Distortion/deflection temperature, impact

To enhance the resistance to heat softening his-phenol A is substituted by a stiffer molecule. Conventional bis-phenol A polycarbonates have lower heat distortion temperatures (deflection temperatures under load) than some of the somewhat newer aromatic thermoplastics described in the next chapter, such as the polysulphones. In 1979 a polycarbonate in which the bis-phenol A was replaced by tetramethylbis-phenol A was test marketed. This material had a Vicat softening point of 196 C, excellent resistance to hydrolysis, excellent resistance to tracking and a low density of about l.lg/cm-. Such improvements were obtained at the expense of impact strength and resistance to stress cracking. [Pg.565]

HDT Heat deflection temperature, heat distortion temperature HEMA Hydroxyethyl methacrylate HIPS High impact polystyrene HR Isobutene-isoprene rubber (butyl rubber)... [Pg.131]

ASTM American Standard Test Method BS British Standard CAB Cellulose acetate butyrate DGEBA Diglycidyl ether of bisphenol A DSC Differential scanning calorimetry ENR Epoxidized natural rubber EVA Ethylene-co-vinylacetate EPDM Ethylene propylene diene monomer ESC Environmental stress cracking HDT Heat deflection/distortion temperature HDPE High-density polyethylene HIPS High -impact polystyrene... [Pg.1176]