Poly(allyl diglycol carbonate) (PADC) is a plastic commonly used in the manufacture of eyeglasslenses alongside the material PMMA (polymethyl methacrylate). The monomer is allyl diglycol carbonate (ADC). The term CR-39 technically refers to the ADC monomer, but is more commonly used to refer to the finished plastic.
The abbreviation stands for "Columbia Resin #39", which was the 39th formula of a thermosetting plastic developed by the Columbia Resins project in 1940.[1]
The first commercial use of CR-39 monomer (ADC) was to help create glass-reinforced plastic fuel tanks for the B-17 bomber aircraft in World War II, reducing the weight and increasing the range of the bomber. After the war, the Armorlite Lens Company in California is credited with manufacturing the first CR-39 eyeglass lenses in 1947. CR-39 plastic has an index of refraction of 1.498 and an Abbe number of 58. CR-39 is now a trade-marked product of PPG Industries.[2]
Although CR-39 is a type of polycarbonate, it should not be confused with the general term "polycarbonate", a tough homopolymer usually made from bisphenol A.[3]
CR-39 is made by polymerization of ADC in presence of diisopropyl peroxydicarbonate (IPP) initiator. The presence of the allyl groups allows the polymer to form cross-links; thus, it is a thermoset resin. The polymerization schedule of ADC monomers using IPP is generally 20 hours long with a maximum temperature of 95 °C. The elevated temperatures can be supplied using a water bath or a forced air oven.
Benzoyl peroxide (BPO) is an alternative organic peroxide that may be used to polymerize ADC. Pure benzoyl peroxide is crystalline and less volatile than diisopropyl peroxydicarbonate. Using BPO results in a polymer that has a higher yellowness index, and the peroxide takes longer to dissolve into ADC at room temperature than IPP.
Applications
Optics
CR-39 is transparent in the visible spectrum and is almost completely opaque in the ultraviolet range.[4] It has high abrasion resistance, in fact the highest abrasion/scratch resistance of any uncoated optical plastic. CR-39 is about half the weight of glass with an index of refraction only slightly lower than that of crown glass, and its high Abbe number yields low chromatic aberration, altogether making it an advantageous material for eyeglasses and sunglasses. A wide range of colors can be achieved by dyeing of the surface or the bulk of the material. CR-39 is also resistant to most solvents and other chemicals, gamma radiation, aging, and to material fatigue. It can withstand the small hot sparks from welding, something glass cannot do. It can be used continuously in temperatures up to 100 °C and up to one hour at 130 °C.[citation needed]
Radiation detection
In the radiation detection application, CR-39 is used as a solid-state nuclear track detector (SSNTD) to detect the presence of ionising radiation. Energetic particles colliding with the polymer structure leave a trail of broken chemical bonds within the CR-39. When immersed in a concentrated alkali solution (typically sodium hydroxide) hydroxide ions attack and break the polymer structure, etching away the bulk of the plastic at a nominally fixed rate. However, along the paths of damage left by charged particle interaction the concentration of radiation damage allows the chemical agent to attack the polymer more rapidly than it does in the bulk, revealing the paths of the charged particle ion tracks. The resulting etched plastic therefore contains a permanent record of not only the location of the radiation on the plastic but also gives spectroscopic information about the source. Principally used for the detection of alpha radiation emitting radionuclides (especially radon gas), the radiation-sensitivity properties of CR-39 are also used for proton and neutron dosimetry and historically cosmic ray investigations.
The ability of CR-39 to record the location of a radiation source, even at extremely low concentrations is exploited in autoradiography studies with alpha particles,[5] and for (comparatively cheap) detection of alpha-emitters like uranium.[6] Typically, a thin section of a biological material is fixed against CR-39 and kept frozen for a timescale of months to years in an environment that is shielded as much as possible from possible radiological contaminants. Before etching, photographs are taken of the biological sample with the affixed CR-39 detector, with care taken to ensure that prescribed location marks on the detector are noted. After the etching process, automated or manual 'scanning' of the CR-39 is used to physically locate the ionising radiation recorded, which can then be mapped to the position of the radionuclide within the biological sample. There is no other non-destructive method for accurately identifying the location of trace quantities of radionuclides in biological samples at such low emission levels.
^A quantitative method for determining the biodistribution of alpha radionuclides using whole-body cryosectioning and alpha-track autoradiography 2013-10-14 at the Wayback Machine Cebrián, D., Morcillo, M.A.; Radiation Dosimetry, CIEMAT Avd. Complutense 22; 28040-Madrid Spain.
^Busby Busby Chris and Williams Dai, Further Evidence of Enriched Uranium in guided weapons employed by the Israeli Military in Lebanon in July 2006: Ambulance Air Filter Analysis 2012-12-24 at the Wayback Machine Green Audit Research Note 7/2006 Nov 3rd 2006.
April 09, 2023
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Poly allyl diglycol carbonate PADC is a plastic commonly used in the manufacture of eyeglass lenses alongside the material PMMA polymethyl methacrylate The monomer is allyl diglycol carbonate ADC The term CR 39 technically refers to the ADC monomer but is more commonly used to refer to the finished plastic Poly allyl diglycol carbonate Polymer structureNamesOther names 2 5 8 10 Tetraoxatridec 12 enoic acid 9 oxo 2 propen 1 yl ester homopolymerIdentifiersCAS Number 25656 90 0Abbreviations PADCPropertiesDensity 1 31Refractive index nD 1 498Except where otherwise noted data are given for materials in their standard state at 25 C 77 F 100 kPa Infobox references Diallyl diglycol carbonate Monomer structureNamesIUPAC name 2 2 prop 2 enoxycarbonyloxyethoxy ethyl prop 2 enyl carbonateOther names allyl diglycol carbonate ADC diethyleneglycol bis allylcarbonateIdentifiersCAS Number 142 22 3 DDC 95567 48 9 ADC deprecatedPubChem CID 8879Except where otherwise noted data are given for materials in their standard state at 25 C 77 F 100 kPa Infobox references The abbreviation stands for Columbia Resin 39 which was the 39th formula of a thermosetting plastic developed by the Columbia Resins project in 1940 1 The first commercial use of CR 39 monomer ADC was to help create glass reinforced plastic fuel tanks for the B 17 bomber aircraft in World War II reducing the weight and increasing the range of the bomber After the war the Armorlite Lens Company in California is credited with manufacturing the first CR 39 eyeglass lenses in 1947 CR 39 plastic has an index of refraction of 1 498 and an Abbe number of 58 CR 39 is now a trade marked product of PPG Industries 2 An alternative use includes a purified version that is used to measure neutron radiation a type of ionizing radiation in neutron dosimetry Although CR 39 is a type of polycarbonate it should not be confused with the general term polycarbonate a tough homopolymer usually made from bisphenol A 3 Contents 1 Synthesis 2 Applications 2 1 Optics 2 2 Radiation detection 3 See also 4 ReferencesSynthesis EditCR 39 is made by polymerization of ADC in presence of diisopropyl peroxydicarbonate IPP initiator The presence of the allyl groups allows the polymer to form cross links thus it is a thermoset resin The polymerization schedule of ADC monomers using IPP is generally 20 hours long with a maximum temperature of 95 C The elevated temperatures can be supplied using a water bath or a forced air oven Benzoyl peroxide BPO is an alternative organic peroxide that may be used to polymerize ADC Pure benzoyl peroxide is crystalline and less volatile than diisopropyl peroxydicarbonate Using BPO results in a polymer that has a higher yellowness index and the peroxide takes longer to dissolve into ADC at room temperature than IPP Applications EditOptics Edit CR 39 is transparent in the visible spectrum and is almost completely opaque in the ultraviolet range 4 It has high abrasion resistance in fact the highest abrasion scratch resistance of any uncoated optical plastic CR 39 is about half the weight of glass with an index of refraction only slightly lower than that of crown glass and its high Abbe number yields low chromatic aberration altogether making it an advantageous material for eyeglasses and sunglasses A wide range of colors can be achieved by dyeing of the surface or the bulk of the material CR 39 is also resistant to most solvents and other chemicals gamma radiation aging and to material fatigue It can withstand the small hot sparks from welding something glass cannot do It can be used continuously in temperatures up to 100 C and up to one hour at 130 C citation needed Radiation detection Edit In the radiation detection application CR 39 is used as a solid state nuclear track detector SSNTD to detect the presence of ionising radiation Energetic particles colliding with the polymer structure leave a trail of broken chemical bonds within the CR 39 When immersed in a concentrated alkali solution typically sodium hydroxide hydroxide ions attack and break the polymer structure etching away the bulk of the plastic at a nominally fixed rate However along the paths of damage left by charged particle interaction the concentration of radiation damage allows the chemical agent to attack the polymer more rapidly than it does in the bulk revealing the paths of the charged particle ion tracks The resulting etched plastic therefore contains a permanent record of not only the location of the radiation on the plastic but also gives spectroscopic information about the source Principally used for the detection of alpha radiation emitting radionuclides especially radon gas the radiation sensitivity properties of CR 39 are also used for proton and neutron dosimetry and historically cosmic ray investigations The ability of CR 39 to record the location of a radiation source even at extremely low concentrations is exploited in autoradiography studies with alpha particles 5 and for comparatively cheap detection of alpha emitters like uranium 6 Typically a thin section of a biological material is fixed against CR 39 and kept frozen for a timescale of months to years in an environment that is shielded as much as possible from possible radiological contaminants Before etching photographs are taken of the biological sample with the affixed CR 39 detector with care taken to ensure that prescribed location marks on the detector are noted After the etching process automated or manual scanning of the CR 39 is used to physically locate the ionising radiation recorded which can then be mapped to the position of the radionuclide within the biological sample There is no other non destructive method for accurately identifying the location of trace quantities of radionuclides in biological samples at such low emission levels See also EditCorrective lensReferences Edit Optical Products Corporateportal ppg com Archived from the original on 2009 06 13 Retrieved 2012 09 15 Optical Products Corporateportal ppg com Archived from the original on 2006 04 19 Retrieved 2012 09 15 A Field study PDF Dtic mil Archived PDF from the original on October 2 2012 Retrieved 2012 09 16 OptiCampus com Spectral Transmittance Charts opticampus opti vision Retrieved 2019 03 09 A quantitative method for determining the biodistribution of alpha radionuclides using whole body cryosectioning and alpha track autoradiography Archived 2013 10 14 at the Wayback Machine Cebrian D Morcillo M A Radiation Dosimetry CIEMAT Avd Complutense 22 28040 Madrid Spain Busby Busby Chris and Williams Dai Further Evidence of Enriched Uranium in guided weapons employed by the Israeli Military in Lebanon in July 2006 Ambulance Air Filter Analysis Archived 2012 12 24 at the Wayback Machine Green Audit Research Note 7 2006 Nov 3rd 2006 Retrieved from https en wikipedia org w index php title CR 39 amp oldid 1122566314, wikipedia, wiki, book, books, library,
