Polyether-ester

Nonionic detergents, as the name implies, are not electrolytes, although they do possess the general polar-nonpolar character typical of surfactants. Examples of common types would include polyether esters, for... 

Polybutester (10) is a polyether—ester produced by the condensation polymerization of dimethyl terephthalate, polytetramethylene ether glycol [25190-06-17, and 1,4-butanediol [110-63-4]. Polybutester sutures are available in clear, ie, undyed, or blue, ie, melt-pigmented with (phthalocyaninato(2-)) copper. Monofilament polybutester is sold under the trade name Novafil. 

With the expiry of the basic ICI patents on poly(ethylene terephthalate) there was considerable development in terephthalate polymers in the early 1970s. More than a dozen companies introduced poly(butylene terephthalate) as an engineering plastics material whilst a polyether-ester thermoplastic rubber was introduced by Du Pont as Hytrel. Polyfethylene terephthalate) was also the basis of the glass-filled engineering polymer (Rynite) introduced by Du Pont in the late 1970s. Towards the end of the 1970s poly(ethylene terephthalate) was used for the manufacture of biaxially oriented bottles for beer, colas and other carbonated drinks, and this application has since become of major importance. Similar processes are now used for making wide-neck Jars. 

There has also been active interest in blends of PBT with other polymers. These include blends with PMMA and polyether-ester rubbers and blends with a silicone/polycarbonate block copolymer. 

With these polymers hard blocks with T s well above normal ambient temperature are separated by soft bloeks which in the mass are rubbery in nature. This is very reminiscent of the SBS triblock elastomers discussed in Chapter 11 and even more closely related to the polyether-ester thermoplastic elastomers of the Hytrel type deseribed in Chapter 25. 

In the 1990s novel polyols included polyether-esters, which provided good prerequisites for flame retardancy in rigid foams and polyether carbonates with improved hydrolysis stability. 

Block copolymers can contain crystalline or amorphous hard blocks. Examples of crystalline block copolymers are polyurethanes (e.g. B.F. Goodrich s Estane line), polyether esters (e.g. Dupont s Hytrel polymers), polyether amides (e.g. Atofina s Pebax grades). Polyurethanes have enjoyed limited utility due to their relatively low thermal stability use temperatures must be kept below 275°F, due to the reversibility of the urethane linkage. Recently, polyurethanes with stability at 350°F for nearly 100 h have been claimed [2]. Polyether esters and polyether amides have been explored for PSA applications where their heat and plasticizer resistance is a benefit [3]. However, the high price of these materials and their multiblock architecture have limited their use. All of these crystalline block copolymers consist of multiblocks with relatively short, amorphous, polyether or polyester mid-blocks. Consequently they can not be diluted as extensively with tackifiers and diluents as styrenic triblock copolymers. Thereby it is more difficult to obtain strong, yet soft adhesives — the primary goals of adding rubber to hot melts. 

If R is a polymeric ester, or ether, of molecular weight 1000-3000 a flexible elastic material will result. By reacting MDI and active hydrogen components (polyether/ester and a short chain glycol) in equivalent stoichiometric quantities, a linear polymer with virtually no crosslinks is obtained. 

The interest of that type of material has been largely demonstrated, f.i. by the Hytrel-type of products (i.e. polyether-ester multiblocks), particularly in the field of thermoplastic elastomers thanks to the efficient cross-linking action of the harder blocks. Due again to the swift development of increasingly sophisticated catalytic techniques, more and more original achievements... 

When the cyclic anhydride is maleic anhydride, the product understandably becomes an unsaturated polyether ester somewhat similar to traditional unsaturated polyester resins (UPRs). 

ISO 23711 2003 Elastomeric seals - Requirements for materials for pipe joint seals used in water and drainage applications - Thermoplastic elastomers ISO 14910-1 1997 Plastics - Thermoplastic polyester/ester and polyether/ester elastomers for moulding and extrusion - Part 1 Designation system and basis for specifications ISO 14910-2 1997 Plastics - Thermoplastic polyester/ester and polyether/ester elastomers for moulding and extrusion - Part 2 Preparation of test specimens and determination of properties... 

Figure 6. Thermal transition temperatures (T = melting, = isotropization) versus n, the number of methylene units in the polymers containing 4,4 -dihydroxybiphenyl for 1) polyethers ( ) esters (A) T, (A) T. (data from reference 25).

Sepe (1998) discussed polyether-ester dendrimers synthesized from glycerol and lactic acid as globular monodisperse polymers composed of branched repeating units emitting from a central core. The key constituents of the polymer are combined with reiterative reaction steps from simple and abundant starting materials. 

Physical properties are related to ester-segment structure and concentration in thermoplastic polyether-ester elastomers prepared hy melt transesterification of poly(tetra-methylene ether) glycol with various diols and aromatic diesters. Diols used were 1,4-benzenedimethanol, 1,4-cyclo-hexanedimethanol, and the linear, aliphatic a,m-diols from ethylene glycol to 1,10-decane-diol. Esters used were terephthalate, isophthalate, 4,4 -biphenyldicarboxylate, 2,6-naphthalenedicarboxylate, and m-terphenyl-4,4"-dicarboxyl-ate. Ester-segment structure was found to affect many copolymer properties including ease of synthesis, molecular weight obtained, crystallization rate, elastic recovery, and tensile and tear strengths. 

T nterest in polyether-ester block copolymers that are both thermoplastic - and elastomeric continues at a sustained pace (1-9). Most of the recent communications have dealt with the tetramethylene terephthalate/ poly(tetramethylene ether) terephthalate copolymers which are continuing to find increased use in commercial applications requiring thermoplastic elastomers with superior properties. 

The work reported here is concerned with the syntheses and properties of polyether-ester block copolymers containing poly (tetramethylene ether) units of molecular weight of approximately 1000 as the amorphous polyether blocks and a variety of esters as the crystallizable hard segments. The purpose of this study is to correlate changes in synthesis and properties of these thermoplastic and elastomeric copolymers with changes in the concentration and nature of the ester segments, particularly the types of diol and diacid. 

Copolymer compositions are expressed as weight percentages of the ester units with the remainder being polyether-ester units. For instance, 40% tetramethylene terephthalate/PTME terephthalate copolymer represents a block copolymer containing 40 wt % of tetramethylene terephthalate units and by difference 60 wt % of poly(tetramethylene ether) terephthalate units. 

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-... 

Figure 1. Synthesis and structure of polyether-ester block copolymers (D — hydrocarbon portion of diol Ar = aromatic portion of the ester x,y = the number of repeat units in the respective ester and polyether-ester blocks)...

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. 

Elastomeric polyether-ester block copolymers were prepared by melt transesterification of poly(tetramethylene ether) glycol of molecular weight approximately 1000 with a variety of diols and esters. The ease of synthesis and the properties of these thermoplastic copolymers have been related to the chemical structure and concentration of the ester hard segments. 

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. 

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