borosilicate glass tube, borosilicate glass rods, borosilicate glass bar Color: clear, red, yellow, green, blue, purple, amber, pink Special Shape Tube: Triangle tube, Square tube, Ellipse tube, Flat Physical Data: No.Physics PerformanceNumerical ValueUnit1Medium coefficient of linear expansion α20/300 acc.To DIN 52328 3.30.110-6 K-1 2Transformation Temperature 52515 3Viscosity temperatures (dPa·s) 1014.7 51010 1013.2 upper annealing temperature 56010 107.5 softening point 82010 104 working temperature 126020 4Maximum short-time working temperature 500 520 Density ρ 2.230.02g/cm3 6Modulus of elasticity E 64103 N/mm2 7Poissons ratioμ 0.201 8Thermal conductivityλw(20-100) 1.2W/m2K 9Temperature for the specific electrical resistance of 108Ω·cm(DIN52326)tk 100 250 10Electrical volume resistance logarithm(Ω·cm) At 250 8 At 350 6.5 11Dielectric Properties (1MHz,25) Dielectric figureε 4.61 Dielectric loss factor tanδ 3710-4 12Refractive index(λ=587.6nm)nd 1.4731 13Stress-optical constant(DIN52314)K 4.010-6mm2/N Chemical Composition in approx.weight % (main components) SiO2 B2O3 Na2O + K2O Al2O3 81 13 4 2