Polyester-polyether materials

Examples of polymers which form anisotropic polymer melts iaclude petroleum pitches, polyesters, polyethers, polyphosphaziaes, a-poly- -xyljlene, and polysdoxanes. Synthesis goals iaclude the iacorporation of a Hquid crystal-like entity iato the maia chaia of the polymer to iacrease the strength and thermal stabiHty of the materials that are formed from the Hquid crystal precursor, the locking ia of Hquid crystalline properties of the fluid iato the soHd phase, and the production of extended chain polymers that are soluble ia organic solvents rather than sulfuric acid. 

Thermoplastic polyurethane elastomers have now been available for many years (and were described in the first edition of this book). The adipate polyester-based materials have outstanding abrasion and tear resistance as well as very good resistance to oils and oxidative degradation. The polyether-based materials are more noted for their resistance to hydrolysis and fungal attack. Rather specialised polymers based on polycaprolactone (Section 25.11) may be considered as premium grade materials with good all round properties. 

Polyester manufacture, organic titanium compounds in, 25 123 Polyester materials, recycling, 20 22 Polyester/polyether/polycarbonate,... 

Polyether polyurethanes are less stable to higher temperatures than the polyester-based materials. The ether linkage in the soft segment is attacked... 

Newer developments are polyester/polyether block copolymers (Hytrel, Amitel), etc. By choosing various levels of block length ratio, a broad spectrum of stiffnesses (or hardnesses) can be obtained, which practically fills the gap between rubbers and thermoplasts. TPE s form a rapidly growing class of materials, which find an increasing number of applications. 

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... 

Cure of epoxy with combinations of monomeric curing agents and the use of polymers containing reactive groups to cure epoxy systems is rarely touched upon in the literature and could be investigated much further. Amides, polyesters, polyethers etc. used to cure the epoxy network could lead to the creation of materials having interesting and heretofore unfathomed properties. The fundamental kinetics of the reactive polymer epoxy reaction is an area of interest as well. 

Thermoplastic polyurethanes and polyester/polyethers are polar materials thus, their use in polymer blending usually is limited to blends with other polar polymers such as PVC, acrylonitrile-butadiene-styrene copolymers (ABS), and polyesters. However, at this time polymer blending is a fairly small market for these polymers. 

Two-Package Polyol Urethane Coatings (ASTM Type 5). Two-package polyol urethane coatings consist of isocyanate-terminated adducts of polymers that are cured by reaction with di- or polyfunctional hydroxyl-containing materials. The latter may consist of low- to medium-weight polyols with a polyester, polyether, polyether urethane, or castor oil backbone. When the two components (OH- and NC0-) are mixed together, they have only a limited pot life. Therefore, the components are mixed prior to application. Catalysts may be used to speed up the cure either for room temperature or oven cure. 

From Table X, the IPDI based oligomers have better solvent resistance than the TDl based ones. IFDl based oligomers also appear to exhibit better adhesion. Other properties are not affected by dllsocyanate choice. Polyester based materials seem to give better flexibility and solvent resistance than polyether based urethanes (Table XI). The branched polyether in composition N gives better adhesion and solvent resistance than the linear polyether. 

She has pnbhshed more than 45 papers in intematiorral and national refereed journals, more than 60 publications in conference proceedings, and more than 20 invited lectures for international conferences. She has been one of the editors of Malaysian Journal of Chemistry, Berita IKM- Chemistry in Malaysia, and books pnbhshed by Royal Society of Chemistry entitled Natural Rubber Materials, Volume 1 Blends and IPNs and Volume 2 Composites and Nanocomposites. She peer-reviews a few international journals on polymer science. Her research interest is devoted to modified natural rabber-based thermoplastic elastomers, biodegradable polyester/polyether blends, and solid polymer electrolytes... 

Braun and Bergmann [19, 20] used DAS and DAM for the syntheses of polyesters, polyethers, polyurethanes, and polycarbonates. They reported that the thermal and mechanical properties of the obtained polyma-s were similar to those of the respective counterparts obtained from usual petrochemical raw materials. 

Membrane filters are used to remove particulates from samples and solvents prior to HPLC analysis and also for the preparation of liquid samples, where no solvent is used. Typical materials of construction for membrane filters are usually synthetic polymeric materials, although natural substances, such as cellulose, and inorganic materials, such as glass fibers, are also used acrylic copolymer, aluminum oxide, cellulose acetate, glass fiber, mixed cellulose esters, nitrocellulose, nylon, polycarbonate, polyester, polyether sulfone, polypropylene polysulfone, PTFE, PVC, etc. The compatibility of the polymeric material with the solvents used must be a great concern of their different chemical properties. 

Polyurethanes, particularly those based on polyesters, are well known for their oil and grease resistance however, they are susceptible to attack by moisture. The structure of the backbone has a profound influence on the hydrolytic stability. The more hydrophobic the backbone, the greater the resistance of the polyurethane towards hydrolysis. Thus, polyether polyurethanes are inherently more stable to hydrolysis than polyester-based materials, and HTPBD-based polyurethanes are even more stable than the polyether materials. Polyurethanes prepared from polycarbonate diols have also been reported to display very good hydrolytic stability. " ... 

Crystallizable Block Copolymer Morphologies While the largest part of the block copolymer literature describes totally amorphous materials, one or more of the blocks may form semicrystalline regions. Examples include polyester-polyether block copolymers (39), where the poly(tetramethylene terephthalate) polyester blocks crystallize, and the thermoplastic polyurethane elastomers, where the polyurethane hard blocks crystallize (40). 

About a half centuiy has passed since synthetic leather, a composite material completely different from conventional ones, came to the market. Synthetic leather was originally developed for end uses such as the upper of shoes. Gradually other uses like clothing steadily increased the production of synthetic leather and suede. Synthetic leathers and suede have a continuous ultrafine porous structure eomprising a three-dimensional entangled nonwo-ven fabric and an elastic material principally made of polymethane. Polymeric materials consisting of the synthetic leathers are polyamide and polyethylene terephthalate for the fiber and polyurethanes with various soft segments, such as aliphatic polyesters, polyethers and polycarbonates, for the matrix. 

In a similar manner, extended-chain oligomeric polyesters, polyethers, and poly(dimethylsiloxane)s have been fitted with acrylate or methacrylate functional groups, and these materials find a multitude of practical uses such as UV-curable coatings and adhesives. The photoinitiated radical polymerizations of acrylic monomers and oligomers proceed very rapidly in the... 

Warwel et al. applied catalytic methods of olefin chemistry to achieve polymer building blocks as well as polymers like functionalized polyolefins, polyesters, polyethers, polyamides as well as sugar-based surfactants [4]. The fundamental approach was the polymer synthesis based on unsaturated fatty acid methyl esters, which are available by industrially applied transesterification of fats and oils with methanol. In Figure 18 is reported a schematic representation of the potential of plant oil components in the preparation of different polymeric materials. 

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