Polyarylate, properties

Let us consider polyarylates properties change with Dj. (or df) variation. The Eqs. (99), (96) and (103) combination allows to obtain the analytical relationship between T and Dj, In Fig. 61 the comparison of the experimental and obtained by the indicated mode dependences T (Dj.) is adduced, from which their good correspondence follows. The physical basis of the similar correlation is simple — increasing results to vcl reduction (see Fig. 58) and, hence, to T decreasing [166]. 

For a part to exhibit stmctural stiffness, flexural moduH should be above 2000 N/mm (290,000 psi). Notched l2od impact values should be deterrnined at different thicknesses. Some plastics exhibit different notch sensitivities. For example, PC, 3.2 mm thick, has a notched l2od impact of 800 J/m (15 fdbf/in.) which drops to 100 J/m (1.9 fflbf/in.) at 6.4-mm thickness. On the other hand, one bisphenol A phthalate-based polyarylate resin maintains a 250-J /m (4.7-fdbf/in.) notched l2od impact at both thicknesses. Toughness depends on the stmcture of the part under consideration as well as the plastic employed to make the part. Mechanical properties, like electrical properties, ate also subject to thermal and water-content changes. 

Polyarylates are sensitive to heat. Although mechanical properties are not much affected, colors darken. Properties are given in Table 8. Hydrolytic stability and resistance to organic solvents are fair. 

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. 

Many engineering thermoplastics (e.g., polysulfone, polycarbonate, etc.) have limited utility in applications that require exposure to chemical environments. Environmental stress cracking [13] occurs when a stressed polymer is exposed to solvents. Poly(aryl ether phenylquin-oxalines) [27] and poly(aryl ether benzoxazoles) [60] show poor resistance to environmental stress cracking in the presence of acetone, chloroform, etc. This is expected because these structures are amorphous, and there is no crystallinity or liquid crystalline type structure to give solvent resistance. Thus, these materials may have limited utility in processes or applications that require multiple solvent coatings or exposures, whereas acetylene terminated polyaryl ethers [13] exhibit excellent processability, high adhesive properties, and good resistance to hydraulic fluid. 

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. 

The polymerization of cyclic low-molar-mass polycarbonates, polyarylates, and PBT to high-molar-mass thermoplastics has been extensively studied by the General Electric Company during the last decade.57,58 Due to very low viscosity, cyclic oligoesters can be processed like thermosetting resins but retain thermoplastic properties in the final state, after polymerization in the presence of suitable... 

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. 

TABLE 2.13 Topical Properties of Ardel D-100 Bisphenol-A Polyarylate and of Liquid Crystalline Polyesters Vectra A-950 and Xydar SRT-500... 

A variety of polymer compositions that use this type of polymerization chemistry can be envisioned. In addition to the polyarylate homopolymers that have been described in this chapter, random or block copolymers can be prepared with reasonable ease by the combination of different monomers or oligomers. These compositions can be designed to optimize thermal, mechanical, dielectric, or optical properties of a polymer system. Also, the trifluorovinyl ether functionality can be incorporated into other high-performance polymer systems with relative ease.34,35 The perfluorocyclobutane polyarylate chemistry is a versatile approach to the preparation of high-performance polymers, which is just beginning to demonstrate its utility. 

Ardel polyarylate resins, 10 190 Ardeparin, 4 95t Arduengo carbenes, 26 847 Area, exponents of dimensions in absolute, gravitational, and engineering systems, Cross-sectional area Head- area meters Surface area Variable-area flowmeters Area detectors, 26 431 Area per surfactant molecule, 24 136 Arechloral hydrate, anesthetic properties of, 2 69... 

Many researchers have reported the structure-thermal property correlations in LCPs from substituted hydroquinones (HQs) and dicarboxylic acids. Lenz and co-workers have investigated the liquid crystallinity of the polyarylates obtained from substituted HQs and terephthalic acid (TA) [6-10], substituted HQs and l,10-bis(phenoxy)decane-4,4/-dicarboxylic acid [8], and substituted HQs and a,oo-bis(phenoxy)alkane-4,4/-dicarboxylic acid [11], Kricherdorf and Schwarz [12] and Osman [13] reported the liquid crystallinity of the polyarylates obtained from substituted HQs and 1,4-cyclohexanedicarboxylic acid, while Krigbaum el al. [14], Heitz and co-workers [15] and Kricherdorf and Engelhardt [16] investigated the liquid crystallinity of the polyarylates synthesized from substituted HQs and substituted TAs. In addition, Jackson reported the liquid crystallinity and the moduli of fibers and injection molded specimens of the polyarylates... 

The reason for the lower liquid crystalline (LC) temperature of the BB model compound seems to be that the biphenyl unit of this compound was adopting a twisted structure in the LC state [26], Therefore, we prepared various polyarylates containing the BB unit and determined their thermal properties and the moduli of the as-spun fibers, as shown in Table 19.3. 

Table 19.3 Thermal properties and moduli of substituted-HQs/BB polyarylates [19]. From Inoue, T. and Tabata, N., Mol. Cryst. Liq. Cryst., 254, 417-428 (1994), and reproduced with permission of Gordon and Breach (Taylor and Francis) Publishers...

Early and prescient work to develop correlations between biological observables and the physico-chemical properties of polymers were reported by Brocchini and Kohn [3, 32, 166]. Prior to the development of the models, the authors had been engaged in the combinatorial synthesis of a 112-member library of polyarylates, prepared through the condensation of diphenols with diacids (Fig. 12). 

In situ polycondensation leads to aromatic polyamides or polyesters dispersed within the matrix of polyarylate. Mechanical and thermal properties of the films formed... 

Table 15.2 Thermal and Physical Properties of Polyaryl Esters (Typical Values)...

As shown in Table 15.8, polyaryl sulfones have excellent mechanical properties. The commercial products differ somewhat in properties, but all have high heat deflection temperatures (at least 175 C). These thermoplastic engineering polymers have excellent resistance to nonoxidizing acids, salts, and alkalis, and to polar solvents. They are attacked by nonpolar solvents such as benzene. 

POLYARYLATES. These are clear, amorphous thermoplastics that combine clarity, high heat deflection temperatures, high impact strength, good surface hardness, and good electrical properties with inherent ultraviolet stability and flame retardance. No additives or stabilizers are required to provide these properties. Polyarylates are aromatic polyesters that are manufactured from various ratios of iso- and terephthalic acids with bisphenol A.1 The resultant products are free-flowing pellets which can be processed by a variety of thermoplastic techniques in transparent and... 

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). 

The essential requirement for an exact determination of the physicochemical properties of a compound is its stability under the conditions of measurement. Thus, pseudoazulenes are difficult to measure because they are rather unstable in comparison to most azulenes. The simplest unsubstituted representatives of some systems are so thermally unstable that it is nearly impossible to isolate them. Phenyl substitutents have a stabilizing effect, so polyaryl-substituted compounds can be kept at room temperature for some months without decomposing noticeably. An especially strong stabilizing effect is given by the picryl group.106... 

In recent years, remarkable progress has been made in the syntheses of aromatic and heterocyclic polymers to search a new type of radiation resistant polymers. Sasuga and his coworkers extensively investigated the radiation deterioration of various aromatic polymers at ambient temperature [55-57] and reported the order of radiation resistivity evaluated from the changes in tensile properties as follows polyimide > polyether ether ketone > polyamide > polyetherimide > polyarylate > polysulfone. 

Shen, L., Shi, M., Li, F.Y., et al. (2006) Polyaryl ether dendrimer with a 4-phenylacetyl-5-pyrazolone-based terbium(III) complex as core synthesis and photophysical properties. Inorganic Chemistry, 45, 6188-6197. 

Figure 18.18 Map of dielectric properties of engineering plastics. Among engineering plastics, SPS (impact modified and GF-reinforced HB and IR grades) has very low dielectric dissipation factor and dielectric constant following those of fluorocarbon polymers. PSF, polysulfone PPE, poly(phenylene ether) PES, poly(ether sulfone) PAr, polyarylate...

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