Effects of moisture on Arnite®

Arnite absorbs low amounts of moisture making it dimensionally more stable than polyamides. Arnite grades are more suitable for applications where dimensional tolerances and both long-term physical and electrical property retention are critical.

The very low water uptake of polyesters allows them to retain their stiffness under humid conditions. Furthermore, electrical properties are maintained in humid environments.

PBT compounds absorb less than 0.5% water over a period of several thousand hours in ambient conditions.

Moisture absorption vs. Time

Arnite absorbs very little moisture over time.

Material handling

Although polyesters absorb very little water, the presence of water may cause hydrolysis at high temperatures, in particular during processing. As PET is processed at higher temperatures than PBT, hydrolysis occurs more readily for PET than for PBT.

For best results, the maximum allowable moisture contents for molding should be 0.03% for Arnite T (PBT) and 0.02% for Arnite A (PET), which are typical delivery specifications on moisture content. At these moisture levels, no significant deterioration of properties will occur during processing.

Arnite properties

Arnite home
Mechanical properties
Effects of moisture
Electrical properties
Flammability
Chemical resistance
Thermal properties
Tribology
Processing

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The air-flow mass meter used in cars holds its dimensions through the life of the car. The part is made in Arnite.

Arnite is used to make the air-flow mass meter to ensure dimensional stability over the life of the component.

Arnite® is a registered tradename of Royal DSM.