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PPE

Éter de Polifenileno

PPE·Polyolefins·Amorphous

PPE (Polyphenylene Ether, also called PPO — Polyphenylene Oxide) is an engineering plastic with a curious feature: in pure form it's practically impossible to injection mold. Its Tg of 211°C and melting point of 268°C push it right against the degradation limit on any conventional machine. That's why nearly 100% of commercial PPE is sold as a blend with polystyrene (PPE+HIPS) —the famous Noryl launched by GE Plastics in 1966 (now SABIC Specialties). Asahi Kasei sells theirs as Xyron.

The modified blend keeps the best of PPE: HDT between 100-175°C (depending on grade and reinforcement), the lowest moisture absorption among engineering plastics (~0.1%), excellent dimensional stability, notably low density (1.06-1.10 g/cm³), and inherent flame retardancy —UL94 V-0/V-1 ratings achievable with non-halogenated additives, a massive advantage over PC or PA which use brominated additives with SVHC labels.

Flagship applications: water meters and pump housings (doesn't swell in water), electrical connectors and solar PV junction boxes (high dielectric strength), automotive under-hood components, white appliance housings, HVAC. Specialty blends: Noryl GTX (PPE+PA) for extra temperature, PPE+PP for low-cost parts. Are you running Noryl or any PPE blend? Share your experience in the comments.

The ranges shown in these data tables were compiled by the MVPS team from various parameter sheets and literature, integrating the lower and upper limits for each material type.

This information must be carefully reviewed when developing injection molding processes. Final ranges and processing tolerances are the responsibility of the engineer in charge.

These ranges are not recommended for developing specific process tolerances. MVPS always recommends requesting and consulting the supplier's data sheet.

General Properties

Chemical StructureAmorphous
Specific Gravity (Density)1.1:1
L/D Ratio18 – 24
Compression Ratio2 – 3
Tonnage Factor3.09 – 6.18kN/cm²
Thermal Diffusivity0.1359mm²/s
Max Shear Rate40,0001/s
Shrinkage0.5 – 0.8%
Regrind⚠ Caution
Heat Deflection (HDT) @ 1.82 MPa91°C
Glass Transition (Tg) @ 10°C/min216°C
Vicat Softening @ 50N90°C

Drying

Drying Temperature60 – 79°C
Drying Time2 – 4h
Recommended Moisture0.03%
Recommended Dryer TypeAir
Dew Point-40°C

Temperatures

Melt260 – 310°C
Nozzle260 – 310°C
Front254 – 304°C
Middle249 – 299°C
Rear238 – 288°C
Demolding77 – 116°C
Mold (Cooling)60 – 104°C
Feed Throat35 – 79°C

Processing

Back Pressure3.4 – 6.9bar
Screw Speed40 – 80RPM
Injection SpeedMedium
Barrel Occupancy25 – 75%
Injection Pressure700 – 1,600Pbar
Holding Pressure175 – 1,280Pbar
Cushion6.4 – 12.7mm

Mold

Runner Diameter3.05 – 6.1mm
Gate Diameter0.76 – 1.52mm
Gate Area0.46 – 1.82mm²
Wall Thickness1.02 – 4.06mm

Venting

Depth (Vent Depth)0.0203 – 0.0508mm
Land (Vent Land)0.508 – 1.02mm
Width (Vent / Clearance)3.05 – 10.2mm
Relief (Relief Channel)0.2032 – 0.4064mm

Frequently asked questions

**PPE** (poly(p-phenylene oxide), where "ether" and "oxide" are used interchangeably for this molecule) has a rigid aromatic structure with Tg ~211°C. That gives it fantastic properties but **makes it nearly impossible to injection mold pure**: to flow it needs ~330°C+, and at that temperature it starts degrading fast. **Solution**: blend it with **polystyrene (HIPS or GPPS)** —they're molecularly miscible (a rare case between polymers). The blend reduces effective Tg to 130-180°C, keeps most of PPE's properties, and processes like a normal plastic.
**Yes, in practice**: - **PPO/PPE**: the pure base polymer (rarely sold this way). - **mPPE** (modified PPE) or **PPE+PS blend**: generic industrial name. - **Noryl**: SABIC's trade name (originally GE Plastics, 1966), dominates the world market. - **Xyron**: Asahi Kasei equivalent. - **LATI ULight, RTP** and others: third-party compounds with the same base blend. When someone says "Noryl" they technically mean modified PPE+PS; day-to-day they're used as synonyms.
**Five** that no other engineering plastic combines: - **(1)** Moisture absorption **<0.1%** —the lowest of all engineering plastics (vs 2-3% for PA6). - **(2)** **Exceptional dimensional stability** under humidity and temperature. - **(3)** **Inherent flame retardancy** without needing halogens (V-0 achievable). - **(4)** **Good resistance to aqueous acids and bases**. - **(5)** **Low density** (1.06-1.10 g/cm³, similar to HDPE) translating to lightweight parts. The low-moisture + stability combo makes it **the #1 material for water-contact components** (meters, valves, pumps).
For typical unreinforced grades: - **Drying**: 80-110°C × 2-4 h in desiccant dryer. **No more than 8 h** —excessive drying causes property loss and color shift. - **Melt**: 260-310°C (varies by blend; low PPE+PS runs 250-280, PPE+PA Noryl GTX reaches 290-320). - **Mold**: 80-110°C (hot — improves flow, knitline strength, and finish). - **Residence**: max ~5-8 min. Glass-reinforced grades (30% GF) run +10-20°C higher in melt and mold.
Three combined reasons: **(1)** Moisture absorption <0.1% —the part **doesn't change dimensions** with the dry-wet cycle of hot and cold water (unlike PA or POM which swell), **(2) excellent hydrolysis resistance** —PPE doesn't break down in hot water for years (>25 year service life in water meters), **(3) NSF/ANSI 61 certification** available in specific grades for potable water. Brands like **Sensus, Itron** (meters) and **Watts** (valves) use Noryl or equivalent extensively.
**PPE blend wins on**: much lower moisture absorption, dimensional stability in humidity, non-halogen flame retardancy, lower density, cost (~30% lower). **PC wins on**: transparency (PC is clear, PPE blend is opaque), unnotched impact strength (PC's notched Izod >800 J/m), optical clarity, unreinforced use temperature (PC HDT ~130°C vs Noryl ~120°C standard). **Rule of thumb**: for opaque parts in water contact or needing halogen-free FR → **PPE/Noryl**. For transparent or max-impact parts → **PC**.
Shrinkage **0.5-0.8%** for unreinforced grades, **0.2-0.5%** with 30% GF. It's notably **low and predictable** for an amorphous blend, comparable to PC and better than PA. Flow-orientation directionality in thin parts is less than in other amorphous plastics. That's why it's ideal for dimensionally critical parts like **gears, fine-pitch electrical connectors, hermetic-seal housings**.
**Noryl GTX** is a special **PPE+PA** blend (polyamide, typically PA6 or PA66). It combines PPE's low absorption and dimensional stability with nylon's **chemical resistance to hydrocarbons** —pure PPE is only attacked by gasoline, MEK, toluene. **Iconic application**: **online-painted automotive exterior panels** (fenders, side panels) —withstands the paint oven cycle (~190°C) without deformation, holds paint-class A tolerances, and tolerates fuel spills. That's why many GTX parts are found on European premium cars.
**Yes, easily**. It's weldable by **ultrasonic** (excellent, one of its advantages), **vibration**, and **laser**. For adhesives: epoxies and cyanoacrylates work well. **Solvent welding** with methylene chloride or chloroform is viable but less common. **Overmolding** with TPE for seals is standard in water meters. Welded joints retain >90% of base material strength.
**Degradation from over-drying or excess temperature**. Symptoms: part with **color shift** (yellower or more opaque), impact loss, phenolic odor during molding. **Causes**: drying >8 h or >120°C, sustained melt >320°C, residence >10 min. **Cure**: respect drying time, conservative temperature profile with lower rear zones (typical: 280/295/305°C), **purge with HDPE or GPPS** when changing material or at shift end (don't use halogen-containing polymers in same machine without thorough purge).

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