PE) is polymerized from ethylene (ethene). Antioxidant, UV-stabilizer and pigment are added to a total of 0.5%. The antioxidant is usually a phenol compound and the ultraviolet stabilizer consists of amines or carbon black. Other additives are also used in larger or smaller proportions, such as flame retardants, mainly aluminium or magnesium hydroxide; chloroparaffins can be used as well. Exposure to ethylene (ethene) may occur in the workplace. The majority of polyethylene products do not emit problematic substances in the user phase. As waste they are difficult to decompose, but can be burned for energy recovery without giving off problematic substances with the exception of carbon dioxide.

Polypropylene (PP) is produced by polymerization of propylene. Ultraviolet stabilizers, antioxidants and colouring are usually added. Phenol compounds are used as antioxidants and amines as ultraviolet

Table 9.7 Plastics in the building industry

Type

Important areas of use

Thermoplastics:

Acrylonitrile butadiene styrene (ABS)

Pipes, door handles, electric fittings, electrical switches

Cellulose acetate (CA)1

Tape, sheeting

Ethylene vinyl acetate (EVA)

Paints, adhesives

Methyl metacrylate (MMA)

Paints

Polyacryl nitrile (PAN)

Carpets, reinforcement in concrete

Polyamide (PA)

Pipes, fibre for reinforcements and carpets (needle-punched carpet), electric fittings, electric switches, cable insulation, sealing strips, tape

Polycarbonate (PC)

Greenhouse glass, roof lights

Polyethylene (PE):

- hard (HDPE)

Drainpipes, water pipes, interior furnishings and detailing

- soft (LDPE

Vapour barriers and retarders, geomembranes, cable insulation, flooring, roofing

Polyethylene terephthalate (PET)

Fibre for bonding of natural fibres (when melted)

Polyisobutylene (PIB)

Roofing felt, water-proofing membranes

Polymethyl methacrylates(PMMA)

Rooflights, boards, flooring, bath tubs, paint, mastics

Polyoxymethylene (POM)

Pipes, boards, electric fittings

Polyphenyloxide (PPO)

Thermally insulated technical equipment

Polypropylene (PP)

Sheeting, boards, pipes, carpets (needle-punched carpets), electric fittings, electric switches, cable insulation, geomembranes, fibre for melting of natural fibres (when melted)

Polystyrene (PS, XPS, EPS)

Sheeting, thermal insulation (foamed), electrical insulation, light fittings

Polytetrafluor ethylene (PTFE)

Thermally insulated technical equipment, electrical equipment, gaskets

Polyvinyl acetate (PVAC)

Paints, adhesives

Polyvinyl alcohol (PVA)

Fibre reinforcement in concretes

Polyvinyl chloride (PVC)

Flooring, roofing, window frames, vapour barriers, wallpapers, sealing strips, gutters, pipes, cable insulation

Thermosetting plastics:

Butadiene acrylonitrile rubber (NBR)

Sealants, cable insulation

Butyl rubber (IIR)

Flooring, sealing strips

Casein plastic (CS)2

Door handles

Chloroprene rubber (CR)

Sealing strips

Epoxy (EP)

Filler, adhesives, paint, floor finishes, varnishes, moulding of electrical components

Ethylene propylene rubber (EPDM)

Flooring, roofing, sealing strips

Melamine formaldehyde (MF)

Electrical fittings, laminates, adhesives

Metylene diphenylisocyanate (MDI)

Adhesives

■Table 9.7 (Continued)

Type

Important areas of use

Phenol formaldehyde (PF)

Handles, black and brown electrical fittings, thermal insulation (foamed), laminates, adhesives for plywood and chipboard

Polyisocyanurate (PIR)

Thermal insulation (foamed)

Polysulphide rubber (T)

Mastics, selants, adhesives

Polyurethane (PUR)

Thermal insulation (foamed), adhesives, varnishes, paints, mastics, sealing strips moulding of electrical components

Silicone rubber (SR)3

Mastics, vapour repellants, electrical insulation

Styrene butadiene rubber (SBR)

Flooring, sealing strips, water-proofing membranes

Unsaturated polyester (UP)

Roof lights, window frames, gutters, adhesives, clear finishes, floor finishes, rooflight domes, tanks, bath tubs, boards, paint

Urea formaldehyde (UF)

Light-coloured and white electrical fittings, socket outlets, switches, adhesive for plywood and chipboard, toilet seats, thermal insulation (foamed)

1 Produced from cellulose.

2 Produced from milk.

3 Based on silicon dioxide, but polymerization requires the help of hydrocarbons.

Table 9.8 Additives in plastic products

Area of use

Additive /type of plastic*

Antioxidants and ultraviolet stabilizers (0.02-1.8% by weight)

Phenols (e.g. bisphenol A)/various; phosphorous compounds/various; hydroxyphenyl benzotriazoles/various; soya oil/PVC; lead compounds/PVC; organic tin compounds/PVC; organic nickel compounds/PVC; barium-cadmium compounds/PVC; calcium-zinc compounds/PVC

Anti-static agents (up to 4% by weight)

Ammonia compounds of alkanes/various; alkyl sulphonates, sulphates and phosphates/ various; polyethylene glycol, esters and ethers/various; fatty acid esters/various; ethanolamides/various; mono- and diglycerides/various; ethoxylated fatty amides/various

Colour pigments (0.5-1% by weight)

Zn, Cu, Cr, Ni, Nd, Pb/various

Fillers (up to 50% by weight)

Zinc oxide, wood flour, stone flour, talcum, kaolin/various

Fire retardants (up to 10% by weight)

Chloroparaffins/PE, PP,PS, PVC,UP; brominated hydrocarbons, EPS, XPS, PUR, PC; organophosphates/ABS, PE, PP, PS, PUR; aluminiumhydroxide/various; magnesiumhydroxide/various; antimon trioxide/PE, PVC, PS

Foaming agents

CFCs/XPS, PUR, UF, PF; HCFCs/XPS, PUR, UF,PF; HFCs/XPS, PUR; Pentane/EPS, PF, PUR; CO2/EPS, PUR; oxygen/UF; water/PF

Lubricants

Stearates, paraffin oils, paraffin waxes, amide waxes/various

Smoke reducer (approx. 2.5-10% by weight)

Aluminium trihydrate/various; antimony trioxide metals/various; molybdenum oxide/PVC

Softeners (up to 50% by weight)

Phthallic acid esters/various; aliphatic esters from dicarbon acid/various; esters from phosphonic acid/various; esters and phenols from alkylsulphonic acid/various; esters from citric acid/various; trimellitate/various; chlorinated paraffins/various; polyesters/various

* Abbreviation, see Table 9.7.

* Abbreviation, see Table 9.7.

Table 9.9 Material pollution from basic plastics in production (P) and in the house (H)

Plastic1

Potential emissions2,3

Chloroprene rubber (CR)

Butadiene (P), Chloroprene (P)(H)

Epoxy (EP)

Bisphenol-A (P), epichlorohydrin (P), amines (P)(H)

Ethylene propylene rubber (EPDM)

Hexane (P)

Melamineformaldehyde (MF)

Phenol (P), formaldehyde (P)

Polyamide (PA)

Benzene (H), ammonia (H)

Polycarbonate (PC)

Dichloromethane (P), bisphenol-A (P)(H)

Polymethylmethacrylate (PMMA)

Acetonitrile (P), acrylonitrile (P)

Polysulphide rubber (T)

Formaldehyde (P), toluene (P)(H), chloroparaffines (P)(H)

Silicone (Si)

Chlorinated hydrocarbons (P), Xylene (P)(H), amines (P)(H), siloxanes (P)(H)

Styrene rubber (SBR)

Styrene (P)(H), xylene (P)(H), butadiene (P), hexane (P)(H), toluene (P)(H), amines (P)(H)

Unsaturated polyester (UP)

Styrene (P)(H), dichloromethane (P)

Ureaformaldehyde (UF)

Formaldehyde (P)(H)

1 See main texts for info on polyethylene (PE), polypropylene (PP), polystyrene (PS), polyurethane (PUR) and polyvinyl chloride (PVC).

2 Emissions from optional additives, e.g. flame retardants, are not included. Additionally there will be large emissions of carbon dioxide from the production of all plastics.

3 See Table 2.5 for details on toxicity.

1 See main texts for info on polyethylene (PE), polypropylene (PP), polystyrene (PS), polyurethane (PUR) and polyvinyl chloride (PVC).

2 Emissions from optional additives, e.g. flame retardants, are not included. Additionally there will be large emissions of carbon dioxide from the production of all plastics.

3 See Table 2.5 for details on toxicity.

stabilizers, to a total of about 0.5%. Other additives are used in variable proportions, in some flame retardants.

Exposure to propylene during its manufacture can be damaging, although there are no dangerous emissions from the finished product.

Table 9.10 Combustion gases emitted from plastics in fires and waste treatment

Type of plastic

Potential combustion gases1

Acrylonitrile-butadiene-styrene (ABS)

Carbon monoxide, hydrogen cyanide, nitrogen oxide

Chloroprene rubber (CR)

Carbon monoxide, hydrogen chloride, dioxines

Melamine formaldehyde (MF)

Carbon monoxide, hydrogen cyanide, ammonia

Polyamide (nylon) (PA)

Carbon monoxide, acrolein, hydrogen cyanide, hydrogen chloride, nitrogen oxide

Polycarbonat (PC)

Carbon monoxide

Polyisocyanurate (PIR)

Carbon monoxide, hydrogen chloride, acrolein

Polymethylmethacrylate (PMMA)

Carbon monoxide (large volumes)

Polystyrene (PS, EPS, XPS)

Carbon monoxide, benzene, styrene, formaldehyde

Polyurethane (PUR)

Carbon monoxide, nitric oxide, nitrogen dioxide, acrolein, benzonitrile, acetonitrile, ammonia, hydrogen cyanide, isocyanates, aromatic hydrocarbons

Polyvinyl chloride (PVC)

Carbon monoxide, methane, hydrogen chloride, phosgene, cadmium, dioxines

Styrene butadiene rubber (SBR)

Carbon monoxide, sulphur dioxide, nitrogene oxides

Unsaturated polyester (UP)

Carbon monoxide, benzene, styrene, formaldehyde

1 Large emissions of carbon dioxide coming from incineration of all plastics are not included, see Table 2.8. When chlorinated, fluorinated or brominated additives are used there will also be emissions of dioxines. Chlorinated flame retardants will emit hydrochloric acid.

1 Large emissions of carbon dioxide coming from incineration of all plastics are not included, see Table 2.8. When chlorinated, fluorinated or brominated additives are used there will also be emissions of dioxines. Chlorinated flame retardants will emit hydrochloric acid.

As waste it is difficult to decompose, but it can be burned for energy recovery without emitting dangerous substances with the exception of carbon dioxide.

Polystyrene (PS) is produced by the polymerization of styrene. It can be made into transparent sheeting, but the dominating polystyrene products are foamed expanded polystyrene (EPS) and extruded polystyrene (XPS). Both are used as insulation and the latter, having high resistance to moisture, also in foundations. EPS comprises 98% styrene; XPS only 91%. Additives include an antioxidant, an ultraviolet stabilizer, and often a fire retardant. The antioxidant used is usually phenol propionate in a proportion of 0.1%, amines are used as the ultraviolet stabilizer and the flame retardant is organic bromine compounds, with or without antimony salts, up 1% in EPS and 2% in XPS. An inhibitor can also be included in the product to prevent spontaneous polymerization; this is usually hydrochinon in a proportion of about 3%. EPS is then foamed using pentane and XPS usually with chlorofluor-ocarbons.

During production, emissions of benzene, ethyl benzene, styrene, pentane and chlorofluorocarbons are quite likely. In production plants the health effects of benzene, ethylene and styrene have been registered.

The finished product can have some unstable residues of monomers of styrene (less than 0.05%) which may be released into the atmosphere, depending upon how the material has been installed in the building. XPS will also release fluorocarbons used as foaming agent.

As a waste product, polystyrene can be environmentally damaging through the leakage of additives. It is also difficult to decompose.

Polyurethane (PUR). The basis for polyurethane is the isocyanates where production involves the highly toxic substance phosgene, known from the Bophal disaster in India in 1984. Isocyanates are amongst the most allergenic substances known. Polyurethane is produced in a reaction between isocyanates (40%) and different poly-ethers (4%), using organic tin compounds as catalyst. Antioxidants and flame retardants are also used. Phenol propionate is the usual antioxidant, and the flame retardant can be an organic bromine compound. Fluorocarbons, pentane gas or carbon dioxide, in a proportion of 10-15%, are used to foam the plastic.

Substances that can be released during production are chlorinated hydrocarbons, phenol, formaldehyde and ammonia, possibly even organic tin compounds and chlorofluorocarbons. Workers are exposed, not least, to isocyanates - which are considered to be the single most common cause of work-related asthma (Bakke, 2000). Exposure often leads to chronic hypersensitivity. Reaction can be triggered by doses as low as 0.14 mg/m3 which, in practice, are almost undetectable (Motzl, 2004).

In the finished product there will often be residues of untransformed isocyanates; for example about 0.5% in polyurethane glues (Zwiener et al., 2006). These will be emitted at normal temperatures. At around 150 °C which can occur near heating apparatus in buildings, the polyurethane compounds themselves can start to break up, leading to much larger emissions of isocyanates. At even higher temperatures, such as in fires, the lethal neurotoxin hydrogen cyanide is formed.

At normal temperatures polyurethane products can also emit small amounts of amines, and significant emissions of brominated compounds have also been registered when these are used as flame retardant (Schmidt, 2006). Emissions of fluorocarbons, if used as foaming agents, will also take place. Approximately 10 to 20% of the amount used will leak out during the first year, and then 0.5 to 1.5% per year thereafter (Harnisch et al., 2004). Environmentally damaging substances can leach out of the waste product, and polyurethane has a long decomposition time.

Polyvinyl chloride (PVC) is produced by a polymerization of vinyl chloride, which in turn is produced from 51% chlorine and 43% ethylene. Bisphenol A is often used as a polymerization inhibitor. Many other additives are also used; for example, about 0.02% antioxidants and ultraviolet stabilizers, a maximum of 10% flame retardants, 2.5-10% smoke reducing agents, up to 4% antistatic agents, 0.5-1 % pigment; in some cases as much as 50% plasticizers as well as fillers. Constituents that are critical for the environment are substances such as plasticizers containing phthalates, ultraviolet stabilizers containing cadmium, lead or tin (in the case of windows) and flame retardants with chloroparaffinsand antimony trioxide. In PVC gutters, cables and pipes, lead is often used as the ultraviolet stabilizer.

Production plants for PVC are likely to emit chlorine gas, ethylene, dioxins, vinyl chloride, the solvent dichloroethane, mercury and other problematic substances. Certain larger plastics plants have emissions of several tons of phthalates into the air every year. During production, workers can also be exposed to organic acidic anhydrides.

Emissions of phthalates or organic acidic anhydrides (when heated) can occur from the completed product in buildings, together with a series of other volatile substances such as aliphatic and aromatic hydrocarbons, phenols, aldehydes and ketanes, though only in small amounts. Leftover monomers from vinyl chloride may also be released (approximately 10mg/kg PVC). There is also greater microbiological growth on plastics containing phthalates, which probably functions as a source of carbon and nitrogen.

As a waste product, PVC contains environmentally dangerous substances that can seep out, not least when heavy metals have been used as pigments or cadmium as an ultraviolet stabilizer. PVC is considered to be the largest source of chlorine in waste products. When burnt, it can form concentrated hydrochloric acid and dioxins, the most toxic and persistent of all chemical groups. PVC waste can form hydrogen chloride when exposed to solar radiation. It decomposes slowly.

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