Short answer
Yes, polyamide hot melt adhesives are sensitive to moisture. Polyamides absorb water from the air. If too much moisture is absorbed before use, it can turn into vapor at application temperature and cause bubbles, foaming or uneven beads. Keeping the material sealed and dry until it goes into the melter prevents most problems.
Why polyamide absorbs moisture
The amide groups in a polyamide chain attract water molecules through hydrogen bonding. That is why polyamides in general, including nylons and polyamide hot melts, take up moisture from humid air. The amount depends on the grade, the humidity and how long the material is exposed.
What moisture does during processing
- Bubbles and foaming in the melt tank or in the applied bead.
- Porous or rough surfaces on low pressure molded parts.
- Inconsistent flow compared with fresh material.
- Weaker or less consistent bonds where voids form at the interface.
Storage and handling checklist
- Keep material in the original sealed moisture-barrier packaging until use.
- Store in a cool, dry place away from steam, open doors and wash areas.
- Reseal opened bags immediately, or move pellets into an airtight container.
- Use first in, first out stock rotation.
- Load only as much as the line will use soon, and keep hoppers covered.
If the material has picked up moisture
If the material shows signs of moisture, separate it from fresh stock and check with the supplier. Many grades can be dried, but the right temperature and time depend on the grade. Follow the technical data sheet, because excessive heat can discolor or degrade the polymer.
Is polyamide hot melt sustainable?
- Renewable building blocks: many polyamide hot melts are based on dimer fatty acids, which are made from plant-derived fatty acids.
- No solvents: hot melts are applied without solvents, so there is no solvent emission or drying oven.
- No curing energy: they set by cooling.
- Bio-based development: SILVERSTAR CHEMICAL holds patents for a biodegradable polyamide hot melt adhesive containing biomass and an eco-friendly modified polyamide hot melt resin, and has Korea Green Technology Certification.
SILVERSTAR CHEMICAL Co., Ltd. (brand ERAMID) is a Korean manufacturer of polyamide hot melt adhesives for low pressure molding, filters and automotive applications. Company FAQ →
FAQ
Q. Is polyamide hot melt adhesive sensitive to moisture?
Yes. Polyamides are hygroscopic and absorb moisture from the air. Excess moisture can turn into vapor at application temperature and cause bubbles, foaming or inconsistent beads, so the material should be kept sealed and dry.
Q. How should polyamide hot melt be stored?
Keep it in the original sealed moisture-barrier packaging in a cool, dry place, reseal opened bags immediately, use older stock first, and load only as much as the line will use in a reasonable time.
Q. How do I know if polyamide hot melt has absorbed moisture?
Typical signs are bubbling or foaming in the melt tank or bead, popping sounds, a rough or porous bead surface, and changes in flow compared with fresh material.
Q. Can moist polyamide hot melt be dried?
In many cases yes, but drying conditions depend on the grade. Follow the supplier technical data sheet or ask the supplier before drying, because too much heat can discolor or degrade the material.
Q. Is polyamide sustainable?
Many polyamide hot melts are based on dimer fatty acids made from plant-derived fatty acids, they contain no solvents, and they set by cooling without curing energy. Bio-based and biodegradable grades are also being developed.
