Chemical Composition
Pyrex® borosilicate glass has a very high resistance to attack from water,
acids, salt solutions, halogens and organic solvents. It also has a moderate
resistance to alkaline solutions. Only hydrofluoric acid, hot concentrated
phosphoric acid and strong alkaline solutions cause appreciable corrosion of
the glass.Pyrex® glass has the following typical composition (percentage by weight):
| SiO2 | = | 80.6% |
| B2O3 | = | 13.0% |
| Na2O | = | 4.0% |
| AI2O3 | = | 2.3% |
Physical Properties
| Coefficient of Expansion (20°C – 300°C) | 3.3 x 10-6 K-1 |
| Density | 2.23 g/cm3 |
| Refractive index (Sodium D line) | 1.474 |
| Dielectric Constant (1MHz,20°C) | 4.6 |
| Specific heat (20°C) | 750J/kg°C |
| Thermal conductivity (20°C) | 1.14W/m°C |
| Poisson's Ratio (25°C – 400°C) | 0.2 |
| Young's Modulus (25°C) | 6400 kg/mm2 |
Optical Data
Pyrex® borosilicate glass has the ability to transmit light through the visible range of the spectrum and can be used effectively in the near ultra-violet range, making it ideally suitable for work in the field of photochemistry.
The graph above shows the degree of transmission of light as a function of wavelength in the ultra-violet, visible and infra-red sectors of the spectrum, for the thickness of glass generally encountered in laboratory ware (up to 5mm)
| Refractive index (Sodium D line) | = | 1.474 |
| Visible light transmission, 2mm thick glass | = | 92% |
| Visible light transmission, 5mm thick glass | = | 91% |
WHILE EVERY ATTEMPT HAS BEEN MADE TO VERIFY THE SOURCE OF THE INFORMATION, NO RESPONSIBILITY IS ACCEPTED FOR ACCURACY OF DATA.
