CR-39 or allyl diglycol carbonate (ADC) is a plastic widely used as a lens material for glasses . The abbreviation CR stands for the name of a project for the development of thermoactive plastics - “Columbia Resin”, in which the ADC formula was thirty ninth in a row [1] .
| CR-39 | |
|---|---|
 | |
| Are common | |
| Systematic name | Allyl diglycol carbonate |
| Chem. formula | C 12 H 18 O 7 |
| Physical properties | |
| condition | solid |
| Molar mass | 274.27 g / mol |
| Density | 1.32 g / cm³ |
| Optical properties | |
| Refractive index | 1,498 |
| Classification | |
| Reg. CAS number | 95567-48-9 |
| Pubchem | |
| Reg. EINECS number | |
| SMILES | |
| Inchi | |
| Chemspider | |
For the first time, the CR-39 monomer was used to create a GRP fuel tank for a B-17 bomber during World War II , which made it possible to reduce the weight and increase its flight range. In 1947, the company "Armorlite Lens" from California for the first time made lenses for glasses made of CR-39 plastic. This material has a refractive index of 1.498 and an Abbe number of 58. CR-39 is a registered trademark of PPG Industries .
CR-39 is also used in dosimetry to measure one of the types of ionizing radiation - neutron radiation .
CR-39 should not be confused with polycarbonate , an elastic homopolymer derived from bisphenol A [2] .
Content
Synthesis
CR-39 is obtained by polymerization of diethylene glycol bis-allyl carbonate (ADC) with the participation of diisopropyl peroxydicarbonate (IPP) as an initiator. The presence of allyl groups allows the polymer to form crosslinks , which makes it a reactoplast . Monomeric structure:
The time of polymerization of ADC with the participation of IPP is approximately 20 hours at a maximum temperature of 95 ° C. Maintaining the desired temperature is ensured by a water bath or forced circulation of hot air.
Alternatively, IPP for the polymerization of ADC can be used benzoyl peroxide (BPO). Pure BPO has a crystalline structure and is less volatile than diisopropyl peroxydicarbonate. As a result of using BPO, a polymer with a higher yellowness index is obtained. At room temperature, peroxide dissolves in ADC longer than IPP.
Properties
The CR-39 is transparent in the visible spectrum and almost completely opaque in the ultraviolet range . Of all types of optical plastic without coating, CR-39 is most resistant to abrasion and scratches. The density of CR-39 is about half the density of glass, while its refractive index is only slightly lower than that of crown glass , and the high Abbe number provides low chromatic aberrations , which gives a significant advantage in the manufacture of medical and sunglasses . Dyeing lenses in different colors is carried out both by applying dyes on the surface of the finished lenses, and by adding dyes to the material during their manufacture. CR-39 is resistant to most solvents and other chemicals, gamma radiation , not subject to aging and " material fatigue ." Unlike glass, it withstands sparks from welding . Retains all properties with continuous exposure to temperatures up to 100 ° C, and up to one hour at 130 ° C.
The direct analogue of the CR-39 is manufactured by Acomon AG under the trademark RAV, as well as by the Chinese company Danyang Yueda FineChemichal Co. Ltd.
See also
- Glass
- Organic glass
- Polycarbonates
Notes
- ↑ “Optical products” Corporateportal.ppg.com. Retrieved 2012-09-15. (eng.)
- A Field Study . Dtic.mil. Retrieved 2012-09-16. (eng.)