Mauro Zammarano - Academia.edu (original) (raw)
Papers by Mauro Zammarano
Fire and Materials, Jul 2, 2022
Wildland Urban Interface (WUI) fires are a rapidly increasing hazard. Cellulosic materials play a... more Wildland Urban Interface (WUI) fires are a rapidly increasing hazard. Cellulosic materials play a key role in the spread of WUI fires. The physics controlling the glowing ignition of cellulosic materials is not well understood. In this work, an experimental and computational study of the glowing ignition of wood was performed. Eight wood specimens (Balsa, Red Cedar, Pine, Douglas Fir, Cypress, Redwood, Purpleheart, and Ipe) were tested under a cone calorimeter in the vertical configuration. Non‐uniform glowing propagation due to sample‐specific surface cracking was observed for all wood samples. The average temperature at the center of each sample was measured using an optical pyrometer. The inflection point in the pyrometer temperature‐versus‐time curve, which was identified by the maximum peak of the first temperature derivative, was used to identify the onset of glowing ignition. Additionally, a comprehensive model was applied to predict the glowing ignition. The comparisons between model predictions and experimental results showed that the surface temperature, the time to glowing ignition, and the glowing ignition temperature of medium‐density wood (ρ = 300–500 kg m−3) could be reasonably predicted. For lighter (e.g., Balsa, ρ = 150 kg m−3) and denser wood (e.g., Ipe ρ = 960 kg m−3), however, significant discrepancies were observed. Hence, further work is needed to understand the influence of wood density on the thermo‐physical and thermodynamic properties that can significantly affect glowing.
Reduced-scale mock-ups had been developed to assess and regulate smoldering ignition resistance o... more Reduced-scale mock-ups had been developed to assess and regulate smoldering ignition resistance of residential upholstered furniture (RUF). However, there are limited data available on the effect of the mock-up test configuration on smoldering propensity and how it affects the degree of correlation with full-scale performance. In this work, the smoldering propensity for standard mock-ups (SMs, where the foam is in contact with a support frame) and modified mock-ups (MMs, where an air gap is introduced between the foam and the frame), were computationally simulated and compared to experimental results. Experimental data showed an up to a four-fold increase in smoldering mass loss in a MM as compared to a SM for a test time of 35 min with a 51 mm-thick foam. The model results indicated that the buoyant airflow at the bottom of the mock-up was enhanced in the MM, giving rise to a higher foam oxidation rate, a higher peak smoldering temperature and higher mass loss rate as compared to the SM, and; that oxygen supply was dominated by diffusion-driven transport from the boundaries in proximity of the heating source in the SM. Additionally, the effects of foam thickness on smoldering propensity were studied experimentally and numerically with foam thicknesses of 51 mm (2 inch) and 76 mm (3 inch). With an increase in the foam thickness, the smoldering propensity is weakened in the MM but enhanced in the SM. The model was able to predict the ranking of smoldering propensity quantified by the mass loss in experiments: ML(t)SM2 < ML(t)SM3 < ML(t)MM3 < ML(t)MM2, where MLSM2 is the mass loss (ML) with a 51 mm-thick foam in SM, MLSM3 is the ML with a 76 mm-thick foam in SM, MLMM3 is the ML with a 76 mm-thick foam in MM and MLMM2 is the ML with a 51 mm-thick foam in MM. These results indicate that reduced-scale tests based on SM2 tends to underpredict smoldering propensity and that MM2 may offer a near-worst-case scenario, useful to identify the This publication is available free of charge from: https://doi.org/10.6028/NIST.TN.2087 upholstery materials that prevent most smoldering ignitions independent of the construction and geometry of the actual furniture.
Scientists are shifting their attention towards technology sustainability and sustainable materia... more Scientists are shifting their attention towards technology sustainability and sustainable materials, specifically in terms of energy and environmental impacts. The flame retardant community is also more concerned about these aspects. The recent banning of some brominated flame retardants in Europe and USA points out that environment impact in terms of persistency and bio-accumulation is becoming a key factor for public perception. Intumescent systems based on phosphorous compounds have been suggested as highly efficient alternative to halogenated flame retardants. Lately, not only halogen based flame retardants but also phosphorous based flame retardants are under scrutiny for their environmental and health safety (EHS) issues. It appears that there is a need for sustainable flame retardants with low EHS impact. In this work we show how natural derived products, like modified lignin, can be used for preparing sustainable intumescent systems with high efficiency. Lignin is the second most abundant organic substance on earth after cellulose and is increasingly available as by-product of cellulose production. Its price (20¢/lb) is significantly lower than commodity polymers, thus lignin is commonly used as polymer filler. Here, we show that modified lignin is also an effective flame retardant. Epoxy resin is used as a case study. The mass loss rate of the epoxy-lignin composites is investigated by means of gasification apparatus. Preliminary results show that lignin-based products produce a continuous protective char capable to protect the underlying polymer throughout the combustion process and, thus, decrease the heat release rate. MATERIALS * Three different grades of kraft lignin were kindly provided by MeadWestvaco Corporation: (1) unsulfonated lignin (Indulin AT), (2) sulfonated lignin (REAX 907) and (3) sulfonated ethoxylated lignin (REAX 825E). Talc (Polyststormor, Mallinckrodt) was used as control filler. Ammonium tartrate (Aldrich) and melamine (Melamine 003 fine, DSM) were used as blowing agents. An epoxy monomer (DER331) was obtained from Dow Plastics. Jeffamine D230 (Huntsman Corp.), a diamine terminated polypropylene glycol, was used as curing agent. The samples were prepared by: drying the fillers (12h at 80 ºC) and dispersing them in the epoxy monomer with a mechanical stirrer; cooling the mixture to room temperature; adding the curing agent in a stoichiometric amount and stirring for 5 min; curing (room temperature for 24h, 80 ºC for 2h, 125 ºC for 3h). The total amount of * This work was carried out by the National Institute of Standards and Technology (NIST), an agency of the US government and by statue is not subject to copyright in USA. The identification of any commercial product or trade name does not imply endorsement or recommendation by NIST.
Polymer Degradation and Stability, Aug 1, 2014
Smoldering poses a severe fire hazard due to the potentially lethal amount of toxic carbon monoxi... more Smoldering poses a severe fire hazard due to the potentially lethal amount of toxic carbon monoxide released, and the possible transition from smoldering to flaming (eventually leading to rapid fire growth and flash-over) with ignition sources otherwise too weak to directly induce flaming. Smoldering in residential-furniture upholstery materials can be assessed at a bench-scale by using reference materials with consistent smoldering behavior. However, the preparation of a reference foam has proven to be a challenging task, and the bench-scale tests currently in use may underestimate smoldering in actual furniture. The aim of this work is to provide guidance for the selection/development of: (i) a reference flexible polyurethane foam with reproducible and well-characterized smoldering behavior, and; (ii) the development of a bench-scale smoldering test capable of identifying the upholstery materials (e.g., fabric, filling/padding, barrier, welt cord) that most likely prevent smoldering ignition in actual furniture. In the first part of this paper, the impact of foam morphology on smoldering is discussed. It is shown how reticulated flexible polyurethane foams, possibly filled with carbon black, can be exploited as reference foam materials. Their fully open cell structure ensures consistent air permeability with an adjustable smoldering intensity as a function of their average cell size. In the second part of this paper, a bench-scale smoldering test (currently employed in a number of test procedures and standards) is redesigned in such a way that the buoyant airflow within the foam is enhanced. Up to a threefold increase in the rate of smoldering propagation and 400 C increase in smoldering temperature is observed in the modified test as compared to the current tests. Transition to flaming was observed, only in the modified test, when an external enclosure was used. The modified test may offer a near-worst-case scenario, useful to identify the upholstery materials that prevent most smoldering ignitions independent of the construction and geometry of the actual furniture.
InTech eBooks, Nov 30, 2016
The components of wood, especially lignin and cellulose, have great potential for improving the p... more The components of wood, especially lignin and cellulose, have great potential for improving the properties of polymer composites. In this chapter, we discuss some of the latest developments from our lab on incorporating wood-based materials into epoxy composites. Lignosulfonate was used as a flame retardant and cellulose nanocrystals were used as reinforcing materials. Lignosulfonate will disperse well in epoxy, but phase separates during curing. An epoxidation reaction was developed to immobilize the lignosulfonate during curing. The lignosulfonate-epoxy composites were characterized using microcombustion and cone calorimetry tests. Cellulose also has poor interfacial adhesion to hydrophobic polymer matrices. Cellulose fibers and nanocrystals aggregate when placed in epoxy resin, resulting in very poor dispersion. The cellulose nanocrystal surface was modified with phenyl containing materials to disrupt cellulose interchain hydrogen bonding and improve dispersion in the epoxy resin. The cellulose nanocrystal-epoxy composites were characterized for mechanical strength using tensile tests, water barrier properties using standardized water absorption, glass transition temperatures using differential calorimetry, and aggregation and dispersion using microscopic techniques.
Poly(lactic acid) was flame-retarded using cellulose-based intumescing flame retardants. Cellulos... more Poly(lactic acid) was flame-retarded using cellulose-based intumescing flame retardants. Cellulose was found to be an excellent carbon source, and when added in combination with ammonium polyphosphate (APP), PLA composites exhibited good thermal stabilities and UL-94 ratings of V-0. Nanofibrillated cellulose was phosphorylated to eliminate the need for APP. The fibers were further modified by quaternization and with glycidyl phenyl POSS to increase the char yield during pyrolysis. Fibers were analyzed by elemental analysis, potentiometric titration, and thermogravimetric analysis. The composites prepared without APP exhibited good thermal stability, but they failed the UL-94 vertical burn test.
A study of a limited number of commercial fire-retardant coatings (FRCs) designed for wood in out... more A study of a limited number of commercial fire-retardant coatings (FRCs) designed for wood in outdoor applications, film-forming or non-film forming (stains), and top-coatings (used in combination with a FRC to increase its durability) were characterized by microscale combustion calorimetry (MCC) and cone calorimetry (50 kW/m 2). All coatings were applied on western red cedar and according to the manufacturers' specifications. A standard accelerated-weathering protocol alternating cycles of UV, spray, and condensation was used to evaluate the outdoor durability of the coated wood samples. Prior to accelerated-weathering, four of the FRCs showed a significant reduction on the flammability of western red cedar wood with a decrease in peak heat release rate (PHRR) and total heat release (THR). After accelerated-weathering equivalent to an estimated outdoor time of 14 days to 28 days, the cone results revealed that all FRCs became ineffective (no significant reduction in PHRR and THR of the wood substrate). The use of five top-coatings was investigated to extend the durability of FRCs. Only two dual-coated systems based on FRCs and top-coatings maintained good compatibility (no suppression of the intumescent char expansion) and fire behavior. An outdoor durability of up to seven months was estimated based on accelerated-weathering for the best FRC/top-coating combination. After this period, this dual-coated system did not show any flammability reduction by cone calorimetry. The results of this study suggest that weathering drastically reduces the durability and fire resistance of FRCs on wood-based products.
Applied Thermal Engineering, Nov 1, 2020
Buoyant airflow is suppressed by the presence of frame in the standard mock-up. • Buoyant airflow... more Buoyant airflow is suppressed by the presence of frame in the standard mock-up. • Buoyant airflow is enhanced by the presence of air gap in the modified mock-up. • The mechanisms of O 2 supply in the standard and modified mock-ups are revealed. • The smoldering propensity increases with foam thickness in the standard mock-up. • The smoldering propensity decreases with foam thickness in the modified mock-up.
Journal of Fire Sciences, Jul 1, 2019
Cone calorimetric experiments of flexible polyurethane foam (FPUF) and FPUF covered with a variet... more Cone calorimetric experiments of flexible polyurethane foam (FPUF) and FPUF covered with a variety of fire-blocking barrier fabrics (BFs) were used to characterize and rank the effectiveness of BFs for reducing the flammability of residential upholstered furniture (RUF). In addition to BF properties, it was demonstrated that the burning behaviors of the FPUF/BF composites were sensitive to a wide range of experimental parameters including the sample configuration, heat losses to the underlying support base, and the two-stage pyrolysis behavior of the FPUF. Measurements using thermocouples (TCs) placed within the FPUF provided insights on FPUF pyrolysis behavior, the collapse rate of FPUF, and the thermal protective properties of barrier materials.
Polymer Degradation and Stability, Nov 1, 2009
Clay-based SAN nanocomposites with zinc chloride as a catalyst were prepared by the solvent casti... more Clay-based SAN nanocomposites with zinc chloride as a catalyst were prepared by the solvent casting method to explore possible synergistic flame retardant effects involving enhanced char formation using a catalyst and the formation of a surface-protective layer having a clay network structure. Although the heat release rate and total heat release were significantly reduced by the use of this combination, each additive contributed independently without the desired synergism. This is due to the early formation of many small cracks in the surface layer for SAN-clay nanocomposites (vigorous bubbling associated with evolving thermal degradation byproducts were observed in the cracks) while the rapid char formation by zinc chloride occurred only at the late stage of the fire test. Char formation at long times does not prevent the crack formation or crack growth, so that an effective protective surface layer without openings was not obtained.
This manuscript describes a methodology to measure the influence of an upholstery cover fabric to... more This manuscript describes a methodology to measure the influence of an upholstery cover fabric to promote smoldering mass loss of a small-scale mock-up constructed of standard polyurethane foam, a cover fabric, and cotton cover cloth, and a standard cigarette. The primary test metric is total mock-up mass loss after 45 min exposure to the cigarette smoldering ignition source. The testing materials are available through NIST as Standard Reference Material (SRM) 1202: Fabric Smoldering Ignition Testing Materials.
Polymer Degradation and Stability, Mar 1, 2022
Acs Symposium Series, 2012
Poly(lactic acid) was flame-retarded using cellulose-based intumescing flame retardants. Cellulos... more Poly(lactic acid) was flame-retarded using cellulose-based intumescing flame retardants. Cellulose was found to be an excellent carbon source, and when added in combination with ammonium polyphosphate (APP), PLA composites exhibited good thermal stabilities and UL-94 ratings of V-0. Nanofibrillated cellulose was phosphorylated to eliminate the need for APP. The fibers were further modified by quaternization and with glycidyl phenyl POSS to increase the char yield during pyrolysis. Fibers were analyzed by elemental analysis, potentiometric titration, and thermogravimetric analysis. The composites prepared without APP exhibited good thermal stability, but they failed the UL-94 vertical burn test.
Proceedings of the 12th Asia-Oceania Symposium on Fire Science and Technology (AOSFST 2021)
Fire and Materials, 2020
SummaryHerein, we describe a reduced‐scale test (“Cube” test), measuring the fire performance of ... more SummaryHerein, we describe a reduced‐scale test (“Cube” test), measuring the fire performance of specimens including a fire barrier (FB) and a flammable core material, which acts as the main fuel load. The specimen is intended to reproduce a cross‐section of a composite product where heat/mass transfer occurs primarily in a direction perpendicular to the FB. The Cube test procedure and benefits are discussed in this work by adopting residential upholstery furniture as an exemplary study. One flexible polyurethane foam, one polypropylene cover fabric, and 10 commercially available FBs were selected. They were used to compare the fire performance of FBs, measured in terms of peak of heat release rate, in the ASTM E1474‐14 standard test and the newly developed Cube test. Edge effects severely affected the performance of FBs in the ASTM E1474‐14 standard test but not in the Cube test. Furthermore, appropriate test conditions were determined in the Cube test to measure the so‐called “wet...
Fire and Materials, Jul 2, 2022
Wildland Urban Interface (WUI) fires are a rapidly increasing hazard. Cellulosic materials play a... more Wildland Urban Interface (WUI) fires are a rapidly increasing hazard. Cellulosic materials play a key role in the spread of WUI fires. The physics controlling the glowing ignition of cellulosic materials is not well understood. In this work, an experimental and computational study of the glowing ignition of wood was performed. Eight wood specimens (Balsa, Red Cedar, Pine, Douglas Fir, Cypress, Redwood, Purpleheart, and Ipe) were tested under a cone calorimeter in the vertical configuration. Non‐uniform glowing propagation due to sample‐specific surface cracking was observed for all wood samples. The average temperature at the center of each sample was measured using an optical pyrometer. The inflection point in the pyrometer temperature‐versus‐time curve, which was identified by the maximum peak of the first temperature derivative, was used to identify the onset of glowing ignition. Additionally, a comprehensive model was applied to predict the glowing ignition. The comparisons between model predictions and experimental results showed that the surface temperature, the time to glowing ignition, and the glowing ignition temperature of medium‐density wood (ρ = 300–500 kg m−3) could be reasonably predicted. For lighter (e.g., Balsa, ρ = 150 kg m−3) and denser wood (e.g., Ipe ρ = 960 kg m−3), however, significant discrepancies were observed. Hence, further work is needed to understand the influence of wood density on the thermo‐physical and thermodynamic properties that can significantly affect glowing.
Reduced-scale mock-ups had been developed to assess and regulate smoldering ignition resistance o... more Reduced-scale mock-ups had been developed to assess and regulate smoldering ignition resistance of residential upholstered furniture (RUF). However, there are limited data available on the effect of the mock-up test configuration on smoldering propensity and how it affects the degree of correlation with full-scale performance. In this work, the smoldering propensity for standard mock-ups (SMs, where the foam is in contact with a support frame) and modified mock-ups (MMs, where an air gap is introduced between the foam and the frame), were computationally simulated and compared to experimental results. Experimental data showed an up to a four-fold increase in smoldering mass loss in a MM as compared to a SM for a test time of 35 min with a 51 mm-thick foam. The model results indicated that the buoyant airflow at the bottom of the mock-up was enhanced in the MM, giving rise to a higher foam oxidation rate, a higher peak smoldering temperature and higher mass loss rate as compared to the SM, and; that oxygen supply was dominated by diffusion-driven transport from the boundaries in proximity of the heating source in the SM. Additionally, the effects of foam thickness on smoldering propensity were studied experimentally and numerically with foam thicknesses of 51 mm (2 inch) and 76 mm (3 inch). With an increase in the foam thickness, the smoldering propensity is weakened in the MM but enhanced in the SM. The model was able to predict the ranking of smoldering propensity quantified by the mass loss in experiments: ML(t)SM2 < ML(t)SM3 < ML(t)MM3 < ML(t)MM2, where MLSM2 is the mass loss (ML) with a 51 mm-thick foam in SM, MLSM3 is the ML with a 76 mm-thick foam in SM, MLMM3 is the ML with a 76 mm-thick foam in MM and MLMM2 is the ML with a 51 mm-thick foam in MM. These results indicate that reduced-scale tests based on SM2 tends to underpredict smoldering propensity and that MM2 may offer a near-worst-case scenario, useful to identify the This publication is available free of charge from: https://doi.org/10.6028/NIST.TN.2087 upholstery materials that prevent most smoldering ignitions independent of the construction and geometry of the actual furniture.
Scientists are shifting their attention towards technology sustainability and sustainable materia... more Scientists are shifting their attention towards technology sustainability and sustainable materials, specifically in terms of energy and environmental impacts. The flame retardant community is also more concerned about these aspects. The recent banning of some brominated flame retardants in Europe and USA points out that environment impact in terms of persistency and bio-accumulation is becoming a key factor for public perception. Intumescent systems based on phosphorous compounds have been suggested as highly efficient alternative to halogenated flame retardants. Lately, not only halogen based flame retardants but also phosphorous based flame retardants are under scrutiny for their environmental and health safety (EHS) issues. It appears that there is a need for sustainable flame retardants with low EHS impact. In this work we show how natural derived products, like modified lignin, can be used for preparing sustainable intumescent systems with high efficiency. Lignin is the second most abundant organic substance on earth after cellulose and is increasingly available as by-product of cellulose production. Its price (20¢/lb) is significantly lower than commodity polymers, thus lignin is commonly used as polymer filler. Here, we show that modified lignin is also an effective flame retardant. Epoxy resin is used as a case study. The mass loss rate of the epoxy-lignin composites is investigated by means of gasification apparatus. Preliminary results show that lignin-based products produce a continuous protective char capable to protect the underlying polymer throughout the combustion process and, thus, decrease the heat release rate. MATERIALS * Three different grades of kraft lignin were kindly provided by MeadWestvaco Corporation: (1) unsulfonated lignin (Indulin AT), (2) sulfonated lignin (REAX 907) and (3) sulfonated ethoxylated lignin (REAX 825E). Talc (Polyststormor, Mallinckrodt) was used as control filler. Ammonium tartrate (Aldrich) and melamine (Melamine 003 fine, DSM) were used as blowing agents. An epoxy monomer (DER331) was obtained from Dow Plastics. Jeffamine D230 (Huntsman Corp.), a diamine terminated polypropylene glycol, was used as curing agent. The samples were prepared by: drying the fillers (12h at 80 ºC) and dispersing them in the epoxy monomer with a mechanical stirrer; cooling the mixture to room temperature; adding the curing agent in a stoichiometric amount and stirring for 5 min; curing (room temperature for 24h, 80 ºC for 2h, 125 ºC for 3h). The total amount of * This work was carried out by the National Institute of Standards and Technology (NIST), an agency of the US government and by statue is not subject to copyright in USA. The identification of any commercial product or trade name does not imply endorsement or recommendation by NIST.
Polymer Degradation and Stability, Aug 1, 2014
Smoldering poses a severe fire hazard due to the potentially lethal amount of toxic carbon monoxi... more Smoldering poses a severe fire hazard due to the potentially lethal amount of toxic carbon monoxide released, and the possible transition from smoldering to flaming (eventually leading to rapid fire growth and flash-over) with ignition sources otherwise too weak to directly induce flaming. Smoldering in residential-furniture upholstery materials can be assessed at a bench-scale by using reference materials with consistent smoldering behavior. However, the preparation of a reference foam has proven to be a challenging task, and the bench-scale tests currently in use may underestimate smoldering in actual furniture. The aim of this work is to provide guidance for the selection/development of: (i) a reference flexible polyurethane foam with reproducible and well-characterized smoldering behavior, and; (ii) the development of a bench-scale smoldering test capable of identifying the upholstery materials (e.g., fabric, filling/padding, barrier, welt cord) that most likely prevent smoldering ignition in actual furniture. In the first part of this paper, the impact of foam morphology on smoldering is discussed. It is shown how reticulated flexible polyurethane foams, possibly filled with carbon black, can be exploited as reference foam materials. Their fully open cell structure ensures consistent air permeability with an adjustable smoldering intensity as a function of their average cell size. In the second part of this paper, a bench-scale smoldering test (currently employed in a number of test procedures and standards) is redesigned in such a way that the buoyant airflow within the foam is enhanced. Up to a threefold increase in the rate of smoldering propagation and 400 C increase in smoldering temperature is observed in the modified test as compared to the current tests. Transition to flaming was observed, only in the modified test, when an external enclosure was used. The modified test may offer a near-worst-case scenario, useful to identify the upholstery materials that prevent most smoldering ignitions independent of the construction and geometry of the actual furniture.
InTech eBooks, Nov 30, 2016
The components of wood, especially lignin and cellulose, have great potential for improving the p... more The components of wood, especially lignin and cellulose, have great potential for improving the properties of polymer composites. In this chapter, we discuss some of the latest developments from our lab on incorporating wood-based materials into epoxy composites. Lignosulfonate was used as a flame retardant and cellulose nanocrystals were used as reinforcing materials. Lignosulfonate will disperse well in epoxy, but phase separates during curing. An epoxidation reaction was developed to immobilize the lignosulfonate during curing. The lignosulfonate-epoxy composites were characterized using microcombustion and cone calorimetry tests. Cellulose also has poor interfacial adhesion to hydrophobic polymer matrices. Cellulose fibers and nanocrystals aggregate when placed in epoxy resin, resulting in very poor dispersion. The cellulose nanocrystal surface was modified with phenyl containing materials to disrupt cellulose interchain hydrogen bonding and improve dispersion in the epoxy resin. The cellulose nanocrystal-epoxy composites were characterized for mechanical strength using tensile tests, water barrier properties using standardized water absorption, glass transition temperatures using differential calorimetry, and aggregation and dispersion using microscopic techniques.
Poly(lactic acid) was flame-retarded using cellulose-based intumescing flame retardants. Cellulos... more Poly(lactic acid) was flame-retarded using cellulose-based intumescing flame retardants. Cellulose was found to be an excellent carbon source, and when added in combination with ammonium polyphosphate (APP), PLA composites exhibited good thermal stabilities and UL-94 ratings of V-0. Nanofibrillated cellulose was phosphorylated to eliminate the need for APP. The fibers were further modified by quaternization and with glycidyl phenyl POSS to increase the char yield during pyrolysis. Fibers were analyzed by elemental analysis, potentiometric titration, and thermogravimetric analysis. The composites prepared without APP exhibited good thermal stability, but they failed the UL-94 vertical burn test.
A study of a limited number of commercial fire-retardant coatings (FRCs) designed for wood in out... more A study of a limited number of commercial fire-retardant coatings (FRCs) designed for wood in outdoor applications, film-forming or non-film forming (stains), and top-coatings (used in combination with a FRC to increase its durability) were characterized by microscale combustion calorimetry (MCC) and cone calorimetry (50 kW/m 2). All coatings were applied on western red cedar and according to the manufacturers' specifications. A standard accelerated-weathering protocol alternating cycles of UV, spray, and condensation was used to evaluate the outdoor durability of the coated wood samples. Prior to accelerated-weathering, four of the FRCs showed a significant reduction on the flammability of western red cedar wood with a decrease in peak heat release rate (PHRR) and total heat release (THR). After accelerated-weathering equivalent to an estimated outdoor time of 14 days to 28 days, the cone results revealed that all FRCs became ineffective (no significant reduction in PHRR and THR of the wood substrate). The use of five top-coatings was investigated to extend the durability of FRCs. Only two dual-coated systems based on FRCs and top-coatings maintained good compatibility (no suppression of the intumescent char expansion) and fire behavior. An outdoor durability of up to seven months was estimated based on accelerated-weathering for the best FRC/top-coating combination. After this period, this dual-coated system did not show any flammability reduction by cone calorimetry. The results of this study suggest that weathering drastically reduces the durability and fire resistance of FRCs on wood-based products.
Applied Thermal Engineering, Nov 1, 2020
Buoyant airflow is suppressed by the presence of frame in the standard mock-up. • Buoyant airflow... more Buoyant airflow is suppressed by the presence of frame in the standard mock-up. • Buoyant airflow is enhanced by the presence of air gap in the modified mock-up. • The mechanisms of O 2 supply in the standard and modified mock-ups are revealed. • The smoldering propensity increases with foam thickness in the standard mock-up. • The smoldering propensity decreases with foam thickness in the modified mock-up.
Journal of Fire Sciences, Jul 1, 2019
Cone calorimetric experiments of flexible polyurethane foam (FPUF) and FPUF covered with a variet... more Cone calorimetric experiments of flexible polyurethane foam (FPUF) and FPUF covered with a variety of fire-blocking barrier fabrics (BFs) were used to characterize and rank the effectiveness of BFs for reducing the flammability of residential upholstered furniture (RUF). In addition to BF properties, it was demonstrated that the burning behaviors of the FPUF/BF composites were sensitive to a wide range of experimental parameters including the sample configuration, heat losses to the underlying support base, and the two-stage pyrolysis behavior of the FPUF. Measurements using thermocouples (TCs) placed within the FPUF provided insights on FPUF pyrolysis behavior, the collapse rate of FPUF, and the thermal protective properties of barrier materials.
Polymer Degradation and Stability, Nov 1, 2009
Clay-based SAN nanocomposites with zinc chloride as a catalyst were prepared by the solvent casti... more Clay-based SAN nanocomposites with zinc chloride as a catalyst were prepared by the solvent casting method to explore possible synergistic flame retardant effects involving enhanced char formation using a catalyst and the formation of a surface-protective layer having a clay network structure. Although the heat release rate and total heat release were significantly reduced by the use of this combination, each additive contributed independently without the desired synergism. This is due to the early formation of many small cracks in the surface layer for SAN-clay nanocomposites (vigorous bubbling associated with evolving thermal degradation byproducts were observed in the cracks) while the rapid char formation by zinc chloride occurred only at the late stage of the fire test. Char formation at long times does not prevent the crack formation or crack growth, so that an effective protective surface layer without openings was not obtained.
This manuscript describes a methodology to measure the influence of an upholstery cover fabric to... more This manuscript describes a methodology to measure the influence of an upholstery cover fabric to promote smoldering mass loss of a small-scale mock-up constructed of standard polyurethane foam, a cover fabric, and cotton cover cloth, and a standard cigarette. The primary test metric is total mock-up mass loss after 45 min exposure to the cigarette smoldering ignition source. The testing materials are available through NIST as Standard Reference Material (SRM) 1202: Fabric Smoldering Ignition Testing Materials.
Polymer Degradation and Stability, Mar 1, 2022
Acs Symposium Series, 2012
Poly(lactic acid) was flame-retarded using cellulose-based intumescing flame retardants. Cellulos... more Poly(lactic acid) was flame-retarded using cellulose-based intumescing flame retardants. Cellulose was found to be an excellent carbon source, and when added in combination with ammonium polyphosphate (APP), PLA composites exhibited good thermal stabilities and UL-94 ratings of V-0. Nanofibrillated cellulose was phosphorylated to eliminate the need for APP. The fibers were further modified by quaternization and with glycidyl phenyl POSS to increase the char yield during pyrolysis. Fibers were analyzed by elemental analysis, potentiometric titration, and thermogravimetric analysis. The composites prepared without APP exhibited good thermal stability, but they failed the UL-94 vertical burn test.
Proceedings of the 12th Asia-Oceania Symposium on Fire Science and Technology (AOSFST 2021)
Fire and Materials, 2020
SummaryHerein, we describe a reduced‐scale test (“Cube” test), measuring the fire performance of ... more SummaryHerein, we describe a reduced‐scale test (“Cube” test), measuring the fire performance of specimens including a fire barrier (FB) and a flammable core material, which acts as the main fuel load. The specimen is intended to reproduce a cross‐section of a composite product where heat/mass transfer occurs primarily in a direction perpendicular to the FB. The Cube test procedure and benefits are discussed in this work by adopting residential upholstery furniture as an exemplary study. One flexible polyurethane foam, one polypropylene cover fabric, and 10 commercially available FBs were selected. They were used to compare the fire performance of FBs, measured in terms of peak of heat release rate, in the ASTM E1474‐14 standard test and the newly developed Cube test. Edge effects severely affected the performance of FBs in the ASTM E1474‐14 standard test but not in the Cube test. Furthermore, appropriate test conditions were determined in the Cube test to measure the so‐called “wet...