Mechanical Performance Evaluation for Nylon Material Selection

This study conducts a comparative investigation on the mechanical properties of GSM nylon （MoS₂-filled nylon 6） and modified MC nylon （alkali-catalyzed polymerized nylon 6）, including tensile, compressive, and shear characteristics. The results indicate that both types of nylon exhibit a surface layer with lower strength but higher elongation, while the intermediate layer demonstrates higher strength but lower elongation, primarily due to moisture absorption effects. Modified MC nylon exhibits superior toughness （intermediate layer elongation of 31.6% vs. GSM nylon’s 22.2%） and compressive strength （643–705 MPa vs. GSM nylon’s 468 MPa）. Moisture absorption experiments confirm that nylon experiences a significant drop in strength after water exposure （a 13.7% reduction in tensile strength after 45 minutes of boiling）, and drying cannot fully restore its performance. The shear strength is approximately 0.6 times the tensile strength, with no significant anisotropy observed. This study provides material selection guidance for engineering applications, recommending modified MC nylon for high-load components while emphasizing the influence of humidity on performance.