Montmorillonite disperses in amorphous phase of RIM PA6 matrix via anionic ring opening polymerisation

Abstract

The reaction injection moulding process was employed to prepare montmorillonite (O-MMT)/polyamide 6 (PA6) nanocomposites. O-MMT was functionalised by aminosilane in order to improve the compatibility and decrease the viscosity of caprolactam melts, which swell O-MMT. Small angle X-ray diffraction and transmission electron microscopy results demonstrated that PA6 was sufficiently polymerised via in situ anionic ring opening route at the interlayer of the premodified O-MMT that yields a disordered exfoliated structure. Wide angle X-ray diffraction, polarising optical microscopy and differential scanning calorimetry analysis indicated that the crystallinity of nanocomposites decreased as the loading of O-MMT increased. O-MMT can induce γ-phase crystals and eliminate perfect α-phase crystals into smaller imperfect crystals. The O-MMT primarily disperses in the amorphous phase of RIM PA6 matrix that improves the mechanical properties and heat distortion temperature (HDT) of nanocomposites. For the nanocomposite at 5 wt-% O-MMT, the HDT of neat RIM PA6 was improved from 78 to 163°C.