Quantity of Polyurethane

If the mold has been made from a CAD/CAM design, there is often a facility in the package to estimate the volume of material to use. The weights of the smaller and larger parts in a series can be used for gauging the amount of material required. 

Sufficient material to overfill the mold should be prepared for the first pour so that the mold will definitely be filled. Noncritical molds should be available to use up any excess material prepared. 

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Polyurethane. SmaU quantities of polyurethane film are produced as a tough mbber-like film. Polyurethane is more commonly used to produce foamed sheet, both flexible and rigid. The flexible foam is used as cushioning in furniture and bedding the rigid foam is widely used for architectural insulation because of its outstanding thermal insulation efficiency (see Urethane POLYMERS). 

The fillers can be isolated by ashing a quantity of polyurethane to yield the desired quantity of ash for spectroscopic (or wet chemical method) analysis. Often the filler can be identified by infrared without any elemental analyses. Usable spectra of inorganic compounds may be obtained by grinding with a mortar and pestle to a powder, spreading uniformly between two salt plates, and gently moving one plate over the other until good contact between plates and sample is achieved. A demountable cell is normally required to centre the plates in the spectrophotometer beam. 

The behavior of samples derived from polyurethane isocyanmate networks imder conditions of thermomechanical and TGA analyses were considered. Figure la shows thermomechanical curves of seven samples containing different quantity of polyurethane (PU) component and TDI, also differing by the elasticity modulus values. 

Solvent resistance This varies from very poor (for chlorinated rubbers) to good (for polyurethanes). All paint binders have specific susceptibilities and the presence of small quantities of the appropriate solvent in the atmosphere in the region of an item of plant can cause rapid failure. 

Aniline, which is used not only to synthesise drugs, pesticides and explosives but also as a building block for materials such as polyurethane foams, rubber, azo dyes, photographic chemicals and varnishes, is manufactured at a quantity of approximately three million tons each year [61]. The toxic effects of aniline include increased nitration of proteins in the spleen [62]. 

Catalysts are commonly used to control the pouring and gel times of polyurethane systems. As catalysts are used in small quantities, the addition must be carried out very carefully otherwise, very erratic results may be obtained. Catalysts may be made into a concentrated solution with an inert carrier such as a plasticizer. This reduces a potential dispensing error. They also may be added to a liquid chain extender. 

Another method for expressing thermal conductivity is to determine the quantity of heat passing through a unit area of the material, when the temperature gradient (when measured across unit thickness in the direction of the heat flow) is unity (Smith, 1993). The thermal conductivity of a polyurethane is on the order of 0.1 to 0.3 W/m.K. Other references give a value of approximately 1.7 to 3.5 x 10 4 cal.-cm/sec. cm2.°C (Gallagher Corporation, 1994). 

Shot The accurate dispensing of a pre-calculated quantity of mixed polyurethane from a polyurethane-dispensing machine. The shot... 

A material that is added to a formulation that increases the quantity of formulation required for a process without actually changing the formulation s reactivity. Example Barium sulfate is sometimes added during processing to increase the density of polyurethane (solid) foam. (CAPICO) A system in which potential cosmetic emulsion ingredients are numerically categorized so that one may calculate their influence on the phase inversion temperature of a formulated emulsion. 

Saxena et al. [512] used polyurethane foams to concentrate trace quantities of six representatives of polynuclear aromatic hydrocarbons (fluoranthene, benzo(k)fluoranthene, benzo(j)fluoranthene, benzo(a) pyrene, benzo(ghi) perylene, and indeno(l,2,3-cd)pyrene) prior to regular screening of these compounds in US raw and potable waters. Final purification and resolution of samples was by gas chromatography and two-dimensional thin layer chromatography, followed by fluorometric analysis and quantification. 

The value of a for poly(propylene oxide) was obtained from the data of Moacanin 189) for polyurethanes prepared by condensation of toluene-2,4-diisocyanate with atactic polypropylene glycols of molecular weights about 1000 and 2000. The small quantity of diisocyanate present in these compositions can make only a negligible effect on the chain dimensions (less than one per cent on the freely rotating chain, as is... 

The largest quantity of low-density foam is polyurethane, made by mixing liquid polyols... 

Polyethersiloxancs have surfactant properties. They ate utilized in large quantities as foam stabilizers in the manufacture of polyurethane hard and soft foams, the polyether component for this application being a copolymer of ethene oxide and propene oxide. Polyethersiloxancs are, however, also used in antifoaming formulations, as a gloss and deaeration additive in paints and as textile auxiliaries. 

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