01 What Is Rexolite?
Rexolite is a cross-linked polystyrene plastic. Unlike conventional thermoplastics that can be re-melted and reshaped, Rexolite is a thermoset-like engineering polymer that forms permanent covalent cross-links during curing — giving it dimensional stability and electrical consistency that straight polystyrene cannot match.
Its defining characteristic is an extraordinarily low and stable dielectric constant across frequencies ranging from audio all the way through microwave and into the millimetre-wave spectrum. For engineers working in radar, antenna design, or high-frequency circuit fabrication, this consistency is critical to system performance.
Rexolite 1422 maintains a dielectric constant of 2.53 ± 0.02 from audio frequencies up to 500 GHz — very few engineering plastics can claim such consistency across such a broad spectrum.
02 Chemistry & Structure
Rexolite is produced by co-polymerising styrene monomer with divinylbenzene (DVB). The DVB acts as a cross-linking agent, forming a three-dimensional polymer network. Unlike linear polystyrene chains that can slide past one another under heat or stress, the cross-linked network in Rexolite is locked in place once cured.
The result is a material that behaves like a thermoset — it will not soften and flow at elevated temperatures. This architecture is directly responsible for Rexolite's outstanding dimensional stability, low moisture absorption, and consistent dielectric properties.
03 Key Technical Properties
| Property | Value / Range | Test Standard |
|---|---|---|
| Dielectric Constant (1 MHz – 500 GHz) | 2.53 ± 0.02 | ASTM D2520 |
| Dissipation Factor (10 GHz) | 0.00066 | ASTM D2520 |
| Dielectric Strength | 1,000 V/mil | ASTM D149 |
| Water Absorption (24 hr) | < 0.08% | ASTM D570 |
| Tensile Strength | 6,000 psi (41.4 MPa) | ASTM D638 |
| Flexural Modulus | 400,000 psi (2.76 GPa) | ASTM D790 |
| Continuous Service Temp. | Up to 71°C (160°F) | — |
| Thermal Expansion (CTE) | 68 × 10⁻⁶ /°C | ASTM E831 |
| Density | 1.05 g/cm³ | ASTM D792 |
| Machinability | Excellent — like acrylic | — |
04 Applications & Industries
Radar & Antennas
Radomes, antenna lenses, feed horns, and wave-guide windows where RF transparency is critical.
Laboratory & Metrology
Dielectric calibration standards, microwave test fixtures, coaxial connectors, and precision spacers.
Aerospace & Defence
Missile guidance windows, conformal radomes, and satellite communication components.
Telecommunications
5G millimetre-wave lenses, microstrip circuit substrates, and delay lines.
Optical & Photonic
Optical windows, prism mounts, and components requiring transparency with tight tolerances.
Industrial Sensing
Level sensors, proximity detectors, and process measurement using microwave technology.
05 Machining Rexolite
One of Rexolite's practical advantages is that it machines exceptionally well on standard CNC equipment. It cuts cleanly, holds tight tolerances, and produces a fine surface finish without the burring or smearing common with softer plastics.
Use sharp HSS or carbide tooling with moderate speeds and feeds. Air cooling or light misting is preferred over flood coolant. Because Rexolite stock is cast rather than extruded, residual stress is minimal — machined parts retain dimensional accuracy without significant springback.
06 Rexolite vs. Competing Materials
| Material | Dk (10 GHz) | Df (10 GHz) | Key Advantage | Key Limitation |
|---|---|---|---|---|
| Rexolite 1422 | 2.53 | 0.00066 | Best-in-class stability & machinability | Max service ~71°C |
| PTFE (Teflon) | 2.08 | 0.00020 | Lower Dk; excellent chemical resistance | Difficult to machine to tight tolerance |
| UHMW Polyethylene | 2.30 | 0.00030 | Very low cost; good impact strength | Poor dimensional stability; creeps |
| RT/Duroid 5880 | 2.20 | 0.00090 | PCB-ready laminate form factor | Not a machinable solid; expensive |
| Quartz (fused silica) | 3.78 | 0.00001 | Extremely low loss; high temp | Expensive; hard to machine |
07 Strengths & Limitations
Strengths
- Ultra-stable Dk from DC to 500 GHz
- Extremely low dissipation factor
- Minimal moisture absorption (<0.08%)
- Excellent machinability & dimensional stability
- Good optical transparency
- Wide availability in rod, sheet & tube
- Predictable, consistent batch-to-batch properties
Limitations
- Maximum service temperature ~71°C
- Brittle under impact — not a structural material
- Not suitable for continuous chemical immersion
- Cannot be re-melted or thermoformed
- Higher cost than standard polystyrene
- Not recommended for outdoor UV exposure without coating
08 Sourcing Through Emco
Emco Industrial Plastics stocks Rexolite 1422 in a comprehensive range of rod, sheet, and tube forms. We supply material to OEM quantities and short-run prototype requirements alike, with cutting services available for near-net blanks.
Contact our technical sales team with your dimensions and application details. We'll confirm stock availability and provide a quote.