The chemical and physical properties of PA6 (Nylon 6) closely resemble those of PA66 (Nylon 66), though PA6 features a lower melting point and broader processing temperature range. While PA6 demonstrates better impact resistance and solubility compared to PA66, it also exhibits significantly higher moisture absorption characteristics. This hygroscopic nature critically influences product quality attributes, making moisture management essential in PA6 product design.
To enhance mechanical properties, PA6 is commonly modified with various additives. Glass fiber represents the most frequent reinforcement, while synthetic rubbers like EPDM and SBR are incorporated to improve impact resistance. Unmodified PA6 typically shows shrinkage between 1% and 1.5%. Glass fiber addition reduces this to approximately 0.3% (slightly higher perpendicular to flow direction). Both molding shrinkage and long-term dimensional stability are significantly influenced by material crystallinity and moisture absorption.
PA6 Processing Guidelines:
Drying: Essential due to high hygroscopicity. Recommended: 16 hours at 80°C+ for humidity >0.2%; 8+ hours at 105°C under vacuum if exposed >8 hours
Melt Temperature: 230-280°C (250-280°C for reinforced grades)
Mold Temperature: 80-90°C for optimal crystallinity and mechanical properties
Injection Pressure: 750-1250 bar
Gate Design: Minimum diameter = 0.5 × part thickness
PA66 Characteristics:
PA66 maintains strength and stiffness at elevated temperatures but remains hygroscopic post-molding. Its lower viscosity provides better flow characteristics than PA6 (though less than PA6’s inherent flow). Shrinkage ranges 1.5-2.0% (0.2-1.0% with glass fiber), with significant directional variation. While resistant to most solvents, PA66 shows limited resistance to acids and chlorinated compounds.
PA66 Processing Guidelines:
Drying: 12 hours vacuum drying at 105°C if humidity >0.2%
Melt Temperature: 260-290°C (275-280°C for glass-filled)
Mold Temperature: 80°C recommended
Injection Pressure: 750-1250 bar
