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 ?
This is used again to produce chlorine and sodium hydroxide, two chemicals that in turn are needed as raw materials for polycarbonates.
The report studies the North America polycarbonate markets and estimates its size in terms of value and volume for the forecast period.
This unique balance of performance and processability is well suited to bridge the gap between previous copolyester families and other clear plastics such as polycarbonate.
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.
Prices of recycled polycarbonates run about half that of comparable virgin resins.
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.
It is used to produce chlorine and sodium hydroxide two chemicals that in turn are needed as raw materials for polycarbonates.
Acrylic birefringence measures less than 20 nanometers, well below the 60-80 nm exhibited by polycarbonate.
World Trade Matrix for polycarbonates for 2008 - these are grids that show import and export volumes for virtually every country worldwide.
Market development in the overall polycarbonate business has changed dramatically in recent years, with new competitors and overcapacities exacerbated by insufficient demand from the customer industries.
Alkalube glyceryl, simple, and complete esters function as internal, external, or intermediate lubricants and flow modifiers for rigid PVC, polycarbonates, phenolics, acrylics, and nylons.
com/reports/c52322) has announced the addition of Polycarbonates Market Research to their offering.