Polyurethane mixtures, properties

Fly ash floaters - tiny hollow spheres of ash from the scrubbers of power plants - are used by the US processor Power Composites for mechanical and acoustic properties in a polyurethane mix, for moulding automobile loudspeaker enclosures. They flow easily and uniformly in the mould as part of the polyurethane mixture, giving good additional strength to the enclosure. 

Only a few commercial uses for TDA per se have been found. In epoxy curing appHcations, 2,4- I DA has been used as a component of a eutectic mixture with short chain aUphatic glycidal ether resins (46) as well as by itself (46,47) TDA (46) and single isomers (47) are also used as amine curatives. TDA can be used as a chain extender in polyurethanes (48,49). TDA is cited as a monomer in making aromatic polymers with unique properties, eg, amorphous polyamides (50), powdered polyamides (51), and low melting, whoUy aromatic polyamides (52). 

Hyperbranched polyurethanes are constmcted using phenol-blocked trifunctional monomers in combination with 4-methylbenzyl alcohol for end capping (11). Polyurethane interpenetrating polymer networks (IPNs) are mixtures of two cross-linked polymer networks, prepared by latex blending, sequential polymerization, or simultaneous polymerization. IPNs have improved mechanical properties, as weU as thermal stabiHties, compared to the single cross-linked polymers. In pseudo-IPNs, only one of the involved polymers is cross-linked. Numerous polymers are involved in the formation of polyurethane-derived IPNs (12). 

We achieved, that by contact of polyurethane foam with water solution of molybdophosphate, contain by pH 1-2,5 mixture of saturated (5 NMR P=-3.20 p.p.m. apply to 85 % H PO ) and unsaturated monovacant (x=0-t-4) (5 NMR P = -0,96 p.p.m.) heteropolycomplexes Keggin staicture, equilibrium discharge in the direction produced of saturated heteropolycomplex of Dowson stmcture and on the surface of polyurethan foam formed 18-molybdo-2-phosphate acid ( P = -2,40 p.p.m. in ether extract). The formed surfaces heteropolycomplex is stable for action 1 M solution of strong acids and basics and have ion exchanged properties in static and dynamic conditions to relation to macro and micro amount of M(I) ... 

Experimental Materials. All the data to be presented for these illustrations was obtained from a series of polyurethane foam samples. It is not relevant for this presentation to go into too much detail regarding the exact nature of the samples. It is merely sufficient to state they were from six different formulations, prepared and physically tested for us at an industrial laboratory. After which, our laboratory compiled extensive morphological datu on these materials. The major variable in the composition of this series of foam saaqples is the aaK>unt of water added to the stoichiometric mixture. The reaction of the isocyanate with water is critical in determining the final physical properties of the bulk sample) properties that correlate with the characteristic cellular morphology. The concentration of the tin catalyst was an additional variable in the formulation, the effect of which was to influence the polymerization reaction rate. Representative data from portions of this study will illustrate our experiences of incorporating a computer with the operation of the optical microscope. 

While the properties of polyurethane as an extractant are useful, several problems make it less than ideal. Polyurethanes are far more specific than activated charcoal in removing contaminants. Charcoal separates particles by size, and while it has some specificity, it is well suited for mixtures of diverse chemistries (PAHs vs. halogenated hydrocarbons). Polyurethanes, however, operate on the principle that like dissolves like. They consist of hydrophobic isocyanates and hydrophobic polyalcohols. Thus, the molecules are hydrophobic. The polyalcohol backbone has some polarity, but it is hindered and therefore has a low net polarity. Inasmuch as the extraction effect is based, at least in part, on polarity, polyurethanes are most effective for nonpolar pollutants... 

Flow sheets for preparing the components of various monomer and oligomer reactant mixtures do not differ significantly from each other, although they may have different sets of reactors. The choice depends mainly on the physical and chemical properties of the initial components. Fig. 4.2 shows a flow sheet for obtaining continuously molded polyurethane elastomers. Fig. 4.3 illustrates an elementary flow sheet for a batch process unit for manufacturing moldings of epoxy resin or epoxy-based composites filled with quartz sand. 

High-brisance crystalline explosives, such as RDX or octogen, can be embedded in curable or polyadditive plastics such as polysulfides, polybutadiene, acrylic acid, polyurethane, etc. The mixture is then cured into the desired shape. Other components such as aluminum powder can also be incorporated. The products obtained can be of any desired size, and specified mechanical properties can be imparted to them, including rubber-like elasticity (-> LX and -> PBX). They can also be shaped into foils. 

The major poly isocyanates used (2) are toluene diisocyanate (TDI) and the less volatile 4,4/-methylene diphenylene diisocyanate (MDI), which, because it is a crystalline solid in the pure form, has to be used in a relatively crude form. The crude polyisocyanate is a mixture of MDI variants that is conveniently a liquid product with a mean functionality greater than 2. The use of a pure, liquid diisocyanate, however, would enable polyurethanes to be formed having relatively enhanced physical properties (2) and would also greatly simplify processing by removing the need to use elevated temperatures, solvents, or isocyanate prepolymers as with MDI. 

Preparation of Plasticized Polyurethane Compositions. The procedure given immediately above was repeated, except that 10.5 grams of butylcyclohexyl phthalate (BCPH) were added to the original mixture as a plasticizer, and 0.5 gram of di-p-phenylphenylenediamine and 0.05 gram of ferric acetonylacetonate were used as catalysts. The properties of the resulting cured polymer are given in Table I (sample 4). 

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