Polyurethanes waterproofing

Liquid polyurethane waterproofing systems are coal-tar modified products. Two-component materials are catalysed curing systems, and one-component materials are cured by exposure to moisture. Both the materials exhibit comparable properties on complete curing. Two-component materials require on-site mixing of the components. One-component materials can be applied directly, but the problem with this type is polymerisation of the product inside the container if it is improperly sealed. Such products are purged with an inert gas when the pack is sealed. 

Liquid-applied polyurethane waterproofing membranes have several advantages, as follows ... 

Figure 4.7 Elastomeric polyurethane waterproofing membrane on a roof terrace. Reproduced with permission from Fosroc...

In the second quarter of the twentieth century, with the development of poly(vinyl chloride), nylon, polyurethane, and other polymers, many new and improved leather-like materials, so-called coated fabrics (qv), were placed on the market. Shortages of leather after World War 11 led to the expansion of these leather-like materials ("man-made" leathers) to replace leather in shoes, clothing, bags, upholstery, and other items. DurabiUty and waterproof quahties superior to leather made coated fabrics advantageous, in spite of imperfection in breathabihty and flexibiUty. Demands for shoes, clothing, and other items are stiU increasing due to growing world population and urbanization. 

Waterproof. Waterproofing barrier systems may be either hot- or cold-appHed. The hot-appHed generaUy involve a bituminous material such as asphalt used in conjunction with a reinforcing fabric such as roofing felt, cotton, or glass cloth. Cold-appHed can be bituminous or elastomeric materials either in Hquid or sheet form, with or without fabric reinforcement. Liquid elastomeric treatments include neoprene, polyurethanes, and blends of these or epoxies with bituminous materials. Among the commonly used precured elastomeric sheet materials are neoprene, polyisobutylene, EPDM mbber, and plasticized PVC. Polyethylene and PVC films and nonwoven plastic or glass fabric coated with bituminous materials also find use (78). Because these... 

Coal tar-modified polyurethane is a cold-applied liquid waterproofing system. The system by Sonneborn is an example of this approach to waterproofing. It is applied as a liquid at the rate of 10-15 mils/coat. The coating dries hard, but has some elasticity. This material may be attacked by acids in groundwater but can be defended by a protection board. The performance of any liquid-applied waterproofing systems is limited by the capabilities of the applicator (it is difficult to achieve even coats on vertical surfaces). 

Polymer-modified asphalt is a cold-applied liquid waterproofing system. As with the Sonneborn system mentioned above, the quality of the installation depends on the applicator (it is difficult to achieve an even coating on a vertical surface). High-grade polymer-modified asphalt is superior to coal tar-modified polyurethane in elasticity, crack-spanning ability, and resealability, but inferior in its resistance to chemicals. 

Other uses for depolymerized PET bottles have been investigated. Used bottles have been glycolized and then used to make unsaturated polyester thermosets and polyol components in rigid polyurethane foam. Evco Research announced in 1999 its EvCote waterproof coatings and adhesives based on recycled PET [17, 18]. 

Isocyanates (RNCO) are industrially relevant compounds which find application in several fields [9, 106]. Many isocyanates serve as the starting materials for the manufacture of plant protection agents, pesticides, dyes, resins and plastics, textile waterproofing agents, detergents, bleaches, and adhesives. They are also widely used in surface coatings such as paints, sealants and finishes, and in the manufacture of rubbery plastics such as those used to coat wires. Traditionally, diisocyanates are the primary feedstock for the production of polyurethanes. The global market for diisocyanates in the year 2000 was 4.4 million tonnes, of which 61.3% was methylene diphenyl diisocyanate (MDI), 34.1% was toluene diisocyanate... 

Single component systems rely in most cases for the cure to take place by the reaction of moisture in the air with the prepolymer to form a solid polymer. Carbon dioxide gas is given off during this reaction and either escapes into the air or is trapped by fillers in the system. These systems are used to make waterproof barriers and single pack polyurethane paints. 

Motor Cycling. One- or two-piece protective suits normally are made from fabric-supported flexible vinyl or from polyurethane materials. A typical garment would be sewn but with welds over the seams to ensure that it is waterproof. With polyurethane, welding alone often is quite satisfactory. In some parts of the garments, patches are over-welded as re-inforcement. 

In this book I have confined discussion to those polymeric materials which are cured by chemical reaction and which have found widespread application in the construction industry. As such, the book covers materials based on epoxies, polyurethanes, silicones, polysulphides, alkyds and polyesters. In addition, there is a chapter on hybrid polymer systems and one on acrylics. It is true that acrylic emulsions are not strictly thermosetting polymer systems, but their widespread use and importance made their exclusion difficult. These materials find use as coatings, sealants, adhesives, grouts, flooring compounds, repair compounds and waterproofing agents. 

The high elasticity, low water permeability and excellent bonding make liquid polyurethane systems suitable for a wide range of waterproofing applications such as for foundations, basements, tunnels, multilevel... 

Dinitrotoluenes are intermediates in the production of toluene diisocyanate but are also used as gelatinizing and waterproofing agents in commercial and military explosives and in the production of polyurethane foams. 

Several sections of this chapter discuss building materials (hoses and pipes, pavement, roofing, sealants, siding, and waterproofing). Here, we focus on wall materials and insulation in various extruded and molded profiles. Numerous polymers are used for these two applications. They include polystyrene, phenolic resin, polyvinylchloride, and polyurethanes for insulation purposes and polyvinylchloride, polyurethanes, and polyesters for wall systems and structural elements. The major methods of production include molding, extrusion, and pultrusion. 

Polyurethane grout supplied shall be water-reactive liquid polyurethane base solutions which when reacted expand by foaming to at least seven (7) times the initial liquid volume and when set produce a flexible, closed void solid resistant to degradation by wet and dry cycles and chemicals found in concrete construction. Specific waterproofing grouts meeting these requirements are marketed by the following manufacturers.... ... 

ORIGIN/INDUSTRY SOURCES/USES intermediate for polyurethanes, explosives, dyes, smokeless gunpowders, toluidines, organic synthesis manufacture of 2,4-diaminotoluene propellant additive gelatinizing and waterproofing agent... 

In the absence of foaming, we can produce a material hard enough for roller blade wheels or soft and pliable enough to mimic leather. In fact, at the New York World s Fair of 1964, DuPont proudly introduced shoes made of Corfam, a polyurethane-based synthetic leather. The shoes were durable and waterproof, and they could be cleaned with a moist cloth. Best of all, Corfam was porous, so the shoes breathed like leather. Within a year, seventy-five million pairs of Corfam shoes had been sold, and the leather industry stopped breathing. But the Corfam fad didn t last. Despite the material s porosity, many complained of hot, sweaty feet, and furthermore, women didn t like the idea of shoes that lasted forever — they wanted new styles every year. So, Corfam became DuPont s Edsel. 

The main advantage of polyurethane-modified mortar is an improvement in the strength development at low temperatures or under wet conditions, good adhesion to wet substrates, waterproofness, and abrasion resistance. The properties of the polyurethane-modified mortar are shown in Table... 

Acrylates are inexpensive materials suitable for waterproof coatings in lower quality applications but polyurethane (see below) is better suited for higher quality applications. 

One of the important developments in, and applications of, textiles is the manufacture of intelligent waterproof breathable fabrics based on shape memory polymers using shape memory polyurethanes. The fabric restricts the loss of body warmth by stopping... 

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