Properties
- Light Transmission - CR-39 monomer cast sheet has the highest light transmission of all optical plastics including acrylic, polycarbonate and cellulose acetate butyrate. CR-39 has a light transmission of 92% which is equal to crown glass.
- Refractive Index - The refractive index of CR-39 sheet is 1.50. This compares with the refractive index of glass which is 1.52.
- Yellowing Resistance - CR-39 sheet has the lowest yellowness index and resists yellowing due to aging and environmental conditions more than all other transparent plastics.
- Stress Birefringence - CR-39 cast sheet is non-birefringent, free of residual stresses and internal strain. CR-39 sheet is cast optically flat with precise thickness control.
- Infrared Transmission - CR-39 cast sheet has unique infrared transmission properties. CR-39 is transparent to near infrared radiation with a transmission of 90% between 700 to 1100 nm and an average transmission of 80% at wavelengths from 1100-2000 nm.
- Dispersion / ABBE Value - CR-39 sheet has an ABBE value of 57 which is the amongst the highest of all transparent plastics and close to 60.2 for glass. An ABBE value close to glass reduces chromatic aberration or dispersion from color displays.
- Haze - CR-39 cast optical sheet has lower haze value than other typical transparent plastics.
- Scratch Resistance - CR-39 cast optical sheet has superior scratch resistance compared to other optical plastics.
- Chemical Resistance - CR-39 cast sheet is virtually unaffected by most organic and inorganic chemicals as well as most substances encountered in harsh environments. CR-39 is resistant to the following:
- Alcohols
- Acids, Mineral
- Ketones
- Aliphatic Hydrocarbons
- Aromatic Hydrocarbons
- Halogenated Hydrocarbons
- Fruit Juices
- Soft Drinks
- Gasoline
- Greases and Oils
- Detergents
- Silicone oil
|
Property Values
| Optical Property |
ASTM Test Method |
Standard CR-39 Sheet |
| Transmission, Visible (%) 400-700 nm |
D1003 |
89-92 |
| Transmission, Infrared (%) 700-100 nm |
------ |
89-91 |
| Refractive Index at 20°C |
D542 |
1.501nD |
| Haze (%) |
D1003 |
0.21 |
| Yellowness Index |
D1925 |
0.73 |
| Dispersion Factor (Abbe number) |
D542 |
57 |
| Thermal Property |
Standard CR-39 Sheet |
ASTM Test Method |
| Specific Heat (Btu/lb/°F) |
.55 |
C351 |
| Thermal Expansion (m/m/ C)
from 20 to 45°C
from 46 to 82°C
from 83 to 130°C |
1.058 x 10-4
3.246 x 10-4
1.821 x 10-4
|
D696 |
|
Thermal Conductivity (Btu/hr/ft2/°F/in) |
1.45 |
C177 |
| Maximum Operating Temperature (°C)
Continuous Service
Intermittent (1 hour duration) |
100
130 |
----- |
| Mechanical |
Standard CR-39 Sheet |
ASTM Test Method |
| Density (gm/cm3 at 25°C) |
1.320 |
D792 |
| Tensile Modulus (kg/mm2) |
3.5-4.2 |
D638 |
| Hardness, Rockwell M95-M100 |
97 |
D785 |
| Flexural Modulus (kg/mm2) |
185-235 |
D790 |
| Impact Resistance |
|
--- |
| IZOD test, 25°C (ft.lb/in2) |
|
D256 |
| Notched |
0.2-0.4 |
--- |
| Unnotched |
2-3 |
--- |
| Electrical |
Standard CR-39 Sheet |
ASTM Test Method |
| Dielectric Constant (60Hz) |
4.4 |
D150 |
| Dielectric Strength (short time 23°C) |
354 |
D149 |
| Flammability |
Standard CR-39 Sheet |
ASTM Test Method |
| Meets UL Horizontal Burn Rating |
UL 94HB |
UL |
Product Availability
Standard Cast Sheet Sizes
960 mm x 480 mm
Cutting
All parts can be cut to any shape or size using a computer controlled laser with general tolerance of ± 0.1 mm
Standard Thicknesses
0.70 mm
|
1.00 mm
1.40 mm
1.50 mm |
2.00 mm
2.50 mm
|
3.00mm |
4.00mm |
5.0mm |
|
1.70 mm |
|
|
|
|
Custom thicknesses are available upon request. Please contact us for more information.
(Tolerances: ± 10% of nominal value)
Standard Colors
Clear (Colorless)
Orange
Yellow
Laser Red, 670 nm |
Brown
Red
Green
Laser Red, 650 nm |
Grey
Blue
Aqua (Blue-Green)
IR Transmitting Only |
Custom Colors
Available per customer specification.
Luminous Transmission
Variable range from 92% to less than 1%.
Antiglare Finishes
Four surface finishes available, one side or two sides.
Gloss per Gardner 60º Glossmeter (G7 units).
| Smooth |
No matte finish |
| Light glare reduction |
135 gloss units |
| Medium glare reduction |
110 gloss units |
| Heavy glare reduction |
85 gloss units |
UV Radiation Absorption
Absorber “A” blocks UV up to 100% at 400 nm
Absorber “B” blocks UV up to 98% at 380 nm
Custom UV Radiation Absorption available. Please contact us for more information.