Polyether-ester copolymer

Polymer Preparation. The polyether-ester copolymers were prepared by titanate-ester-catalyzed, melt transesterification of a mixture of PTME glycol, the dimethyl ester of an aromatic diacid, and a diol present in 50-100% molar excess above the stoichiometric amount required (Figure 1). The reactions were carried out in the presence of no more than 1 wt %, based on final polymer, of an aromatic-amine or hindered-... 

Up to this point the discussion has been concerned with alkylene terephthalate/PTME terephthalate copolymers in which the concentration of alkylene terephthalate and the chemical structure of the alkylene groups have been varied. The next section of this report is concerned with polyether-ester copolymers in which aromatic esters other than terephthalate are used in combination with PTME glycol and various diols. The objective is the same, to correlate changes in copolymer structure with changes in copolymerization results and copolymer properties. Once again the 50% tetramethylene terephthalate/PTME terephthalate copolymer (Tables I and II) with its excellent properties and relative ease of synthesis will be used as the point of reference to which the other polymers will be compared. 

Alkylene Isophthalate/PTME Isophthalate Copolymers. Polyether-ester copolymers having the compositions 50% alkylene isophthalate/ PTME isophthalate were prepared using as diols ethylene glycol (2G),... 

Alkylene w-Terphenyl-4,4f -dicarboxylate/PTME w-Terphenyl-4,4"-dicarboxylate Copolymers. Polyether-ester copolymers with the composition 50% alkylene rn-terphenyl-4,4"-dicarboxylate/PTME rn-ter-phenyl-4,4"-dicarboxylate were prepared using as diols 1,3-propanediol (3G) and 1,4-butanediol (4G). Both copolymers exhibit excellent tensile and tear strength as shown in Table IX. They both have very poor resistance to compression set. 

Among the terephthalate-based polyether-ester copolymers, those prepared using 1,4-butanediol as the diol monomer exhibit the best overall physical properties. The use of ethylene glycol as the diol monomer retards the rate of polymer formation and results in copolymers which crystallize slowly. Other aliphatic ,w-diols yield terephthalate-based polyether-ester copolymers which are low in tensile strength and tear strength relative to the 1,4-butanediol-based copolymer. Terephthalate-based copolymers prepared with 1,4-benzenedimethanol as the diol monomer are relatively low in inherent viscosity, tensile strength, and tear strength. 

When 1,4-cyclohexanedimethanol is used as the diol monomer, phase separation occurs in the polymerizing melts of terephthalate-based polyether-ester copolymers but not those of the analogous isophthalate-based copolymers. Phase separation in the melt during copolymerization, if sufficiently severe, drastically impairs the properties of the product. 

All of the isophthalate-based polyether-ester copolymers which were prepared using various diols are slow to crystallize. Those copolymers that eventually do crystallize exhibit excellent tensile strength and tear strength. All of the 2,6-naphthalenedicarboxylate copolymers prepared using linear ,o>-diols exhibit excellent tensile strength and tear strength. Phase separation in the melt is encountered with 4,4 -biphenyldicarboxyl-ate-based copolymer at the 50-wt % ester level when 1,4-butanediol is used as the diol monomer but not when 1,3-propanediol, 1,5-pentanediol, and 1,6-hexanediol are used. 

Polyether-ester copolymers based on ra-terphenyl-4,4"-dicarboxylate exhibit excellent tensile strength and tear strength despite an apparent... 

Figure 11. Schematic diagram of the proposed morphology of polyether ester copolymers A = crystalline domain B = junction area of crystalline lamella C = polymer hard segment that has not crystallized D = polymer soft segment...

This effort bore fruit in 1968, with the production (under the direction of Bill Witisiepe) of the material known today as HYTREL - a polyether-ester copolymer which has excellent thermal and melt stability, and combines desirable elastomeric properties with thermoplastic processability. Because this completely new resin was a block copolymer of randomized hard and soft segments, it offered a combination of resilience and strength that had never been seen in any thermoplastic. And it is this combination that today positions polyester elastomers perfectly for economic replacement of parts currently made from other flexible materials. 

N. K. Kaforglou, Thermomechanical studies of semicrystalline polyether-ester copolymers,/. Appl. Polym. Sci., 21 543-554,1977. 

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