Engineering Load Test
Acrylic Sheet: Physical Property Specifications
Purpose is to encourage the proper use of acrylic sheet plastic in construction, and to aid architects in designing and preparing specifications consistent with the properties and characteristics of the material. [ Tables and literature from Rohm & Haas, Philadelphia, PA, CO-EX Corp. Rocky Hill, CT.] Commercial grade acrylic sheet is suitable for most building glazing applications.
The figures below show that various thickness of acrylic sheet have greater impact resistance than other types of glass when impacted with a hard object, such as a stone.
IMPACT RESISTANCE OF ACRYLIC SHEET AND OTHER MATERIALS
|Material||Nominal Thickness:||Energy to Break (ft-lb)|
|Single strength Window Glass
Double Strength Window Glass
|Laminated Safety Glass||.250 in||1.1|
|Rough Wire Glass
Polished Wire Glass
AIR CANNON IMPACT STRENGTH
Nominal Thickness (mm)
|Baseball ( 0.32# )||Steel Tipped Dart
( 0.6 lb 1/2" Rad. Tip )
The colorless form, Acrylic sheet is as transparent as the finest optical glass. Its total light transmittance is 92 percent, and haze measurement for colorless sheet averages only 1 percent.
SOLAR ENERGY TRANSMITTANCE and SHADING COEFFICIENTS
|Acrylic Sheet||Transmittance ( % )||Transmittance ( % )||Shade Coefficients
|Visible Light||Solar Energy|
|2370 Bronze (Dark)
2412 Bronze (Med.)
2404 Bronze (Light)
|Colorless ( Clear )||92||85||0.98|
- 2412 Bronze is our standard (recommend) sheet in bright solariums.
- Super White Translucent grades are preferred in south face roof areas for alleviation of extreme heat build-up in solariums - this transmits and bathes areas below in a natural cool white light plus delivering all your required light for the growth of plants, yet shades the area for human activity.
Ultraviolet Transmittance: Regular Acrylic glaze sheet ( G & MC ), will block some portions of the UV spectrum, but special grades are required when all ( UF-3 ) or most ( UF-4 ) of the UV needs to be absorbed.
Acrylic Sheet is approximately less than 50% as heavy as glass and 43% as heavy as aluminum.
Lexan "MacroLux" Panels [ double wall extruded sheet ] is 1/8 the weight of glass.
COMPARATIVE WEIGHTS (lb/ft² )
|Thickness (mm)||Acrylic Sheet||MacroLux Panels||Glass
The amount of heat conducted throught Acrylic glazing is lower than for glass of the same thickness.
U-Factor: ( BTU/hr/sq.ft./ ° F )
While most household cleaners can safely be used with acrylic sheet, the material is affected by alcohol, paint thinners, turpentine, and similar petroleum solvents. To clean paint and grease, utilize NAPHTHA or KEROSENE for safe removal. Regular cleaning with a mild dish detergent and plenty of water is preferred, dry with clean cotton or air dry. A good grade of automobile wax can be applied as a polish, and is very useful in removal of minor surface abrasions.
Acrylic sheet has proved its ability to withstand weather and sun exposure with negligible loss of light transmission and clarity. The manufacturers warranty expresses a 10 year guarantee of less than 3% CHANGE in light transmission and clarity within this interval. No other type of plastic offers this assurance of satisfactory outdoor performance.
When acrylic sheet is heated to its optimum forming temperature (approximately 325°F - 350°F), it becomes soft and pliable, and can be formed to almost any desired shape. As the material cools in its formed shape, it stiffens and retains the shape to which it has been formed. This permits architects to specify complex designed panels in small quantity at reasonable tooling costs.
Flat sheets of acrylic can be cold-formed ... bent while cold to a smooth contour ... and held to the radius by springing the material into a curved channel support. The recommended radius of curvature for "G sheet" should be at least 180 times the thickness of the sheet.
Minimum Radius of Curvature for Cold-Formed Acrylic Sheet
|Sheet Thickness (mm)||Min. Radius (in)|
Our standard minimum radius for 4.5 mm sheet is 36"
Acrylic sheet offers equal to or better sound loss characteristics than glass. It also has much better breakage resistance, so it can be used as a transparent sound barrier to reduce noise levels and increase safety at the same time.
Comparison of Noise Reduction Characteristics of Acrylic Sheet and Other Materials
|Construction Material||Approximate dB (A) Noise Reduction|
|Acrylic Sheet 3 mm
Acrylic Sheet 6 mm
Acrylic Sheet 12 mm
Sheet Lead (1/16")
Wood Stud Partition (4")
Thermal Expansion & Contraction Factor
Due to the thermal expansion and contraction, acrylic sheet is subject to greater dimensional change than other materials with which it is used in construction. This is factored into account when dimensions are laid out for any project. Considerations must be given to the overall temperature gradient ( max. & min. values ) that the glazed structure will be subjected to, and allowances are made to the sheet dimensions according to those values.
Thermal Expansion and Contraction Factor
|Material||Expansion Coefficients ("/"/°F)||Typical Modulus (psi)|
Example: (Sheet Location: = 25 1/2" x 14' ) If the ambient temperature at time of dimensional cutting is room temp. - then sheet is trimmed to 25 1/4" x 13' 5/8". Thereby, if sheet is cold at dimensioning, you must realize it is now contracted, and if the sheet is hot at time of trim, the sheet may be fully expanded. You therefore trim to what the opposite extreme temperature would consist of. Generally, on a sheet at 14 ft., the max. off-cut is approx. 1/2" - 5/8" in length, and approx. 3/16" to 1/4" in width. For smaller sheets, the maximal length off-cut is reduced proportionally.
Different temperature and/or humidity conditions on the inner and outer surfaces of thinner acrylic sheet may cause sheet to bow somewhat in the direction of the higher temperature and/or humidity. However, this type of bowing is reversible, and the sheet will return to its original flatness once the temp./humidity differentials are equalized. Bowing does not affect visibility through flat transparent sheet, but may cause distorted reflection. In translucent or opaque panels where visibility through the material is not required, this nature exhibits a specular disguise to reflective distortions. This will not occur in curved glaze, cold formed or heat formed. This event is lessened by use of thicker glaze panels on narrow width dimensions.
The allowable continuous service temperature range for Acrylic sheet is 170° F to 200° F for exterior applications.
To avoid stress crazing [ light surface checking of panel ], design stress limits for continuously imposed loads should not exceed 1500 psi for acrylic "G" sheet, and 750 psi for acrylic "MC" sheet at or below room temperature.