Modified montmorylonite (MMT) as a nanofiller in polymer-ceramic nanocomposites

Ewa Stodolak, Łukasz Zych, Agnieszka Łącz, Wojciech Kluczewski

Quarterly No. 2, 2009 pages 122-127

DOI:

keywords: montmorylonite, nanofillers, nanocomposites, intercalation methods, MMT exfoliation

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abstract Aim of this work was fabrication of a polymer-matrix nanocomposite based on polyacrylonitrile (PAN) and a layered sili-cate (phyllosilicate) - montmorillonite (MMT) as nanofiller. Nanoparticles of the filler, which originated from a natural depo-sit, were subjected to a chemical treatment (ethylenediamine, MMT-amine), or thermal treatment (nanofiller carbonisation, MMT-amineMMT-carbo) which objective was to reach better compatibility between the matrix and the nanofiller. In or-der to improve compatibility of MMT-type particles with a polymer matrix they are subjected to chemical treatments which consist in an introduction of cations of alkylamonium or alkylophosphonate salts between stocks of aluminasilicate piles. The introduction of organic matter between the stocks of piles is called intercalation. The additional objective of this treatment, apart form inducing organophilic character of the particles (i.e. formation of organoclays), is increase of an inter-pile spacing. Better results of nanocomposite strengthening with MMT-type particles are achieved when an organoclay undergoes exfolia-tion i.e. when it completely loses layered structure, and the nanofiller plates are separated with the polymer chains. Usually both above mentioned phenomena occur simultaneously i.e. part of the piles is intercalated, while the rest is completely dela-minated (exfoliated). In such case a flocculated nanocomposite is produced. Montmorylonite fraction was separated by sedimentation from bentonite from Jelesovy Potok deposit (Slovakia). Particle size distribution was determined by DLS method using NanoSizer Nano-ZS apparatus. The second type of the nanofiller was montmorylonite intercalated with secondary amine. The main purpose of this treatment was hydrophobisation of MMT piles, which was expected to improve a compatibility of the nanofiller with the polymer matrix. The intercalation process was car-ried out by mixing MMT with the secondary amine (proportion MMT:amine; 1:2). The third type of the nanofiller, was pro-duced by thermal treatment of MMT-amine at 1000oC for 15 min in oxidising atmosphere. Influence of the treatment method on the nanofiller characteristics was determined by structure (XRD), and microstructure (SEM) analysis of MMT and its de-rivatives. MMT-PAN nanocomposites were produced by casting method. It was observed, that a form of the nanofiller influ-enced efficiency of dispersion of the nanometric phase within the polymer matrix, as well as the thermal stability of the nano-composite (TG/DSC). Mechanical tests (stretching) revealed better compatibility of an exfoliated nanofiller (MMT-carbo) with the polymer matrix, which resulted in increase of the nanocomposite strength.