Structure and Properties Study of PA6 Nanocomposites Flame Retarded by Aluminium Salt of Diisobutylphosphinic Acid and Different Organic Montmorillonites

Abstract

Two different types of organic montmorillonite, namely quaternary ammonium salt intercalated MMT (CMMT) and quaternary phosphonium salt intercalated MMT (PMMT) were used as fillers in the flame-retardant polyamide (PA6) based on aluminium salts of diisobutylphosphinic acid (ABPA). The influence of different types of organic montmorillonite (OMMT) on the structure and properties of flame-retardant PA6 nanocomposites were systematically investigated. The X-ray diffraction and transmission electron microscopy results suggested that the introduction of OMMT improved the dispersion of the flame retardant particles independently of the type of OMMT. The derivative thermogravimetry (DTG) curve transformed to one peak from two peaks (representing the degradation of ABPA and PA6, respectively) after incorporation of the OMMT, which further confirmed better ABPA dispersion. Viscoelastic measurements demonstrated that a mechanically stable network structure was formed with the introduction of OMMT or ABPA and OMMT, while PA6/ABPA/PMMT presented the highest storage modulus and viscosity, suggesting a more efficient network structure. From UL-94 and limited oxygen index (LOI) tests, PA6/ABPA/PMMT presented the best flame performance, with a UL-94 of V-0 and a LOI of 33%. In addition, the PA6/ABPA/PMMT presented the lowest peak heat release rate (pHRR) among the investigated samples. Combined with the char layer analysis, it can be deduced that the introduction of PMMT improved the dispersion of ABPA, and promoted the formation of more efficient network structure, before promoting more compact char structures, which finally resulted in improved flame retardancy.

Organobentonites Modified with Poly(Acrylic Acid) and Its Sodium Salt for Foundry Applications

“…The modification usually results in an interlayer ion exchange between hydrated inorganic and organic cations, causing an increase in the hydrophobicity of the clay. Therefore, such materials are used as fillers in polymer-clay nanocomposites or also as adsorbents of organic pollutants [ 4 , 5 , 6 ]. The interest in clay minerals results mainly from their availability in the form of numerous deposits and diversity in terms of structure and chemical composition, which combined with the knowledge of numerous methods of their modification, favor targeted modification [ 7 ].…”

Flame Inhibition and Charring Effect of Aromatic Polyimide and Aluminum Diethylphosphinate in Polyamide 6

“…Thus, as an alternative to BFRs, the halogen-free flame retardant system has become the focus of interest. In current studies on PA6 with halogen-free flame retardant systems, research teams have mainly developed polyamide materials with high flame retardant performance by using the following four methods: (1) constructing an efficient flame retardant system by blending different components and utilizing the component synergistic effect [6,7,8,9,10,11,12,13,14]; (2) obtaining a new flame retardant system by bonding different flame retardant groups into one molecule [15,16,17,18,19,20,21]; (3) designing novel flame retardant chemical structures [22,23,24]; and (4) preparing intrinsically flame retardant polyamide [25,26]. However, traditional halogen-free flame retardants for polyamide, such as melamine polyphosphate (MPP) [27] and melamine cyanurate (MCA) [28], have been unable to meet commercial demands for improved physical-mechanical properties because of their low flame retardant efficiency.…”

Investigation on the Properties of PMMA/Reactive Halloysite Nanocomposites Based on Halloysite with Double Bonds

“…Nanocomposites are a new class of composite-filled particles, at least one dimension of which is in the range of nanometers [1,2,3,4]. There are three types of nanocomposites, depending on whether one, two, or three dimensions of the particles are in the range of nanometers [5,6,7,8]. Recently, polymer-layered silicate nanocomposites have attracted widespread interest for their improvement on the barrier properties, resistance to fire and ignition, and stiffness and toughness of the polymers [9,10,11].…”