Ceramic precursor in flame retardant systems

Effect of Silicone Oil on Properties and Performance of Ceramizable Styrene-Butadiene Rubber-Based Composites

New trends in the circular economy and sustainability are pointing towards the gradual elimination of standard flame retardants such as phosphorus compounds or halogenated compounds. New solutions are therefore being sought in this area and ceramizable composites could be an interesting alternative. Weak rheological properties are one of the main disadvantages of ceramizable composites. This study tested ceramizable composites composed of styrene-butadiene rubber (SBR) as a polymer matrix and mica as a mineral filler and aimed to improve the viscoelastic properties of silicone oil as a plasticizer. To characterize this composite's mechanical properties before and after ceramization, the viscoelastic properties were tested with a dynamic oscillating rheometer and the thermal behavior with a cone calorimeter. This paper also provides results showing differences (via the abovementioned properties) between vulcanization with sulfur and that with peroxide for the ceramizable composites based on SBR. The presented results, showing changes in mechanical properties, dynamic viscosity or flammability, among others, allow a better understanding of elastomeric composites with ceramizable flame-retardant systems. Such composites can find a wide range of applications, from lagging for electrical cables to building elements such as floor coverings and fire barriers.

Synergistic Effects of Diatoms on Intumescent Flame Retardant High Impact Polystyrene System

In this work, aiming to improve the flame retardancy performance of high impact polystyrene (HIPS), HIPS compounds were synthesized with the addition of intumescent flame retardant (IFR: mass ratio of APP and PER was 3:1) and diatoms into HIPS matrix by melt blending method. It was found the IFR/diatoms system exhibited high flame retardant efficiency and catalytic carbonization effect to HIPS matrix in the burning process. The LOI value of HIPS-2 compound with the addition of 28 wt% IFR and 2 wt% diatoms was increased to 29.0% and passed V-0 rating. The value of PHRR for HIPS-2 compound is about 460.58 kW/m² compared with 937.22 kW/m² of pure HIPS and the value of THR for HIPS-2 compound is about 32.9 MJ/m² compared with 62.7 MJ/m² of pure HIPS, suggesting that the addition of IFR/diatoms system can decrease the values of PHRR and THR, which shows the synergistic effect between IFR and diatoms on reducing heat release. The 21.9% reduction in Av-EHC and 41.4% reduction in TSP seen on introducing an IFR/diatoms system indicates effective smoke suppression, which potentially would significantly reduce the death rate in real fire accidents. The TG-IR results indicated that the IFR/diatoms flame retardant system functioned in the gas phase to suppress the flame. The SEM images showed the char residue produced was more compact and continuous, which suggests that the IFR/diatoms flame retardant system exhibits barrier and catalytic effects to block heat transferring and promote char forming. The tensile strength and impact strength of HIPS-2 compound were 22.95 MPa and 2.63 KJ/m², respectively. The tensile strength and impact strength were increased by 34.13% and 19.55% compared with that of pure HIPS.

Preparation of a Ceramifiable Phenolic Foam and Its Ceramization Behavior

Ceramifiable phenolic foam (GC-PF) with a low ceramization temperature has been prepared by incorporation of low melting point glass frits (LMG) containing B₂O₃ and Na₂O as main components into a phenolic resin matrix. Fourier transform infrared spectrometry, X-ray diffractometry, and scanning electron microscopy were used for assessment of the structure, phase composition, and morphology of GC-PF before and after combustion analysis, respectively. A glassy ceramic protective layer is formed when GC-PF is exposed to flame or a high temperature environment. The presence of LMG not only reduces the level of defects in the phenolic foam cell wall (gas escape pore), but also promotes the generation of a glassy ceramic protective layer that could inhibit heat feedback from the combustion zone and reduce the rate of formation of volatile fuel fragments. Thermogravimetric analysis and differential scanning calorimetry were used to establish that GC-PF exhibits excellent thermal stability. Limiting oxygen index (LOI) determination suggests that GC-PF displays good flame retardancy. The LOI of GC-PF was as high as 45.6%, and the char residue at 900 °C was six times greater than that for ordinary phenolic foam (O-PF). The area of the raw material matrix of GC-PF after combustion for 60 s was about 1.7 times larger than that for O-PF. A possible mode of formation of glassy ceramics has been proposed.

Influence of Antimony Oxide on Epoxy Based Intumescent Flame Retardation Coating System

Ethylenediamine modified Ammonium polyphosphate (EDA-MAPP), and Charring-Foaming Agents (CFA) was prepared via a simple chemical approach and further utilizes for the preparation of Epoxy resin based intumescent flame retardation coatings. The ratio belongs to MAPP and CFA was fixed at 2:1 ratio. Comparative thermo gravimetric analysis TGA study of Modified Ammonium polyphosphate (MAPP) and Ammonium polyphosphate (APP) investigated. Sb₂O₃ was introduced into flame retardation coating formulation at various amounts to evaluate the synergistic action of Sb₂O₃ along with flame retardant coating system. The synergistic action of Sb₂O₃ on flame retardation coating formulation was studied by vertical burning test (UL-94V), thermo gravimetric analysis (TGA), Limited Oxygen Index (LOI), and Fourier Transform Infra-Red spectroscopy (FTIR). The UL-94V results indicated that adding Sb₂O₃ effectively increased flame retardancy and meets V-0 ratings at each concentration. The TGA results revealed that the amalgamation of Sb₂O₃ at each concentration effectively increased the thermal stability of the flame retardant coating system. Cone-calorimeter study results that Sb₂O₃ successfully minimized the combustion parameters like, Peak Heat Release Rate (PHRR), and Total Heat Release (THR). The FTIR result shows that Sb₂O₃ can react with MAPP and generates the dense-charred layer which prevents the transfer of heat and oxygen.

Impact of Basalt Filler on Thermal and Mechanical Properties, as Well as Fire Hazard, of Silicone Rubber Composites, Including Ceramizable Composites

This article illustrates the impact of basalt filler, both in the form of basalt flakes and basalt fibers, on thermal and mechanical properties, as well as on the fire hazard, of silicone rubber (SR) composites, including ceramizable composites. In addition to basalt filler, ceramizable composites contain mineral fillers in their composition in the form of silica and calcium carbonate, inorganic fluxes such as zinc borate and glass frit, and melamine cyanurate as a flame retardant. The obtained composites were analyzed from the point of view of their morphology, rheological and thermal properties, flammability, and mechanical properties before and after the ceramization process. The obtained research results indicate that the basalt filler has an unambiguous impact on the improvement of thermal properties and the reduction of flammability in the analyzed composites. The results of morphological analyses of ceramizable composites before and after the process of their ceramization indicate a definite impact of the basalt filler on the structure of the formed ceramic layer. An increase in its homogeneity exerts a direct impact on the improvement of its mechanical parameters.

Improving the Mechanical and Electrical Properties of Ceramizable Silicone Rubber/Halloysite Composites and Their Ceramic Residues by Incorporation of Different Borates

Ceramizable silicone rubber (MVQ)/halloysite (HNT) composites were fabricated by incorporation of three different borates, including sodium tetraborate decahydrate, ammonium pentaborate, and zinc borate into MVQ matrix, respectively. The composites without any borates were also prepared as control. The effect of the borates on the mechanical and electrical properties of MVQ/HNT composites was investigated. The ceramic residues were obtained from the decomposition of the composites after sintering at 1000 °C. The effect of the borates on the linear shrinkage, weight loss, and flexural and impact strength of the residues was also studied. The fracture surfaces of the composites and their corresponding residues were observed by SEM. The proposed ceramizable mechanism of the composites by incorporation of different borates was revealed by XRD analysis.

Combination of montmorillonite and a Schiff-base polyphosphate ester to improve the flame retardancy of ethylene-vinyl acetate copolymer

Different flame retardant ethylene-vinyl acetate copolymer (EVA) formulations were prepared to evaluate the synergistic effect between organo-montmorillonite (OMMT) and a Schiff-base polyphosphate ester (PAB) on the combustion behavior of EVA. X-ray diffraction (XRD) and transmission electron microscopy (TEM) results revealed that montmorillonite platelets selectively dispersed in the PAB phase. EVA/PAB/OMMT(80/15/5) had better thermal stability and flame retardancy than EVA/PAB(80/20), as indicated by the results of thermogravimetric analysis (TGA), limited oxygen index (LOI), vertical burning test (UL-94) and microscale combustion colorimeter (MCC), showing a synergism between OMMT and PAB. For example, the onset decomposition temperature (T5%) increased from 233°C to 296°C, the char residue at 600°C increased from 6.6% to 11.0%, and the peak heat release rate (PHRR) decreased from 718.1 W/g to 706.6 W/g. This is caused by the silicoaluminophosphate (SAPO) structure formed by reactions between the phosphoric acid generated from PAB and OMMT.