Performance of halogen-free flame retardant EVA/MH/LDH composites with nano-LDHs and MH

Abstract

The flammability properties of three series of Ethylene-Vinyl Acetate/Magnesium Hydroxide/Layered Double Hydroxide (EVA/MH/LDH) composites as well as the flame retardance effect between LDH and the conventional flame retardant additive MH are investigated. In addition to acting as an insulating barrier, LDH assists the dispersion of MH particles in the EVA matrix, and promotes the formation of the char residues because of its abundant interlayer hydroxyl groups. Composites containing LDH show good flame retardancy in Cone and LOI testings. This means that the combustion properties of the composites have decreased, which may lessen the fire hazard when this materials are used. Ethylene-vinyl acetate copolymers (EVA) with different vinyl acetate (VA) contents are extensively used in many fields, especially in the cable industry as excellent insulating materials with good physical and chemical properties [1]. However, EVA resins are particularly flammable and emit a large amount of smoke when burnt. Magnesium hydroxide is a conventional non-toxic, smoke-suppressing halogen-free flame retardant additive with a high decomposition temperature that is used in flame retardant polymeric materials. However, its flame retardant efficiency is low, so very large amounts must be used, leading to a sharp drop in the mechanical properties of the flame retardant materials. To minimize this effect, the dispersion of MH and its compatibility with the polymer matrix must be improved. The use of very small (hyperfine) particles and surface treatment of MH are two important methods to achieve this. The usual surface modifiers for MH are organic reagents or polymers, which could be detrimental to combustion properties such as the limiting oxygen index (LOI). Hyperfine magnesium hydroxide has been very effective at improving the flame retardance and mechanical properties of polymeric materials, but its dispersion in polymer matrices is very difficult [2]. In recent years, the intercalated or exfoliated polymer/ LDH nanocomposites have attracted great interest in the field of materials science, because of their excellent thermal stability, flame retardance, and physico-chemical properties [3][4][5][6]. In the present work, we use MH and organic modified LDH layers as a flame retardant system and study their synergistic effects on the morphology and structure, flame retardant properties and mechanical properties of EVA/MH/ LDH nanocomposites. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), LOI, dynamic mechanical thermal analysis (DMTA), and cone calorimetry (Cone) tests are performed. The aim is to study the effects of adding LDH and MH to EVA resin (in particular its flame retardant and mechanical properties), and also to explore three difference synergistic systems containing MgAl-LDH, ZnAl-LDH, or MgFe-LDH. The main purpose of this study is to develop a new type of low smoke, halogen-free flame retardant Ding Y Y, et al. Chinese Sci Bull December (2011) and sodium dodecyl sulfate...

Flame retardant polymer/layered double hydroxide nanocomposites

“…Similarly, synergistic effects of MgAl, ZnAl, and MgFe LDHs with MH have also been compared. 102 The cone calorimetry data show that all LDHs led to good ame retardant properties with EVA. The EVA/ MH/MgAl LDH nanocomposites resulted in a remarkable reduction in PHRR of 59% relative to EVA/MH.…”

“…The presence of an addition additive can not only enhance the ame retardant properties of polymer-LDH nanocomposites, but also reduce the required loading of HFFR agents in polymer matrix so as to improve the mechanical properties of polymer nanocomposites. These agents include HFMH, 93,102 APP, 53,82,94 red phosphorus, 65,103 zinc borate, 59 expandable graphite, 65,104,105 and IFRs 64,104 (Table 3). Here the commonly used synergistic systems are summarized and optimal synergistic effects between LDH and the other HFFR materials are described.…”

A new bio‐based flame retardant simply synthesized: Improving the flame retardancy and thermal stability of low‐density polyethylene together with melamine cyanurate

“…It can be seen from Figure 4b that the fracture surface of LDPE/MHPA composite has a diameter of about 1–5 μm particles are embedded in LDPE, which is MHPA prepared by the reaction of MH and PA. The addition of MHPA does not significantly damage the internal structure of LDPE, and there are no cracks and voids at the junction of MHPA and LDPE, which indicates that MHPA and LDPE have certain compatibility 27,28 . After adding MCA, the internal structure of LDPE/MHPA/MCA composite changes significantly.…”

“…The addition of MHPA does not significantly damage the internal structure of LDPE, and there are no cracks and voids at the junction of MHPA and LDPE, which indicates that MHPA and LDPE have certain compatibility. 27,28 After adding MCA, the internal structure of LDPE/MHPA/MCA composite changes significantly. From Figure 4c, it can be seen that many small particles appear on the fracture surface of LDPE/MHPA/MCA composite, and obvious cracks appear at the junction of these particles and LDPE, which indicates that the compatibility between MCA and LDPE is poor, forming an obvious island structure.…”

Shelter Forest Inspired Superhydrophobic Flame‐Retardant Composite with Root‐Soil Interlocked Micro/Nanostructure Enhanced Mechanical, Physical, and Chemical Durability

“…Many efforts, such as physical blending, chemical modification, and micro/nanostructure construction have been used to improve the flame retardancy, hydrophobicity, and anti-icing property of the EVA insulating materials. [7][8][9][10][11] Nevertheless, the perfection of single performance cannot solve the problem of poor adaptability and durability of the EVA flame retardant materials, especially in the outdoor environment with diverse requests. Therefore, the development of insulating flame retardant materials with wide adaptability and enough durability is essential for the intelligent and modern process of human society.…”