Comparison of Polyamide‐6 Nanocomposites Based on Pristine and Organic Montmorillonite Obtained via Anionic Ring‐Opening Polymerization

Abstract

Summary: Exfoliated Na+‐MMT/polyamide‐6 and intercalated organic MMT/polyamide‐6 nanocomposites were prepared using sodium montmorillonite with water dispersion and organic MMT with acetone dispersion via anionic ring‐opening polymerization, respectively. The effects of Na+‐MMT and OMMT on the polyamide‐6 were compared. Analysis shows that incorporation of exfoliated Na+‐MMT obviously improved mechanical properties, thermal stability, crystalline rate and favored formation of a γ‐crystalline form of matrix, but intercalated OMMT has no obvious effect on it. Nanoscale dispersing Na+‐MMT dramatically elevated the viscosity of matrix comparing with pure polyamide‐6. FTIR analysis indicates that the exfoliated Na+‐MMT improved the stability of hydrogen bonding comparing with the OMMT treated by alkylammonium salt modifier, which is different from previous studies. It is believed that hydrogen bonding between Na+‐MMT and polyamide‐6 plays a pivotal role.FTIR spectra of the NH stretching region of (a) PA, (b) PAM and (c) PAO.imageFTIR spectra of the NH stretching region of (a) PA, (b) PAM and (c) PAO.

Mechanical and Optical Properties of Polyamide 6/Clay Nanocomposite Cast Films: Influence of the Degree of Exfoliation

“…Interestingly, the yield stresses of PA6/Na + MMT films are close to the one of PA6/C10A films in spite of the presence of large micrometer scaled clay tactoids. This may be explained by the homogeneous dispersion of these tactoids evidenced by NMR measurements and the good affinity between the clay platelets and the PA6 chains45 thanks to hydrogen bonding 46…”

Clay distribution and crystalline structure evolution in polyamide 6/montmorillonite composites prepared by activated anionic polymerization

“…It modifies the overall crystallinity index as well as the amount of a-and c-polymorphs, which could change the whole set of NPC properties. 18 As evident from Figure 5 and Tables I and II, in the exfoliated PA6/o-MMT samples with 0.5 and 1.0 wt % of clay produced via solid-state AAROP (i.e., below T m of the forming PA6), both polymorphs are formed but the amount of the a-crystals is larger or at least close to that of the less stable c-form. Deconvolution of all WAXS profiles in Figure 5 was performed as indicated previously 38,39 and the results for total crystallinity, content of a-and c-PA6, as well as of the relation between the two crystalline forms were calculated (Tables I and II).…”

“…The Crystalline Structure of the PA6 in the Presence of MMT The presence of silicate layers in the PA6 matrix is known to influence the conformation of polyamide molecules and their arrangement. In all these 18,26,27,40 The presence of large c-PA6 amounts was even considered a proof for exfoliation of the nanoclay. MMT type, its content and the temperature of the AAROP (or that of some subsequent annealing) are the most important factors that control the crystalline structure of the matrix PA6.…”

“…11,12 Changing the activator amount or its chemical composition not only influences the AAROP rate but also can result in PA6 materials with linear or star-shaped macromolecules possessing unusual mechanical and rheological properties, 13 as well as in flame retardant properties without any addition of fillers. 17,18 Copolymer PA6/PA12-MMT nanocomposites were also prepared very recently using pristine Na-MMT clay. Thus, according to Liu et al 15 both pristine and organically treated MMT (o-MMT) were unsuitable for AAROP of ECL due to their severe inhibiting effect on the initiator-activator complex.…”

The influence of montmorillonite on the processing and properties of anionic polyamide 6/montmorillonite composites via vacuum assisted resin infusion

“…There exist, however, only few studies on the PA6/MMT nanocomposites prepared by anionic polymerization. A. Liu et al developed a novel method to directly prepare exfoliated monomer casting PA6/pristine Na + ‐MMT nanocomposites via anionic polymerization. The effects of Na + ‐MMT and organically modified montmorillonite (OMMT) on the polyamide‐6 were compared.…”