Abstract

Three types of shell bio-fillers, including eggshell (CES), conch shell (CHS) and clamshell (CMS), were prepared by cleaning, ultrasonication and pulverizing processes of biowastes, and then applied to intumescent fire-retardant coatings. The effects of shell bio-fillers with different polymorphs on the fire resistance and char-forming of intumescent fire-retardant coatings were investigated by cone calorimeter test, fire protection tests, smoke density test, thermogravimetric analysis (TG), and the fire resistance and char-forming mechanism of bio-fillers in intumescent fire-retardant coatings were proposed. The results show that three kinds of bio-fillers exert an excellent synergistic effect on enhancing the fire resistance and char-forming properties of the intumescent fire-retardant coatings, while clamshell has the best synergistic efficiency among the bio-fillers. Especially, IFRC-CMS coating containing 3 wt% clamshell shows the best fire protection performance and lowest smoke production and heat release, which offers an equilibrium backside temperature of 134.6 °C at 900 s, a flame-spread rating of 14.4, and a smoke density rating value of 22.8%. The synergistic efficiency of bio-fillers in the intumescent coatings depends on the polymorphs of CaCO3 in bio-fillers, and aragonite CaCO3 shows a higher synergistic efficiency compared to calcite CaCO3 and the mixture of aragonite and calcite CaCO3. The CMS composed of aragonite shows the best synergistic effect, CHS composed of aragonite and calcite comes second, and CES composed of calcite has the weakest synergistic effect.

Highlights

  • Intumescent fire-retardant coatings are considered one of the most influential and economical materials for reducing fire hazards of buildings owing to their excellent fire resistance and heat-insulation performance, which usually include organic intumescent coatings and inorganic intumescent coatings and are widely used in wood, concrete, steel, etc. [1,2,3]

  • The characteristic peaks of shell bio-fillers are located at 700, 713, 859, 876, 1082, 1452, 1481, 1794, 2347, 2519, 2923, 3422 cm−1, while the peaks at 1481, 876, 713 cm−1 are associated with the forms of calcite, and the peaks at 1425, 1082, 859, 713, 700 cm−1 are assigned to the forms of aragonite [15]

  • Three kinds of shell bio-fillers were prepared from eggshell, conch shell, In this paper, three kinds of shell bio-fillers were prepared from eggshell, conch and clamshell, respectively, and carefully characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TG) analshell, clamshell, respectively, by FTIR, XRD, SEM,asand TG

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Summary

Introduction

Intumescent fire-retardant coatings are considered one of the most influential and economical materials for reducing fire hazards of buildings owing to their excellent fire resistance and heat-insulation performance, which usually include organic intumescent coatings and inorganic intumescent coatings and are widely used in wood, concrete, steel, etc. [1,2,3]. Bio-fillers, as an environmentally-friendly material, are widely applied in fire-retardant coatings, plastics, and concrete to enhance the fire resistance, thermal stability, char formation, and mechanical performance of the materials owing to their excellent characteristics such as lightweight, high quantity, and affordability [6,7,8]. Calcite CaCO3 has strong thermal stability, while aragonite CaCO3 has superior advantages on enhancing the mechanical properties and processing properties of polymeric materials. Few studies have reported the effect of polymorphs of calcium carbonate on the fire resistance and char-forming properties of intumescent fire-retardant coatings. Four kinds of intumescent fire-retardant coatings were prepared with APP-PER-MEL as intumescent flame retardant, shell bio-fillers as synergists, and waterborne epoxy resin as binder, and the effects of bio-filler polymorphs on the combustion properties of intumescent fire-retardant coatings were investigated. Thermogravimetric analysis (TG), scanning electron microscopy (SEM), cone calorimeter test, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD) were used to analyze the synergistic mechanism of different bio-fillers in the intumescent coatings

Materials
Preparation of the Shell Bio-Fillers
Preparation of Intumescent Fire-Retardant Coatings
Fire Protection Tests
Thermogravimetric Analysis
Morphology and Composition of Bio-Fillers
Cone Calorimeter Test
Thecan
Thermal Stability Analysis
Fire Resistance and Char Formation Mechanism
Conclusions

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