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AR-GLAS / Physical and Chemical Properties	- Introduction | Tubing | Rod | Properties -
Soda lime 9.1

Physical Data

Mean coefficient of linear expansion a (20 ºC;300 ºC) acc. to ISO 7991 9.1 · 10-6 K-1 Transformation temperature Tg 525 ºC Temperature fixed points at viscosity h in dPa · s:             1013 upper annealing point 530 ºC           107.6 softening point 720 ºC           104 working point 1040 ºC Density r at 25 ºC 2.50 g · cm-3 Modulus of elasticity E (Young's modulus) 73 · 103 N · mm-2 Poisson's ratio m 0.22 Thermal conductivity lw at 90 ºC 1.1 W · m-1 · K-1 Temperature for the specific electrical resistance of 108 W · cm (DIN 52 326) tk 100 200 ºC Logarithm of the electric volume resistance (W · cm)             at 250 ºC 7.1           at 350 ºC 5.7 Dielectric properties (1 MHz, 25 ºC)             Dielectric figure (permittivity) e 7.2           Dielectric loss factor (dissipation factor) tan d 70 · 10-4 Refractive index nd (l = 587.6 nm) 1.514 Stress-optical constant (DIN 52 314) K 2.7 · 10-6 mm2 · N-1

Resistance to Thermal Shock

Resistance to thermal shock is not an exact, by defined physical quantity (for more details see ISO 718); it depends on the measuring method, the shape, the wall thickness and the surface and end properties of the glass object in question. Rapid temperature changes cause high temporary stress in the glass, meaning that rapid cooling processes are very dangerous, since in this case a thin outer layer of the glass is placed under tensile stress over the still hot inner core. Glass is much more susceptible to tensile stress than to compressive stress. The following graph shows the resistance to thermal shock of the tubes Duran, Durobax, Fiolax Clear, Fiolax Amber, Illax and AR-Glas:

Chemical Composition (main components in approx. weight %)	SiO2 B2O3 K2O Al2O3 Na2O BaO CaO MgO 69 1 3 4 13 2 5 3

Chemical Data	Hydrolytic Class (ISO 719) HGB 3 Acid Class (DIN 12116) Class S 1 Alkali Class (ISO 695) Class A 2

Transmission (%)	Wavelength (nm) * Measured on processed glass with a wall thickness = 1 mm

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