Polycarbonate

Polycarbonate is a tough, dimensionally stable, transparent thermoplastic that has many applications which demand high performance properties. This versatile thermoplastic maintains its properties over a wide range of temperatures, from -20°C to 140°C It has the highest impact resistance of any thermoplastic, transparent up to 32mm thick in special grades, outstanding dimensional and thermal stability, exceptional machine ability, stain resistant and non-toxic with low water absorption. Polycarbonate is optically clear, providing total luminous transmittance and a very low haze factor. The high impact strength makes it resistant to repeated blows, shattering and spalling.

Impact strength:
Un notched polycarbonate is virtually unbreakable, making it extremely safe in areas where parts may be exposed to impact. When exposed to repeated heavy blow, the material tends to cold form rather than shatter.

Electrical:
Polycarbonate is excellent for electrical applications, because of its high dielectric strength and high volume resistivity which decreases only slightly as temperature or humidity is increased.

Machinability:
Parts can be easily machined from standard metal working tools. No special tools are needed, and finished parts can be polished to a high gloss. Water or water-soluble cutting oils should be used when machining polycarbonate, since some standard cutting oils will attack the material. Polycarbonate can be machined on standard metalworking or woodworking equipment. Its unique properties permit it to be machined without chipping, splitting, or breaking.

Annealing:
In some instances where extensive machining is required, an annealing of semi-finished parts is highly recommended. Annealing can be accomplished by heating parts at 120°C in a desiccated air circulating oven for one hour per 25mm of thickness. After heating, the oven should be turned off and allowed to cool to room temperature spontaneously.

Bonding:
Polycarbonate can be mechanically bonded by standard methods. It can also be cemented by using a solvent such as methylene chloride or adhesives such as epoxy, urethane and silicone. Polycarbonate and also be ultrasonically or vibrational welded.

Removing paint or other materials:
Fresh paint may be removed by rubbing lightly with a cleaning material such as isopropyl alcohol. Then the sheet should be washed immediately with a mild soap or detergent in warm water, and rinsed thoroughly with clean water. Grease and glazing compound may similarly be removed from the surface with the above mentioned cleaning materials. Weathered paint may be lifted off the sheet with masking tape. Razor blades or other sharp scraping tools should never be used.

Formability:
Standard polycarbonate sheet can be heat formed with proper pre-drying. Polycarbonate sheet may also be cold formed under special conditions.

Cleaning:
Is best done with warm soapy water, specialised plastic cleaners and polishes, such as, Sheenmaster, Plexus, Novus #1 or Meguiars #18 may remove slight scratches. Products such as abrasive or highly alkaline cleaners, acetone, carbon tetrachloride, benzene or petrol should not be used, and the sheet should not be cleaned in hot sun or at high temperatures.

Scratch Removal:
Sheenmaster, Plexus, Novus #1 and #2 or Meguiars #18 and #17 may remove hairline scratches and minor abrasions. Any polish, however, should be tested first on a sample area of the polycarbonate sheet.

Decorating:
Polycarbonate products will accept painting, printing, or vacuum metallising as decorating methods.

UV Stabilisation:
Standard grade Polycarbonate sheet, tube and rod is not UV stabilised, however, sheet is available in UV stabilised and mar resistant grades.

Applications:
Lenses, high temperature and pressure windows, face shields. Industrial equipment, guards and housings. Medical equipment components. Instrument components, electrical insulators and connectors. Windows in pressure chambers, automotive parts.

Materials available:
Standard Grade:
Clear and tinted sheet. 2440 x 1220 or 2440 x 1830 sheet up to 13mm thick

UV and Mar resistant sheet:
Clear and tinted sheet. 2440 x 1220 or 2440 x 1830 sheet up to 32mm thick

Rod and Tube is available in natural clear.

Typical Properties of Polycarbonate

 Property  ASTM  Value
General    
Specific gravity
D 792  1.20
Tebsuke Strength, Ultimate
D 638  9,000 psi
Elongation at break
D 638  130 %
Tensile modulus
D 638  3.1x10˜5 psi
Rockwell Hardness
D 785
 R118
Impact strenght (73° F) (notched)
D 256  17.0 ft-lb/inch
Flexural strenght
D 790
 14,200 psi
Flexural Modulus
D790  3.4x10˜5 psi
Wear factor against steel 40 psi 50fpm

 2500x10˜10
Coefficient of friction 40 psi 50fpm

0.38 Dynamic



Thermal


Meltig point

155°C
Heat Delfection at 66 psi
D 648
140°C
Heat Delfection at 264 psi
D 648
130°C
Max serving temperature for short term

135°C
Max serving temperature for long term

115°C
Thermal conductivity
C 177
1.35 Btu-inch/hr-ft˜2- °F
Specific heat

0.30 Btu/lb- °F
Coefficient of linear thermal expansion
D 696
3.7x10˜5
Temp range for thermal expansion

0-95° C



Electrical


Dielectric constant at 60Hz (23°C)
D 150
3.2
Dissipation factor at 60Hz (23°C) D 150
0.001
Volume resistivity
D 257
10˜17 OHM-CM
Dielectric strength
D 149
380 v/MIL



Miscellaneous


Water absorption - 24 hours
D 570
0.15%
Water absorption - Saturation
D 570
0.35%
Density
D 792
0.0434 lb/inch˜3
Flammability
UL 94
V-2
Weathering Resistance

Limited resistance

These values are representative of those obtained under standard ASTM conditions and should not be used to design parts which function under different conditions.

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