ASTM D4802 Specs

The American Society for Testing and Materials (ASTM) specifications for what is commonly known as trademarked Plexiglas govern a range of standards that must be met before it can be ASTM certified. This Plexiglas is extremely versatile, being used for everything from hockey rink barriers to sneeze guards at restaurant buffets to artifact casements. There are 15 standards ASTM requires, chief among them is that acrylics are constructed from at least 80 percent polymerized monomers of methyl methacrylate, a clear colorless liquid. Plexiglas must meet ASTM standards for refraction, specific gravity, transparency, haze, water absorption, shrinkage, thermal stability, temperature deflection, tensile strength, impact strength, clarity, abrasion resistance, coating adhesion and chemical resistance.

Transparency and Clarity

• Without the addition of coloring, Plexiglas has a 92 percent total white light transmittance, which exceeds the nominal ATSM standards. In other words, it is suitable for optical uses such as in glasses and is refined for such uses.

Impact Strength

• Plexiglas exceeds ATSM standards for its impact resistance. At thicknesses of 1/8 to 1/4 inch, its impact resistance is 6 to 17 times greater, respectively, than ordinary glass twice as thick. Because of its light weight compared to glass, when impact resistance is surpassed it breaks into large, dull-edged pieces at a much lower velocity than untempered or untreated glass. Acrylic sheeting is less than half as heavy as glass, 43 percent the weight of aluminum and 70 percent lighter than magnesium. There are 10 standard test methods established by ATSM for Plexiglas to meet or exceed impact resistance standards.

Shrinkage and Thermal Stability

• Much like glass, acrylic plastic is relatively free from shrinking and deterioration over long periods. Although it has a much lower boiling or melting point than glass, Plexiglas is able to remain stable for sustained periods at 180 degrees, surpassing ATSM standards.

Abrasion Resistance

• Of all the ATSM standards, abrasion resistance standards are the most hazy. For practical purposes of everyday use, however, the main concern is the maintenance of optical clarity. ATSM relies on more than four testing methodologies depending on the acrylic use, but concedes many of the procedures are unreliable due to variables introduced by the types of testing equipment. See ATSM specification D1044 for detailed information on the particular uses and abrasion standards.

Detailed ATSM Specifications References

• To review testing methodology and standards in each of the 15 categories, refer to the appropriate ATSM section of relevance to your particular use: D256 for impact resistance, D542 for transparency, D570 for water absorption, D638 for tensile strength, D648 for temperature absorption and deflection, D792 for specific gravity, D1003 for haze and transparency, D1044 for resistance to abrasion, 1308 for the effects of household chemicals, D2565 for outdoor uses, D3002 for coatings, D3359 for adhesion and D3892 for packaging.