ACRYLITE® GP – Physical Properties
ACRYLITE® cell cast acrylic sheet is made to exacting standards. It offers excellent optical characteristics, thickness tolerances, light stability, and low internal stress levels for consistent performance.
Colorless Acrylite® cell cast carries an exclusive 30-year limited warranty on light transmission, which is your assurance of a quality product.
Acrylite® sheet is a lightweight, rigid thermoplastic material that has many times the breakage resistance of standard glass and is highly resistant to weather conditions.
Acrylite® cell cast can be easily sawed, machined, thermoformed, and cemented and is ultraviolet light absorbing up to approximately 360 nanometers. Because of its unique properties, Acrylite® cell cast is ideal for a wide range of applications, such as:
- Retail store displays
- Security glazing
- Industrial and residential glazing
- Decorative paneling
- Spectator shielding
Acrylite® cell cast is available in clear, colors and a wide range of standard sizes and thicknesses from .118” (3mm) to 1.0” (24mm). Acrylite® cell cast is also available as Acrylite® Satinice with a velvet frost surface on one or both sides. It is available in a plethora of colors with varying degrees of transmitted and reflected light. Acrylite® Satinice retains the same physical properties of standard cell cast acrylic.
Acrylite® sheet is more impact-resistant than glass. If subjected to impact beyond the limit of its resistance, it does not shatter into small slivers but breaks into comparatively large pieces. Acrylite® sheet meets the requirements of ANSI Z 97.1 for use as a Safety Glazing material in Buildings (for thicknesses 0.080” [2.0 mm] to 0.500” [1 2.7mm]).
Acrylic offers better weather resistance than other types of transparent plastics. Acrylite® cell cast will withstand exposure to blazing sun, extreme cold, sudden temperature changes, salt water spray and other harsh conditions. It will not deteriorate after many years of service because of the inherent stability of acrylic. Acrylite® sheet has been widely accepted for use in skylights, school buildings, industrial plants, aircraft glazing and outdoor signs.
Although the Acrylite® sheet will expand and contract due to changes in temperature and humidity; it will not shrink with age. Some shrinkage occurs when Acrylite® cell cast is heated to forming temperature.
Acrylite® sheet is half the weight of glass, and 43% the weight of aluminum. One square foot of 1/8” (3.0 mm) thick Acrylite® sheet weighs less than 3/4 pound (1/3 kilogram).
Acrylite® sheet is not as rigid as glass or metals. However, it is more rigid than many other plastics such as acetates, polycarbonates, or vinyls. Under wind load, a sheet will bow and foreshorten as a result of deflection. For glazing installations, the maximum wind load and the size of the window must be considered when the thickness of the panel and the depth and width of the glazing channels are to be determined.
If the Acrylite® sheet is formed into corrugated or domed shapes, rigidity is increased and deflection minimized.
Large, flat Acrylite® sheet may deform due to continuous loads such as snow, or even from its own weight if not sufficiently supported. Increased rigidity obtained by forming will minimize cold flow.
Strength and Stresses
Although the tensile strength of Acrylite® cell cast is 10,000 psi (69 M Pa) at room temperature (ASTM D638), stress crazing can be caused by continuous loads below this value.
For most applications, continuously imposed design loads should not exceed 1,500 psi (10.4 M Pa). Localized, concentrated stresses must be avoided. For this reason, and because of thermal expansion and contraction, large sheets should never be fastened with bolts, but should always be installed in frames.
All thermoplastic materials-including Acrylite® cell cast-will gradually lose tensile strength as the temperature approaches the maximum recommended.
Expansion and Contraction
Like most other plastics, Acrylite® sheet will expand 3 times as much as metals, and 8 times as much as glass. The designer should be aware of this rather large coefficient of expansion. A 48” panel will expand and contract approximately .002” for each degree Fahrenheit change in temperature.
In outdoor use, where summer and winter temperatures differ as much as 100°F, a 48” sheet will expand and contract approximately 3/16”. Glazing channels must be of sufficient depth to allow for expansion as well as for contraction.
Acrylite® sheet also absorbs water when exposed to high relative humidities, resulting in expansion of the sheet. At relative humidities of 100%, 80%, and 60%, the dimensional changes are 0.6%, 0.4% and 0.2%, respectively.
Acrylite® cell cast can be used at temperatures from -40°F (-40°C) up to +200°F (93°C), depending on the application. It is recommended that temperatures not exceed 180°F for continuous service, or 200°F for short, intermittent use.
Components made of Acrylite® cell cast should not be exposed to high heat sources such as high wattage incandescent lamps unless the finished product is ventilated to permit the dissipation of heat.
Colorless Acrylite® cell cast has a light transmittance of 92%. It is warranted not to lose more than 3% of its light-transmitting ability in a 30-year period. Contact Evonik Cyro for the complete warranty.
Acrylite® cell cast has excellent resistance to many chemicals including:
- solutions of inorganic alkalies such as ammonia
- dilute acids such as sulfuric acid up to a concentration of 30%
- aliphatic hydrocarbons such as hexane
Acrylite® sheet is not attacked by most foods, and foods are not affected by it. It is attacked, in varying degrees, by:
- aromatic solvents such as benzene and toluene
- chlorinated hydrocarbons such as methylene chloride and carbon tetrachloride
- ethyl and methyl alcohols
- some organic acids such as acetic acid
- lacquer thinners, esters, ketones and ethers
For a listing of the resistance of the Acrylite® sheet to more than 70 chemicals, refer to the table on page 6.
Acrylite® sheet will soften gradually as the temperature is increased above 210°F (99°C). At temperatures from 340°F to 380°F (171°C to 193°C), it becomes soft and pliable and can be formed into almost any shape using inexpensive molds.
The optimum forming temperature within this range depends on the thickness and desired depth of draw. Acrylite® sheet will typically shrink 1.5% when heated without a frame. As the sheet cools, it will harden and retain the formed shape.
Because Acrylite® cell cast is a thermoplastic material; heating a formed part to temperatures above 210°F (99°C) may cause it to revert to its original flat condition.
Cutting and Machining
Acrylite® sheets can be sawed with circular saws or band saws. It can be drilled, routed, filed and machined much like wood or brass with a slight modification of tools. Cooling of the cutting tool is recommended to keep the machined edge of the sheet as cool and stress-free as possible.
Heat buildup should be avoided because it could lead to stress crazing. Tool sharpness and “trueness” are also essential to prevent gumming, heat buildup and stresses in the part.
Laser technology is ideal for quick and accurate cutting, welding, drilling, scribing, and engraving of plastics. CO2 lasers focus a large amount of light energy on a very small area which is extremely effective for cutting complex shapes in the acrylic sheet. The laser beam produces a narrow kerf in the plastic allowing for close nesting of parts and minimal waste.
CO2 lasers vaporize the acrylic as they advance resulting in a clean polished edge but with high stress levels; annealing acrylic sheet after laser cutting is recommended to minimize the chance of crazing during the service life of the part.
Acrylite® sheets can be cemented using common solvent or polymerizable cements, such as ACRIFIX®. The most critical factor is the edge of the part to be cemented. The edge must have been properly machined so as to have a square flat surface and no stresses.
Annealing of the part prior to cementing is recommended. Cement and cement fumes should not contact formed or polished surfaces.
To eliminate stresses caused by machining and/or polishing, annealing is recommended.
Acrylite® cell cast may be annealed at 180°F (82°C) with the heating and cooling times determined by the sheet thickness. An approximate guideline is: annealing time in hours equals the sheet thickness in millimeters and the cool-down period is a minimum of 2 hours ending when sheet temperature falls below 140°F. For example, 1/8” (3 mm) Acrylite® cell cast would be heated for 3 hours at 180°F (82°C) and slowly cooled for at least 2 hours.
Acrylite® cell cast is a combustible thermoplastic. Precautions should be taken to protect the material from flames and high heat sources. Acrylite® usually burns rapidly to completion if not extinguished. The products of combustion, if sufficient air is present, are carbon dioxide and water.
However, in many fires, sufficient air will not be available and toxic carbon monoxide will be formed, as it is from other combustible materials. We urge good judgment in the use of this versatile material and recommend that building codes be followed carefully to ensure it is used properly.
Other properties related to flammability:
- The burning rate is 1.2 inches per minute (for 3 mm thickness) according to ASTM D 635.
- Smoke density: Measured by ASTM D 2843 is 11.4%.
- The self-ignition temperature is 910°F (488°C) when measured in accordance with ASTM D 1929.
While these test data are based on small scale laboratory tests frequently referenced in various building codes, they do not duplicate actual fire conditions.
Acrylite® cell cast meets the requirements of the following building codes for use as a Light Transmitting Plastic:
- NES (See National Evaluation Services, Inc., Report # NER-582)
- ICBO (See ICBO Evaluation Services, Inc., Evaluation Report #3715-CC2 Classification)
- BOCA and SBCCI (Accept National Evaluation Services, Inc., Report # NER-582)
The thermal conductivity of a material-its ability to conduct heat-is called the k-Factor. The k-Factor is an inherent property of the material and is independent of its thickness and of the surroundings to which it is exposed.
The k-Factor of Acrylite® sheet is:
1.3 B.T.U. / (hour) (sq. ft.) (°F /inch) or 0.19 W/m.K
Whereas the k-Factor is a physical property of the material, the U-Factor—or overall coefficient of heat transfer—is the value used to calculate the total heat loss or gain through a window.
The U-Factor is the amount of heat, per unit time and area, which will pass through a specific thickness and configuration of material per degree of the temperature difference between each of the two sides.
This value takes into account the thickness of the sheet, whether the sheet is in a horizontal or vertical position, as well as the wind velocity.
U-Factors are based on specific conditions (e.g., single-glazed or double-glazed installations) and are different for summer and winter. Listed below are U-Factors for several thicknesses of Acrylite® sheet for single-glazed, vertical installations, based on the standard ASHRAE* summer and winter design conditions.
The total heat loss or gain through a window (due to temperature difference only) can be calculated by multiplying the area of the window, times the difference between indoor and outdoor temperatures, times the appropriate U-Factor (from Table above). Heat intake through solar radiation must be added to arrive at the total heat gain.
Acrylite® sheet is a better insulator than glass. Its U-Factor or heat transfer value is approximately 10% lower than that of glass of the same thickness. Conversely, its RT-Factor is about 10% greater.
Thermal Shock and Stresses
Acrylite® cell cast is more resistant than glass to thermal shock and to stresses caused by substantial temperature differences between a sunlit and a shaded area of a window, or by temperature differences between opposite surfaces of a window.
The table on the next page gives an indication of the chemical resistance of clear Acrylite® sheet. The code used to describe chemical resistance is as follows:
R = Resistant
Acrylite® cell cast withstands this substance for long periods and at temperatures up to 120°F (49°C).
LR = Limited Resistance Fabrication
Acrylite® cell cast only resists the action of this substance for short periods at room temperatures. The resistance for a particular application must be determined.
N= Not Resistant Application of Chemicals
Acrylite® cell cast is not resistant to this substance. It is swelled, attacked, dissolved or damaged in some manner.
Plastic materials can be attacked by chemicals in several ways. The methods of fabrication and/or conditions of exposure of the Acrylite® sheet, as well as the manner, in which the chemicals are applied, can influence the final results even for “R” coded chemicals. Some of these factors are listed below.
Fabrication- Stress generated by sawing, sanding, machining, drilling, polishing, and/or forming.
Exposure- Length of exposure stresses induced during the life of the product due to various loads, changes in temperatures, etc.
Application of Chemicals- by contacts, rubbing wiping, spraying, etc.