Block copolymers copolyester

FTIR polarisation spectroscopy was used to study the orientational behaviour of the different constituents of a liquid crystalline block copolymer (copolyester-imide) during uniaxial elongation at different temperatures. Differences in the degree of alignment (as well as in the response to the application of the mechanical load) were observed. With increasing temperature, the level of the applied stress and the induced degree of orientation decreased, while the differences in the orientational behaviour of the mesogen and the flexible spacer were retained (243). 

Thermoplastic elastomers (TPEs) continue to grow in commercial importance. These materials combine the functional properties of comparable thermoset elastomers with the fabrication advantages of thermoplastics. As a class, TPEs comprise several types of materials such as elastomeric alloys (EAs), styrenic block copolymers, copolyesters, and thermoplastic polyurethanes. 

Ester-Ether Block Copolymers [Copolyester TPEs (COPs)]. Ester-ether block copolymer TPEs, also called copolyester TPEs, are segmented block copolymers with the -A-B-A-B- structure, where A and B are alternating hard and soft polymeric segments connected by ester linkages. A general chemical structure can be expressed as follows ... 

Thermoplastic copolyester elastomers are generally block copolymers produced from short-chain aUphatic diols, aromatic diacids, and polyalkjlene ether-diols. They are often called polyesterether or polyester elastomers. The most significant commercial product is the copolymer from butane-l,4-diol, dimethyl terephthalate, and polytetramethylene ether glycol [25190-06-1J, which produces a segmented block copolyesterether with the following stmcture. 

Aromatic block copolymers, 282-284 Aromatic copolyesters, 18 Aromatic coupling, catalysts for, 289 Aromatic diamines, 180... 

Blend formulations, with amorphous polyarylates, 47-48 Block copolyesters, 18 Block copolymers, 6, 20... 

Aluminum isopropoxide has been used for the preparation of block copolyesters [147, 148]. Tri-block poly(e-CL-b-DXO-e-CL) was prepared by the sequential addition of different monomers to a living polymerization system initiated with aluminum isopropoxide in THF or toluene solution [95]. An alternative route for the preparation of the tri-block copolymer was to react the diblock poly(e-CL-b-DXO) containing an -OH functionality at the chain end using a difunctional coupling agent such as isocyanate or acid chloride (Scheme 18). However, the molecular weights were low and full conversion of monomers was not achieved. 

The above copolyesters, when irradiated at 365 nm in the presence of vinyl or acrylic monomers, give rise to block copolymers (Scheme 51). 

Thermoplastic copolyesters are condensation block copolymers based on a crystalline polyester hard segment and an amorphous long-chain polyether soft s ment. The hard segment, for example, formed... 

Most TPEs fall in one of six categories, listed in order of increasing cost and performance styrenic block copolymers, polyolefin blends (TPOs), elastomeric alloys, thermoplastic polyurethanes (TPUs), thermoplastic copolyesters, and thermoplastic polyamides [3]. 

To check the influence of the length of the aliphatic and aromatic sequences in the chains, we synthesised copolyesters of different structure, such as (blends), block copolymers, random copolymers and alternating BTA copolyester, all with the same fraction of terephthalic acid (50 mol % of the total acid components) (Fig 5). 

Block copolyesters also form in reactions between hydroxy and acid chloride-terminated prepolymers. This can take place in the melt or in solution in such solvents as chlorobenzene or o-dichlorobenzene. For relatively inactive acid chlorides, like terephthaloyl chloride, high reaction temperatures are required. Phosgene also reacts with hydroxy-terminated polyesters to form block copolymers. The reactions must be carried out in an inert solvent. Block copolyethers also form readily by ester interchange reactions with low molecular weight diesters ... 

He Xiao-Hua., Wang Xia-Yu. (2002). Synthesis and Properties of Thermotropic Liquid-Crystalline Block-Copolymers Containing Links of Polyaiylate and Thermotropic Liquid-CtystaUine Copolyester (HTH-6) Natur. Sci. J. Xiangtan Univ, 23(1), 49-52. 

For most of the results discussed below, the following is valid concerning COP, PC and mixtures if not otherwise stated. The thermotropic copolyester derived from p-hydroxybenzoate and poly(ethylene terephthalate) [10] containing 60 mol% PHB was used exclusively as the PLC component because this composition has the best mechanical properties [10,118] of these copolymers. It was obtained from Eastman Kodak, Kingsport, TN, and had an average molar mass estimated from solvent viscosity of about 19000 g mol . The sequence distribution was calculated from C-NMR as described by Lenz et al. [119] and was nearly random the statistical parameter which describes the randomness of the copolymer is = 1 for a block copolymer and P = 0 for a completely random copolymer. The copolymer used for the experiments had P = 0.15. 

The morphology is that of typical block copolymers, as shown in the upper right quadrant of Fig. 4.38. The polyamide TPEs typically have higher temperature and chemical resistance than do TPUs or copolyesters, and their cost is greater. 

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