Polyether soft segments

Spandex Elastic fiber consisting of a block copolymer of a PU, hard segment, and a polyester or polyether, soft segment. 

Polyurethane-based FTPEs are produced by reacting fluorinated polyether diols with aromatic disocyanates. The resulting block copolymers contain fluorinated polyether soft segments.68 Another possible method of preparation of fluorinated TPE is dynamic vulcanization. Examples are a blend of a perfluoroplastic and a perfluoroelastomer containing curing sites or a combination of VDF-based fluo-roelastomers and thermoplastics, such as polyamides, polybutylene terephtalate, and polyphenylene sulhde.69 70... 

The fuel properties of the pyrolysis oil of an aliphatic polyether-segmented PU could be predicted by taking into account the linear and cyclic oxygenated saturated and olefinic hydrocarbon nature of the components. Elimination of the reactive and toxic diisocyanate from the pyrolysis oil of PU in a lower temperature pyrolysis step is easier in the case of polyether soft segment, because of the larger temperature difference of decomposition steps compared to that of polyester-segmented PU. 

Commercial copoly(ether-ester) elastomers (e.g., Hytrel , DuPont Lomod , GEC) are segmented block copolymers containing a polyether soft segment such as poly(tetramethylene oxide) and a hard segment that is chemically identical to polybutylene terephthalate. When the soft segment is > 50%, these block copolymers exhibit... 

These contain a methylene bis(p-phenyIdiisocyanate) (MDl) hard segment, an ethylene diamine chain extender, and a polyether soft segment in mole ratios of 2/1/1 respectively. The soft segment materials were polyethyleneoxide (PEO) and polytetramethyleneoxide (PTMO), both of 1000 molecular weight, and polydimethyIsiloxane (PDMS) of 2000 molecular weight. In this paper, these polymers will be refered to as PEO-PEUU, PTMO-PEUU and PDMS-PEUU respectively. These were dissolved in N,N-dimethyl acetamide (DMA) to make a 0.1 wt.% solution. 

Example 5.6 The tendency for hard segment-soft segment phase separation in urethane copolymers increases in the order polybutadiene and/or polyisoprene soft segment polyether soft segment > polyester soft segment. Explain. 

Thermoplastic polyester elastomers (see Chapter 4) contain readily oxidizable polyether soft segments that make stabilization necessary. Essentially two antioxidants, namely, 4,4 -di(terf-butyl-4-hydroxyphenyl)-propionamide are in use in concentrations of up to 1%. The antioxidants can be added during pelletizing, or even better, already during polycondensation. When added during polycondensation, NdVl -hexamethylenebis-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionamide is partly chemically bound to the polymer because of its amide structure. The antioxidant thus becomes highly stable to extraction. 

Upper the "equilibrium spectrum based on 1 ms of crosspolarization contact and a 2-second pulse repetition delay. The 0(1H2 resonance of the butanediol chain extender is indicated by the dashed line, and the polyether soft-segment signals are identified. 

Lower the "interrupted-decoupling spectrum of the same material. Only i3C signals in the mobile polyether soft segment and the non-protonated i3C resonances in the hard segment survive the 50 ps dipolar dephasing delay. 

Interdomain Communication Between the Urethane Hard Segment and the Polyether Soft Segment via Proton Spin Diffusion... 

Lower spectrum the initial condition before proton spin diffusion is initiated. The two-strong signals at 27 ppm and 72 ppm which survive the 15 ps dipolar dephasing delay are unique to the polyether soft segment. 

The Durometer hardness was measured after the cast elastomers were aged for at least 7 days at 23 °C and 50% relative humidity. The details are given in Table 8.3. From the results, it is evident that as the crystalline hard segment content of the elastomer is decreased, the elastomer hardness also decreases. By analysing the soft and hard segments and their relation to hardness, it appears that the amorphous hard segment behaves like the polyether soft segment. 

The behavior of soft-segment polyurethanes (SPU) may be used to clarify the above question. The polymers used in ref. 63 were bicomponent polymers with a polyurethane hard segment and an aliphatic polyether soft segment. The surface energy of the soft... 

Dow Plastics Pellethane t TPU elastomers are based on both polyester and polyether soft segments. ... 

Fig. 3.20. Strain-induced elongation crystallization of polyether soft segments in a segmented polyurethane elastomer by elongating it to 200% extension (Allport Janes, 1973).

One such polymer, Elast-Eon (AorTech International, Melbourne, Australia) has recently been used as an insulator for ICD leads (Riata ST Optim, St Jude, Syhnar, CA). This product is part of a large family of polyurethane-silicone rubber hybrids which can be prepared for the specific needs of the pacemaker/ ICD industry. An insulator with the strength of PeUethane 55D can be created with the characteristics of sihcone rubber by replacing the polyether soft segment of polyurethane with silicone rubber. 

Several smdies demonstrated that, despite the hydrolytic stabihty of polyether soft segments, they are susceptible to oxidative degradation and consequently undergo environmental stress cracking (Christenson et al., 2004a,b). 

The PEBA are produced by a aiolten state polycondensation reaction of a dicarboxylic polyamide and a polyether diol. The reaction of the rigid polyamide (hard) segments and amorphous polyether (soft) segments in the presence of heat, vacuum and catalyst yields the polyether block amide with the general formula shown below. 

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