Oxygen Index Method Research Articles

Fabrication of green montmorillonite modified bio-based rigid polyurethane foam with improved flame retardancy and enhanced mechanical properties

A low-carbon and sustainable green rigid polyurethane foam was prepared by compounding montmorillonite (MMT) with homemade barium phytate (BAPA). The flame retardancy, thermal stability and mechanical properties of the modified RPUFs investigated using the limiting oxygen index (LOI) method, cone calorimetry (CONE) and thermogravimetry. The results showed that the BAPA/MMT2 composite containing 2 wt% MMT had the highest LOI (25.1 %), and its peak heat release rate (PHRR) and total heat release (THR) were reduced by 14.33 % and 34.68 %, respectively, compared with that of the BAPA/MMT0 material without added MMT. In addition, the smoke production rate (SPR) and total smoke release (TSR) were reduced by 20.54 % and 30.77 %, respectively. BAPA/MMT2 had good flame retardancy and smoke suppression effect. The mechanical properties of BAPA/MMT2 with 2 wt% MMT were improved. The flame retardant mechanism confirmed that BAPA and MMT synergistically improved the quality of the carbon layer. At the same time, phosphorus-containing compounds (PO·), CO2 and water vapor were produced, which diluted the combustible gas in the gas phase and inhibit the flames spread. The current results provided a new strategy for the preparation of high-performance RPUFs.

Thermal and Combustion Properties of Biomass-Based Flame-Retardant Polyurethane Foams Containing P and N.

Biomass has been widely used due to its environmental friendliness, sustainability, and low toxicity. In this study, aminophosphorylated cellulose (PNC), a biomass flame retardant containing phosphorus and nitrogen, was synthesized by esterification from cellulose and introduced into polyurethane to prepare flame-retardant rigid polyurethane foam. The combustion properties of the PU and PU/PNC composites were studied using the limiting oxygen index (LOI), UL-94, and cone calorimeter (CCT) methods. The thermal degradation behavior of the PU and PU/PNC composites was analyzed by thermogravimetric analysis (TGA) and thermogravimetric infrared spectroscopy (TG-IR). The char layer after combustion was characterized using SEM, Raman, and XPS. The experimental results showed that the introduction of PNC significantly improved the flame-retardant effect and safety of PU/PNC composites. Adding 15 wt% PNC to PU resulted in a vertical burning grade of V-0 and a limiting oxygen index of 23.5%. Compared to the pure sample, the residual char content of PU/PNC15 in a nitrogen atmosphere increased by 181%, and the total heat release (THR) decreased by 56.3%. A Raman analysis of the char layer after CCT combustion revealed that the ID/IG ratio of PU/PNC15 decreased from 4.11 to 3.61, indicating that the flame retardant could increase the stability of the char layer. The TG-IR results showed that PNC diluted the concentration of O2 and combustible gases by releasing inert gases such as CO2. These findings suggest that the developed PU/PNC composites have significant potential for real-world applications, particularly in industries requiring enhanced fire safety, such as construction, transportation, and electronics. The use of PNC provides an eco-friendly alternative to traditional flame retardants. This research paves the way for the development of safer, more sustainable, and environmentally friendly fire-resistant materials for a wide range of applications.

Improved thermal stability and flame‐retardant performance of rigid polyurethane foam modified by hydrolyzed keratin‐modified polyol and aluminium hypophosphite

AbstractRigid polyurethane foam (RPUF) was prepared using hydrolyzed keratin‐modified polyol and aluminium hypophosphite as flame retardants. The effects of aluminium hypophosphite on the thermal stability and flame‐retardant properties of hydrolyzed keratin‐modified RPUFs were studied by limiting oxygen index (LOI) method, thermogravimetric analysis, pyrolysis kinetic analysis, cone analysis and smoke density analysis. The results showed that RPUF added with 7.5 wt% aluminium hypophosphite (RPUF‐HK5‐7.5AL) had the highest LOI, which was 26.1%. RPUF‐HK5‐7.5AL had the highest initial decomposition temperature, the highest T5% at a heating rate of 10 °C min−1 and the highest activation energy. In addition, RPUF‐HK5‐7.5AL possessed the lowest heat release rate at 50 kW m−2 of 125.10 kW m−2, and the lowest total heat release rate of 5.30 MJ m−2. Results indicated that RPUF‐HK5‐7.5AL had the best thermal stability and flame‐retardant properties. Scanning electron microscopy showed that hydrolyzed keratin and aluminium hypophosphite had a synergistic effect on the flame retardancy of the RPUFs. The current research results provide a useful reference for the preparation of RPUFs with good flame‐retardant properties by bio‐based modification. © 2024 Society of Industrial Chemistry.

The Morphology, Mechanical and Dynamic Properties, Fire Hazard and Toxicity of Chloroprene and Butadiene Rubber Composites Cross-Linked with Zinc.

This paper presents the influence of zinc on the cross-linking process, mechanical and dynamic properties, morphologies and balance of thermal degradation of blends containing chloroprene rubber (CR) and butadiene rubber (BR). The novel aspect of this research is a comprehensive approach presenting a new curing agent for the CR/BR blends to increase their cross-linking density and final properties, including non-flammability and low fire hazard. This is due to the need to find an alternative to zinc oxide, which is the standard curing agent for chloroprene rubber. The regulations of the European Union enforce a significant limitation on the use of this compound in elastomer technology, due to its harmful effect on aquatic organisms. In this paper, the CR/BR composites were cured with zinc and filled with natural silica fillers (sillitin or chalcedonite) or synthetic silica filler (aerosil). The investigation focused on the morphology characterization of the obtained compounds, their cross-linking degree, swelling, mechanical and dynamic properties, fire hazard and toxicity. The structure of cured CR/BR blends was characterized via scanning electron microscopy (SEM). The fire resistance studies were performed using cone calorimetry or oxygen index methods, whereas toxicity tests were performed with the use of the FB-FTIR (fluidized bed reactor coupled with FTIR analyzer) method. The results showed that obtained CR/BR products were characterized by satisfactory final properties. The properties determined by the oxygen index and cone calorimetry methods, including the behaviors of the tested CR/BR vulcanizates in fire conditions, showed that the produced compounds were characterized by a low fire hazard and can be classified as non-combustible rubber products. However, the toxicity of the decomposition products, determined at 450, 550 and 750 °C, was very high.

О корреляции кислородного индекса с результатами оценки воспламеняемости и горючести полимерных композиционных материалов, полученных маломасштабными методами

PURPOSE. Most polymer composite materials (PCMs) are highly flammable, which significantly limits their use in the construction industry. Therefore, in the Russian Federation, much attention is paid to the development of effective methods for reducing the flammability of PCM. To assess the flammability and combustibility of PCMs, various small-scale methods are being studied, based on determining the temperature, thermal, concentration and kinetic parameters of combustion and flame propagation over their surface. This significantly complicates the analysis of scientific and technical literature. Therefore, the purpose of this work is to establish correlation between small-scale methods for assessing the combustibility and flammability of PCM. The objects of study were PCM for construction purposes (fiberglass, foam and polymer solutions) based on polymers of various chemical structures. METHODS. While assessing the flammability and combustibility of PCM, both GOST methods and methods described in the scientific and technical literature were used. Findings. Correlation has been established for the values of the oxygen index (OI) with the results of assessing the flammability of polymer composites using calorimetry methods and the flammability index Кср when tested by the “ceramic pipe” method, the values of the heat of combustion and the critical density of the ignition heat flux. For gas-filled polymers, OI = 30,18⋅Кср , which makes it possible to calculate the OI value of foam plastics based on the results of determining the flammability of materials using the ceramic pipe method. It is shown that with an oxygen index value of more than 26–27%, composites belong to moderately flammable materials, and with OI > 30% – for low-flammable materials. Data are presented on the influence of the chemical structure of oligoether methacrylates on the heat of combustion and oxygen index of cross-linked polyester methacrylates. It was revealed that the proportionality coefficient (A) in the equation OI/г = А/∆Hcг is different for individual homologous series of the studied polymers. At the same time, polymers of linear structure (polyethylene, polypropylene, polystyrene, polymethyl methacrylate) have lower values of coefficient A (2.68 kJ/g) compared to network polyether methacrylates (A = 2.86–3.27 kJ/g). RESEARCH APPLICATION FIELD. The established correlation of the OI values with the results of assessing the flammability and combustibility of PCM obtained by small-scale methods will make it possible to use the OI method in the development of fire-resistant PCM of a new generation. CONCLUSIONS. The established correlation between OI values and other indicators of flammability and combustibility of PCM will significantly reduce the amount of research in the development of composites for construction purposes. The results of the work can be used in various fields of science and technology.

Thermal Stabilities and Flame Retardancy of Polyamide 66 Prepared by In Situ Loading of Amino-Functionalized Polyphosphazene Microspheres.

The flame-retardant polyamide 66 composites (FR-PA66) were prepared by in situ loading of amino-functionalized polyphosphazene microspheres (HCNP), which were synthesized in the laboratory and confirmed by a Fourier transform infrared spectrometer (FTIR), scanning electron microscope (SEM), and transmission electron microscope (TEM). The thermal stabilities and flame retardancy of FR-PA66 were measured using thermogravimetric analysis (TGA), a thermogravimetric infrared instrument (TG-IR), the limiting oxygen index (LOI), the horizontal and vertical combustion method (UL-94), and a cone calorimeter. The results illustrate that the volatile matter of FR-PA66 mainly contains carbon dioxide, methane4, and water vapor under heating, accompanied by the char residue raising to 14.1 wt% at 600 °C and the value of the LOI and UL-94 rating reaching 30% and V-0, respectively. Moreover, the addition of HCNP decreases the peak of the heat release rate (pHRR), total heat release (THR), mass loss (ML), and total smoke release (TSR) of FR-PA66 to 373.7 kW/m2, 106.7 MJ/m2, 92.5 wt%, and 944.8 m2/m2, respectively, verifying a significant improvement in the flame retardancy of PA66.

Enhancement of thermal characteristics of flexible poly(vinyl chloride) for automotive applications by using environmentally friendly heavy metal-free modifier

This work intends to develop an effective heavy metal-free modifier having properties comparable to traditional stabilizers and flame retardants, simultaneously being environmentally friendly and may be superior in many aspects. The important requirement focused on is: how to increase thermal stability and flame retardancy of flexible poly(vinyl chloride). Due to the typical materials now used with poly(vinyl chloride), which increases health and environmental concerns, utilizing a novel heavy metal-free additive will make poly(vinyl chloride) substantially safer. We have used an artificial silicate for this aim, which proved to be an efficient flame retardant and surprisingly showed excellent heat stabilizing effect. Thermal stability of flexible poly(vinyl chloride) was tested by both discoloration and hydrochloric-acid release methods. Fire properties were tested by limiting oxygen index (L.O.I) method. And penetration resistance of poly(vinyl chloride) has been tested by vicat test. The improvement rate in the thermal stability time during the dehydrochlorination test was 110.7% at 160°C and 90.1% at 180°C. Also, the improvement rate in the L.O.I test was 22.2%, which increased from 21.6% for the poly(vinyl chloride) to 26.4% when 5wt.% of artificial silicate was added. The artificial silicate also increases the thermal stability of the poly(vinyl chloride) and maintains its appearance of more saturated chromatic saturated (brighter). In addition, artificial silicate increases the resistance to hot penetration of poly(vinyl chloride). Where the resistance of poly(vinyl chloride) increased by 8.9% after adding 5wt.% of artificial silicate.

Synergistic effect of combining amino trimethylphosphonate calcium and expandable graphite on flame retardant and thermal stability of rigid polyurethane foam

Amino trimethylphosphonate calcium (Ca-ATMP) has been synthesized and applied to rigid polyurethane foam (RPUF). Synergistic effect of Ca-ATMP and expandable graphite (EG) on flame retardant and thermal stability of RPUFs has been investigated by using the limiting oxygen index (LOI) method, smoke toxicity analysis, Cone calorimeter analysis (CONE), and thermogravimetric analysis (TGA). The experimental results indicated that LOI of the RPUF was 26.3% when the ratio of Ca-ATMP and EG was 1:5. And the peak heat release rate (PHRR) of this proportion of RPUF decreased by 52.4% compared with that of RPUF without flame retardant. In addition, this modified RPUF possessed the maximum apparent activation energy (E) and produced the least toxic gas. On the basis the above data, it can be found that the synergistic effect of Ca-ATMP and EG on flame retardant and thermal stability of RPUFs has the most significant effect when the addition amount of Ca-ATMP and EG is 1:5, which is helpful for improving flame retardation of the RPUF.

Effect of modified layered double hydroxide on the flammability of intumescent flame retardant PP nanocomposites

AbstractThe dodecyl sulfate intercalated CaMgAl‐hydrotalcites (layered double hydroxides [LDHs]) were successfully prepared by co‐precipitation method, and characterized by X‐ray diffraction analysis, infrared spectroscopy (Fourier transform infrared spectra [FT‐IR]), thermogravimetry (TG‐DTA), scanning electron microscope, and Brunner−Emmet−Teller (BET). The prepared LDHs were added to the intumescent flame retardant (IFR) polypropylene (PP) nanocomposites, and the limiting oxygen index method (LOI), vertical combustion method (UL‐94), cone calorimetry (CCT), and other test methods were used to study its thermal stability and combustion performance. The results showed that when the flame retardant was composed of 23 wt% IFR and 2 wt% O‐SDS‐LDHs, the LOI value of the material was increased to 31.5%, reaching the V‐0 level, and the flame retardant performance was significantly improved. The results also showed that there was a significant synergistic effect between IFR and O‐SDS‐LDHs, which could improve the thermal stability and graphitization degree of PP nanocomposites. In addition, the peak heat release rate, total heat release, and total smoke production of the PP/IFR/O‐SDS‐LDHs system were 177 kW/m2, 101 MJ/m2, and 15.4 m2, respectively, which were 82.2%, 51.0%, and 23.0% lower than those of pure PP, respectively. These improvements could be attributed to the presence of dense and continuous char layer formed by the synergistic effect.

Thermal and Flammability Properties of Glass Fabric/MWCNT/Epoxy Multilayered Laminates

Multiwalled Carbon Nano Tube (MWCNT) filled glass fabric reinforced epoxy composites (MWCNT/GEC), and neat GEC were prepared by hand-lay-up followed by hot compression molding method. As per the ASTM standard, specimens were prepared and investigated the influence of the addition of MWCNTs on flammability properties of GEC through the UL-94 vertical flammability test and the limiting oxygen index (LOI) method. The thermal degradation was studied by thermogravimetric analysis (TGA). It was found that the GEC improved upon the thermal stability and fire-retardant properties due to the addition of MWCNTs. It was observed that the 0.3 wt.% MWCNTs-glass fabric reinforced epoxy composite (0.3MWCNT/GEC) exhibits better properties than neat GEC and 0.075 wt.% MWCNT-glass fabric reinforced epoxy composite (0.075MWCNT/GEC) and 0.15 wt.% MWCNT-glass fabric reinforced epoxy composites (0.15MWCNT/GEC). Hence, this material may be suitable for electrical devices and appliances based on the other required properties’ further fulfillment.

Fabrication and characterization of flame‐retardant and smoke‐suppressant of flexible polyurethane foam with modified hydrotalcite

AbstractThe hydrotalcite has been chemically modified by using the ion exchange method to insert dihydrogen phosphate between the carbonate‐type magnesium–aluminum hydrotalcite layers. And then, the effect of modified hydrotalcite on the flame retardancy and smoke suppression properties of flexible polyurethane foam (FPUF) has been investigated using limiting oxygen index (LOI) method, cone calorimeter test (CONE), smoke density chamber, flue gas analyzer, and scanning electron microscope (SEM). The current indicated that the LOI of flame‐retardant modified FPUF was increased to 25.4%. And the peak heat release rate (PHRR) and total heat release (THR) of the samples were decreased by 74.9 kW/m2 and by 9.7 MJ/m2, respectively. Additionally, the total amount of flue gas produced by combustion was reduced by 157.7 m2/m2, and the maximum concentration of carbon monoxide (CO) gas decreased from 51.3 to 23.8 mg/m3. Based on these data, it can be found that the hydrotalcite modified by dihydrogen phosphate intercalation had an excellent flame‐retardant and smoke‐suppressant effect, and 15% of modified hydrotalcite was the most appropriate amount during the combustion process of the modified FPUFs.

ОЦЕНКА ЭФФЕКТИВНОСТИ АНТИПИРЕНОВ, ПЕРСПЕКТИВНЫХ ДЛЯ СОЗДАНИЯ НОВЫХ ПОЛИМЕРНЫХ КОМПОЗИЦИОННЫХ МАТЕРИАЛОВ, ПРЕДНАЗНАЧЕННЫХ ДЛЯ АВИАЦИОННОЙ ТЕХНИКИ

Studies have been carried out on the effectiveness of the action of two types of fire retardants – graphene and an organic phosphorus-containing compound DOPO-THPO, introduced into an epoxy resin. The amount of fire retardants introduced was 0; 2 and 4% of the amount of epoxy resin. The efficiency was assessed by the oxygen index method (LOI). It was shown that for this epoxy resin, the introduction of graphene provided an increase in the oxygen index from 21 to 27%, and the introduction of the phosphorus-containing fire retardant DOPO-THPO – from 21 to 23%. With the simultaneous introduction of graphene (3%) and DOPO-THPO (1%), it was possible to achieve an increase in the oxygen index up to 28%.

Study on the Effect of Zinc on the Rheological, Mechanical and Thermal Properties and Fire Hazard of Unfilled and Filled CR/BR Vulcanizates.

This paper discusses the cross-linking and functional properties of elastomer composites containing chloroprene rubber (CR) and butadiene rubber (BR) cured in the presence of zinc (Zn) and reinforced with mineral fillers. The research aimed to evaluate the effectiveness of zinc as a new cross-linking substance with the simultaneous production of elastomer materials with good mechanical properties and a reduced fire hazard. The article concerns the study and explanation of the dependencies influencing the processing and functional properties of unfilled or filled elastomer blends containing different elastomers ratio or different zinc’s amount. The following fillers were used: silica, kaolin, chalk and montmorillonite. The results revealed that the cross-linking degree of CR/BR blends decreased with the increasing amount of butadiene rubber in the blends. The mechanical properties of the cured blends depended on the proportion of elastomers in the composites, the zinc amount, and the presence and type of filler. The flammability of CR/BR/Zn vulcanizates has been investigated before and after the filling. The parameters assessed by the oxygen index method and cone calorimetry, characterizing the behavior of the tested CR/BR/Zn vulcanizates under fire conditions, have shown that they constitute a low fire hazard and can be considered as non-flammable materials.

Mechanical, flame‐retarding, and creep‐recovery proprieties of ethylene–propylene–diene monomer enhanced with nano‐hydroxide for undersea tunnel sealing gasket

AbstractThis study investigates the mechanical, flame‐retarding, and creep‐recovery proprieties of ethylene–propylene–diene monomer (EPDM) composites. The EPDM composites are filled with different contents of nano‐Mg(OH)2 (NMH) or nano‐Al(OH)3 (NATH). To examine the effect of contents of NMH (or NATH) and seawater immersion, mechanical tests are conducted and the limiting oxygen index (LOI) method was applied. Creep‐recovery tests are then conducted to obtain the creep resistance property of EPDM composites with contents of NMH (or NATH). The microstructure of EPDM composites is investigated by using scanning electron microscopy (SEM). The results indicate that NMH (or NATH) can enhance the flame‐retarding, creep resistance, and hardness properties, whereas tensile strength and elongation at break increase at first and then decrease with increasing content of NMH (or NATH). The Findley power law and the Weibull distribution function show good correspondence with the results of creep‐recovery tests for EPDM composites. Furthermore, SEM results show good interfaces between nanoparticles and the matrix implying the mechanism of the above results.

Synthesis of New Star-Shaped Liquid Crystalline Cyclotriphosphazene Derivatives with Fire Retardancy Bearing Amide-Azo and Azo-Azo Linking Units.

Two series of new hexasubstituted cyclotriphosphazene derivatives were successfully synthesized and characterized. These derivatives are differentiated by two types of linking units in the molecules such as amide-azo (6a–j) and azo-azo (8a–j). The homologues of the same series contain different terminal substituents such as heptyl, nonyl, decyl, dodecyl, tetradecyl, hydroxyl, carboxyl, chloro, nitro, and amino groups. All the intermediates and final compounds were characterized using Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (NMR), and Carbon, Hydrogen, and Nitrogen (CHN) elemental analysis. Liquid crystal properties for all compounds were determined using polarized optical microscope (POM). It was found that only intermediates 2a–e with nitro and alkoxyl terminal chains showed a smectic A phase. All the final compounds with alkoxyl substituents are mesogenic with either smectic A or C phases. However, other intermediates and compounds were found to be non-mesogenic. The study on the fire retardancy of final compounds was determined using limiting oxygen index (LOI) method. The LOI value of pure polyester resin (22.53%) was increased up to 24.71% after treating with 1 wt% of hexachlorocyclotriphosphazene (HCCP). Moreover, all the compounds gave positive results on the LOI values and compound 6i with the nitro terminal substituent showed the highest LOI value of 27.54%.

Experimental study on the influence of different laying methods on the thermomechanical properties of carbon fiber/epoxy hybrid composite

The thermomechanical tests were carried out on the composite materials under different laying methods (thickness and angle) based on cone calorimetry, high temperature oxygen index method, vertical/horizontal combustion method and high temperature mechanics test method. The results show that the peak values of ignition time and heat release rate of carbon fiber/epoxy composite increase with the increase of the thickness of the layer. Time to peak is advanced. The mass loss rate increases. The high temperature oxygen index of the material increases. The vertical/horizontal combustion rate decreases. Time to reach peak production rate of CO/CO2 is shortened. The peak value of smoke production rate decrease. The time needed to reach the peak of smoke production rate is longer. Total smoke emission increased. The flue gas release process lasts longer. The function model of mass loss rate and heat radiation intensity is obtained. The vaporization heat of carbon fiber/epoxy composite with different thickness was calculated. The effects of laying angle on oxygen index, smoke production rate and CO/CO2 parameters are not obvious. When the laying angle [0°/90°] is the same as the fire spreading direction, the vertical/horizontal burning speed is higher. The difference between the laying angle [±45°] and the flame spreading direction is beneficial to the smoke emission from the bottom layer. Total smoke emission increased. The mechanical properties of materials at high temperature are related to the laying angle. When the temperature is 150 °C, the mechanical properties of the material are lower than that of 25 °C. The fitting functions of high temperature mechanics in the range of 25 °C−150 °C were obtained. It can predict the mechanical properties of materials at different temperature points in this temperature range.

Green Approach for the Development of Novel Flame Retardant Waterborne Polyurethanes: Synthesis and its Characterizations

Waterborne polyurethanes (WBPUs) are developed from water as a medium instead of solvent. Due to high volatile organic compounds (VOC) content in the solvents, the government has banned solvent based polyurethanes in few countries. Therefore, in present work attempts have been made to synthesize polyurethanes by the green approach in terms of utilizing water as a solvent medium. Waterborne polyurethane is one of the unique utmost quickly developing environmental friendly material. It has been found extensively useful in the field of applications like coatings, adhesives for automobiles and wood. Furthermore, extremely useful in flexible substrates such as leather, membranes, textiles and rubbers. These fields require a prominent flame retardancy of the materials, but the instant flammability is a major disadvantage of WBPU, which limits its use in further application in a rigorous situation of fire. Hence, flame retardancy has been improved in present work by incorporating phosphorous moiety in the polymeric chain in a reactive way. By the use of prepolymer mixing process and varying NCO:OH mole ratio, various flame retardant waterborne polyurethanes were synthesized. These synthesized WBPUs were coated on mild steel panels, glass panels and wood. Characterization was done through Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. Microtrac particle size analyzer was used to investigate the particle size. Scratch resistance, pencil hardness, adhesion (cross hatch), flexibility 1/4“ mandrel test, chemical resistance and solvent resistance test of the coated panels were also performed. Flame retardancy was inspected by limiting oxygen index (LOI) and UL-94 test methods.

Fire performance and leach resistance of pine wood impregnated with guanyl-urea phosphate/boric acid and a melamine-formaldehyde resin

Scots pine (Pinus sylvestris L.) wood impregnated with guanyl-urea phosphate/boric acid and a melamine-formaldehyde resin exhibited considerably increased resistance to leaching, while sustaining superior fire retardancy as tested by the limiting oxygen index (LOI) method. It was found that guanyl-urea phosphate has been well trapped in the wood structure by the cured resin network as evidenced by FTIR spectroscopy. Markedly, weight percentage gain (WPG) losses of fire retardant as low as 7.4% were achieved after excessive leaching of treated wood (EN 84). This was attributed to the effect of melamine-formaldehyde resin. Overall, this type of treatment could be a reliable method for producing fire-resistant pine wood for exterior uses.

Fire Properties of Acrylonitrile Butadiene Styrene Enhanced with Organic Montmorillonite and Exolit Fire Retardant

In this paper an experimental investigation on fire retardancy of a new polymer nanocomposite derived from organic montmorillonite and exolit fire retardant in an acrylonitrile- butadiene-styrene copolymer by analyzing the flammability and fire behavior is described. The samples were prepared by melting and mixing nanocomposites and fire retardant in different concentrations in an acrylonitrile-butadiene-styrene base polymer. It was found that using only one component (organic montmorillonite or fire retardant) the burning stops in 10 s on the sample. Confirmation of synergy in flammability by combining both montmorillonite and flame retardants was noticed and is discussed regarding the flame-retardant mechanisms assessed by means of the Limiting oxygen index (LOI), UL 94, and cone-calorimeter methods. The acrylonitrile- butadiene-styrene preparation with 15–20 wt% fire retardant and 1–2 wt% organic montmorillonite reached a UL-94 V-0 classification, contrasting with the pure acrylonitrile- butadiene-styrene and the acrylonitrile-butadiene-styrene with 15 wt% fire retardant and acrylonitrile-butadiene-styrene with 1–2 wt% organic montmorillonite formulations, which completely burned. Finally, the samples showed a very good synergy going to a higher reduction of the peak heat release rate and to a minimum mass reduction, as obtained from cone calorimeter tests.

Comparative Study on the Flame-Retardant Properties and Mechanical Properties of PA66 with Different Dicyclohexyl Hypophosphite Acid Metal Salts.

Three metal salts of dicyclohexyl hypophosphite, namely dicyclohexyl aluminum hypophosphite (ADCP), dicyclohexyl magnesium hypophosphite (MDCP), and dicyclohexyl zinc hypophosphite (ZDCP), were synthesized. These flame retardants were subjected to thermogravimetric analysis, and the results showed that ADCP and ZDCP had higher thermal stabilities than MDCP. They were then separately mixed with polyamide 66 (PA66)to prepare composite materials, of which the combustion properties were determined by the limiting oxygen index method and horizontal/vertical burning experiments. The mechanical properties of the materials were further evaluated using an electronic universal testing machine. The results showed that all the three flame retardants exerted a flame-retardant effect on PA66, but the flame-retardant effect of MDCP was inferior to those of ADCP and ZDCP. All the composites also showed similar mechanical properties. Among the three flame retardants, ADCP had the best overall performance for raw materials, showing good flame-retardant properties while maintaining the mechanical properties of the raw materials. The optimal dosage of ADCP was 15 wt %, at which a V-0 rating in the vertical burning test (UL 94 test) can be obtained.