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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. In contrast to other common polymers such as polyethylene and polystyrene, polyurethane term does not refer to the single type of polymer ...
Moisture-cure polyurethanes -- or polyurethane prepolymer -- are isocyanate -terminated prepolymers that are formulated to cure with ambient water. [1] Cured PURs are segmented copolymer polyurethane-ureas [2] exhibiting microphase-separated morphologies. One phase is derived from a typically flexible (subambient glass transition temperature, T ...
Due to the closed-cell nature of rigid polyurethane foams, PUR insulation has minimal water absorption, which coupled with an appropriate cover, makes it a particularly suitable in applications where bacterial growth is a concern. Polyurethane insulation is suitable for insulating pipes with surface temperatures ranging from -196°C to 148°C. [7]
Thermoplastic polyurethane. Thermoplastic polyurethane (TPU) is any of a class of polyurethane plastics with many properties, including elasticity, transparency, and resistance to oil, grease, and abrasion. Technically, they are thermoplastic elastomers consisting of linear segmented block copolymers composed of hard and soft segments.
Blowing agent. A blowing agent is a substance which is capable of producing a cellular structure via a foaming process in a variety of materials that undergo hardening or phase transition, such as polymers, plastics, and metals. [1] They are typically applied when the blown material is in a liquid stage. The cellular structure in a matrix ...
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]
The so-called flexible polyurethane foam (FPF) is produced from the reaction of polyols and isocyanates, a process pioneered in 1937. [1] FPF allows for some compression and resilience that provides a cushioning effect. Because of this property, it is often used in furniture, bedding, automotive seating, athletic equipment, packaging, footwear ...
Cold shock response is a series of neurogenic cardio-respiratory responses caused by sudden immersion in cold water. In cold water immersions, such as by falling through thin ice, cold shock response is perhaps the most common cause of death. [1] Also, the abrupt contact with very cold water may cause involuntary inhalation, which, if ...