Polyurethane 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 is produced from a wide range of starting materials. This chemical variety produces polyurethanes with different chemical structures leading to many different applications. These include rigid and flexible foams, and coatings, adhesives, electrical potting compounds, and fibers such as spandex and polyurethane laminate (PUL). Foams are the largest application accounting for 67% of all polyurethane produced in 2016.
In organic chemistry, isocyanate is the functional group with the formula R−N=C=O. Organic compounds that contain an isocyanate group are referred to as isocyanates. An organic compound with two isocyanate groups is known as a diisocyanate. Diisocyanates are manufactured for the production of polyurethanes, a class of polymers.
Petrochemicals are the chemical products obtained from petroleum by refining. Some chemical compounds made from petroleum are also obtained from other fossil fuels, such as coal or natural gas, or renewable sources such as maize, palm fruit or sugar cane.
In materials science, a thermosetting polymer, often called a thermoset, is a polymer that is obtained by irreversibly hardening ("curing") a soft solid or viscous liquid prepolymer (resin). Curing is induced by heat or suitable radiation and may be promoted by high pressure or mixing with a catalyst. Heat is not necessarily applied externally, and is often generated by the reaction of the resin with a curing agent. Curing results in chemical reactions that create extensive cross-linking between polymer chains to produce an infusible and insoluble polymer network.
Oxazolidine is a five-membered heterocycle ringwith the formula (CH2)3(NH)O.The O atom and NH groups are not mutually bonded, in contrast to isoxazolidine. Oxazolidines are derivatives of the parent oxazolidine owing to the presence of substituents on carbon and/or nitrogen. Oxazolines are unsaturated analogues of oxazolidines.
In organic chemistry, a polyol is an organic compound containing multiple hydroxyl groups. The term "polyol" can have slightly different meanings depending on whether it is used in food science or polymer chemistry. Polyols containing two, three and four hydroxyl groups are diols, triols, and tetrols, respectively.
In polymer chemistry, step-growth polymerization refers to a type of polymerization mechanism in which bi-functional or multifunctional monomers react to form first dimers, then trimers, longer oligomers and eventually long chain polymers. Many naturally-occurring and some synthetic polymers are produced by step-growth polymerization, e.g. polyesters, polyamides, polyurethanes, etc. Due to the nature of the polymerization mechanism, a high extent of reaction is required to achieve high molecular weight. The easiest way to visualize the mechanism of a step-growth polymerization is a group of people reaching out to hold their hands to form a human chain—each person has two hands. There also is the possibility to have more than two reactive sites on a monomer: In this case branched polymers production take place.
Triethylamine is the chemical compound with the formula N(CH2CH3)3, commonly abbreviated Et3N. It is also abbreviated TEA, yet this abbreviation must be used carefully to avoid confusion with triethanolamine or tetraethylammonium, for which TEA is also a common abbreviation. It is a colourless volatile liquid with a strong fishy odor reminiscent of ammonia. Like diisopropylethylamine (Hünig's base), triethylamine is commonly employed in organic synthesis, usually as a base.
Isophorone diisocyanate (IPDI) is an organic compound in the class known as isocyanates. More specifically, it is an aliphatic diisocyanate. It is produced in relatively small quantities, accounting for only 3.4% of the global diisocyanate market in the year 2000. Aliphatic diisocyanates are used, not in the production of polyurethane foam, but in special applications, such as enamel coatings which are resistant to abrasion and degradation from ultraviolet light. These properties are particularly desirable in, for instance, the exterior paint applied to aircraft.
A thermoset polymer matrix is a synthetic polymer reinforcement where polymers act as binder or matrix to secure in place incorporated particulates, fibres or other reinforcements. They were first developed for structural applications, such as glass-reinforced plastic radar domes on aircraft and graphite-epoxy payload bay doors on the Space Shuttle.
In polymer chemistry, the term prepolymer or pre-polymer, refers to a monomer or system of monomers that have been reacted to an intermediate-molecular mass state. This material is capable of further polymerization by reactive groups to a fully cured, high-molecular-mass state. As such, mixtures of reactive polymers with un-reacted monomers may also be referred to as pre-polymers. The term "pre-polymer" and "polymer precursor" may be interchanged.
Polyaspartic ester chemistry was first introduced in the early 1990s making it a relatively new technology. The patents were issued to Bayer in Germany and Miles Corporation in the United States. It utilizes the aza-Michael addition reaction. These products are then used in coatings, adhesives, sealants and elastomers. Pure polyurea reacts extremely quickly making them almost unusable without plural component spray equipment. Polyaspartic technology utilizes a partially blocked amine to react more slowly with the isocyanates and thus produce a modified polyurea. The amine/diamine or even triamine functional coreactant for aliphatic polyisocyanate is typically reacted with a maleate. Polyaspartic esters (PAE) initially found use in conventional solvent-borne two-component polyurethane coatings.
Moisture-cure polyurethanes -- or polyurethane prepolymer -- are isocyanate-terminated prepolymers that are formulated to cure with ambient water. Cured PURs are segmented copolymer polyurethane-ureas exhibiting microphase-separated morphologies. One phase is derived from a typically flexible polyol that is generally referred to as the “soft phase”. Likewise the corresponding “hard phase” is born from the di- or polyisocyanates that through water reaction produce a highly crosslinked material with softening temperature well above room temperature.
Polyurethane dispersion, or PUD, is understood to be a polyurethane polymer resin dispersed in water, rather than a solvent, although some cosolvent maybe used. Its manufacture involves the synthesis of polyurethanes having carboxylic acid functionality or nonionic hydrophiles like PEG incorporated into, or pendant from, the polymer backbone. Two component polyurethane dispersions are also available.
Tetramethylxylylene diisocyanate (TMXDI) is an organic compound with the formula C6H4(CMe2NCO)2 (Me = CH3). Introduced in the 1980s by American Cyanamid, the molecule features two isocyanate groups. TMXDI is generally classified as an aliphatic isocyanate, which are generally more UV stable than their aromatic counterparts.
Dimethylolpropionic acid (DMPA) is a chemical compound that has the full IUPAC name of 2,2-bis(hydroxymethyl)propionic acid and is an organic compound with one carboxyl and two hydroxy groups. It has the CAS Registry Number of 4767-03-7.
Waterborne resins are sometimes called water-based resins. They are resins or polymeric resins that use water as the carrying medium as opposed to solvent or solvent-less. Resins are used in the production of coatings, adhesives, sealants, elastomers and composite materials. When the phrase waterborne resin is used, it usually describes all resins which have water as the main carrying solvent. The resin could be water-soluble, water reducible or water dispersed.
Hydrogenated MDI (H12MDI or 4,4′-diisocyanato dicyclohexylmethane) is an organic compound in the class known as isocyanates. More specifically, it is an aliphatic diisocyanate. It is a water white liquid at room temperature and is manufactured in relatively small quantities. It is also known as 4,4'-methylenedi(cyclohexyl isocyanate) or methylene bis(4-cyclohexylisocyanate) and has the formula CH2[(C6H10)NCO]2.
Blocked isocyanates are organic compounds that have their isocyanate functionality chemically blocked to control reactivity. They are the product of an isocyanate moiety and a suitable blocking agent. It may also be a polyurethane prepolymer that is NCO terminated but this functionality has also been chemically reacted with a blocking agent. They are usually used in polyurethane applications but not always. They are extensively used in industrial applications such as coatings, sealants and adhesives.
Diethyl toluene diamine (DETDA) is a liquid aromatic organic molecule with formula C11H18N2. It is chemically an aromatic diamine and has the CAS Registry number of 68479-98-1. It has more than one isomer and the mixture of the two main isomers is given a different CAS number of 75389-89-8. It is often marketed as a less toxic version of 4,4'-methylenedianiline (MDA). It is also used to replace the more toxic 4,4'-methylenebis(2-chloroaniline) (MOCA). The toxicology is reasonably well understood.
