Thermoplastic polyurethanes preparation

Owing to their improved stability towards hydrolysis and oxidation, dimer diol polyethers (and dimer diol polycarbonates) are used as soft segments in the preparation of thermoplastic polyurethanes. Polyurethanes prepared from such oleo-chemical building blocks are very hydrophobic and show the expected stability. 

In an earlier investigation by the authors (2) poly(carbonate-co-urethane) resins consisting of 1,6-hexanediol, dimethyl carbonate, and 4,4 -diphenylmethanedi-isocyanate were prepared and used as flexible thermoplastic polyurethane resins. 

To prepare a lacquer of Estane, dissolve 6 grams of Estane 5702 into 480 grams of methyl ethyl ketone. Estane 5702 is a thermoplastic, polyurethane elastomer manufactured by the B. F. Goodrich Co. 

Thermoplastic polyurethane resins were also prepared by the author [2] from 4,4 -methylene diphenylisocyanate with poly(3,3-bis-(2,2,3,3,4,4,4-hepta-fluorobutoxymethyl)-co-3-(2,2,3,3,4,4,4-heptafluorobutoxymethyl)-3-methy-loxetane) using dibutyltin dilaurate as catalyst and used in low surface energy coating applications... 

In coating applications, urethane chemistry is used to cross-link coatings and also to prepare thermoplastic polyurethanes or isocyanate-terminated pre-polymers. 

Polyurethane pre-polymer or thermoplastic polyurethanes are prepared by the reaction of polyester or polyether diols with diisocyanates. The reaction can be conducted in bulk, in a solvent, or in an aqueous solution or dispersion. Unless the reaction is carried out at an elevated temperature a catalyst is required. Organotin compounds are the prime catalyst for this reaction. 

Thermoplastic polyurethanes (TPU) are a versatile family of elastoplastic materials characterized by outstanding toughness and abrasion resistance. These materials are prepared from three principal reactants, a difunctional polyol, a difunctional chain extender and a diisocyanate in accordance with the following reaction ... 

TPU, Thermoplastic polyurethane, Estane 58111, Goodrich POM polyoxymethylene, Celcon M 140, Hoechst Celanese. Test specimens were prepared according to ASTM D638 and D648. 

The cationic polymerization of tetrahydrofuran is used commercially to produce a,CD-dihydroxypoly(tetramethylene oxide) (PTMO glycol). Although this polymer is not used by itself as an elastomer, it is used as one of the elastomeric block components for preparation of segmented thermoplastic polyurethane [133] and thermoplastic polyester [134] elastomers. The cationic polymerization of tetrahydrofuran (THF) is a living polymerization under proper experimental conditions [135-139], i.e., it does not exhibit any termination step, very much like the analogous anionic polymerizations which are discussed in Section VIII. However, these polymerizations are complicated by the fact that the ceiling temperature, where the free energy of polymerization is equal to zero, is estimated to be approximately 83 2°C in bulk monomer solution [140] therefore, the polymerization is reversible and incomplete conversion is often observed, especially in the presence of added solvent. For... 

A.K. Barick, and D.K. Tripathy, Preparation, characterization and properties of acid functionahzed multi-walled carbon nanotube reinforced thermoplastic polyurethane nanocomposites. Materials Science and Engineering B Solid-State Materials for Advanced Technology, 176 (18), 1435-1447, 2011. 

Wang et al. (2007a) prepared compatibilized ethylene-octene copolymer blends with polyurethane using maleated ethylene-octene copolymer and amine-functionalized polyurethane. However, a study by Stutz et al. (1996) found no evidence for copolymer formation between thermoplastic polyurethane and either EAA or SMA under the specific conditions studied. 

Composites of carbon nanofibers and thermoplastic polyurethanes with shape memory properties prepared by chaotic mixing. Polym. Eng. Sd., 49,... 

Barick et al. investigate the thermal stability of thermoplastic polyurethane (TPU) nanocomposite based on organically modified layered silicate (OMLS) prepared by intercalation process followed by compression molding, founding that... 

Y. Wei, C. Zong, F. Wang, Preparation of vinyl polymer/polyurethane hybrid latex particles and their application in nano-sized vinyl polymer particle/thermoplastic polyurethane blends, E-Polymers 10 (1) (2010). 

R. Chen, C. Huang, Q. Ke, C. He, H. Wang, X. Mo, Preparation and characterization of coaxial electrospun thermoplastic polyurethane/collagen compound nanofibers for tissue engineering applications. Colloids and Surfaces B 79 (2) (2010) 315-325. 

A.K. Barick, D.K. Tripathy, Thermal and dynamic mechanical characterization of thermoplastic polyurethane/organoclay nanocomposites prepared by melt compounding. Materials Science and Engineering A 527 (2010) 812-823. 

The preparation of polyurethane lattices is possible in several ways. In one instance special monomers are polymerized in an aqueous medium to produce a thermoplastic polyurethane emulsion. Or thermoplastic polyurethanes made in solution or dissolved in solvents are emulsified in water, then solvent is removed. Or an isocyanate-terminated urethane prepolymer, possibly with hydrophilic branches, is blocked with an appropriate isocyanate blocking agent, and emulsified in water together with a crosslinking agent. 

A typical method for the preparation of a thermoplastic polyurethane (TPU) elastomer involves the following procedure the desired polyol/... 

Thermally induced property loss in polyurethanes occurs by two mechanisms physical, or reversible, breakdown of the polymer network and degradation due to chemical, or irreversible, processes. Physical breakdown is more of a problem with linear, thermoplastic polyurethanes and is related to such problems as softening and creep at elevated temperatures. This can be overcome by incorporating chemical crosslinks into the polymer matrix. Irreversible thermal degradation is a much more serious problem. The thermal stability of these materials is dependent upon their method of preparation and, more importantly, upon the structure of the resulting polymer. Thermolysis usually occurs within the isocyanate-derived portions of the polymer. The order of stability of the various isocyanate-derived linkages most commonly found in polyurethanes is ... 

Lee SH, Cyriac A, Jeon JY, Lee BY. Preparation of thermoplastic polyurethanes using in situ generated poly (propylene carbonate)-diols. Polym Chem March 2012 3(3) 1215. 

---