polycarbonate

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polycarbonate

(pŏl″ē-kăr′bĭ-nāt, -nĭt) [″ + ″]
A transparent polymer used to manufacture eye protectors, shields, and other medical devices.

Polycarbonate

A very strong type of plastic often used in safety glasses, sport glasses, and children's eyeglasses. Polycarbonate lenses have approximately 50 times the impact resistance of glass lenses.

index of refraction

The ratio of the speed of light in a vacuum or in air, c, to the speed of light in a given medium, v. Symbol: n. Hence,
n = c/v
The speed of light in a given medium depends upon its wavelength. Consequently, the index of refraction varies accordingly, being greater for short wavelengths (blue) than for longer wavelengths (red). The index of refraction forms the basis of Snell's law, which quantitatively determines the deviation of light rays traversing a surface separating two media of different refractive indices. Syn. refractive index. Plural: indices. See dispersion; law of refraction; gradient-index lens; high index lens; speed of light; refractometer.
Table I3 Refractive indices of some transparent media at selected wavelengths
spectral lineGFDCA
OriginCalciumHydrogenSodiumHydrogenOxygen
wavelength (nm)430.8486.1589.3656.3759.4
aqueous or vitreous humour1.34401.34041.33601.33411.3317
crystalline lens1.43071.42591.42001.41751.4144
spectacle crown1.53481.52931.52301.52041.5163
dense flint1.63971.62901.61701.61221.6062

Table I4 Index of refraction n of various media for sodium light (λ = 589.3)
air1.00
water (at 20ºC)1.333
spectacle crown glass1.523
flint glass (dense)1.62
flint glass (extra dense)1.65-1.70
titanium oxide glass1.701
calcite crystal
ordinary ray1.658
extraordinary ray1.486
quartz crystal
ordinary ray1.544
extraordinary ray1.553
diamond2.42
Canada balsam1.53-1.54
CR-391.498
polycarbonate1.586
silicone rubber1.44
CAB1.47
PMMA1.49
HEMA1.43
hydrogel polymer
20% water content1.46-1.48
75% water content1.37-1.38
eye
tears1.336
cornea1.376
aqueous humour1.336
crystalline lens (average effect)1.42
vitreous humour1.336

plastic 

Various organic or synthetic materials (e.g. CR-39, HEMA, polymethyl methacrylate, polycarbonate, etc.) that can be transformed into solid shapes to make spectacle frames, contact lenses, ophthalmic lenses, etc. and can be made to have good optical surfaces, high light transmission and refractive indices and dispersions similar to that of crown or flint glass. See acetone; index of refraction; plastic spectacle frame.
References in periodicals archive ?
Acrylic birefringence measures less than 20 nanometers, well below the 60-80 nm exhibited by polycarbonate.
polycarbonate suppliers have presses outfitted to mold DVDs, they are now considering installing more or less complete DVD replicating lines.
Heating tests that simulated stove-top sterilization triggered the bottles to release 5 percent of the unbound BPA into a mixture of alcohol and water designed to mimic the baby formula and fatty foods that might be stored in polycarbonate containers.
In a less extreme experiment, distilled water was held in large polycarbonate containers for 39 weeks at room temperature.
On the demand side, exporters and strategic planners focusing on polycarbonates, alkyd resins, and other polyesters in primary forms in France face a number of questions.
This report was created for strategic planners, international marketing executives and import/export managers who are concerned with the market for polycarbonates, alkyd resins, and other polyesters in primary forms in France.
BPA (Bisphenol A) and phosgene are among the major raw materials employed in the production of polycarbonate.
This report comprises in-depth analysis and forecast of the polycarbonate market on a global as well as regional level.
Over the last few months, the company has developed and commercialized Paraloid EXL-5137, a gloss-reducing agent for engineering resins; Paraloid EXL-3657, an MBS-based toughener that dramatically improves the impact strength of polycarbonate systems; and Paraloid EXL-3361, an acrylic core-shell toughener that provides strong thermal and uv stability to polycarbonate and polycarbonate blends.
His team recently gained one such insight while examining the molecular structure of polycarbonate, a material serendipitously discovered in the 1950s and long ranked as the toughest polymer, Yee says.
This review examines the global and CIS markets for polycarbonates.
The polycarbonates are a biodegradable, multiblock, polymeric drug delivery system based on two well-known polymers.