Properties at elevated temperature

A combination of excellent chemical and mechanical properties at elevated temperatures results in rehable, high performance service to the chemical processing and related industries. Chemical inertness, heat resistance, toughness and flexibiUty, stress-crack resistance, excellent flex life, antistick characteristics, Htfle moisture absorption, nonflammability, and exceptional dielectric properties are among the characteristics of these resins. 

Chemical Properties. A combination of excellent chemical and mechanical properties at elevated temperatures result in high performance service in the chemical processing industry. Teflon PEA resins have been exposed to a variety of organic and inorganic compounds commonly encountered in chemical service (26). They are not attacked by inorganic acids, bases, halogens, metal salt solutions, organic acids, and anhydrides. Aromatic and ahphatic hydrocarbons, alcohols, aldehydes, ketones, ethers, amines, esters, chlorinated compounds, and other polymer solvents have Httle effect. However, like other perfluorinated polymers,they react with alkah metals and elemental fluorine. 

Unsaturated resias based on 1,4-cyclohexanedimethanol are useful ia gel coats and ia laminating and molding resias where advantage is taken of the properties of very low water absorption and resistance to boiling water (6). Thermal stabiHty is imparted to molding resias, both thermoplastic (71,72) and thermoset (73—76), enabling retention of physical and electrical properties at elevated temperatures (77). Additionally, resistance to chemical and environmental exposure is characteristic of products made from these resias (78). 

The water hberated during the cure has no apparent effect on the composite properties. Glass-filled composites prepared in this manner retain mechanical properties at elevated temperatures as well as solvent and flammabiUty resistance (88). PhenoHc-graphite-fiber composites that exhibit superior mechanical properties have also been prepared by this process. 

Fig. 8. Flexural properties at elevated temperatures. Laminates constmcted from alternating pHes of 46.7-g (1.5-02) mat and 746-g/m (24-o2/yd ) woven roving at a nominal glass content of 45%. A represents bisphenol fumarate (T = 130° C) B, novolak epoxy methacrylate (T = 130° C) C, epoxy dimethacrylate (T = 100° C) D, isophthaUc resin (T = 100° C) and E, oAy f -phthahc resin (T = 80° C).

Thermal Properties. The inherent thermal stabiUty of PPS translates into high temperature resistance for short- as well as long-term exposure and retention of properties at elevated temperature. 

The effect of specific chemicals and environments on polymer properties at elevated temperatures. 

Polyesters exhibit excellent physical properties. They have high tensile strength, high modulus, they maintain excellent tensile properties at elevated temperatures, and have a high heat distortion temperature. They are thermally stable, have low gas permeability and low electrical conductivity. For these reasons, polyesters are considered engineering polymers. 

The moisture uptake in the cured samples appears to have no effect on the room temperature tensile properties as demonstrated in Table I. A critical study to be done is to determine the moisture effect on properties at elevated temperatures. 

The tensile properties of BCB/BMI are not affected by the absorption of water as shown in Table II. Future studies will be done to determine the effect of water uptake on the mechanical properties at elevated temperatures. 

Further studies are continuing to determine the s chanical properties at elevated temperatures of cured BCB resin systes s when saturated, and to determine the properties of BCB resins when used as matrices in composites. Work is currently being conducted to determine the neat resin properties of the BCB sionomer (without BMI) and of the BCB oligomer blended with a BMI resin. 

Sensor Properties at Elevated Temperatures, Influence of Hydrogen... 

The mechanical properties at elevated temperatures can be still improved by forming composites that contain the ionomer resin that... 

We close our discussion of thermal conductivity with the observation that experimental determinations of this property at elevated temperatures have large error bars. Indeed, the two measurements of which we are aware differ by roughly 50%. (The experimental line in Fig. 8 is the recommended linear... 

The properties of the epoxide/cyanate compositions are inferior to those of non-modified cyanate polymers. They are, however, better in comparison with the properties of crosslinked BPA/ECH epoxide resin and epoxynovolaks [72]. Equimolar epoxide/cyanate ratio was recommended. Outstanding water resistance and dielectric properties at elevated temperatures are emphasized. In many patent applications, improved solvent resistance is mentioned. 

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