Applications polyurethane

TABLE 4.1 Polyurethanes Applications, Properties, and Processing Methods... 

Perhaps the most significant recent issue for the industry was the phase-out of CFCs as blowing agents resulting from the Montreal Protocol (1987) and Clean Air Act (1990).19 These regulations mandate specific timelines for discontinuation and, since foams comprise the bulk of polyurethane applications, have prompted a worldwide search for alternatives. Hydrochlorofluorocarbons, HFCs, and hydrocarbons (HCs) are now the blowing agents of choice. Which one is... 

Polypropylene ether) polyol is the single most important product from propylene oxide and enjoys a predominant position in polyurethane applications. The ether linkages are very abundant in these polyols and they contribute to the physical and chemical properties in many applications such as surfactant action and hydrogen-bond formation. 

In recent years, industrial research has created new opportunities for the use of new types of plant-derived oils in polyurethane applications [25]. In addition to the use of natural glycerin or sugars as a starter for conventional petrochemical polyols. 

Castor oil is a triglyceride that is well suited for use in polyurethane applications. Unlike most other oil-producing plants, the castor plant produces a triglyceride containing >90% of a single fatty acid, that being ricinoleic acid. Ricinoleic acid contains secondary hydroxyl groups appended to the Cjg fatty acid backbone (Fig. 8). 

The ready availability of ESO has contributed strongly to the commercial development of polyurethane polyols derived from this chemistry. Of all the approaches to developing renewable polyols for polyurethane applications, the... 

The most import uni cyclic ethers arc (he furan compounds Furfural is manufactured by treating pentosan with sulfuric acid and steam stripping mil the furfural a n is formed The sources of pentosan arc such agricultural products uv comet tbs. oat hulls, and hagavtc Furfural is used to produce furan and tetrahydro furan fTHF) These products are used as organic intermediates, extraction solvent, polymer solvents, and in polyurethane applications... 

The heat generated when work is done to the polyurethane must be removed or the material will become overheated. The thermal conductivity of polyurethane is poor compared to metals. Unless the product is properly designed, there can be failures in some polyurethane applications. 

Epoxidised oils (with isolated double bonds), such as epoxidised soybean are used as plasticisers. The natural occurrence of epoxidised fatty acids could be exploited to reduce processing costs on the pathway to polymerisation. For example, seed oils derived from Vernonia galamensis and Euphorbia lagascae both contain significant proportions (60-80%) of the epoxy acid vemolic acid, with interesting applications in greases and polyurethane applications (Turley et al., 2000). 

Amine catalysts for polyurethane applications are sold by Air Products (Dabco), Abbott (Polycat), Kao Corporation (Kaolizer), Tosoh Corporation (Toyocat), and Union Carbide (Niax). 

With the lifting of Allied restrictions on research in German industry, polyurethane applications were advanced by Bayer. This included the important foaming technology,... 

In the polyurethane applications described so far, care has to be taken to exclude moisture. Any water, which is present, will react with isocyanate groups to give carbon dioxide gas, which can form bubbles in the product (Eq. 21.22). 

This occurrence significantly affects the stoichiometry, not only from consumption of the isocyanate functionality in the process, but also by production of an amine product with two active hydrogens, which adds reactive functional groups to the glycol component of the polyurethane reaction. For these reasons care has to be taken to exclude moisture for the polyurethane applications described so far. However, for the production of flexible and rigid polyurethane foams the reaction of isocyanate with water is exploited to produce bubbles. 

Polyurethanes represent approximately 6% of global plastic consumption, and 50% of the entire PU consumption occurs in North America and Europe. Roughly 30 /o of PUs are used for furniture and mattresses, 15 /o for vehicles, and 13%i for construction. In all of these applications, PU foams are used. In fact, over 80 /o of polyurethane applications use foam materials. Other forms of PU available include solid blocks, fibers, paints, adhesives, and coatings. 

VotyuX tkcLneA. Polyurethanes are a versatile group of polymers which span a wide range of physical properties and applications. Polyurethane markets are predicted to grow at an annual rate of 7-10% in the next 10 years (7). Many polyurethane applications are for network polymers, and these have been reviewed elsewhere in this treatise (7). ... 

The main field of polyurethane application is the furniture industry, around 30% of the total polyurethanes produced worldwide is used for the production of mattresses from flexible slabstock foams. Automotive manufacture is the second important application for flexible and semiflexible polyurethanes (seat cushioning, bumpers, sound insulation, and so forth). Rigid polyurethane foams are used in thermal insulation of buildings and refrigerators, cold stores, pipe insulation, refrigerated transport, thermal insulation in chemical and food industries. The polyurethane elastomers are used for shoe soles,... 

Chapter 12.5). Polyester polyols in reality, have the theoretical functionality, which is a great advantage for many polyurethane applications. For polyester diols the functionality is 2 OH groups/mol. This structural aspect results in the polyester diols giving PU elastomers with excellent physico-mechanical properties, superior to all polypropylene glycols obtained by anionic PO polymerisation. 

Both structures (13.2 and 13.3) are used successfully in rigid PU foams. Structure 13.2, having a high hydroxyl number, is used more frequently as crosslinker in many polyurethane applications (rigid PU foams, coatings). 

Impact of Composition on Polyurethane Properties 126 7.6 Polyurethane Applications 137... 

Advances in Urethane Science and TechncSfd Materials for Polyurethane Applications... 

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