Polymerization thermoplastic polyurethane

Mastication studies of fully polymerized thermoplastic polyurethane elastomer were performed in the Plasticorder by adding polymer granules at room temperature to the preheated mixing chamber with the rotors in motion. 

Pattanayak, A. and Jana, S.C. (2005) Properties of bulk-polymerized thermoplastic polyurethane nanocomposites. Polymer, 46, 3394. 

The Hquid monomers are suitable for bulk polymerization processes. The reaction can be conducted in a mold (casting, reaction injection mol ding), continuously on a conveyor (block and panel foam production), or in an extmder (thermoplastic polyurethane elastomers and engineering thermoplastics). Also, spraying of the monomers onto the surface of suitable substrates provides insulation barriers or cross-linked coatings. 

Thermoplastic polyurethane (TPU) is a type of synthetic polymer that has properties between the characteristics of plastics and rubber. It belongs to the thermoplastic elastomer group. The typical procedure of vulcanization in rubber processing generally is not needed for TPU instead, the processing procedure for normal plastics is used. With a similar hardness to other elastomers, TPU has better elasticity, resistance to oil, and resistance to impact at low temperatures. TPU is a rapidly developing polymeric material. 

Block copolymers were developed rapidly in the 1960s when living anionic polymerization was first utilized to synthesize triblock thermoplastic elastomers or elastoplastics. At the same time, step or condensation polymerization to produce thermoplastic polyurethanes, urea-urethane spandex fibers, and later more specialized materials, such as the semicrystalline polyester-polyether copolymers were developed [10]. Imide block or segmented copolymers utilizing... 

Santra RN et al. (1995) In-situ compatibilization of thermoplastic polyurethane and polydimethyl siloxane rubber by using ethylene methyl acrylate copolymer as a reactive polymeric compatibilizer. Adv Poly Technol 14(l) 59-66... 

Soft blocks are composed of linear, dihydroxy poly ethers or polyesters with molecular weights between 600 and 3000. In a typical polymerization of a thermoplastic polyurethane elastomer, the macroglycol is end capped with the full amount of aromatic diisocyanate required in the final composition. Subsequently, the end-capped prepolymer and excess diisocyanate mixture reacts further with the required stoichiometric amount of monomeric diol to complete the reaction. The diol links the prepolymer segments together while excess diol and diisocyanate form short hard-block sements, leading to the (AB)n structure illustrated in Figure 1. Block lengths in (AB)n polymers are frequently much shorter than those in anionically synthesized ABA block copolymers. 

Thermoplastic Polyurethane Elastomer Melt Polymerization Study... 

Published information on urethane polymerization detail largely concerns thermoset urethane elastomers systems.4 13 In particular, the work of Macosko et. al. is called to attention. The present paper supplements this literature with information on the full course of linear thermoplastic urethane elastomer formation conducted under random melt polymerization conditions in a slightly modified Brabender PlastiCorder reactor. Viscosity and temperature variations with time were continuously recorded and the effects of several relevant polymerization variables - temperature, composition, catalyst, stabilizer, macroglycol acid number, shortstop - are reported. The paper will also be seen to provide additional insight into the nature and behavior of thermoplastic polyurethane elastomers. 

In the present study we utilized Plasticorder torque values (polymer viscosity) on a relative basis, principally to follow the course of thermoplastic polyurethane elastomer polymerization, and the effect of several relevant variables on this polymerization. These torque data, expressed in meter-grams, served our purposes well, and we have not attempted to translate them to absolute rheological units. Such translation, which is a rather complex problem, has been addressed by others using a different rotor type and other polymers in the Plasticorder.14 That study concluded that the shear rate, y, of the Brabender Plasticorder with a somewhat different rotor configuration (roller blade) is in the range of 23 - 228 sec 1 over the rotor speed range of 30 - 200 rpm. 

Comparison of Polymers 14 and 15 in Figure 9 shows fairly similar polymerizations up to the point of shortstop addition. The control, Polymer 5, was slower but alive and growing at 18 minutes of polymerization time, reaching a final torque value of 660 meter-grams. Its steady intermediate polymerizarion rate is seen to be characteristic of uncatalyzed thermoplastic polyurethane elastomer polymerizations based on low acid number PTAd while Polymers 14 and 15 formed faster than usual from such a low acid number polyester glycol component. 

Thus, substantial polymer molecular weight modification (reduction) is seen to be a consequence of deliberate stoichiometric reactant imbalance via MDI deficiency. This not only represents a method of thermoplastic polyurethane elastomer molecular weight control but also demonstrates what inadvertent reactant imbalance can do to the polymerization and the polymer product. 

The Brabender Plasticorder is also a useful device for studying the effect of shear and heat on fully formed polymeric materials. And this is another way that we used it in the present study. The technique employed was to bring the Plasticorder mixing chamber to temperature, then add granules of thermoplastic polyurethane elastomer (at 25°C) to the chamber and record the viscosity-time-temperature pattern that developed. ... 

It also has been shown that azelate esters can also be used in place of adipate polyesters in thermoplastic polyurethanes, which also indicated improved hydrolytic stability as well as somewhat improved low-temperature properties as compared to those of the corresponding adipate polyester based urethanes (90). The tendency of polyester-based urethanes to hydrolyze, particularly at high humidities and elevated temperatures, can partly be reduced by incorporation of small amounts of polymeric carbodiimides (91). Alternately, the use of diisocyanate-containing carbodiimide groups helps to confer greater hydrolytic stability to polyester urethanes (92). 

Estaloc. [BFGoodrich BFGoodrich UK] Mixture of thermoplastic polyurethane, reinforcement, polymeric alloys, ad(ti-tives reinforced engineeriitg thermoplastic. 

Sonnenschein, M. R, Ginzburg, V. V., Schiller, K. S., Wendt, B. L. (2013). Designing, polymerization, and properties of high performance thermoplastic polyurethane elastomers from seed-oil derived soft segments, Po/h 1 j 18,1350-1360. 

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... 

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