Reinforcing polyamide 1212 nanocomposites with aligned carbon nanofibers

• The tensile strength of the composites was improved effectively after drawing.
• The CNFs and PA1212 chains were aligned and oriented during the drawing process.
• The reinforcing effect is attributed to the improved crystal orientation degree.
• The reinforcing effect is also attributed to the oriented fibril structures.

In this study, the mechanical properties and structure orientation of pure polyamide 1212 (PA1212) were compared with those of PA1212–carbon nanofibers (CNFs) nanocomposites. The tensile strength of the composite containing 0.3 wt.% modified CNFs was improved from 328 MPa (pure PA1212) to 373 MPa after drawing. The reinforcing effect was investigated in terms of crystallization behavior, crystal morphology, alignment of CNFs, and crystal orientation degree. Spherulites developed into oriented crystals after drawing, and the CNFs aligned along the drawing direction. The heterogeneous nucleation effect of the aligned CNFs improved the crystal orientation degree, which produced the reinforcing effect. The oriented fibril structures with rigid nanofibers acting as nuclei reinforced the entire oriented crystals in the composites.