TECHNICAL INFORMATION
414
Glass Properties
PHYSICAL PROPERTIES OF GLASS Glass is an inorganic product of fusion that has cooled to a rigid condition without crystallizing and, therefore, has no melting point as such. There are, however, four temperatures that are of interest to the glassblower. They are: 1. The Working Point — the temperature at which glass has a viscosity of 10 4 poises. At this temperature, glass is soft enough for most lampworking or sealing operations. 2. The Softening Point — the temperature at which glass has a viscosity of 10 7.6 poises. In this temperature range glass will deform noticeably under its own weight: ASTM C 338. 3. The Annealing Point — the temperature at which the internal stress caused by rapid cooling from lampworking or forming temperatures may be substantially removed in a matter of minutes. It is determined by measuring the elongation rate versus temperature of a fiber of glass under conditions prescribed by ASTM Designation C 336. The values given herein are typical for production glasses. 4. The Strain Point — the temperature at which the internal strain in a glass is substantially relieved only after a matter of hours and not at a commercially desirable rate. It is determined by extrapolation of annealing point data for fiber elongation: ASTM C 336.
Table 2 Physical Properties of 33 Expansion Borosilicate Glass and 51 Expansion Borosilicate Glasses 33 Expansion
51 Expansion
Borosilicate Glass
Borosilicate Glass
Working Point
1255°C
1140°C
Strain Point
513°C 565°C 827°C
530°C 570°C 785°C
Annealing Point Softening Point
Linear Coefficient of Expansion (from 0 to 300°C), in./in./°C
32x10 -7
55x10 -7
Density grams per cm 3
2.22 1.47 92%
2.33 1.49 91%
Refractive Index—Sodium D line (.5893 microns) Visible Light Transmission, 2 mm thickness
Specific Heat (in g. cals per g. deg.)
0.204
0.204
(25 to 175°C)
(25 to 175°C)
Thermal Conductivity (in cals/cm/cm 2 /sec/°C)
0.0027
0.0026
Working Point o C
Softening Point o C
Annealing Point o C
Strain Point o C
Expansion Coefficient 0-300 o C x10 -7 / o C
Contraction Coefficient Annealing Point to 25 o C x 10 -7 / o C
Stress Optical Coefficient mµ/cm/kg/cm2
Density g/cm3
Refractive Index Sodium D Line
Glass
Type
Principal Use
General Pharmaceutical Containers Pharmaceutical Contianer
Amber 203
Borosilicate
1105
765
558
520
54
71
2.39
1.51
3.4
CA-2 Soda Lime
1035
730
560
525
89
103
2.50
1.52
2.6
Expansion Borosilicate Glass Expansion Borosilcate Glass
33
General
1255
827
565
513
32
35
2.23
1.47
3.7
51
General
1140
785
570
530
55
70
2.33
1.49
3.5
NOTE: All data subject to normal manufacturing variation.
Calculated Thermal Conductivity Units Expressed Cal/cm/cm 2 / sec o Cx10 -3
Young’s Modulus x 10 6 psi
Volume Resistivity ohm- cm Logarithm
Dielectric Properties 25 o C 1 Megahertz
Estimated ∆T Thermal Shock Resistance o C
Chemical Durability U.S.P. XIX mL N/50 H 2 SO 4
Glass
Loss Factor %
⅛ Thick
¼ Thick
½ Thick
250 o C
350 o C
-100 o C
0 o C
100 o C
K
∆ %
Amber 203
7.4
6.0
5.7 0.60
3.4
105
85
60
0.44
2.0
2.5
2.8
10.3
CA-2
6.7
5.4
7.1 0.71
5.1
70
55
35
5.9
2.0
2.5
2.7
11.1
33 expansion borosilicate glass 51 expansion borosilicate glass
7.9
6.4
4.6 0.48
2.2
180 150
100
0.20
2.1
2.7
3.1
9.5
7.0
5.7
5.8 0.84
4.9
105
85
60
0.36
2.0
2.6
2.9
10.4
Powered by FlippingBook