Polyamide 6 composites: a solid-state NMR study

Abstract

The search for new thermoplastic materials with electromagnetic interference (EMI) properties led to the preparation of PA6 micron-sized particles carrying 10-20 wt.% of metal payloads. To assess their applicability in various applications, e.g., in magnetic resonance imaging, systematic analysis by means of solid state NMR are necessary. The main idea of this work is to study the influence of well-dispersed metal fillers (Al, Cu, and Mg) on the semi-crystalline structure and molecular dynamics of PA6 microparticles obtained by anionic polymerization in suspension. The response of the amorphous and crystalline PA6 phases are recorded using conventional 13C MAS and CP-MAS RF pulse sequences, respectively. NMR relaxation studies were performed to determine the motions in the kHz and MHz frequency scales, characterized by the relaxation times T1ρ (ms) and T1 (s) of the C1-C6 carbons of the PA6 matrix. Finally, metal loaded PAMC are tested as EMI shielding materials by means of 15N solid state NMR at 30 MHz.