Papers by Keyword: Flame Retardant

Abstract: The use of ammonium polyphosphate (APP) and expanded graphite (EG) as a flame retardant for polymer generally requires a relatively high amount of addition to achieve a flame-retardant effect, and is liable to cause a decrease in strength of the material. Therefore, in this study waste diatomite was used as an eco-friendly flame-retardant for high density polyethylene (HDPE) to reduce the amount of APP and EG and can reach the flame-retardant level. Moreover, the waste diatomite was heat treatment and surface modified by silane coupling agent to improve its compatibility with HDPE. The results show that the tensile strength of the HDPE drops sharply after the addition of the APP and EG. However, replace some of the APP and EG by the modified diatomite can slow down the decline and maintain the basic physical properties of the material. The impact strength of HDPE was also decreased by the addition of APP, EG and untreated diatomite. However, the impact strength of HDPE was increased after adding the surface modified diatomite. It can be seen from the experimental results that the addition of the waste diatomite modified by the silane coupling agent can reduce the usage of the flame retardant such as APP and EG, and increase the strength by increasing the compatibility between the plastic and the inorganic material. Moreover, this eco-friendly formulation can reach the UL-94 HB level, and it can be applied to interior decoration or as building materials in the future. Thus, it can not only recycle the wastes, but also reduce the threat caused by fire.

Abstract: In the present study, a low viscous (complex viscosity between 200 to 500 mPas at 60 °C), flame retardant epoxy resin formulation is prepared and transferred to the carbon fiber reinforced plastic (CFRP) laminate using resin transfer molding (RTM) method. For the laminate production, a 12k carbon fiber fabric with an areal weight of 400 g/m2 is used to achieve a fiber volume content of approximately 60 vol % carbon fibers. Subsequently the unmodified laminate is produced, varying carbon fiber volume content to study its effect on flame retardant properties. As additives, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) modified epoxy resin and nanosilica particles delivered in an epoxy novolac masterbatch are added to the neat novolac resin system. The mixture is cured with isophorone diamine (IPDA) and polyetheramine hardener blend, resulting in a glass transition temperature of 104 °C for the unmodified laminate. Flame retardant properties of the materials are tested using cone calorimeter and thermal gravimetrical analysis. In addition, the mechanical behavior of the systems is evaluated via three-point bending method in static and dynamical loadings. In order to get deeper information on the resulting flame retardant mechanisms of the additives, the residual cone calorimeter char is analyzed with scanning electron microscopy, indicating the different flame retardant mechanisms of phosphorous and silica as well as the combination of both additives.

Abstract: The thermal decomposition kinetics of polybutylene terephthalate (PBT) and flame-retardant PBT (FR-PBT) were investigated by thermogravimetric analysis at various heating rates. The kinetic parameters were determined by using Kissinger, Flynn-Wall-Ozawa and Friedman methods. The y (α) and z (α) master plots were used to identify the thermal decomposition model. The results show that the rate of residual carbon of FR-PBT is higher than that of PBT and the maximum mass loss rate of FR-PBT is lower than that of PBT. The values of activation energy of PBT (208.71 kJ/mol) and FR-PBT (244.78 kJ/mol) calculated by Kissinger method were higher than those of PBT (PBT: 195.54 kJ/mol) and FR-PBT (FR-PBT: 196.00 kJ/mol) calculated by Flynn-Wall-Ozawa method and those of PBT and FR-PBT (PBT: 199.10 kJ/mol, FR-PBT: 206.03 kJ/mol) calculated by Friedman methods. There is a common thing that the values of activation energy of FR-PBT are higher than that of PBT in different methods. The thermal decomposition reaction models of the PBT and FR-PBT can be described by Avarami-Erofeyev model (A₁).

Abstract: A new phosphorus-containing flame-retardant curing agent PPDTA was synthesized from phenylphosphonic dichloride (PPD) and 3-amino-1,2,4-triazole (TA) in tetrahydrofuran solvent to improve the flame retardancy of epoxy resin. The structure of the compound was analyzed and confirmed by infrared spectroscopy. The effects of reaction time, reaction temperature and ratio of reactants on yield were studied by using three-factor three-level orthogonal experiment. The results show that the yield of PPDTA can reach 86.4%, when the reaction time is 10h, reaction temperature is 70 °Cand the molar ratio of TA to PPD is 2.2:1.

Abstract: The effects of external heat radiation on combustion and toxic gas release characteristics of flame retardant cables, which were XLPE insulated, flame retardant PVC sheathed and steel armoured cables, were investigated. The combustion characteristics of the level A and the level C flame retardant cables were explored by the cone calorimeter. For the level C cables, heat release rate (HRR) and CO concentration in cable fires increased and the ignition time decreased with increase of the external radiation heat flux. For level A cables, the HRR and CO concentration showed two-stage variations with the external radiation heat flux. When the external radiation heat flux was smaller than 35 kW/m², the cable self-extinguished quickly after the ignition. When the external radiation heat flux was larger than 50 kW/m², the cables showed continuous burning phenomena after the ignition. The level A cable had smaller HRRs compared with that of the level C cable under the same external radiation heat flux. However, the CO concentration of level A cable was remarkably higher than that of the level C cable in the present study. The high CO release rate of cable with well flame retardant ability under large external radiation heat flux requires more caution in the cable fires.

Abstract: Containing phosphorus compound is widely used in the modification of flame retardant polyester due to the excellent flame retardant properties. But it is difficult to solve the droplet problems, especially the polyester fiber. In this paper the copolyesters and fiber with flame retardant and anti-droplet were prepared using reaction containing phosphorus flame retardant [(6-Oxido-6H-dibenz [c, e] [1, 2] oxaphosphorin-6-yl) methyl] butanedioic acid (DDP) and silica sol by in-situ polymerization. The structure and properties of modification flame retardant were measured by nuclear magnetic resonance (NMR), thermal gravity analysis (TGA). The results indicated that the modification flame retardant was more suitable for polymerization. The TGA, limiting oxygen index (LOI), vertical flame test, and scanning electron microscope (SEM) were devoted to discuss the flame retardant properties. It suggested that the nanoSiO₂ particles increased char residue, and the nanoSiO₂ particles were conducive to the formation of dense stable carbon layer, inhibiting the expansion of the carbon layer to form holes, the nanoSiO₂ particles improved the droplet of copolyester. The highest LOI of copolyester is 34.8±0.1%, the UL94 is V-0 grade. The copolyester fiber has excellent mechanical, flame retardant and anti-droplet. This can meet the requirement of household textile decoration and use.

Abstract: The rheological behaviour of sisal fibre/HDPE composites containing two types of flame retardants as magnesium hydroxide and ammonium polyphosphate was studied using a capillary rheometer. The mass ratio of HDPE to sisal fibre was set as 20 phr. Flame retardants were added at 10, 20 and 30 phr. Results showed that the composites exhibited pseudoplastic behaviour as the shear viscosity decreased with increasing shear rate. Shear stress and real shear viscosity increased with increasing flame retardant, with magnesium hydroxide giving higher values than ammonium polyphosphate. Therefore, magnesium hydroxide had a marked effect on the processing power, while ammonium polyphosphate did not greatly affect the shear viscosity of the composites. An increase in elongation rate reduced the elongation viscosity. The flame retardant contents had no significant effect on the elongation viscosity at high elongation rate. The materials showed increased extrudate swell with increasing apparent shear rate, but this significantly decreased with the addition of flame retardant. The power law index (n) for all composites was less than 1 and the flow consistency index K was higher for composites with flame retardant than those without. Moreover, magnesium hydroxide was more effective than ammonium polyphosphate causing an increase in the K value.

Abstract: The organophosphorus compound N-methylol dimethyl phosphonopropionamide (MDPA) is extensively used for durable flame retardant (FR) treatments for cotton fabrics. For optimum finishing treatment, MDPA is used with the Trimethylol melamine (TMM) or dimethylol dihydroxyethylene urea (DMDHEU) for cotton fabric treatments. The amino resins TMM known to pose severe toxic problems such as; breathing problems, headache and most importantly, cancer. In the production, consumption and eventually in the disposal phase of FR with TMM treated cotton fabrics, the release of TMM and toxic emissions cannot be ignored. In this study, mineralization and degradation of the organophosphorus FR compound from the cotton fabric using Advanced Oxidation Process (AOP) was successfully employed. The kinetics of degradation of FR substance from the cotton fabric was studied. The rate of degradation of the FR substance from the cotton fabrics was observed with chemical oxygen demand (COD). The kinetic rate constant equations and characterization of the mineralization and degradation of the FR substance by the AOP reaction was developed with the COD values. The organophosphorus FR on the fabric found to follow the first-order of kinetics of degradation from the cotton fabric.

Abstract: The effects of incorporating three different types of flame retardant (FR) and two variants of graphene into 10 %wt palm EFB natural fibre (NF) filled epoxy composites were investigated in term of the flammability, thermal and mechanical properties through standard Bunsen burner experiment, bomb calorimetry, TGA and tensile tests. The types of FR employed include zinc borate (ZB), ammonium polyphosphate (APP) and alumina trihydrate (ATH) while a lab synthesised and a commercial form of graphene were used in the current work. Compared to the neat NF filled epoxy composite, specimens loaded with 15 %wt of either ZB or APP demonstrated a drip-free condition as observed from the Bunsen burner tests, which could be attributed to the strong char forming characteristic of the compositions. In specimens containing 15 %wt of either ZB or ATH, results from Bomb calorimetry revealed that these specific formulations produced the lowest mean gross heat release amongst others, suggesting better resistant to flame. Relative to the graphene incorporated composites, the post TGA measured mass residue was observed to be greater in FR rich formulations, suggesting that FR additives capable of yielding a much superior flame retardancy compared to graphene. While a slight increases in Young’s modulus was recorded in composites loaded with FR, such formulations produced several main drawbacks whereby reduction in ultimate tensile strength and elongation to break were being measured in large proportion of the specimens.

Abstract: Epoxy was effectively resin infused with 15 %wt intumescing Alumina Trihydrate (ATH) flame retardant (FR) formulations into a 10 %wt palm EFB natural fiber (NF) mat. The effects of ATH and its intumescing blend with Zinc Borate (ZB) and Ammonium Polyphosphate (APP) on flammability, thermal and mechanical properties of the composites were investigated. Compared to neat NF filled epoxy composites, specimens loaded with intumescing blend of FR formulations demonstrated an improved thermal properties, showing greater mass residual which can be attributed to the formation of cross-linked network amongst the NF, FRs and epoxy matrix upon combustion at elevated temperature tested within a TGA instrument. Incorporation of fibers drastically enhanced the mass residue and lowered the heat release compare to the pure epoxy. Addition of the intumescing blend of FR formulations also drastically reduces the combustion heat release, total mass loss and zero drip flame in the NF composites. The optimum FRs formulation with 5 %wt ATH and 10 %wt APP exhibited self-extinguishing property, achieved lowest mass loss and no drip flame under Bunsen burner tests, signifying the synergistic effects between ATH and APP within the NF epoxy composites. APP reacts with the carbonaceous network of NF throughout the ignition period, such interaction formed a thick char layer acting as gas and thermal barrier against the fire mechanism. This reaction does not take place in NF composite specimens without APP. In terms of mechanical properties, NF composites loaded with FRs broadly showed poorer tensile strength, mainly due to the existence of FRs, which acted as a nucleating agent affected the physico-mechanical characteristics of the composites. Amongst the FR rich formulations, specimens with APP or ZB blends seem to possess a more superior tensile strength compared with the neat ATH filled formulation. In addition, composites loaded with FRs showed enhanced Young’s modulus relative to those without addition of FRs.