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Coefficients of Thermal Expansions of Plexiglas


Plexiglas® acrylic sheet will expand and contract with changes in temperature and humidity. Different temperature and/or humidity conditions on the inner and outer surfaces of Plexiglas® sheet may cause it to bow slightly in the direction of the higher temperature and/or humidity. However, this type of bowing is reversible. The sheet will return to its original flat state when the temperature and humidity differentials become zero.

Bowing does not affect visibility through flat Plexiglas® sheet, but may distort reflections. For translucent or opaque panels in which it is unnecessary to see objects through the sheet, surface textures or formed designs will help disguise specular reflection distortions.

In construction, Plexiglas® sheet is often used with other materials that undergo less expansion and contraction. The listing in the below compares the coefficients of thermal expansion of Plexiglas® sheet with other common construction materials.

Coefficients of Thermal Expansions
Inches/Foot/100 °F
Plexiglas® sheet
Plate glass

To ensure good performance in environments where temperature varies widely, Plexiglas® sheet should be installed in a channel frame that permits the sheet to expand and contract freely. The channel frame should be deep enough for the sheet to contract fully and still stay within the frame.

Avoid inflexible fasteners such as bolts that do not permit expansion and contraction. Tapes and sealants that adhere to both the acrylic sheet and the frame should be sufficiently extensible to accommodate thermal expansion of both.

Plexiglas® sheet may develop permanent deformation under long-term continuous loading. This cold flow characteristic may be minimized by using thicker sheet, reducing the size of unsupported areas, or using thermoformed configurations.

The statements, technical information and recommendations obtained herein are believed to be accurate as of the date hereof. Since the conditions and methods of use of the product and of the information referred to herein are beyond our control, Arkema expressly disclaims any and all liability. NO WARRANTY OF FITNESS FOR ANY PARTICULAR PURPOSE, WARRANTY OR MERCHANTABILITY, OR ANY OTHER WARRANTY, EXPRESS OR IMPLIED, IS MADE CONCERNING THE GOODS DESCRIBED OR THE INFORMATION PROVIDED HEREIN. The information provided herein relates only to the specific product designated and may not be applicable when such product is used in combination with other materials or in any process. The user should thoroughly test any application before commercialization. Nothing contained herein should be construed as an inducement to infringe any patent, and the user is advised to take appropriate steps to be sure that any proposed use of the product will not result in patent infringement.