Polyester chains

When PET is extracted with water no detectable quantities of ethylene glycol or terephthaUc acid can be found, even at elevated extraction temperatures (110). Extractable materials are generally short-chained polyesters and aldehydes (110). Aldehydes occur naturally iu foods such as fmits and are produced metabohcaHy iu the body. Animal feeding studies with extractable materials show no adverse health effects. 

TABLE 2.15 Building Blocks Used in Main-Chain Polyester LCP Mesogenic Units... 

Macromolecules dendritic, 285 hyperbranched, 284-286 Main-chain liquid crystalline polymers, 49 Main-chain polyester LCP mesogenic units, 50... 

The ester class also comprises natural oils, such as vegetable oil [75] spent sunflower oil [940,941,992,993] and natural fats, for example, sulfonated flsh fat [161]. In water-based mud systems no harmful foams are formed from partially hydrolyzed glycerides of predominantly unsaturated Ci6 to C24 fatty acids. The partial glycerides can be used at low temperatures and are biodegradable and nontoxic [1280]. A composition for high-temperature applications is available [1818]. It is a mixture of long chain polyesters and polyamides. 

The generic name given, in the USA, to stretch fibres based on elastomeric long-chain polyester polyurethanes. Trade names are, e.g., Lycra and Vyrene . 

The structure of the B6 phase is also illustrated in Figure 8.17. This achiral, orthogonal smectic phase is one of the class of intercalated smectics wherein the layer spacing is actually about half the molecular length. This phase, which has full translational symmetry within the layers, has the same symmetry (D2h), and the same basic structure as the all-anticlinic SmCA phase. Intercalated SmCA phases of this type were first described in pioneering work of Watanabe in main-chain polyesters.37... 

Preparation of a Liquid Crystalline (LC), Aromatic Main-Chain Polyester by Polycondensation in the Melt... 

The correct calculation of WAXS patterns of Condis phases and smectic LC phases would provide us additional information, because in some of these systems, intramolecular torsions and rotations occur which do not affect the lateral chain packing. We chose the high-temperature phase of PTFE (phase I) and a SE-phase of a LC main-chain polyester as model systems. 

Fig. 27. Equatorial WAXS intensity of SE-phase of a uniaxially oriented LC main chain polyester. 110- and 200-reflections contribute to the main reflection. No second order (220 and 400) appears...

Mecking showed an efficient way to produce a,G>diesters from fatty acid esters yielding excellent monomers for semicrystalline polyesters [63], Some part of the diesters was hydrogenated to diols and was transesterified with the diesters from the hydroesterification of methyl oleate into long-chain polyesters (Scheme 24). The properties of this thermomorphic polymer are related to those of polyethylene. 

S.M. Aharoni, and D. Masilamani, Process for preparing extended chain polyesters and block or graft copolyesters, US Patent 4568720, assigned to Allied Chemical Corporation, February 4,1986. 

No SRG could be formed on films from main-chain polyesters containing azobenzene in the side chains, even though they had similar absorption coefficients. 

Ramanujam, P. S., Holme, N. C. R., and Hvilsted, S. Atomic force and optical near-field microscopic investigations of polarization holographic gratings in a liquid crystalline azobenzene side-chain polyester. Appl. Phys. Lett. 1996, 68, pp. 1329-1331. 

Kuiinna, C., Hvilsted, S., Hendann, C., Sieslei H. W., and Ramanujam, P. S. Selectively deuterated liquid crystalline cyanoazobenzene side-chain polyesters. 3. Investigations of laser-induced segmental mobility by fourier transform infrared spectroscopy. Macromolecules, 1998, 31, pp. 2141-2151. 

Long-Chain Polyester and Acid Anhydride Diols. These compounds include the hydroxy-terminated or EO-capped derivatives of simpler building blocks ... 

Liquid crystalline aromatic polyamides were the first chemical class to be commercialised. The best known example is Kevlar fibre which is spun from liquid crystalline solution to obtain the benefit of the high orientation present in the nematic phase. Subsequently, melt-processable main-chain polyesters were developed and brought to the market (Amoco with Xydar, Hoechst-Celanese with Vectra). 

Polyesters with longer alkyl substituents, with x = 3-6 or so, are also produced by a variety of bacteria, generally in the form of copolymers which have low degrees of crystallinity and low Tm and Tg values. As a result, these longer alkyl chain polyesters are useful as thermoplastic elastomers, which can have excellent strength and toughness, and are also inherently biodegradable [9]-... 

Li MH, Brulet A, Davidson P, Keller P, Cotton JP (1993) Observation of hairpin defects in a nematic main-chain polyester. Phys Rev Lett 70 2297... 

Li MH, Brulet A, Cotton JP, Davidson P, Strazielle C, Keller P (1994) Study of the chain coirformation of thermotropic nematic main chain polyesters. J Phys II France 4 1843... 

Figure 3. Phase assignment of combined main-chain/side-chain polyesters, and visualization of the orientation of the two types of mesogen.

Figure 4. Comparison of a combined main-chain/side-chain polyester with the corresponding main-chain and side-group polymalonates. Ar c, the temperature range of the LC phase.

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