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Coatings were prepared by moisture curing of IPDI capped hydroxyl terminated polybutadiene/clay dispersions in a relative humidity (RH) of 50% at 25 °C. Moisture cured polyurethane–urea coatings have been made by reacting 1,2,3-triazole rich polyether polyols with HMDI at NCO/OH eq. ratio of 1.2 to obtain isocyanate-terminated polyurethane ...
Polyurethane dispersion, or PUD, is understood to be a polyurethane polymer resin dispersed in water, rather than a solvent, although some cosolvent may be used.Its manufacture involves the synthesis of polyurethanes having carboxylic acid functionality or nonionic hydrophiles like PEG (polyethylene glycol) incorporated into, or pendant from, the polymer backbone. [1]
Polyurethane may also be applied over a straight oil finish, but because of the relatively slow curing time of oils, the presence of volatile byproducts of curing, and the need for extended exposure of the oil to oxygen, care must be taken that the oils are sufficiently cured to accept the polyurethane.
Figure 4: Evolution in time of storage modulus G' and loss modulus G" during a curing reaction. A simple way to monitor the change in viscosity, and thus, the extent of the reaction, in a curing process is to measure the variation of the elastic modulus. [7] To measure the elastic modulus of a system during curing, a rheometer can be used. [7]
Acrylic and waterborne varnishes dry by evaporation of the water but will experience an extended curing period for evaporation of organic solvents absorbed on the latex particles, and possibly chemical curing of the particles. Oil, polyurethane, and epoxy varnishes remain liquid even after evaporation of the solvent but quickly begin to cure ...
Polyurethane synthesis, wherein the urethane groups −NH−(C=O)−O− link the molecular units A kitchen sponge made of polyurethane foam . Polyurethane (/ ˌ p ɒ l i ˈ jʊər ə ˌ θ eɪ n,-j ʊəˈr ɛ θ eɪ n /; [1] often abbreviated PUR and PU) refers to a class of polymers composed of organic units joined by carbamate (urethane) links.
Blocked isocyanates are particularly useful in products with a dual cure mechanisms. As an example, Ultraviolet light initiates the polymerization of an acrylate based polymer that contains hydroxy groups on the polymer backbone. The system would also contain an isocyanate blocked with a malonate. This is now a one-component system.
Spray foam insulation or spray polyurethane foam (SPF) is an alternative to traditional building insulation such as fiberglass. A two-component mixture composed of isocyanate and polyol resin comes together at the tip of a gun, and forms an expanding foam that is sprayed onto roof tiles, concrete slabs, into wall cavities, or through holes ...
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