Acrylic (PMMA) has the best optics of the common resins, about 92% light transmission, and it weathers very well outdoors. It is stiff and scratch resistant but notch-sensitive, so it suits lenses, light guides, displays, signs and covers where toughness is not the top need.
Typical Acrylic (PMMA) properties
| Property | Typical value | US units | Test method |
|---|---|---|---|
| Density | 1.18–1.19 g/cm³ | ~0.043 lb/in³ | ASTM D792 / ISO 1183 |
| Tensile strength | 60–75 MPa | 8,700–10,900 psi | ASTM D638 / ISO 527 |
| Flexural modulus | 2.9–3.3 GPa | 421,000–479,000 psi | ASTM D790 / ISO 178 |
| Notched Izod impact | 15–25 J/m | 0.3–0.5 ft·lb/in | ASTM D256 |
| Heat deflection, 1.8 MPa (264 psi) | 85–100°C | 185–212°F | ASTM D648 / ISO 75 |
| Water absorption, 24 h | 0.20–0.40% | ASTM D570 / ISO 62 | |
| Mold shrinkage | 0.2–0.7% | 0.002–0.007 in/in | ASTM D955 / ISO 294-4 |
Typical ranges for standard grades, dry as molded, from published data sheets. Your grade’s own data sheet and the lot COA are what count. Notched Izod uses 3.2 mm (1/8 in) bars.
Processing and drying
| Processing | Typical |
|---|---|
| Melt temperature | 340–520°F / 171–271°C |
| Mold temperature | 100–205°F / 38–96°C |
| Drying | 158–208°F / 70–98°C, 2–4 h |
| Target moisture | <0.02% strict / 0.05–0.1% non-critical |
| Max barrel residence | Not published |
| General | Typical |
|---|---|
| Clarity | Clear; best optics |
| Chemical resistance | Fair: solvents attack it; weathers well |
Starting points only. See the full processing temperature chart and drying guide for every resin.
What changes these numbers
- Low impact. Notched Izod is only about 15–25 J/m. Impact-modified grades help, at some cost to clarity and stiffness.
- Heat vs. flow. Heat-resistant grades are stiffer to fill. High-flow grades fill thin, long parts but deflect at lower temperatures.
- Grows with humidity. Allow 0.1–0.3% for growth in service, on top of mold shrinkage.
- Solvents. Alcohols and many solvents craze stressed acrylic.
Common Acrylic (PMMA) grades
- General-purpose grades
- High-flow grades
- Heat-resistant grades
- Impact-modified grades
- UV-blocking and UV-transmitting grades
- Light-diffusing grades
Common questions
How clear is acrylic?
About 92% light transmission, the highest of the common molding resins and slightly better than polycarbonate.
Acrylic or polycarbonate?
Acrylic for clarity, scratch resistance and outdoor life. Polycarbonate for impact. See PC vs. acrylic.
Does acrylic need drying?
Yes, for clear parts. Dry at about 70–98°C (158–208°F) for 2–4 hours. A common rule is 10–15°C below the grade’s Vicat softening point.
Need Acrylic (PMMA), or something close?
A polymer chemist reviews every request, then matches your grade or finds a qualified equivalent and prices it.
What to send for an accurate quote
- The grade name, from any supplier, or a data sheet
- Color (natural, black or a custom match)
- Fill type and percentage, if any
- Melt flow, if you know it
- Quantity for this order and what you use in a year
- Ship-to city and state or province