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30) Polyamide 6 (nylon 6):
Nylon 6 is made from one component namely Caprolactum, which has six carbon
atom. Nylon 6's crystal structure contains parallel chains with hydrogen bonds
between each chain, forming a more open structure with less internal hydrogen
bonding.
Density 1.12 - 1.14 g/cm 3
Glass transition temperature 47 °C
Max / Min continuous Service temperature 80 - 120 °C /-40 to -20 °C
Melting temperature 210-220°C
Drying before processing is highly recommended at temperatures range of 80 to
110°C till moisture content be less than 0.2%. PA6 is thermally stable, but on
decomposition forms mainly carbon monoxide, ammonia and caprolactam.
Injection Moulding: screw L/D ratio of 18-22 is recommended. Melt temperature:
240-270°C. Mould temperature: 55-80°C
Extrusion: Only highly viscous grades can be processed by extrusion. A three-
section screw with a L/D ratio of 20-30 is recommended. The processing
temperature: 240 - 270°C
Nylon 6 is a tough, abrasion-resistant material. PA 6 exhibits compared to PA 6.6
exhibit better processablity, better hydrolytic stability, slightly lower cost, excellent
surface appearance, creep resistance and better long term heat ageing, slightly
lower HDT and similar stiffness at temperature below 180°C. It also can be moulded
with less mould shrinkage because it is slightly less crystalline.
Adversely, nylon 6 has a lower modulus and absorbs moisture more rapidly than
nylon 6/6. Moisture acts as a plasticizer, reducing tensile strength and stiffness and
increasing elongation but it increases its toughness, but this does affect
dimensional tolerances.
Strengths: Self lubricating, High strength and stiffness at high temperature, Good
impact strength, even at low temperature, very good flow for easy processing, Good
abrasion and wear resistance, excellent fuel and oil resistance, good fatigue
resistance, Good electrical insulating properties
Limitations: High water absorption degrades electrical and mechanical properties,
requires UV stabilization, high mould shrinkage, low dimensional stability, attacked
by strong acids, bases and oxidizing agents, Pre-drying before processing is
needed,High notch sensitivity
Applications: primarily used in the textile industry for making clothing, ropes,
threads, nets and garments, bristles for toothbrushes, surgical sutures, strings for
classical musical instruments. Industrial gear and bearings, automotive industry for
under-the-hood parts, power tools housings, films for food packaging (mono or
multi layer), cable ties, zips, nuts and bolts, pump housings, laboratory equipment.
31) Polyamide 6.6 (Nylon 6.6):
Nylon 66 is made from two component s namely adipic acid and hexamethylene
diamine each monomer has six carbon atoms. Nylon 6.6 has stronger, shorter
hydrogen bonds giving it a tighter, denser polymer structure than nylon 6, making it
the stronger and more resistant to heat of the two Nylons.

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