Nylon 6,10 used for bristles has lower water absorption than nylon 6,6. Nylon 6,10 belongs to which polymer family?

Introduction / Context:
Nylons are designated by numbers indicating the carbon count of monomer units. Performance differences, such as water absorption and stiffness, depend on chain structure and amide group density. Nylon 6,10 is well known for bristles because it absorbs less water than nylon 6,6, maintaining stiffness in wet service (e.g., toothbrushes and industrial brushes).

Given Data / Assumptions:

• Nylon 6,10 forms from hexamethylene diamine (6 carbons) and sebacic (decanedioic) acid (10 carbons).
• Amide linkage density affects moisture uptake.

Concept / Approach:
All nylons are polyamides, created by condensation of diamines and diacids (or by ring-opening of lactams). Nylon 6,10 is therefore a polyamide. Its lower amide concentration per unit length compared to nylon 6,6 contributes to lower water absorption, stabilising stiffness and dimensional stability for bristle applications.

Step-by-Step Solution:

Verification / Alternative check:
Materials datasheets list nylon 6,10 properties, explicitly classifying it as a polyamide with reduced moisture uptake compared to nylon 6,6.

Why Other Options Are Wrong:

• Polyester/polyisoprene/polystyrene/polyacetal: different backbones and properties.

Common Pitfalls:
Misreading “6,10” as a copolymer with different families; it is within the nylon (polyamide) family.

Final Answer:
Polyamide