Influences of 4ZnO·B₂O₃·H₂O whisker based intumescent flame retardant on the mechanical, flame retardant and smoke suppression properties of polypropylene composites

Abstract

In this work, the influences of 4ZnO·B2O3·H2O zinc borate (ZB) whisker based intumescent flame retardant (IFR) containing ammonium polyphosphate and dipentaerythritol on the mechanical, flame retardant and smoke suppression properties of polypropylene (PP) composites were characterized by the universal testing machine, UL‐94, limiting oxygen index (LOI), and cone calorimeter tests, respectively. The results indicate that only 1 phr of ZB could effectively improve the LOI value and slow down the burning rate of PP composite. The peak heat release rate, average of HRR, total heat release, peak smoke production rate, and total smoke production values are all decreased from 413.8 kW/m2, 166.3 kW/m2, 82.3 MJ/m2, 0.0995 m2/s, and 17.9 m2 for PPc/20IFR composite to 267.8 kW/m2, 128.3 kW/m2, 66.8 MJ/m2, 0.0478 m2/s, and 12.6 m2 for PPc/20IFR/1ZB composite, respectively. The scanning electron microscopy images, energy dispersive spectrometry, and Raman spectra of char residue reveal that ZB is helpful to form a compact and graphitized intumescent char residue so that the heat diffusion and oxygen transmission are greatly hindered. The thermogravimetry analysis‐fourier transform infrared spectroscopy (TGA‐FTIR) results show that less combustible volatiles and more H2O vapor are generated with the appearance of ZB. Hence, the combustion mechanism in gas phase is suppressed.

Advancements in flame-retardant strategies for lithium–sulfur batteries: from mechanisms to materials

“…Thus, oxygen plays an important role during the combustion process because it can cause chain reactions and dehydrogenation reactions to easily proceed, and high-energy free radicals are the fatal cause of thermal degradation. 91,92 Therefore, the methods and mechanisms to realize gas-phase flame retardancy can be summarized as follows: (1) by introducing flame-retardant additives, flammable additives can release nonflammable gases to dilute the concentration of combustible gases and decrease the temperature of the battery. 93 (2) Flame-retardant additives can release low-energy free radicals to capture high-energy free radicals to cut off the chain reaction.…”

Synthesis of Zinc Oxide Doped Magnesium Hydrate and Its Effect on the Flame Retardant and Mechanical Properties of Polypropylene

“…The inner layers of the char residues of PP/40KZO@MH and PP/40ZO@MH composites are stronger and harder than the outers, due to the higher content of carbons. In other words, ZO@MH and KZO@MH migrate to the surface of composites during the burning process and finally form a loose outer layer [41]. XPS is used to further analyze the varieties and states of different elements in the inner layers of the char residues of PP/40KZO@MH and PP/40ZO@MH composites.…”

Preparation of DOPO‐derived magnesium phosphate whisker and its synergistic effect with ammonium polyphosphate on the flame retardancy and mechanical property of epoxy resin

“…Because whiskers can significantly ameliorate the mechanical properties of polymers, the development and application of whiskers have become a hot focus in the field of EP composites 38,39 . Among the reported whiskers, some whiskers such as magnesium borate whisker (MBW) and zinc borate (ZB) whisker can be used as flame retardants 40–42 . When MBW was added to EP, the mechanical properties and flame retardancy of EP composites increased simultaneously 40 .…”