Polymers polyether polyols

Polymerization Solvent. Sulfolane can be used alone or in combination with a cosolvent as a polymerization solvent for polyureas, polysulfones, polysUoxanes, polyether polyols, polybenzimidazoles, polyphenylene ethers, poly(l,4-benzamide) (poly(imino-l,4-phenylenecarbonyl)), sUylated poly(amides), poly(arylene ether ketones), polythioamides, and poly(vinylnaphthalene/fumaronitrile) initiated by laser (134—144). Advantages of using sulfolane as a polymerization solvent include increased polymerization rate, ease of polymer purification, better solubilizing characteristics, and improved thermal stabUity. The increased polymerization rate has been attributed not only to an increase in the reaction temperature because of the higher boiling point of sulfolane, but also to a decrease in the activation energy of polymerization as a result of the contribution from the sulfonic group of the solvent. 

In the manufacture of highly resident flexible foams and thermoset RIM elastomers, graft or polymer polyols are used. Graft polyols are dispersions of free-radical-polymerized mixtures of acrylonitrile and styrene partially grafted to a polyol. Polymer polyols are available from BASF, Dow, and Union Carbide. In situ polyaddition reaction of isocyanates with amines in a polyol substrate produces PHD (polyhamstoff dispersion) polyols, which are marketed by Bayer (21). In addition, blending of polyether polyols with diethanolamine, followed by reaction with TDI, also affords a urethane/urea dispersion. The polymer or PHD-type polyols increase the load bearing properties and stiffness of flexible foams. Interreactive dispersion polyols are also used in RIM appHcations where elastomers of high modulus, low thermal coefficient of expansion, and improved paintabiUty are needed. 

Another family of polyols is the filled polyols.llb There are several types, but die polymer polyols are die most common. These are standard polyether polyols in which have been polymerized styrene, acrylonitrile, or a copolymer thereof. The resultant colloidal dispersions of micrometer-size particles are phase stable and usually contain 20-50% solids by weight. The primary application for these polyols is in dexible foams where the polymer filler serves to increase foam hardness and load-bearing capacity. Other filled polyol types diat have been developed and used commercially (mainly to compete with die preeminent polymer polyols) include the polyurea-based PEID (polyhamstoff dispersion) polyols and the urethane-based PIPA (poly isocyanate polyaddition) polyols. 

The molecular weight of the starting polyether polyol, to some degree, controls the molecular weight of the polymer product, in addition to the degree of condensation. 

Commercially available hyperbranched polymers are Polyglycerol (aliphatic polyether polyol) and Polyethylenimine (aliphatic polyamine) both from Hyperpolymers, Boltom (aliphatic polyesters) from Perstorp and Hybrane (aromatic polyester amide) from DSM. 

Pol30irethane chemistry began with the utilization of polyester polyols, principally prepared from diacids such as adipic acid and various diols. Later, polyester polyols were replaced by polyether polyols due to improvements in mechanical properties and moisture resistance. Polyether polyols now constitute the greater part of the volume in pol3airethane polymers [1]. 

The use of naturally derived complex carbon compounds as raw materials for polyurethane polymers is not new to the industry. Since the advent of polyether polyols, polyurethane polymers have utilized natural sources of renewable carbon. 

Readers, however, should not be prejudiced by these comments. The important consideration is the condensation of any polyalcohol with an isocyanate. Inasmuch as the polyalcohol is the compound that gives us the opportunity to produce a chemically active polymer, a researcher should not be limited by the history of polyurethanes that was guided by the need for a physically strong polymer system. In any case, discussing polyether polyols is a suitable starting point. 

Polyether polyols are high molecular weight polymers that range from viscous liquids to waxy solids, depending on structure and molecular weight. Most commercial polyether polyols are based on the less expensive ethylene or propylene oxide oi on a combination of the two. Block copolymers are manufactured first by the reaction of propylene glycol with propylene oxide to form a homopolymer. 

Thermoset polyurethanes are cross-linked polymers, which are produced by casting or reaction injection molding (RIM). For cast elastomers, TDI in combination with 3,3,-dichloro-4,4,-diphen5lmethanediamine (MOCA) are often used. In the RIM technology, aromatic diamine chain extenders, such as diethyltoluenediamine (DETDA), are used to produce poly(urethane ureas) (47), and replacement of the polyether polyols with amine-terminated polyols produces polyureas (48). The aromatic diamines are soluble in the polyol and provide fast reaction rates. In 1985, internal mold release agents based on zinc stearate compatibilized with primary amines were introduced to the RIM process to minimize mold preparation and scrap from parts tom at demold. Some physical properties of RIM systems are listed in Table 7. 

Chacon D, Hsieh YL, Kurth MJ, Krochta JM (2000) Swelling and protein absorp-tion/desorption of thermo-sensitive lactitol-based polyether polyol (LPEP) hydrogels. Polymer 41 8257-8262... 

Modified polyether polyols have appeared in recent years, i.e., graft polyether polyols (polymer polyols, copolymer polyols) which were first developed by Union Carbide Corp. in the mid-1960 s. 

Graft Polyol Technology. Graft polyols (or polymer polyols) are prepared by grafting both acrylonitrile and styrene monomer or acrylonitrile alone to conventional polyether polyols. Graft polyols provide increased load-bearing ability as well as cell-opening, which prevent or minimize the formation of closed-cell foams, because closed-cell flexible foams readily shrink. 

A reactive liquid epoxide used as an organic solvent and surfactant intermediate its polymers can be used for polyester, polyurethane, and polyacrylic resins, polyether polyols, flame-retardants, etc. 

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