Structure-property relations of novel polyamide-6 elastomers prepared through reactive processing

A series of polyamide-6 elastomers (PAEs) employing polytetramethylene glycol (PTMG) as soft segments, diphenylmethane diisocyanate (MDI) as chain extender and polyamide-6 as hard segments is prepared through reactive processing. The MDI is also employed to suppress the crystallization capacity of soft segments and to regulate the soft segment length in the obtained PAEs. The chemical structures, crystallization properties, morphology, mechanical properties and thermal stability are extensively studied by Fourier transform infrared spectroscopy (FTIR), Hydrogen nuclear magnetic resonance (HNMR), X-ray diffraction (XRD), Differential scanning calorimetry (DSC), Transmission electron microscope (TEM), Dynamic mechanical analyzer (DMA), Tensile test and Thermal gravity analysis (TGA), respectively. TEM images demonstrate that PAE samples exhibit a microphase separated morphology with polyamide-6 domains disperse in the PTMG phase in nano-scale. DMA curves indicate that the prepared PAEs possess a typical elastomer thermodynamic behavior and a broad temperature-independent rubbery plateau. Meanwhile, PAEs exhibit superior mechanical properties with 55 MPa for tensile strength and 1100% for elongation at break. The TGA prove that the thermal stability of PAE can satisfy the requirement of multiple-processing without decomposition.