Thermoplastic elastomers polyester-based

Among the polyurethane, polyester, and polyamide thermoplastic elastomers, those with polyether-based elastomer segments have better hydrolytic stabihty and low temperature flexibiUty, whereas polyester-based analogues are tougher and have the best oil resistance (43). Polycaprolactones and aUphatic polycarbonates, two special types of polyesters, are used to produce premium-grade polyurethanes (12). 

Polyester-based thermoplastic polyurethane elastomers (Section 27.4). 

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. 

Fig. 30a-c. Ordering process in thermoplastic elastomers based on polyester units after annealing near Tro a original b annealed at 150 °C c heated at 220 °C... 

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. 

The principal feature that distinguishes thermosets and conventional elastomers from thermoplastics is the presence of a cross-linked network structure. As we have seen from the above discussion, in the case of elastomers the network structure may be formed by a limited number of covalent bonds (cross-linked rubbers) or may be due to physical links resulting in a domain structure (thermoplastic elastomers). For elastomers, the presence of these cross-links prevents gross mobility of molecules, but local molecular mobility is still possible. Thermosets, on the other hand, have a network structure formed exclusively by covalent bonds. Thermosets have a high density of cross-links and are consequently infusible, insoluble, thermally stable, and dimensionally stable under load. The major commercial thermosets include epoxies, polyesters, and polymers based on formaldehyde. Formaldehyde-based resins, which are the most widely used thermosets, consist essentially of two classes of thermosets. These are the condensation products of formaldehyde with phenol (or resorcinol) (phenoplasts or phenolic resins) or with urea or melamine (aminoplastics or amino resins). 

Chem. Descrip. Sat., aliphatic, linear, hydroxyl-terminated polyester diol based on short chain glycols and polyester Uses Polyester for sol n. coatings and adhesives, thermoplastic elastomers, and castable prepolymers... 

Arnitel UL550, Arnitel UL740. See Polyester elastomer, thermoplastic Arnold s base. See Bis (p-... 

Classification Thermoplastic elastomer Definition Polymer consistg. of hard segments embedded in a soft, elastomeric polyol phase exc. abrasion/impact resist. high str. wide working temp, range good hydrolytic stability two types polyether- or polyester-based Properties Solid... 

Chin Han Chan, PhD, is an associate professor at the Faculty of Applied Sciences, Universiti Teknologi MARA [MARA University of Technology) in Selangor, Malaysia. She has received many research grants, has published many articles in professional journals, has published chapters in books, and has presented at many professional conferences. Her field of interest includes epoxidized natural rubber-based nanostructured blends, thermoplastic elastomer, biodegradable polyester/polyether blends, and solid polymer electrolytes. 

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... 

Other materials include polyester-amides and those formulated from thermoplastic elastomers. The former are said to have the desirable properties of polyesters, but with improved application characteristics. The principal base polymers in thermoplastic elastomers are used mostly in... 

Besides the thermoplastic elastomers based on poly(styrene-6-elastomer- -styrene) block copolymers, five others are of commercial importance polyurethane/elastomer block copolymers, polyester/elastomer block copolymers, polyamide/elastomer block copolymers, polyolefin block copolymers, and polyetherimide/polysiloxane block copolymers. All five have the multiblock A-B-A-B. structure. The morphology of the polyurethane, polyester,... 

---