Building Materials, Plastic

Abstract

AbstractThroughout the 1990s, plastics consumption in building materials was forecast to grow at a 4–5% average annual rate. Contributing to this growth were advances in do‐it‐yourself and professional remodeling products employing plastics, overall growth in the renovation and home remodeling markets, plus the increased penetration of plastics at the expense of traditional materials in building products because of their superior strength in weight performance, corrosion resistance, environmental stability, lower cost, insulation properties, and ability to fabricate complex designs into a single part, ie, low labor assembly intensity. On the other hand, there were concerns over their flammability and smoke toxicity, and the public perception of their negative environmental impact. The physical properties of plastics that are important in building materials are the glass‐transition or melt temperature, ease of processing as indicated by the temperatures and pressures needed for molding, heat deflection temperature, uv stability, tensile and impact strength, oxidative degradation, creep set, fatigue, and elongation. Density, thermal conductivity, and fire resistance are important for foams. Phenolics are consumed at roughly half the volume of PVC, and all other plastics are consumed in low volume quantities, mostly in single application niches, unlike workhorse resins such as PVC, phenolic, urea–melamine, and polyurethane. Except for the potential role of recycled engineering plastics in certain applications, the competitive nature of this market and the emphasis placed on end use economics indicates that commodity plastics will continue to dominate in consumption. The most dynamic growth among important sector resins has been seen with phenolic, acrylic, polyurethane, LLDPE/LDPE,PVC, and polystyrene. Over 60% of the total plastics volume for building materials is consumed for pipes, fittings, conduit, and wood bonding applications. Other important applications include solar heating, glazing, exterior trim, door and window frames, insulation, panels and siding, and flooring (additional 25%). With regard to plastics, urea–formaldehyde insulating foams have received the greatest publicity. In the early to mid‐1980s, they were studied for their formaldehyde release, ie, outgassing. The U.S. EPA has set an acceptable level of formaldehyde within indoor air at 0.1 ppm. Another potential source of formaldehyde release in buildings is from the binder systems used in pressed wood products such as particle board. Smoke, not flames, is the primary cause of death in most fires. However, past efforts to determine which building product components generate the most harmful or toxic smoke emissions have proven inconclusive. Plastic building products almost always incorporate additive such as colorants, plasticizers, uv light stabilizers, and flame retardants. These various additives are under increasing scrutiny for their potential risks with regard to smoke toxicity and their effects upon worker health in processing plants. The plastic building materials industry is facing rapid change. Engineering thermoplastics have better mechanical properties than commodity plastics. Thermoplastics can be combined with fibers, fillers, and traditional building materials, creating composite materials with durability, fireproofing, and stress resistance. A very high price and performance family of polymers called liquid crystal polymers (LCPs) exhibit extremely high mechanical and thermal properties. As their ease of processing and price improve, they may find application in thin‐wall, high strength parts. Thermoset polyurethane as a binder material for gravel systems is also under development. Certain state highway authorities are studying the use of fiber‐reinforced polymers for bridge construction.