Polyurethane oligomers

Off-line coupling of HPLC with FD-MS has been used by several authors [118-121] for the determination of oligomers, oligomeric antioxidants (such as poly-TMDQ), ozonation and vulcanisation products. Pausch [122] reported on rubbers, cyclic polyurethane oligomers, as well as on the determination of the molecular weight distribution (up to 5300 Da) and oligomer analysis of polystyrene. Also the components of an aniline-acetone resin were deduced from FD-MS molecular weights [122]. 

Oligomer I is used as a regulator and stabiliser in the production of elastic polyurethanes based on polyethers, rigid and semirigid polyurethanes oligomer II is used in the production of elastic polyurethanes based on esters. 

Pavlova, M., Oraganova, M. and Novakov, P. (1985). Hydrolytic stability and protective properties of polyurethaner oligomers based on polyester/ether/polyols. Polymer, 26 (11), 1901-1905. 

The electron beam crosslinking of PVC/ENR blends by electron beam irradiation has been extensively reported by Ratnam and coworkers. The influence of MFAs such as trimethylolpropane trimethacrylate (TMPTA), 1,6-hexaediol diacrylate (HDDA) and 2-ethylhexyl acrylate (EHA), as well as acrylated polyurethane oligomer on the 70/30 PVC/ENR blend, was investigated. TMPTA was found to give the blend the best mechanical properties. Studies were also done on the effect of irradiation on various formulations of PVC/ENR blends with doses ranging from 50 to 200 kGy these studies included the influence of various additives on the efficiency of the radiation crosslinking of the blends. 

In a way similar to PDMS and TEOS, other organic polymers have been functionaliz with alkoxysilyl groups and covalently bonded to silica. Polymers that have been coupled with silica are PTMO-based polyurethane oligomers T69 polyoxazolines , polyimide, poly(arylene ether ketone) poly(arylene ether sulfone), polystyrene polyoxopropylene (PPO) ", polyacrylonitrile, copolymers of methyl methacrylate and allyl methacrylate and cyclophosphazenes. ... 

As technological aids, fatty acids and their salts and esters, heavy amines, fatty alcohols, aliphatic hydrocarbons, LMWPE (M = 1000-5000), APP, PIB, PE waxes, silicone oligomers, polyurethane oligomers, etc., are used, as well as some macromolecular compounds such as polyethylene oxide, LDPE, HDPE, EVA, EPDM, PS, etc. [82]. All these products assure a controlled viscosity of compounds, prevent degrada-tive processes, increase production rates, diminish... 

P. Rajjt, A. Kamming. Poliuretanovye Oligomery (Polyurethane Oligomers).- L. Khimija, 1973 (in Russian). 

This phosphoms-rich oligomer can also be incorporated into polyurethanes. Combinations with Eyrol 6 permit the OH number to be adjusted to typical values used in flexible foam, urethane coating, or reaction injection mol ding (RIM) appHcations (115,116). 

Polymeric isocyanates or PMDI ate cmde products that vary in exact composition. The main constituents are 40—60% 4,4 -MDI the remainder is the other isomers of MDI, trimeric species, and higher molecular weight oligomers. Important product variables are functionaHty and acidity. Rigid polyurethane foams are mainly manufactured from PMDI. The so-called pure MDI is a low melting soHd that is used for high performance polyurethane elastomers and spandex fibers. Liquid MDI products are used in RIM polyurethane elastomers. 

In a second step, the prepolymer was then reacted with a low molecular weight difunctional alcohol, commonly referred to as a diol or a diamine, to connect the prepolymer oligomers into a high molecular weight polyurethane. This step was referred to as the chain extension , resulting in the use of the term chain extenders to describe the low molecular weight diols or diamines that reacted with the prepolymer oligomers. 

Fatty acids, both saturated and unsaturated, have found a variety of applications. Brassilic acid (1,11-un-decanedicarboxylic acid [BA]), an important monomer used in many polymer applications, is prepared from erucic acid (Scheme 2), obtained from rapeseed and crambe abyssinica oils by ozonolysis and oxidative cleavage [127]. For example, an oligomer of BA with 1,3-butane diol-lauric acid system is an effective plasticizer for polyvinylchloride. Polyester-based polyurethane elastomers are prepared from BA by condensing with ethylene glycol-propylene glycol. Polyamides based on BA are known to impart moisture resistance. 

Coating materials may be based on short or medium-oil alkyds (e.g. primers for door and window frames) nitrocellulose or thermoplastic acrylics (e.g. lacquers for paper or furniture finishes) amino resin-alkyd coatings, with or without nitrocellulose inclusions, but with a strong acid catalyst to promote low temperature cure (furniture finishes) two-pack polyurethanes (furniture, flat boards) unsaturated polyester resins in styrene with free-radical cure initiated by peroxides (furniture) or unsaturated acrylic oligomers and monomers cured by u.v. radiation or electron beams (coatings for record sleeves paperback covers, knock-down furniture or flush interior doors). 

Hie most representative member of this class of polyesters is the low-molar-mass (M 1000-3000) hydroxy-terminated aliphatic poly(2,2/-oxydiethylene adipate) obtained by esterification between adipic acid and diethylene glycol. This oligomer is used as a macromonomer in the synthesis of polyurethane elastomers and flexible foams by reaction with diisocyanates (see Chapter 5). Hydroxy-terminated poly(f -caprolactonc) and copolyesters of various diols or polyols and diacids, such as o-phthalic acid or hydroxy acids, broaden the range of properties and applications of polyester polyols. 

A three-necked flask equipped with a condenser and stirrer was charged with the PET depolymerization product (0.05 mol of BHET and dimer in the ratio of 80 to 20 wt%), 0.05, 0.10, and 0.15 mol of e-caprolactone (in separate experiments), and 0.1 wt% of dibutyltin dilaurate. The reaction mixture was heated at 150°C for 2 h. The resulting co-oligomer (0.01 mol) was dissolved in 500 mL of tetrahydrofuran in a three-necked flask equipped with a condenser and a stirrer. After the temperature was raised to 67°C, a solution of 0.01 mL of hexamethylene diisocyanate in 50 mL of tetrahydrofuran was added dropwise. After heating and stirring the reaction mixture for 12 h, it was cooled and precipitated in ether. The polyurethane precipitate was collected by filtration and dried at 70°C for 12 h. 

Polyurethanes are thermoset polymers formed from di-isocyanates and poly functional compounds containing numerous hydroxy-groups. Typically the starting materials are themselves polymeric, but comprise relatively few monomer units in the molecule. Low relative molar mass species of this kind are known generally as oligomers. Typical oligomers for the preparation of polyurethanes are polyesters and poly ethers. These are usually prepared to include a small proportion of monomeric trifunctional hydroxy compounds, such as trimethylolpropane, in the backbone, so that they contain pendant hydroxyls which act as the sites of crosslinking. A number of different diisocyanates are used commercially typical examples are shown in Table 1.2. 

Glycolysis of PETP leads to oligomers that are polycondensed with eaprolaetone. The obtained diols are extended with hexamethylene diisoeyanate. In eertain conditions the polyurethanes are totally miseible with PVC, leading to acceptable meehanieal eharaeteristies for the blend. A relation between the strueture of the polyurethane and miscibility with PVC is described. The mechanical characteristics of the blend depends on the polyurethane chemical structure. 34 refs. 

In a polyurethane elastomer analysed by isobutane CI-MS and CI-MS/MS in TD/Py-CIMS (TD, 20-200°C Py, 200-300 °C) mode MDI (diisocyanate), BDO (chain extender), Stabaxol P (stabiliser), AA/ BDO/HDO (cyclic adipate) and residual cyclic ester oligomers were identified [65]. 

---