Hytrel

Hysterosalpingography Hystrene Hysulf process Hytemp HyTex Hytrel... 

Noncrystalline aromatic polycarbonates (qv) and polyesters (polyarylates) and alloys of polycarbonate with other thermoplastics are considered elsewhere, as are aHphatic polyesters derived from natural or biological sources such as poly(3-hydroxybutyrate), poly(glycoHde), or poly(lactide) these, too, are separately covered (see Polymers, environmentally degradable Sutures). Thermoplastic elastomers derived from poly(ester—ether) block copolymers such as PBT/PTMEG-T [82662-36-0] and known by commercial names such as Hytrel and Riteflex are included here in the section on poly(butylene terephthalate). Specific polymers are dealt with largely in order of volume, which puts PET first by virtue of its enormous market volume in bottie resin. 

A smaller but rapidly growing area is the use of PTMEG ia thermoplastic polyester elastomers. Formation of such polyesters iavolves the reaction of PTMEG with diacids or diesters. The diols become soft segments ia the resulting elastomeric materials. Examples of elastomeric PTMEG polyesters iaclude Hytrel (Du Pont) and Ecdel (Eastman Chemicals). 

Product Hytrel 4056 Hytrel Hytrel Hytrel Lomod Lomod... 

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. 

In Chapters 3 and 11 reference was made to thermoplastic elastomers of the triblock type. The most well known consist of a block of butadiene units joined at each end to a block of styrene units. At room temperature the styrene blocks congregate into glassy domains which act effectively to link the butadiene segments into a rubbery network. Above the Tg of the polystyrene these domains disappear and the polymer begins to flow like a thermoplastic. Because of the relatively low Tg of the short polystyrene blocks such rubbers have very limited heat resistance. Whilst in principle it may be possible to use end-blocks with a higher Tg an alternative approach is to use a block copolymer in which one of the blocks is capable of crystallisation and with a well above room temperature. Using what may be considered to be an extension of the chemical technology of poly(ethylene terephthalate) this approach has led to the availability of thermoplastic polyester elastomers (Hytrel—Du Pont Amitel—Akzo). 

Poly(pivalolactone) 739 Table 25.12 Propenies of Hytrel-type thermoplastic elastomers... 

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. 

Thermoplastic polyester elastomers such as the Du Pont product Hytrel were developed later than the polyurethane materials, being first introduced in 1972. They have similar characteristics to the polyurethanes but there is an upward shift in the hardness range (i.e. the softest grades are not so soft, but the hardest grades are harder than the corresponding extreme grades in the polyurethanes). 

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. 

There are five types of thermoplastic rubbers currently available. These are based on (i) Olefinics (e.g. Alcryn, Santoprene) (ii) Polyiuethanes (e.g. Elas-tollan, Caprolan, Pellethane) (iii) Polyesters (e.g. Hytrel, Amitel) (iv) Styrenics (e.g. Solprene, Cariftex) and (v) Polyamides (e.g. Pebax, Dinyl) Some typical properties are given in Table 1.4. 

Properties Test Method Styrenic Elexar 8421 COPE Hytrel 4056 TPU Texin 480AR TPA Estamid 90A TPO TPR 1600 EA, Two Phase, Santoprene 101-73/201-73 EA, Single Phase, Alcryn R12028-80A... 

Hytrel Bulletin 1-25, Blends of Hytrel polyester elastomer with PVC, E.I. DuPont de Nemours and Co., Delaware, 1976. 

The effect of °Co y-ray irradiation on the mechanical properties, surface morphology, and fractography of blends of plasticized PVC and thermoplastic copolyester elastomer, Hytrel (E.I. Du Pont de Nemours Company, Inc., Wilmington, Delaware), have been studied by Thomas et al. [445]. Radiation has two major effects on the blend cross-linking of the Hytrel phase and degradation of PVC phase. Both effects are found more prominent at higher radiation dose. 

The three polymers that were chosen for study, e.g. PMMA (2), BPDN (3), and Hytrel (4), were selected because they represent a wide range of viscoelastic materials. These materials were processed into plaques. The plaques were annealed at 12S°C between highly polished chrome plated flat plates and cooled slowly to minimize the effects of residual stresses. Viscoelastic measurements were made under conditions cited above on two test specimens that were cut from... 

Suppose one wanted to compare the behavior of two polymers and their blends. Let us define the signal as the difference between the logarithims of the viscoelastic quantities and the noise as the error calculated for a specific set of viscoelastic properties associated with a specific composition. The signal to noise ratio would have the appearance of the three curves shown in Figure 2 for a PMMA/Hytrel blend >3/1. Selection of the optimum conditions for comparison is apparent in that figure. Emphasis should be placed at those temperatures with high signal/noise ratios. 

Figure 3. Plot of the loss tangent with temperature for Hytrel in the temperature range of 0 to 140 Deg. The x s represent the experimental values, while the solid line represents the results of smoothing using the Savitzky-Golay technique.

The Hytrel used in this work is Hytrel-4056, a product of the DuPont Co. 

Poly (butylene terephthalate) Poly-1,4-butane diol (Hytrel )... 

The Material of the Example. Poly(ether ester) (PEE) materials are thermoplastic elastomers. Fibers made from this class of multiblock copolymers are commercially available as Sympatex . Axle sleeves for automotive applications or gaskets are traded as Arnitel or Hytrel . Polyether blocks form the soft phase (matrix). The polyester forms the hard domains which provide physical cross-linking of the chains. This nanostructure is the reason for the rubbery nature of the material. 

Figure 16. Effect of temperature on tensile strength. Key O, Hr-BBB-30-55 V, Hytrel 4056 , H2-BIB-34.

Hysys software package, 7 76 Hytrel, commercial block copolymer,... 

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... 

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