Abstract:
A chain extender, styrene-maleic anhydride copolymer SMA-700, was mixed with recycled polyamide 6/carbon fiber composites (r-PA6/CF10) with a twin-screw extruder. The rheological properties, mechanical properties, morphology, crystalline structure, non-isothermal crystallization and subsequent melting behaviors of the resulting r-PA6/CF10 composites were investigated. The results show that SMA-700 has a remarkable chain extension effect on r-PA6/CF10 composites, and can significantly improve the processing performance of r-PA6/CF10. With the increase of mass fraction of SMA-700, the melt mass flow rate of r-PA6/CF10 decreases gradually. Meanwhile, the apparent viscosity and melt pseudo-plasticity of r-PA6/CF10 will increase with the increase of mass fraction of SMA-700. Mechanical tests show that incorporation of chain extender can simultaneously improve the tensile strength and flexural strength of r-PA6/CF10 composites. SMA-700 mass fractions of 1% and 2% maximizes the tensile strength (125.4 MPa) and flexural strength (182.3 MPa) of the r-PA6/CF10 composites, respectively. The impact strength decreases with increased mass fraction of SMA-700. Scanning electron microscopy (SEM) used suggests that there is no phase separation between SMA-700 and r-PA6 matrix, implying a good compatibility between SMA-700 and r-PA6. Non-isothermal crystallization and subsequent melting behaviors characterized by differential scanning calorimetry (DSC) show that when the mass fraction of SMA-700 is 1%, the nucleation effect of SMA-700 may increase the crystallization rate and crystallinity of the r-PA6 matrix. However, with an excessive amount of SMA-700, both the crystallization rate and crystallinity of r-PA6 drop, and the perfection degree of
α crystal form of r-PA6 decreases simultaneously.