Polyurethane-Based Compositions

One of the more important patents in IPNs, by Frisch reveals a 

Each of the Frisch compositions discloses a polyurethane as one of the networks. 

A composition composed of an isocyanate-terminated prepolymer, a multifunctional acrylic such as TEGDM or TMPTM, and an isocyanate-terminated polyhydric polyalkene ether on curing, forms a complex, grafted 

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In a similar spirit, but without any consideration about covalent cross-linking, dry nanostructured silicas have been also used for the synthesis of some sifica/polyurethane composites [48]. Silica nanopowders (e.g., finely divided silicas with characteristic dimensions between 10 nm and 100 pm) have been dispersed in various polyurethane sols. After gelation in the presence of these inorganic fillers, the polyurethane-based composites can be considered as superinsulating materials with thermal conductivities lower than 0.020 W/m K. 

Kucinska-Lipka, J., Gubanska, L, Janik, H., Sienkiewicz, M., 2015. Fabrication of polyurethane and polyurethane based composite flbres by the electrospinning technique for soft tissue engineering of cardiovascular system. Material Science and Engineering C Materials for Biological Applications 46, 166-176. 

Polyols and polyisocyanates are major ingredients for polyurethane (PU)-based composite propellants in addition to chain extenders and catalysts etc. A brief description on these materials is considered necessary in order to understand the chemistry of composite propellants in a better way. Polyols are the largest group of raw materials for PUs. The properties of PUs/PU products are largely determined by their chemical composition and molecular mass. They may be broadly classified [87] as ... 

Caprolactone is claimed as a component in one-paste-type resin compositions for denture bases <2002JPP2002104912> and e-caprolactone copolymers are suggested as components in polyurethane-based multilayered artificial leather sheets <2004JPP2004250808, 2004JPP2004250809>. 

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. 

The most successful application of the RIM-process is in the production of polyurethane-based materials. Other systems, such as composites based on polycaproamide, epoxy resins, and unsaturated polyesters can also be processed by reactive injection molding. New reactive systems have also been specially created for the RIM-process260 because of the exceptional opportunities it offers for manufacture of finished articles from engineering plastics with a high modulus of elasticity and impact strength. The automotive industry, which is the main customer for RIM-articles, can utilize this technology to manufacture of massive parts such as body panels, covers, wings, bumpers and other made of newly developed plastics. 

The principal issues for the materials technology related to the basic properties for polyurethane/CNT composites were already presented in previous sections. It provided the correlation between the structural factors and the properties resulting therefrom. This section, however, is going to present a review of the latest trends in applications for the materials based on polyurethane/CNT composites. 

An alternative to the acrylamide-based composite hydrogel dressing is an acrylamide grafted to a polyurethane film to give a transparent, flexible gel with an equilibrium water content of approximately 50 /o. The hydrated gel has a low modulus of elasticity and a high water permeability that facilitates the adherence of the gel to the wound surface. The permeability... 

For manufacturing composite sandwich panels by laminating, a coating apparatus for the adhesive (chloroprene-base and polyurethane-base adhesives are preferable) and a press is needed. 

Solderable wires are used in telecommunications and the construction of analytical instruments, but they are becoming more and more common in small motors and dry-type transformers. The special characteristic of solderable wire enamels is the direct soldering. When the enameled wire is dipped in a solder bath at temperatures above 350 °C the coating melts and leaves the bare copper wire, avoiding the need for elaborate mechanical or chemical removal of the enamel. This characteristic achieved in solderable poly(ester-imide) by a special polymer composition and in polyurethane based wire enamels is due to the thermally reversible splitting of the polyurethane group. Nevertheless, good thermal stability is necessary and product temperature indexes >155 are required. For temperature indexes of 130, simply polyurethane wire enamels were used. 

Source Reprinted from O. Figovsky, L. Shapovalov, A. Leykin, O. Birukova, and R. Potesshnikova, Nonisocyanate Polyurethanes Based on Cyclic Carbonates and Nanostructures Composites, J. Scientific Israel Technology Advanced 14, no. 4 (2012) 95—106. With permission. 

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