Heat resistance of polyarylates

Polyarylates are used in automotive applications such as door handles, brackets, and headlamp and mirror housings. Polyarylates are also used in electrical applications for connectors and fuses. The polymer can be used in circuit board applications, because its high temperature resistance allows the part to survive exposure to the temperatures generated during soldering. The excellent UV resistance of these polymers allows them to be used as a coating for other thermoplastics for improved UV resistance of the part. The good heat resistance of polyarylates allows them to be used in applications such as fire helmets and shields. ... 

Statistical copolymerization of ethylene glycol and 1,4-butanediol with dimethyl ter-ephthalate results in products with improved crystallization and processing rates compared to poly(ethylene terephthalate). Polyarylates (trade names Ardel, Arylon, Durel), copolymers of bisphenol A with iso- and terephthalate units, combine the toughness, clarity, and proce-sibility of polycarbonate with the chemical and heat resistance of poly(ethylene terephthalate). The homopolymer containing only terephthalate units is crystalline, insoluble, sometimes infusible, and difficult to process. The more useful copolymers, containing both tere- and isophthalate units, are amorphous, clear, and easy to process. Polyarylates are used in automotive and appliance hardware and printed-circuit boards. Similar considerations in the copolymerization of iso- and terephthalates with 1,4-cyclohexanedimethanol or hexa-methylene diamine yield clear, amorphous, easy-to-process copolyesters or copolyamides,... 

All the received block-copolymers relate to the class of thermostable polymers. It is ascertained that the introduction of some quantity of oligoarylensulfonoxidation OASO-IOD into the structure positively influence the heat resistance of polyesters, rising it for 10-20 °C in comparison with polyarylates on the basis of dian and 1,1- dichlor-2,2 di(n-oxyphenyl)ethylene [4], For some BSN the noticeable destructive process begins at 400°C and more, which correspond to good thermostable polymeric materials. Observing the regimen of optimal heat treatment, the heat resistance of the materials may be raisen for SOSO. ... 

The miscibility between polyarylate and PET may be further driven by transesterification reaction within the melt phase, which occurs slowly at T 280°C but more rapidly at T > 300°C [Robeson, 1985 Eguiazabal et al., 1991]. In any case, polyarylate can readily form transparent blends when the PET content is 30% and the melt blending done above 300°C. Hence by adjusting the melt blending conditions, PET can be used to lower the cost and improve the chemical resistance of polyarylate while maintaining an adequate level of transparency. The heat distortion temperature is, of course, sacrificed to some extent. Except for some improved chemical resistance, processability and cost the blend does not seem to offer any compelling advantages over polyarylate and hence its applications appear to be quite limited. 

Polyarylates deliver excellent thermal performance with heat-deflection temperatures ranging from 154 to 174°C at 1.82 MPa (264 psi) and a UL thermal index of 130°C. In addition, a very low coefficient of thermal expansion [5.0-6.2 x 10mm/(mm °C) (60-130°C)] allows for superior performance in polyary-late/metal assemblies. The inherent uv resistance of polyarylate polymers results in excellent retention of mechanical properties under prolonged weathering conditions. As a coating or laminate, polyarylate provides a uv barrier for other performance plastics. 

Exterior Applications. Because of the excellent uv resistance of polyarylates, end use is foimd in such outdoor applications as glazing, skylights, and transparent panels. Polyarylates can be used alone or in multilayer constructions with other polymers. Properties such as transparency, impact and heat resistance, and low haze levels after long-term exposure have suited this resin for use in globes and other lighting components. 

With a somewhat lower level of heat resistance but with many properties that make them of interest as engineering materials alongside the polycarbonates, polysulphones, poly(phenylene sulphides) and polyketones are the so-called polyarylates which are defined as polyester from bis-phenols and dicarboxylic acids. 

Amorphous polyarylates are light-amber transparent materials which exhibit mechanical properties comparable to that of unfilled PET in terms of tensile or flexural strength and modulus (Table 2.13) but are notably superior in terms of heat resistance (HDT = 174°C vs. 85°C for PET) and impact strength. 

Polyarylates have good optical properties. Luminous light transmission can range from 84% to 88% with only 1% to 2% haze. Refractive index is 1.61. An important feature of the polyarylale family is high heat resistance demonstrated by a 34C°F (171°C) heat deflection temperature at 264 psi (1.8 mPa). The material exhibits good retention of properties at high temperature exposures 270,000 psi (1380 mPa) at 300 F (149°C) and over 200,000 psi at 350°F (177°C). 

Aromatic polyesters having an amorphous molecular structure. Compared with other amorphous engineering plastics in terms of heat resistance, polyarylates are generally positioned between polycarbonate on the low side and sulfone and polyether polymers on the high side. Compared with crystalline and semi-crystalline engineering plastics, polyarylate resins offer better resistance to warping, and generally comparable mechanical properties. 

Blends of PET and polyarylates are finding uses in cosmetics packaging due to their high tensile strength (71 MPa compared to 56 MPa for PET) and heat resistance. Containers left in automobiles or transported by trucks in high temperatures will not deform at temperatures up to 80°C. 

Copolymeric aromatic polyesters, though possessing a somewhat lower level of heat resistance are easier to fabricate than are the wholly aromatic polymers they also possess many properties that make them of interest as high-temperature materials. These materials, called polyarylates, are copolyester of terephthalic acid, and bisphenol A in the ratio of 1 1 2. 

By its thermo-mechanical properties the aromatic polysulfone on the basis of bisphenylolpropane takes intermediate place between polycarbonate and polyarylate of the same bisphenol. The glassing temperature of the polysulfone lies in the ranges of 190-195 °C, heat resistance on vetch is 185 °C. The given polysulfone is devised to be used at temperatures below 150 °C and is frost-resistant material (-100 °C). 

Synthesized, within given investigation, polyestersulfoneketones on the basis of phthalic acid polyarylates on the basis of 3,5-dibromine- -oxybenzoic acid and phthalic acids and copolyesters on the basis of teie-phthaloyl-bis( -oxybenzoic) acid are of interest as heat-resistant and film materials which can find application in electronic, radioelectronic, avia, automobile, chemical industries and electotechnique as thermo-stable constmctional and electroisolation materials as well as for the protection of the equipment and devices from the influence of aggressive media. 

Poly(ether ether ketone) (PEEK) was one of the first of the new generation of engineering thermoplastics introduced and developed by ICI in 1977 and was first marketed in 1978 (Chen and Porter 1994). PEEK is one of the highest-rated thermoplastic materials in terms of heat resistance. The material is one of the polyaryl ether ketone families, which are a group of partially crystalline polymers that are suitable for use at high temperatures. The useful properties of the material are retained at temperatures as high as 315°C. 

Since the early discovery of miscibility between the low-cost polystyrene and PPE, several commercial grades of PPE/HIPS have been developed, which offer a wide choice of heat resistance (DTUL), impact strength, and melt processability (Cizek 1969 Fried et al. 1978). This versatility of PPE/HIPS blends led to their unparalleled commercial success, accounting for nearly 50 % of market volume of all engineering polymers commercial blends. PPE/HIPS blends filled the price-performance gap between the styrenic resins (HIPS, ABS) and the engineering resins such as polycarbonate, polyarylate, and polysulfones. The technology of PPE/HIPS blends has already been discussed previously under the styrenic blends section (Sect. 19.3), and the typical blend properties are shown in Tables 19.6 and 19.32. 

Polyarylate polymers are aromatic polyesters derived from aromatic dicarboxylic acids and diphenols. In contrast to liquid crystalline aromatic polyester (derived from dicarboxylic hydroxy acids), polyarylates exhibit amorphous character on molding Tg is ca 198°C. Polyarylates present a competitive cost(performance profile in the context of amorphous engineering thermoplastics, delivering an excellent balance of mechanical properties, particularly practical heat resistance which substantially exceeds that of polycarbonates (qv). 

In addition to epoxy resins, MA has been investigated as a crosslinker for a variety of polymers. For example, poly(oxycyclohexene), polyary-lates, hydroxy-substituted polyspiro resins,and polymethyl-siloxanes have been crosslinked with MA to give thermoplastic adhesives, heat-resistant polyarylates, electrical insulating materials, and other composites. 

Polyarylate It is a form of aromatic polyester (amorphous) exhibiting an excellent balance of properties such as stiffness, UV resistance, combustion resistance, high heat-distortion temperature, low notch sensitivity, and good electrical insulating values. It is used for solar glazing, safety equipment, electrical hardware, transportation components and in the construction industry. 

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