Related Information

Before measuring PBT samples with the VM-E01, you may also want to know:

Common Questions About PBT and Plastics

WKT-A9 Karl Fischer Trace Moisture Analyzer Coulometric

Reference Value Determination

The PBT 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.

Recommended Settings for Plastics Industry Samples

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.

Selecting the Drying Temperature

Figure 1: Same Sample Heated at Different Temperatures

(Click image to enlarge)

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.

Plastic Sample Handling

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.

Operating Steps for PBT (Polybutylene Terephthalate) Samples

Place the VM-E01 in a suitable spot, warm up 30 min, level it (bubble centered), and perform weighing and temperature calibration. Then measure PBT 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.).

Tare Sample Pan

1. Place the empty pan on the center holder, preheat 1 min at 120°C standby, press tare to zero.

Add Sample

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

One-Touch Start

3. Press start; the PBT moisture result appears within minutes.

Test Data

VM-E01 Halogen Moisture Analyzer（0.1mg/0.0001g）

VM-E01 Settings Reference

• Heating mode: Standard

• Heating Temperature: 120°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 Information

• Sample Description: PBT, light gray, 20% glass additive, low hygroscopicity, dimensionally stable.

• Typical Maximum Allowable Moisture Content [%]: 0.04

• Hygroscopicity (23°C/50% rH) [%]: 0.2

Moisture Chart for PBT Samples Before and After Drying

Chart Notes

Moisture Data for PBT Samples Before and After Drying

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.

Dr. Wei's Classroom

PBT (polybutylene terephthalate), a polyester from terephthalic acid and 1,4-butanediol, is an important thermoplastic polyester and one of the five major engineering plastics. Milky-white, translucent to opaque, semi-crystalline, highly heat-resistant; not resistant to strong acids/alkalis but resists organic solvents; flammable, decomposes at high temperature. Widely used in automotive, machinery, precision instrument parts, electronics, and textiles.

Most PBT is used as compounds; additives and blending yield good heat resistance, flame retardancy, insulation, and processability for appliance, automotive, aircraft, telecom, and transport industries. Glass-fiber-modified PBT suits dimensionally stable electronic parts for long-term high-temperature service. Its high breakdown voltage suits high-voltage parts; its excellent melt flow suits complex injection-molded electrical parts — IC sockets, PCBs, keyboards, switches, fuses, thermal switches, protectors, plus automotive bumpers, carburetors, spark plugs, fuel-system and ignition parts, and telecom modules, terminal blocks, and power tools.