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D4802-16 – Standard Test Method Technical Guide
ASTM D4802-16 (Reapproved 2024) provides the standard specification for monolithic poly(methyl methacrylate) (PMMA) acrylic plastic sheets used in general-purpose applications. It consolidates discontinued specifications, including Fed. Spec. L-P-391D, D702, and D1547, into a single comprehensive document. The material must be composed of polymerized acrylic monomers comprising at least 80% methyl methacrylate.
📐 Sheet Types, Classifications, and Dimensional Tolerances
The specification defines two primary classifications based on the manufacturing process. Types A-1 and A-2 are produced directly from monomer via cell casting, offering the highest levels of optical clarity and purity. Types B-1 and B-2 are typically continuous cast or extruded and may incorporate carefully controlled reground or recycled material. Dimensional tolerances are strictly defined and vary by manufacturing type.
| 🟦 Property / Dimension | 📐 Type A (Cell Cast) | 📏 Type B (Extruded / Continuously Cast) |
|---|---|---|
| Thickness (1.5 – 3.0 mm) | ± 0.3 mm | ± 0.5 mm |
| Thickness (3.1 – 6.0 mm) | ± 0.4 mm | ± 0.6 mm |
| Thickness (6.1 – 10.0 mm) | ± 0.5 mm | ± 0.8 mm |
| Recycled / Reground Material | Not Permitted (Produced from monomer) | Permitted (with strict quality control) |
⚙️ Standard Test Methods and Measured Properties
Conformance to D4802 requires conditioning in accordance with Practice D618. The standard references specific ASTM test methods for evaluating mechanical, thermal, and optical performance. The table below summarizes the key metrics and their typical expected values for general-purpose sheets.
| ⚡ Test Method | 📊 Evaluated Property | 🎯 Typical Requirement |
|---|---|---|
| D638 | Tensile Strength | 8,000 – 11,000 psi (55 – 76 MPa) |
| D256 | Izod Impact (Notched) | 0.3 – 0.5 ft·lb/in (16 – 27 J/m) |
| D1003 | Luminous Transmittance / Haze | > 90% / < 1.0% |
| D648 | Deflection Temperature (264 psi) | 170 – 205 °F (77 – 96 °C) |
| D792 | Specific Gravity (Density) | 1.19 |
| D570 | Water Absorption (24 hr) | 0.3% |
| D542 | Refractive Index | 1.49 |
| D1044 | Taber Abrasion Resistance | Per Agreement / Type Dependent |
📊 Material Compliance and Application Guidelines
The polymer matrix must contain a minimum of 80% methyl methacrylate. For applications requiring extreme clarity, lack of optical distortion, and an absence of foreign particulate matter, the standard mandates careful selection of material types. The standard is explicitly intended for general-purpose applications; specialty applications must consult the appropriate use standards.
⚠️ Critical Restriction on Recycled Content: As detailed in Scope (Section 1.4), the use of recycled or reground material is not possible for Type A-1 and A-2 materials since the sheet is produced directly from monomer. For Types B-1 and B-2, reground material is permissible only if strict process control is implemented to avoid adverse effects on optical clarity and contamination.
Users should also note that while this standard addresses the same general subject matter as ISO 7823-1, the technical content and specific requirements differ. D4802 is approved for use by agencies of the U.S. Department of Defense.
🔬 Safety Guidance: Per Section 1.3, the safety caveats apply specifically to the test methods in Section 8 of the standard. It is the responsibility of the user to establish appropriate safety, health, and environmental practices and to determine the applicability of regulatory limitations prior to use.
❓ Frequently Asked Questions
🔍 What types of acrylic sheets are covered under ASTM D4802-16?
The standard covers monolithic methacrylate sheets, defining four specific types: A-1 and A-2 (cell cast directly from monomer) and B-1 and B-2 (extruded or continuous cast sheets that may incorporate recycled content).
💡 Can recycled or reground material be used in sheets conforming to this standard?
Yes, but only for Types B-1 and B-2. The standard explicitly prohibits the use of recycled or reground materials for Types A-1 and A-2 because these sheets are produced directly from monomer. When used in B-Type sheets, careful quality control is required to protect optical properties.
⚡ Which test method is used to evaluate clarity and light transmission?
The optical quality of the sheet is evaluated using ASTM D1003, the Test Method for Haze and