Polyether-block-polyamide

Membranes comprising silicone rubber coated onto polyimides, polyacrylonitrile or other microporous supports membranes are widely used [12,27]. Other rubbers such as ethylene-propylene terpolymers have been reported to have good properties also [28]. Polyamide-polyether block copolymers have also been used for pervaporation of some polar VOCs [29,30]... 

Polyamide-polyether block copolymers (Pebax , Elf Atochem, Inc., Philadelphia, PA) have been used successfully with polar organics such as phenol and aniline [32-34], The separation factors obtained with these organics are greater than 100, far higher than the separation factors obtained with silicone rubber. The improved selectivity reflects the greater sorption selectivity obtained with the polar organic in the relatively polar polyamide-polyether membrane. On the other hand, toluene separation factors obtained with polyamide-polyether membranes are below those measured with silicone rubber. 

Tsubouchi and Yoshikawa [79] are concerned with pervaporation separation of benzene/cyclohexane mixtures using membranes based on polyamide/polyether block copolymers. It has been established that the separation factor increases with the increase in the polyamide component containing polar amide groups capable of forming hydrogen bonds e.g., the 1 1 block copolymer of polyamide 12 and polyoxyethylene has the benzene/cyclohexane separation factor /3p = 2.8 and the flux 2 = 300 g/m h a more rigid 3 1 polyamide 12/polyoxyethylene block copolymer has a much higher separation factor )8p = 5.0 and 2 = 80 g/m h. 

Tsubouchi K and Yoshikawa M. Pervaporation separation of benzene/cyclohexane mixtures through polyamide-polyether block copolymer membranes. Membrane (Maku) 1998 23(6) 322-326. 

NNMR spectra of polyamide/polyether block copolymers based on polyethylene oxide) and either nylon-6 or nylon-12 are dominated by peaks at approximately 119 ppm, arising from the amorphous nylon phase. In addition, both polymers also exhibit a shoulder. Downfield (about 112 ppm) and upheld (about 117 ppm) shoulders indicate that polyamide phases exist as a (nylon-6) and y (nylon-12) forms, respectively (62). 

Polyamide-polyether block copolymers can be formed by a variety of techniques. One of them consists of initial preparation of amine-terminated polyethers. This can be done by reacting hydroxv-terminated polyethers with acrylonitrile and then reducing the nitrile groups to amines ... 

Castaldo L, Maglio G and Palumbo R (1978) Synthesis of polyamide-polyether block copolymers, J Polym Sci Polym Lett Ed 16 643-645. 

Table 6. Trade Names of Multiblock Thermoplastic Elastomers Based on Polyurethane/Elastomer, Polyether/Elastomer, and Polyamide/Elastomer Block Copolymers...

Most of the commercial polymers consist of polyether blocks separated by polyamide blocks. The polyether blocks may be based on polyethylene glycol, polypropylene glycol or, more commonly, polytetramethylene ether glycol. The polyamides are usually based on nylon 11 but may be based on nylons 6 or 66 even a copolymer, e.g. 6/11. 

PEBA thermoplastic polyamide rubber, polyether block amide... 

Pebax is a thermoplastic elastomer PA is an aliphatic polyamide hard block (e.g., nylon-6, nylon-12) and PEG is an amorphous polyether (polyethylene oxide (PEO) or polytetramethylene oxide (PTMO)) soft block (Scheme 4.2). 

Polyamide-polyether (PA-PEG) block copolymers have been studied using deuterated water (2H20) molecules as 2H NMR probes [85, 86, 87]. Well resolved doublets are observed on 2H20 on stretching the samples at room temperature. At a given elongation ratio X, the splitting depends on the water concentration c. The linewidth is that of a liquid and becomes comparable to that in bulk water for c=0.6. This confirms that water... 

The above thermal analysis studies demonstrated the enhanced thermal stability of POSS materials, and suggested that there is potential to improve the flammability properties of polymers when compounded with these macromers. In a typical example of their application as flame retardants, a U.S. patent39 described the use of preceramic materials, namely, polycarbosilanes (PCS), polysilanes (PS), polysilsesquioxane (PSS) resins, and POSS (structures are shown in Figure 8.6) to improve the flammability properties of thermoplastic polymers such as, polypropylene and thermoplastic elastomers such as Kraton (polystyrene-polybutadiene-polystyrene, SBS) and Pebax (polyether block-polyamide copolymer). 

PEBA exhibit a two-phase (crystalline and amorphous) structure and can be classified as a flexible nylon. Physical, chemical, and thermal properties can be modified by appropriate combination of different amounts of polyamide and polyether blocks [149], Hydrophilic PEBAs can be prepared which can have specific applications in medical devices. Similarly to other thermoplastic elastomers, the poiyamide-based ones find applications in automotive components, sporting goods conveyor belting, adhesives, and coatings [150]. In recent years the world consumption was approximately 6400 tons per year with about 80% in Western Europe and the rest equally split between the United States and Japan [143],... 

Poly(dimethylsiloxane), polyether-block-polyamides and polyurethane membranes Polyether-block-polyamides membrane and polybutadiene membrane... 

Nylon-610 and nylon-612 produced by the condensation of hexamethylenediamine and sebacic or dodecanolc acid, respectively, are more resistant to moisture and more ductile than nylon-66. The properties of these polyamides may be improved by the formation of polyether blocks (NBC) and by blending with thermoplastics, such as EPDM, PET, PBT and TPE. 

General Description Elf Atochem Pebax Resins, breathable resins, are polyether block amides (PEBAs), thermoplastic elastomers made of a flexible polymer and a rigid polyamide. Extruded films made with Pebax are compact, thoroughly waterproof, and breathable. 

Polyether Block Amide Polyether Block Amide is a thermoplastic elastomer made of a flexible polymer and a rigid polyamid. 

Uses Release agent lubricant blocking agent chemical intermediate coupling agent in acrylic, epoxy, polyamide, polyether, silicone, vinyl polymers, cellulosics, furan, melamine, nitrocellulose, PU, polyvinyl butyral, and urea-formaldehyde, for adhesives, coatings, filler treatment, foundry, inks, rubber, sealants, and textile applies. Manuf./Distrib. ABCR AP Resources Alfa Aesar Chisso Am. Fluka Gelest Silar Labs TCI Am. United Chem. Tech. 

Figure 13.2 Chemical structures of (a) polyamide and (b) polyether blocks polyamide block could be PA6 (x = 5) or PA12 (x = 11) and polyether block could be polyfethylene oxide) (PEO, y = 2) or polyftetramethylene oxide) (PTMO, y = 4)...

The permeation of gases in such a complex structure is very difficult to model due to the lack of information on the phase structures and properties, as well as the complexity of such modelling. Qualitatively, the reduced mobility and the chain orientation in semi-ordered interphases due to the stiff and ordered crystallites would make the permeability smaller. For the Pebax grades with shorter polyether blocks and longer polyamide blocks, the tortuosity of the diffusion path will increase sharply when the polyether and amorphous PA phases become finely divided by the crystalhne phase. Nevertheless, we tried to use the PA phase crystallinity to simulate the CO2 and nitrogen permeabilities in Pebax films with the simple resistance model [35] to estimate the influence of the Pebax structure on the permeability. 

Tn polyamide block (°C) polyether block (°C) polyether block (°C) wt.% PA crystallinity in Pebax wt. % PA crystallinity in PA block... 

Polyamide TPEs are usually either polyester-amides, polyetherester-amide block copol5nners, or polyether block amides (PEBA) (see Fig. 3.7). PEBA block copol5nner molecular architecture is similar to typical block copol5nners. The polyamide is the hard (thermoplastic) segment, while the polyester, polyetherester, and polyether segments are the soft (elastomeric) segment. ... 

Pebax polyether block amide copolymers consist of regular linear chains of rigid polyamide blocks and flexible polyether blocks. They are injection molded, extruded, blow molded, thermoformed, and rotational molded. 

Ji et al. (1995) studied the influence of hydrophobic adsorbent (such as activated carbon) into polymeric polyether-block-polyamide (PEBA) membranes for 1,1,1-trichloroethane (TCA) removal from water by PV. It is already known, in fact, that carbonaceous adsorbents can be successfully used for the removal of small amounts of chlorinated organic compounds from water. TCA flux increases with feed concentrations (from 40 to 300 ppm) for PEBA membranes filled with both tested activated carbon WPX (a powdered adsorbent produced by Calgon Carbon Corporation, PA) and carbonaceous adsorbent Amersorb 1500 (Rohm and Hass Co., PA). The separation factor increases for membranes filled with activated carbon in comparison with unfilled membranes (axcAffl20= 1742 and 2720 for pure and PEBA membranes filled with 10 wt% activated carbon, respectively). However, membranes filled with Ambersorb 1500 do not show any improvement in the separation factor (o tca/h20= 1681). 

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