ПОРІВНЯННЯ АМІНІВ ЯК ГАЗОУТВОРЮВАЧІВ ВОГНЕЗАХИСНИХ КОМПОЗИЦІЙ ІНТУМЕСЦЕНТНОГО ТИПУ

Purpose. Study of influence of blowing agents amines structure on the construction processes of thermal insulating char layer of intumescent system ammonium polyphosphate/pentaerythritol/amine and fire protection efficiency of this system at high temperatures. Methodology. A fire retardant mixture of ammonium polyphosphate/pentaerythritol/amine was chosen as a model intumescent system. Dispersion of vinyl acetate copolymer with vinyl ether of versatic acid was used as a polymeric component. A step-by-step study of the characteristics of the char layer of the intumescent composition was applied in the study, consisting in the analysis of the characteristics of the char formed after keeping the intumescent composition samples at a certain temperature between 100 and 800 °C, char residue mass (m, %), structure and density of the formed char layer. The method of infrared spectroscopy was used for identification of products of thermolysis of intumescent systems. Determination of fire protection efficiency of intumescent coatings was carried out in a mini-oven under standard fire conditions. Findings. The influence of the structure of amines blowing agents on the formation of char layer of intumescent system ammonium polyphosphate/pentaerythritol/amine was studied. Physico-chemical parameters of char layer formed during high temperature swelling of intumescent system components with varying amine: urea, melamine, dicyandiamide, guanidine, thiocarbamide, formylthiosemicarbazide, thiosemicarbazide, phenylethylcarbamide have been determined. In the temperature range 200–400 oC for systems with linear amines (urea, thiocarbamide, thiosemicarbazide), there is a rapid formation of insulating layer with intense outgassing (high intumescent coefficients K) and the same rapid its destruction with significant losses of char residue mass (Δm). The presence of melamine, dicyandiamide and guanidine in intumescent system provides constancy of intumescent coefficient at minimal mass loss. Chemical transformations of intumescent systems were studied by the method of infrared spectroscopy when the investigated amines were varied. It was found that linear diamines do not form stable spatially branched phosphamide compounds with phosphates as the basis of a thermostable heat-insulating frame. At the same time in IR spectra of char residue systems with melamine, dicyandiamide and guanidine the absorption bands of P-N-C bonds (1070–1050 cm-1) and P-N (980–950 cm-1) up to 600–700 oC are observed. Fire tests proved that melamine, dicyandiamide and guanidine are blowing agents providing maximum protection of metal against fire and can be used for composition of fire retardants for steel constructions.Originality. It has been proved that amines in intumescent polyphosphate system perform at least two functions: blowing agents by means of thermal destruction to incombustible gases and nucleophilic compound that takes part in char layer formation by aminolysis of electrophilic substrates.Practical value. The optimum amine blowing agents for developing formulations of intumescent coatings with enhanced flame retardant properties have been established.

Surface Functionalization of Black Phosphorus via Amine Compounds and Its Impacts on the Flame Retardancy and Thermal Decomposition Behaviors of Epoxy Resin

Recently, lots of effort has been placed into stabilizing black phosphorus (BP) in the air to improve its compatibility with polymers. Herein, BP was chemically functionalized by aliphatic amine (DETA), aromatic amine (PPDA) and cyclamine (Pid) via a nucleophilic substitution reaction, aiming to develop an intensively reactive BP flame retardant for epoxy resin (EP). The -NH2 group on BP-DETA, BP-PPDA and BP-Pid reacted with the epoxide group at different temperatures. The lowest temperature was about 150 °C for BP-DETA. The impacts of three BP-NH2 were compared on the flame retardancy and thermal decomposition of EP. At 5 wt% loading, EP/BP-NH2 all passed UL 94 V 0 rating. The limiting oxygen index (LOI) of EP/BP-PPDA was as high as 32.3%. The heat release rate (HRR) of EP/BP-DETA greatly decreased by 46% and char residue increased by 73.8%, whereas HRR of EP/BP-Pid decreased by 11.5% and char residue increased by 50.8%, compared with EP. Average effective heat of combustion (av-EHC) of EP/BP-Pid was lower than that of EP/BP-DETA and EP/BP-PPDA. In view of the flame-retardant mechanism, BP nanosheets functionalized with aliphatic amine and aromatic amine played a dominant role in the condensed phase, while BP functionalized with cyclamine was more effective in the gas phase.

ПІДВИЩЕННЯ ВОГНЕЗАХИСНОЇ ЕФЕКТИВНОСТІ ІНТУМЕСЦЕНТНИХ ЕПОКСИДНИХ ПОКРИТТІВ СПОЛУКАМИ ІНТЕРКАЛЬОВАНОГО ГРАФІТУ

Investigation of the effect of nitrate oxide graphite on the parameters of char layer, obtained from the system of ammonium polyphosphate / melamine / pentaerythritol / epoxy resin under the influence of temperatures of 200–800 °С. Methodology. A fire retardant mixture was chosen as a model intumescent system ammonium polyphosphate / melamine / pentaerythritol. As a polymer component was used bisphenols A / F epoxy resin together with a polyamidoamine hardener. Nitrate oxide graphite was obtained by oxidation of natural scaly graphite with fuming nitrogen acid. The effect of impurities of nitrate oxide graphite was determined by thermogravimetry on the intumescence coefficient of intumescent compositions and the mass of the char residue intumescent compositions in temperature range of 200–800 °С. Findings. The influence of nitrate oxide graphite on the characteristics was studied of char layer of epoxy intumescent system ammonium polyphosphate / melamine / pentaerythritol / epoxy resin. The study of thermal oxidative degradation was carried out intumescent compositions in the temperature range 200–800 °С. It was shown that intercalated graphite compounds increase the thermal stability of the formed char layer at temperatures > 600 °С. Determined intumescence coefficients and thermogravimetric analysis of modified intumescent systems was performed nitrate oxide graphite with different degrees of intercalation, in the conditions of 200–800 °С. It was established that the optimal parameters of the char layer are in terms of volume intumescence coefficient and mass of the char residue are provided by graphites, which contain 15–25% of intercalant in its composition. But the results obtained allow us to determine nitrate oxide graphite as a promising modifier of epoxy intumescent systems to increase its fire protection efficiency. Originality. The influence of degree of intercalation of nitrate oxide graphite was studied on the characteristics of char layer of epoxy intumescent system for the first time. Practical value. The optimal content of intercalant in nitrate oxide graphite was established for the development of formulations of intumescent epoxy coatings with increased fire retardant properties.

Anti-dripping flame retardancy and mechanical properties of polylactide/ammonium polyphosphate/rayon fiber composites

Polylactide (PLA) composites containing a flame retadant, ammonium polyphosphate (APP), and short rayon fiber were prepared by direct melting compounding in a brabender. The limiting oxygen index (LOI) of the neat PLA sample was only 20.5%, which was increased to 29% by adding 15 wt% APP and 15% rayon to the PLA matrix (sample A15R15) as an example. During the UL-94 vertical flammability test, flame dripping was further avoided by adding the rayon fiber, and a V-0 rating was achieved. The char residue determined by thermogravimetric analysis (TGA) increased with increasing APP content in the PLA composites. However, the PLA composite revealed a loss in mechanical tensile modulus and strength due to the APP addition, which was improved when rayon fiber was added to replace a portion of APP.

Construction of a Phytic Acid–Silica System in Wood for Highly Efficient Flame Retardancy and Smoke Suppression

The intrinsic flammability of wood restricts its application in various fields. In this study, we constructed a phytic acid (PA)–silica hybrid system in wood by a vacuum-pressure impregnation process to improve its flame retardancy and smoke suppression. The system was derived from a simple mixture of PA and silica sol. Fourier transform infrared spectroscopy (FTIR) indicated an incorporation of the PA molecules into the silica network. Thermogravimetric (TG) analysis showed that the system greatly enhanced the char yield of wood from 1.5% to 32.1% (in air) and the thermal degradation rates were decreased. The limiting oxygen index (LOI) of the PA/silica-nanosol-treated wood was 47.3%. Cone calorimetry test (CCT) was conducted, which revealed large reductions in the heat release rate and smoke production rate. The appearance of the second heat release peak was delayed, indicating the enhanced thermal stability of the char residue. The mechanism underlying flame retardancy was analyzed by field-emission scanning electron microscope coupled with energy-dispersive spectroscopy (SEM-EDS), FTIR, and TG-FTIR. The improved flame retardancy and smoke-suppression property of the wood are mainly attributed to the formation of an intact and coherent char residue with crosslinked structures, which can protect against the transfer of heat and mass (flammable gases, smoke) during burning. Moreover, the hybrid system did not significantly alter the mechanical properties of wood, such as compressive strength and hardness. This approach can be extended to fabricate other phosphorus and silicon materials for enhancing the fire safety of wood.

A Study on Circular Economy Material Using Fish Scales as a Natural Flame Retardant and the Properties of Its Composite Materials

Fish scales (FSs) are fishery wastes that can cause environmental pollution. This study aimed to solve this environmental problem. FSs were used as a flame retardant for polymer materials, making them valuable. Fish scales were combined with a commercial flame retardant, ammonium polyphosphate (APP), through synergistic effects to reduce the amount of commercial flame retardant. The use of FSs conforms to the concept of a circular economy and lowers costs by reducing the consumption of APP. Thermogravimetric analysis (TGA), integral procedural decomposition temperature (IPDT), pyrolysis kinetics, limiting oxygen index (LOI), the Underwriters Laboratories 94 (UL94) flammability test, scanning election microscopy, Raman spectroscopy, and energy-dispersive X-ray spectroscopy were used to determine the thermal properties, flame retardant properties, flame retardant mechanism, char morphology, and composition of the composites. The TGA results indicated that the addition of 40% flame retardant raised the char residue from 16.45 wt.% (pure EP) to 36.07 wt.%; IPDT from 685.6 °C (pure EP) to 1143.1°C; LOI from 21% (pure EP) to 30%; and UL94 classification from fail (pure EP) to V-0. These results suggest an increase in char residue, which indicates better protection of the polymer matrix material. The improvements in IPDT, LOI, and UL94 classification, which indicate greater thermal stability, lower flammability (from flammable to fireproof), and higher flammability rating (from fail to V-0), respectively, suggest that the composite material has favorable thermal properties and is less inflammable.

A Study on Circular Economy Material Using Fish Scales as Natural Flame Retardant and the Properties of Its Composite Materials

In this study, a composite flame retardant was created by combining fish scale (FS), fishery waste, and ammonium polyphosphate (APP), a commercially available flame retardant. The composite flame retardant was added to epoxy resin (EP) to form an EP/APP/FS composite that prevents burns and is environmentally friendly. The use of FS conforms to the concept of circular economy and lowers costs by reducing the consumption of APP. Thermogravimetric analysis (TGA), integral procedural decomposition temperature (IPDT), pyrolysis kinetics, limiting oxygen index (LOI), the Underwriters Laboratories 94 (UL94) flammability test, scanning election microscopy, Raman spectroscopy, and energy-dispersive X-ray spectroscopy were used to determine the thermal properties, flame retardant properties, flame retardant mechanism, char morphology, and composition of the composites. The TGA results indicated that the addition of 40% flame retardant raised the char residue from 16.45 wt% (pure EP) to 36.07 wt%, IPDT from 685.6 °C (pure EP) to 1143.1°C, LOI from 21% (pure EP) to 30%, and UL94 classification from fail (pure EP) to V-0. These results suggest an increase in char residue, which indicates better protection of the polymer matrix material. The improvements in IPDT, LOI, and UL94 classification, which indicate greater thermal stability, lower flammability (from flammable to fireproof), and higher flammability rating (from fail to V-0), respectively, suggest that the composite material has favorable thermal properties and is less inflammable.

Synthesis of a Triazine-Based Hyper Branched Macromolecule Charring Agent and its Effect on Flame-Retardant Thermoplastic Polyester Elastomer to Improve Anti-Dripping

A triazine-based charring agent (CDS) was synthesized and combined with diethyl aluminum hypophosphite (AlPi) to develop an intumescent flame retardant (IFR) system to improve thermoplastic polyester elastomer (TPEE) anti-dripping. The results showed that the limiting oxygen index (LOI) of the TPEE/15AlPi/5CDS composite reached 30.2%, and it passed the V-0 test in vertical combustion (UL-94). The results of thermogravimetric analysis (TGA) showed that CDS had good thermal stability and high char residue (50.8wt%) at 700°C. And when combined with AlPi added to TPEE, which can improve its char residue ranges from 1.68wt% to 23.52wt%. The structure evolution during the heating process was studied by heating infrared spectroscopy (IR), and the morphology and chemical structure of char residues were studied by scanning electron microscope (SEM) and laser Raman spectroscopy (LRS). The high-efficiency flame-retardant TPEE composite formed a continuous, dense and porous char layer containing triazine ring and aromatic ring structure after combustion.

Kalsiyum Hipofosfit ve Magnezyum Hipofosfit Emdirilmiş Jüt Elyaf Katkılı Poli (Laktik Asit) Biyokompozitlerinin Isıl Ve Güç Tutuşurluk Özelliklerinin İncelenmesi

The aim of this study is to investigate the thermal and flammability properties of poly(lactic acid) (PLA) biocomposites reinforced with calcium hypophosphite (CHP) and magnesium hypophosphite (MHP) impregnated jute fiber (JE). For this purpose,biocomposites were produced by adding the jute fibers (JEs), which are treated separately with 5% and 10% CHP and MHP solutions and dried, to the PLA at a constant rate (20% wt) by melt blending method. Thermal properties of the PLA biocomposites produced were evaluated by thermogravimetic analysis (TGA), also their flammability properties were investigated by using limit oxygen index (LOI), vertical (UL-94V) and horizontal burning (UL-94HB) tests. As a result of the TGA tests, it was determined that the addition of JEs impregnated with CHP and MHP, the thermal stability and char residue amount of PLA biocomposites increased, and consequently the flame retardancy of the composites were also improved. From the LOI test results, it was observed that the LOI values of PLA biocomposites increased as the percentage of hypophosphites in the JE treatment solution increased. UL-94V and UL-94HB tests indicate that PLA biocomposite reinforced with JEs treated with 10% wt CHP has the highest flame retardancy performance.