Halloysite Nanotubes and Silane-Treated Alumina Trihydrate Hybrid Flame Retardant System for High-Performance Cable Insulation

Abstract

The effect of the presence of halloysite nanotubes (HNTs) and silane-treated alumina trihydrate (ATH-sil) nanofillers on the mechanical, thermal, and flame retardancy properties of ethylene-vinyl acetate (EVA) copolymer/low-density polyethylene (LDPE) blends was investigated. Different weight percentages of HNT and ATH-sil nanoparticles, as well as the hybrid system of those nanofillers, were melt mixed with the polymer blend (reference sample) using a twin-screw extruder. The morphology of the nanoparticles and polymer compositions was studied using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The mechanical properties, hardness, water absorption, and melt flow index (MFI) of the compositions were assessed. The tensile strength increases as a function of the amount of HNT nanofiller; however, the elongation at break decreases. In the case of the hybrid system of nanofillers, the compositions showed superior mechanical properties. The thermal properties of the reference sample and those of the corresponding sample with nanofiller blends were studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Two peaks were observed in the melting and crystallization temperatures. This shows that the EVA/LDPE is an immiscible polymer blend. The thermal stability of the blends was improved by the presence of HNTs and ATH-sil nanoparticles. Thermal degradation temperatures were shifted to higher values by the presence of hybrid nanofillers. Finally, the flammability of the compositions was assessed. Flammability as reflected by the limiting oxygen index (OI) was increased by the presence of HNT and ATH-sil nanofiller and a hybrid system of the nanoparticles.

The Effect of Flame Retardant—Aluminum Trihydroxide on Mixed Mode I/II Fracture Toughness of Epoxy Resin

“…Based on the literature review, a target group of flame retardants was selected [ 54 , 55 , 56 , 57 ]. The investigation concentrated on inorganic flame retardants, such as aluminum silicates (colloidal silica, kaolin, montmorillonite) and metal hydroxides (Al(OH) 3 and Mg (OH) 3 ), due to their excellent thermal stability, nontoxicity, and low price, which is essential for industrial applications.…”

Improvement of flame retardancy and thermal stability of highly loaded low density polyethylene/magnesium hydroxide composites

“…10,11 Therefore, halogen-free flame retardants such as metallic hydroxides, phosphorus and nitrogen-containing compounds, silicon compounds, boron compounds and minerals have become popular substitutes for halogen-containing flame retardants. 12,13 Flame retardants in the polymer matrix act in two ways, chemical and physical. From a chemical point of view, they inhibit radical formation, whereas their physical activity can be explained by cooling the polymer structure via endothermic decomposition, the formation of a protective char layer which creates a barrier between decomposition gases and oxygen, reducing the heat and mass transfer, and interfering the combustion process by releasing inert gases or vapors such as water and carbon dioxide during decomposition, which dilute the combustion gases.…”

“…In the early studies, halogen‐based flame retardants were widely used; however, their use was restricted from an environmental point of view due to the emission of large amounts of smoke and toxic and corrosive gases during the combustion process and their easy migration 10,11 . Therefore, halogen‐free flame retardants such as metallic hydroxides, phosphorus and nitrogen‐containing compounds, silicon compounds, boron compounds and minerals have become popular substitutes for halogen‐containing flame retardants 12,13 …”

Synergistic Improvement of Flame Retardancy and Mechanical Properties of Epoxy/Benzoxazine/Aluminum Trihydrate Adhesive Composites

“…Surface modification is also a common approach to improving mechanical properties. Silane coupling agents having an organic and inorganic end is most frequently used [25][26][27][28].…”