Solution for Measuring PEI Moisture Content with a Halogen Moisture Analyzer
How do you measure moisture content in PEI (polyetherimide) with a halogen moisture analyzer? This is a question of great concern to PEI suppliers and their customers alike. This article provides a moisture determination solution for a typical PEI sample. You will learn how to measure the moisture content of PEI samples with a halogen moisture analyzer, as well as the operating procedure and best practices for the VM-E01 rapid halogen moisture analyzer.
Plastic part suppliers and their customers care about quality and fast production. Proper moisture in raw material ensures trouble-free compounding and molding, smooth surfaces, and ideal mechanical properties. The VicoMeter VM-E01 rapid halogen moisture analyzer is ideal for simple, accurate moisture measurement on the production floor.
Measuring moisture in plastics with a halogen moisture analyzer is a recognized ASTM method: D6980-12, "Standard Test Method for Determination of Moisture in Plastics by Loss in Weight".
A VicoMeter solution for typical PEI (polyetherimide) samples: measuring their moisture with the VM-E01 rapid halogen moisture analyzer, including operating procedures.
Before measuring PEI samples with the VM-E01, you may also want to know:
Can a halogen moisture analyzer replace the oven method? Yes — seeCan Rapid Halogen Moisture Analyzers Replace the Oven Method?as discussed in that article.
How to choose a fast, accurate model? See"Rapid Halogen Moisture Analyzer Selection Guide"as discussed in that article.
Where to learn more about halogen moisture analyzers? See"Basic Knowledge of Rapid Halogen Moisture Analyzers"、"Explanation of Halogen Moisture Analyzer Technical Specifications"、《Halogen Moisture Analyzer》and other articles.
Other questions about measuring plastics? See the FAQ in"FAQ: Measuring Plastics with a Halogen Moisture Analyzer"as discussed in that article.
The PEI reference moisture value was determined with the VicoMeter WKT-A9 Karl Fischer moisture analyzer and WKT-V2 Karl Fischer oven; released moisture is carried by dry nitrogen into the electrolytic cell.
If you have no reference method for plastics samples on the VM-E01, VicoMeter recommends these settings from experimental experience:
Heating mode: Standard
Shutoff mode: Automatic (1 mg/140 s)
Sample size: 30 g
Resolution: High (0.1 mg/0.0001 g)
Warm-up: standby, 100°C; at standby temperature, preheat the empty pan for 1 minute, then tare.
Choose a drying temperature matching the Karl Fischer reference value. Melting or marked color change means the temperature is too high. Some samples inevitably discolor when heated (polyamide unavoidably turns brown).
Figure 1 compares samples after two heating runs. Left: correct temperature — no melting or discoloration. Right: the sample browned, so the temperature was too high.
Measure samples promptly. Otherwise, fill the container completely (use a smaller one if needed) and seal it to minimize air and prevent moisture uptake during storage.
Place the VM-E01 in a suitable spot, warm up 30 min, level it (bubble centered), and perform weighing and temperature calibration. Then measure PEI samples (installation, environment, warm-up, calibration: seePreparation Before Formal Measurement with a Halogen Moisture Analyzeras discussed in that article; click the link to learn more.).

1. Place the empty pan on the center holder, preheat 1 min at 160°C standby, press tare to zero.

2. Quickly spread about 30 g of PEI sample evenly on the pan; wait for a stable reading.

3. Press start; the PEI moisture result appears within minutes.
Heating mode: Standard
Heating temperature: 160°C
Shutoff mode: Automatic (1 mg/140 s)
Sample size: 30 g
Resolution: High (0.1 mg/0.0001 g)
Warm-up: standby, 100°C; at standby temperature, preheat the empty pan for 1 minute, then tare.
Sample Description: PEI, amber, ECO compliant, for food contact.
Typical Maximum Allowable Moisture Content [%]: 0.02
Hygroscopicity (23°C/50% rH) [%]: 0.7

Chart Notes
Recommendation: measure 6 PEI samples with different moisture contents (dry vs. moist).
Green line:Moisture content (average) measured with the WKT-A9 Karl Fischer moisture analyzer and WKT-V2 Karl Fischer oven.
Blue line:Moisture content (average) measured with the VM-E01 rapid halogen moisture analyzer.
Red line:Typical maximum allowable moisture for pellet processing; refer to the supplier's material-specific values.
| Sample Information | PEI Moisture Content Before Drying | PEI Moisture Content After Drying | ||
| Test Method | Halogen Moisture Analyzer | Karl Fischer Moisture Analyzers | Halogen Moisture Analyzer | Karl Fischer Moisture Analyzers |
| Moisture %MC | 0.133 | 0.125 | 0.024 | 0.023 |
| Std Dev Δ | 0.005 | 0.002 | 0.001 | 0.001 |
| Test Time [min] | 15 | 30 | 7 | 30 |
Sample-Specific Test Notes
Maximum allowable moisture for pellet processing must always follow supplier specifications. Values here are typical only and may not suit your material or process.
These drying parameters were obtained on common plastics and do not cover all grades or colors; optimizing them may be needed for best results on a specific material.
Yes. Measuring moisture in plastics with a halogen moisture analyzer is a recognized ASTM method: D6980-12, "Standard Test Method for Determination of Moisture in Plastics by Loss in Weight".
Yes — seeCan Rapid Halogen Moisture Analyzers Replace the Oven Method?).
Yes — reinforced plastics contain glass or other materials that do not affect moisture measurement.
Adjust drying temperature for heat absorption — e.g., black resin about 10°C lower than white.
Take care: loss on drying counts volatilized plasticizer as moisture. Heat at a lower temperature where possible to prevent plasticizer loss.
Not directly. As a rule of thumb, the VM-E01 drying temperature is about 30°C lower than the oven's.
It is a good reference, but should be adapted to the other suppliers' polymer compounds.
Polyetherimide (PEI) is a super engineering plastic made from amorphous PEI, offering top heat resistance and dimensional stability plus chemical resistance, flame retardancy, electrical properties, high strength, and rigidity. PEI resin is widely used in high-temperature terminals, IC sockets, lighting equipment, FPCBs (flexible PCBs), liquid handling equipment, aircraft interiors, medical devices, and household appliances.
Amber (transparent dark yellow) PEI sheet — PEI, i.e. polyetherimide — is an amorphous plastic, a high-performance amorphous polymer extruded at high temperature from amorphous PEI. Common PEI sheet uses GE's Ultem resin; GE began PEI R&D in 1972.
(1) High strength, rigidity, wear resistance, and dimensional stability at high temperatures. (2) An amber transparent solid, inherently flame retardant with low smoke, oxygen index 47%, UL94 V-0. (3) Density 1.28–1.42 g/cm3, glass transition 215°C, heat deflection 198–208°C; long-term use at 160–180°C, intermittent max 200°C. (4) Excellent mechanical strength, insulation, radiation, high/low temperature and fatigue resistance, and processability; reinforcement with glass fiber, carbon fiber, or other fillers.
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