Cone calorimeter and room corner fire testing of balsa wood core/phenolic composite skin sandwich panels

Transcription

1 Original Article Cone calorimeter and room corner fire testing of balsa wood core/phenolic composite skin sandwich panels Journal of Fire Sciences 2014, Vol. 32(4) Ó The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalspermissions.nav DOI: / jfs.sagepub.com Alexander B. Morgan 1 and Elias Toubia 2 Date received: 16 September 2013; accepted: 11 November 2013 Abstract Polymer composite sandwich core panels are of interest for lightweight construction and portable shelter use. In this article, material selection and construction design were considered for an application which required a high level of fire safety performance. Phenolic + fiberglass skin composites with balsa wood core sandwich panels were constructed and first screened for fire performance with the cone calorimeter (ASTM E1354) at different heat fluxes. From these data, fire testing in the room corner test (ISO 9705) was conducted. The results indicated that these composites could only pass the room corner test if an aluminum skin was used to provide some additional fire protection to the underlying composite. Furthermore, it was found that cone calorimeter testing at very high heat flux (100 kw/m 2 ) was not always indicative of fire performance in the room corner test. How the aluminum skin was mechanically attached to the panel as well as underlying composite construction played an important role in the full-scale fire test results. Keywords Cone calorimeter, room corner, fire protection, composites Introduction The use of polymer composite materials as building and structural materials is an area of continued research and development due to the advantages these materials have over 1 Applied Combustion and Energy Group, Energy Technology and Materials Division, University of Dayton Research Institute, Dayton, OH, USA 2 Department of Civil and Environmental Engineering and Engineering Mechanics, University of Dayton, Dayton, OH, USA Corresponding author: Alexander B Morgan, Applied Combustion and Energy Group, Energy Technology and Materials Division, University of Dayton Research Institute, 300 College Park, Dayton OH , USA. alexander.morgan@udri.udayton.edu

2 Morgan and Toubia 329 Figure 1. Balsa wood core sandwich panel. traditional metal, wood, and inorganic materials. Of more recent interest are lightweight composite sandwich panels for mobile construction applications (rapidly assembled buildings) or lighter weight structural components in vehicle construction. These lightweight assemblies are of interest to improve fuel efficiency or to enable faster mobile construction of emergency shelters. These composites are typically composed of polymer + fiberreinforced composite skins and then a lightweight inner core of foam or balsa wood. An example structure of a balsa wood core composite panel is shown in Figure 1. Depending upon the structural end-use application of these sandwich panels, fire protection of the panels may be needed before the panel can be used. Fire protection of the panel would be dictated by end-use conditions and relevant fire threats. In the case of composite sandwich panels used to construct rapid assembly shelters on deployable maritime ships (such as US Naval amphibious vehicles), the fire protection requirements can be quite strict. Fire protection requirements may look at not just fire safety of the deployed structure but also how the panels behave when exposed to fire conditions at sea. Naval stores should not contribute negatively to the fire threat on board a ship at sea, and therefore, composite panels will need to meet strict fire codes to be certified for use. To that end, full-scale fire test performance, such as the room corner test (ISO 9705), may be required for said sandwich panels to be certified as acceptable for use. Since polymer composites can and will burn under such a test, polymer choice, composite construction, and lightweight core choice must be considered carefully. In an effort to develop a new composite sandwich panel that could be stored aboard ships with excellent fire performance criteria, a bench-scale flammability study was conducted via cone calorimeter (ASTM E1354) to try and predict performance prior to full-scale ISO 9705 testing. The cone calorimeter has been successfully used to establish such correlations for thermoset materials as well as fire performance relevant to regulatory fire tests, 1 6 but some care must be taken in interpreting the data. 7,8 In this report, we outline the results of cone calorimeter testing on phenolic resin + fiberglass skin with balsa wood core sandwich panels and how those test results led to new panel designs and a hybrid phenolic and metal skin system which passed the ISO 9705 room corner test requirements.

3 330 Journal of Fire Sciences 32(4) Material construction and test methods Composite panel construction and materials The construction of the sandwich panels developed in this study consists of fiber-reinforced core (FRC) using lightweight Balsa core (SB50) and E-glass skins (or facesheets) on each side of the sandwich panel. The nonflame retardant containing phenolic resin (J2027L) was supplied by Borden Chemicals, Inc., and a 4.5% acid catalyst (Phencat 382) was used. The lightweight balsa wood (90 kg/m 3 ) was supplied by BALTEK Ò. All panels were infused and molded using the vacuum-assisted resin transfer molding (VARTM) process. Several molding trials were executed and monitored through dynamic mechanical analysis (DMA) testing. The small-scale screening tests showed that full curing in such a sandwich panel construction can be achieved with a cure for 3 h at 60 C (140 F) and a transitional post-cure for 7 h at 98.8 C (210 F). The thickness of the skin (each layer on each side) was composed of two layers of E-glass (woven roving (WR) 18 oz = in), giving a thickness of cm for the phenolic skins. The balsa core thickness was in ( cm). For the phenolic skins, the fiber volume fraction is 48% and the matrix volume fraction is 52%, as expected since VARTM process was used. Panel was manufactured using a low-density balsa (SB50), cut into sticks, and wound with E-glass roving constructing the webs in the FRC. The hot-melt thermoplastic adhesive holding the glass roving to the balsa sticks were incorporated on the inside and the outside surface of the core sticks. The top skin layup was constructed of two plies [0/90] knitted E-glass and the bottom thicker skin facing the fire with four plies [0/90] knitted E-glass. Panel has the same layup and construction as panel , but with less amount of hot-melt thermoplastic adhesive in the core. Both panels were molded using the same curing and post-curing cycle established and outlined in the composite panel construction section. Composite mechanical testing Mechanical testing was conducted according to the ASTM specifications (C-393, C-297, and C-365), using a hydraulic MTS machine capable of controlling the load with an accuracy of 61%. All samples were conditioned under standard control temperature (23 C 6 3 C) and humidity (50%). Test specimens were similar to the end-use product with molded skins and the manufacturing process outlined in the previous section. Flammability testing cone calorimeter Balsa wood core with phenolic skin panels or phenolic skin + aluminum skin panels was tested as received (no conditioning) other than allowing the samples to sit out in the laboratories for 24 h prior to testing. Laboratory humidity ranged between 25% and 35% during the dates of testing. Cone calorimeter experiments were conducted on a FTT Dual-Cone Calorimeter at four heat fluxes (25, 50, 75, and 100 kw/m 2 ) with an exhaust flow of 24 L/s using the standardized cone calorimeter procedure (ASTM E ). All samples were tested with frame and no grid, with the backside of each sample wrapped in aluminum foil. Silica wool was used on the backside of all samples, as per ASTM E1354. All samples were tested in triplicate unless indicated otherwise. Due to the force of delamination sometimes

4 Morgan and Toubia 331 encountered with the phenolic skins upon heating, the frame and grid were held down with additional metal clamps which held the frame to the ASTM standard sample holder with greater strength. The clamps would typically grip onto the frame holder screws and then connect to the metal flanges on the bottom part of the sample holder. Data collected from all samples are believed to have an error of 610% as per guidance from the ASTM E1354 standard and were calculated using a specimen surface area of 88.4 cm 2. After each sample was tested, the data were averaged to give a more composite picture of flammability performance for each sample. Flammability testing room corner tests Full-scale room corner burn tests were conducted by Southwest Research Institute (Fire Technology Department, San Antonio, TX, USA) as per ISO The burner used for the experiments was a propane gas burner capable of reaching 100 and 300 kw intensities. Burner position was as indicated for the corner burn requirement under ISO Results and discussion In our efforts to develop a composite sandwich panel that could meet fire requirements for the room corner burn relative to Navy Standard DDS-078-1, 9 we undertook an iterative approach to composite design which was driven by fire test results. Our approach was to begin with low heat release materials, mold and cure a panel, test it in the cone calorimeter, and then study the cone calorimeter results to confirm a potential design for scale-up. Based upon the cone calorimeter heat release interpretation, panels would be produced for the room corner test, and pass/fail results would be compared to cone calorimeter results to further advance the design of the composite system. The beginning of the research focused on phenolic resin + fiberglass skins with balsa wood cores. Phenolic resin was chosen due to its known low heat release, 10,11 and balsa wood was chosen due to its known low heat release and propensity to char when compared to polymeric foams sometimes used in sandwich panels. 12,13 The structural demand for this application dictated the use of the FRC. After construction of the panels, one panel of was cut into cm (4 in) square pieces for cone calorimeter testing at four different heat fluxes. The overall results for these four different heat fluxes are shown in Table 1, and the fire behavior and heat release rates (HRRs) for the panel at the four different heat fluxes are described below at 25 kw/m 2 heat flux Upon exposure to the cone heater, the samples slowly darkened and then began to smoke, but two of the samples never ignited even after 30 min (1800 s) of heat exposure. One sample did ignite though, but did not burn very long nor very intensely. This can be seen in the HRR curves for this sample (Figure 2) as well as in the chars (Figure 3). The middle sample in Figure 3 shows some additional fire damage to the surface skin, but the underlying balsa is only slightly damaged. The other two samples show darkened phenolic at the edges (where the sample was protected by the frame holder) and only a slight amount of charring of the balsa.

5 332 Journal of Fire Sciences 32(4) Table 1. Heat release data for panel Sample description Sample thickness (mm) Time to ignition (s) Peak HRR (kw/m 2 ) Time to Peak HRR (s) Average HRR (kw/m 2 ) Starting mass (g) Total mass loss (g) Total heat release (MJ/m 2 ) Total smoke release (m 2 /m 2 ) MARHE (kw/m 2 ) FIGRA (kw/m 2 )/s kw/m Heat flux Average data 43.1 N/A kw/m Heat flux Average data kw/m Heat flux Average data kw/m Heat flux Average data HRR: heat release rate; FIGRA: fire growth rate; MARHE: maximum average rate of heat emission.

6 Morgan and Toubia 333 Figure 2. HRR for sample at 25 kw/m 2 heat flux. HRR: heat release rate at 50 kw/m 2 heat flux Upon exposure to the cone heater, there was no immediate reaction, but shortly after exposure to the heater, there was some crackling and popping heard from the sample. This was followed by evolution of smoke and charring/blackening of the surface. The sample ignited with slow flame spread growth across the sample surface. The sample burned for a while and then finally extinguished. HRR behavior was reproducible (Figure 4) with some irregularities in the time to ignition and peak HRR noted. Final chars (Figure 5) showed places on the skin where the carbon had been burned away (showing the glass fiber) and charring of the balsa about halfway into the specimen at 75 kw/m 2 heat flux Upon exposure to the cone heater, the sample immediately began to pop and crackle, followed by smoke formation, charring of the surface, additional loud pops, and finally ignition. Smoke was observed coming out the bottom of the sample holder frame, along with occasional flames. The samples took a very long time to extinguish and had a very long, low HRR intensity burn. HRR was very reproducible (Figure 6), and the final chars (Figure 7)

7 334 Journal of Fire Sciences 32(4) Figure 3. Final chars for sample at 25 kw/m 2 heat flux (the sample in the middle is the only one which is ignited). Figure 4. HRR for sample at 50 kw/m 2 heat flux. HRR: heat release rate. show heat damage through the specimen, and there are places in the balsa area where the balsa appears to have undergone extensive thermal damage. Late into the burn of this specimen, one can hear some pops coming from inside the specimen, and likely these sounds are

8 Morgan and Toubia 335 Figure 5. Final chars for sample at 50 kw/m 2 heat flux. Figure 6. HRR for sample at 75 kw/m 2 heat flux. HRR: heat release rate. caused by bursts of gas releasing from the charring balsa which in turn damages the balsa char structure further, leading to the voids we observed on the sides of these specimens tested at this heat flux.

9 336 Journal of Fire Sciences 32(4) Figure 7. Final chars for sample at 75 kw/m 2 heat flux at 100 kw/m 2 heat flux Fire behavior for this sample was identical to that seen at the 75 kw/m 2 heat flux described above. HRR was reproducible in the first 500 s (Figure 8) although there are some deviations in HRR shape and intensity (minor ones) between 500 and 2000 s. Very likely these differences are from the high heat flux burning through the top surface skin and causing additional heat damage deeper in the sample. The final chars for this sample (Figure 9) show heat damage throughout the specimen, and right under the surface skins, the balsa is heavily damaged (white ash only in some spots). The surface skins are almost solely white in color (no remaining carbon left). Some pops were heard late in the burns of these specimens, probably again caused by bursts of gas coming from the burning/charring balsa. Overall, as heat flux increased, HRRs increased and time to ignition shortened, as expected, but fire performance of the panels still suggested that the low heat release of the materials may perform well in larger scale fire tests. With these results in hand, the panels were scaled up and tested in the ISO 9705 room corner test. In this standard test, there are different performance criteria, and the performance criteria for Fire Restrictive Materials were selected. A total of six measurements were focused on during the room corner test including the following: HRR p,n : peak net heat release averaged over any 30-s time period during the test. HRR avg,n : average net HRR. SPR p : peak smoke production rate averaged over any 60-s time period during the test. SPR avg : average smoke production rate. Visual flame spread observations. Flaming droplet or debris observations. The results of the room corner test conducted on panel (see description above) are shown in Table 2. An image showing what the panels looked like prior to the room corner test is shown in Figure 10. From the results in Table 2, the material failed the test. The test was terminated at 16 min due to an excessive HRR (.1.2 MW) building up in the room. Post test, the panels were examined to understand why they failed, and upon closer examination, the results indicated that the panels were not completely burned through, but rather fit the behavior observed for the 50 kw/m 2 heat flux samples in the cone calorimeter, with the surface skin

10 Morgan and Toubia 337 Figure 8. HRR for sample at 100 kw/m 2 heat flux. HRR: heat release rate. Figure 9. Final chars for sample at 100 kw/m 2 heat flux. damaged but the balsa core only charred halfway through (Figure 11). Where the flame was most intense, the surface skin was badly damaged (Figure 12), but even in these spots, the damage to the balsa core was similar to that seen at the 50 kw/m 2 heat flux. This suggested that additional phenolic resin and balsa wood alone would not enable a pass of the ISO

11 338 Journal of Fire Sciences 32(4) Table 2. Summary of ISO 9705 test results for panel Material HRR p,n (kw) HRR avg,n (kw) SPR p (m 2 /s) SPR avg (m 2 /s) Flame spread Flaming droplets or debris N/A N/A Allowed limits Note A Note B HRR: heat release rate; SPR: smoke production rate. Note A: flame spread must not reach any further down the walls than 0.5 m from the test room floor, excluding the area within a 1.2-m radius of the ignition corner. Note B: no flaming droplets or debris was allowed to fall onto the test room floor excluding the floor area that is within a 1.2-m radius of the ignition corner. Figure 10. Room corner panels before test showing roof and sidewalls. Figure 11. Room corner panels after test (showing panels as constructed in the room corner burn test) test and some engineering measures would be needed to buy more ignition time in the structure and improve surface skin durability against flame exposure. Use of even lower heat release resins such as polyimides or ceramic foams was not a cost-effective or practical alternative to the use of engineering measures.

12 Morgan and Toubia 339 Figure 12. Surface skin burned away on ceiling panel directly under corner burner. As stated previously, increasing the polymer and composite portion in the panel penalized the fire performance of the panel by increasing the HRR or the tendency of the material to catch fire. This led to the development of the panel with cladded aluminum sheeting (6061T6 alloy) facing the fire side. Panel had a symmetrical skin layup with two plies of [0/90] E-glass WR. The same practice and level of curing executed on previous panel constructions was maintained. After post-curing, the aluminum sheets with thickness of 1.57 mm were cladded to the fire side or the interior of the structure. The aluminum sheets were attached to the panels using stainless steel bolts, penetrating the whole thickness of the sandwich panel and constructing a grid pattern. This mechanical attachment pattern prevented failure in the ISO 9705 due to flaming droplets or debris reaching the floor. Specifically, it prevented the aluminum skin from falling off in large pieces during burning as the aluminum began to soften and melt. With the aluminum metal skins in place, 4 in square specimens from panel were cut and 1.57 mm (0.062 in, 62 mil) aluminum skins were bolted in place. Bolting of the skin was necessary for the skins as the full panel would have bolts, and it was desirable to see how a mock-up would perform in the cone calorimeter test. Furthermore, some earlier experiments with the aluminum skins in the cone calorimeter found that if the aluminum skin was not attached to the cone calorimeter sample, the skin would deform and give artificial results. At a heat flux of 50 kw/m 2, the sample could not be ignited. Given the results of the room corner test, we could infer that not all the balsa charred away, but a more intense heat source would be needed to mimic the start of the room corner test and its flame source. With this, the samples were tested at a heat flux of 100 kw/m 2 to obtain some heat release information for study and to see how the aluminum skin would perform. Upon exposure to the cone heater, the sample did very little. Without the aluminum skin, the previously tested phenolic samples ignite around 50 s at this heat flux. With the aluminum skin, the time to ignition was around 300 s, almost a full 250 s in delayed ignition. Some popping and crackling were heard before ignition, but the sample was not seen to delaminate at all. Closer to ignition, smoke was observed coming out at the edges of the sample holder, which makes sense in that the smoke cannot penetrate the aluminum skin and must go around the edges of the sample holder. As the test progressed, the surface of the sample was observed to warp and change colors, becoming white in some places where the aluminum had completely oxidized. Heat release (Figure 13) showed reasonable

13 340 Journal of Fire Sciences 32(4) Figure 13. (a) Heat release for sample with 62 mil (1.57 mm) aluminum skin and (b) mass loss curve comparing aluminum skin with composite panel containing no aluminum skin.

14 Morgan and Toubia 341 Figure 14. Final char of sample mil aluminum skin. reproducibility. The final chars (Figure 14) showed significant damage to the aluminum skins with charring throughout the sample. While the test was stopped manually at 1800 s since the heat release had become steady at kw/m 2 for over 5 min (mass loss had decreased as well), it is clear that the aluminum skin was still shielding the underlying material allowing the sample to convert to char and therefore combust/smolder very slowly. Should the test have gone longer, it is very likely that the sample would have continued this low heat release for a long time, but the flames never would have increased further. The mechanism of fire protection provided by the aluminum skin is likely a combination of thermal insulation and infrared reflection. The delay in time to ignition is probably due to infrared reflection, with some heat being reflected away from the sample. 14 This delay in ignition also delays thermal decomposition of the underlying composite, and once the sample does ignite, the aluminum skin provides additional protection as a burn-through barrier (meaning the flame has to burn through/melt away the aluminum) and probably over time begins to become a thermal insulator as the aluminum metal is converted to lower thermal conductivity aluminum oxide. Once the thermal insulator is in place, HRR/mass loss is lowered (Figure 13), and the underlying material is more able to char than burn away over the duration of the test. Data for this sample in comparison to sample are shown in Table 3. The addition of the aluminum metal skin does more than just delay ignition; it also lowers peak HRR, delays time to peak HRR, lowers total heat and smoke release, and lowers other flammability properties as well. Even if it does eventually burn through, it still provides some fire protection throughout the test. Panel with the aluminum skin was taken into ISO 9705 room corner tests and tested, with passing results obtained. Just as seen in the cone calorimeter, the aluminum metal skin provided delays in ignition to the underlying phenolic composite and provided heat release reductions as well. The results from the room corner test are shown in Table 4, and the improvement over the phenolic with no aluminum metal skin is quite noticeable. At the end of the test, the aluminum metal that melted away can be easily seen (Figure 15), but the underlying composite shows char damage, but not as much damage as was observed when the aluminum skin was absent. Upon passing the fire tests, a full test characterization of the sandwich core mechanical properties was evaluated and tested. Table 5 shows the test results, failure modes, and properties of the final certified Fire restricting materials sandwich panel design.

15 342 Journal of Fire Sciences 32(4) Table 3. Heat release data for 100 kw/m 2 phenolic + balsa wood samples with and without aluminum metal skins (62 mil = 1.57 mm). Sample description Sample thickness (mm) Time to ignition (s) Peak HRR (kw/m 2 ) Time to peak HRR (s) Average HRR (kw/m 2 ) Starting mass (g) Total mass loss (g) Total heat release (MJ/m 2 ) Total smoke release (m 2 /m 2 ) MARHE (kw/m 2 ) FIGRA (kw/m 2 )/s kw/m Heat flux Al Skin (62 mil) kw/m 2 HRR: heat release rate; FIGRA: fire growth rate; MARHE: maximum average rate of heat emission.

16 Morgan and Toubia 343 Table 4. Summary of ISO 9705 test results, panel Material HRR p,n (kw) HRR avg,n (kw) SPR p (m 2 /s) SPR avg (m 2 /s) Flame spread Flaming droplets or debris (aluminum skin) Pass Pass (no aluminum skin) N/A N/A Allowed limits Note A Note B HRR: heat release rate; SPR: smoke production rate. Note A: flame spread must not reach any further down the walls than 0.5 m from the test room floor, excluding the area within a 1.2-m radius of the ignition corner. Note B: no flaming droplets or debris was allowed to fall onto the test room floor excluding the floor area that is within a 1.2-m radius of the ignition corner. Table 5. Summary of mechanical properties, panel Core mechanical properties Panel ID (average values) Test method Failure mode Compressive strength, C z (MPa) 6 ASTM C-365 Core compression Compression modulus, E z (MPa) 345 asymmetrical Tensile strength, T z (MPa) 1.5 ASTM C-297 Face core debond Tensile modulus, E Z (MPa) 62 Core shear strength, L direction, S LZ (MPa) 1.55 ASTM C-393 Core shear stress Core shear modulus, L direction, G LZ (MPa) 221 Core shear strength, T direction, S TZ (MPa) 1 Core shear modulus, T direction, G TZ (MPa) 131 L-direction along the webs; T-direction across the webs. Figure 15. Ceiling of room corner test with panel post test.

17 344 Journal of Fire Sciences 32(4) Conclusion To achieve a high level of fire performance, low heat release materials plus the use of a metal shield were used to pass maritime fire restriction requirements in the ISO 9705 test. Cone calorimeter screening was useful, but it did not mimic all the flame exposure phenomena that were observed in actual room corner testing. For example, very high heat fluxes in the cone calorimeter may have mimicked the hotter more intense part of the flame in the room corner test, but it did not mimic the thermal damage actually encountered during the room corner test. Instead, the cone calorimeter was a useful tool for measuring how a protection scheme might affect heat release in the room corner test. In the cone calorimeter, the ability of the aluminum metal skin to delay ignition, lower heat release, and act as a thermal shield was confirmed, similar to what was observed in the room corner test. Overall, the results from cone calorimeter and room corner test make it clear that for fire restrictive composite sections, just using low heat release materials is not sufficient. Additional built-in engineering fire protection is needed and aluminum skins serve that role, provided they are bolted properly to the composite structure. Acknowledgements The authors wish to express their special appreciation to Dr Rob Banerjee and Mr Michael Sheppard of NexGen Composites LLC and Mr John Ducote of Naval Surface Warfare center NAVSEA. UDRI would like to thank Mary Galaska and Kathy Schenck for conducting the cone calorimeter and thank John Stalter for assistance with building a simple clamping device to hold the frame to the sample holder during cone calorimeter testing. Declaration of conflicting interests The authors declare that there is no conflict of interest. Funding This work was supported by the US-NAVY SBIR phase III contract no. N C References 1. Sidor/default.aspx (accessed 20 August 2013) 2. Morgan AB and Bundy M. Cone calorimeter analysis of UL-94 V-rated plastics. Fire Mater 2007; 31: Bartholmai M and Schartel B. Assessing the performance of intumescent coatings using bench-scaled cone calorimeter and finite difference simulations Fire Mater 2007; 31: Quintiere J and Lian D. Inherent flammability parameters room corner test application. In: Proceedings of Fire and Materials 2007 conference, San Francisco, CA, January London: Interscience Communications. 5. Cogen JM, Lin TS and Lyon RE. Correlations between pyrolysis combustion flow calorimetry and conventional flammability tests with halogen-free flame retardant polyolefin compounds. Fire Mater 2009; 33: Laymon RK, Borgerson JL, Ghandhi PD, et al. Use of bench-scale test methods to predict the fire growth of large-scale room corner tests for building materials. In: Proceedings of Fire and Materials 2009 conference, San Francisco, CA, January 2009, pp London: Interscience Communications. 7. Schartel B, Bartholmai M and Knoll U. Some comments on the use of cone calorimeter data. Polym Degrad Stabil 2005; 88: Schartel B and Hull TR. Development of fire-retarded materials interpretation of cone calorimeter data. Fire Mater 2007; 31: NAVSEA DDS-078-1:2004. Composite materials, surface ship, topside structural and other topside applications fire performance requirements. 10. Morgan AB, Gagliardi NA, Price WA, et al. Cone calorimeter testing of S2 glass reinforced polymer composites. Fire Mater 2009; 33: Walters RN and Lyon RE. Molar group contributions to polymer flammability. J Appl Polym Sci 2002; 87: Ulven CA and Vaidya UK. Post-fire low velocity impact response of marine grade sandwich composites. Composites Part A: Appl S 2006; 37:

18 Morgan and Toubia Ulven CA and Vaidya UK. Impact response of fire damaged polymer-based composite materials. Composites Part B: Eng 2008; 39: Schartel B, Beck U, Bahr H, et al. Sub-micrometre coatings as an infrared mirror: a new route to flame retardancy. Fire Mater 2012; 36: Author biographies Alexander B. Morgan received B.S. degree in chemistry from the Virginia Military Institute (1994) and received a PhD in chemistry from the University of South Carolina in He is a Distinguished Research Scientist and Group Leader of at the University of Dayton Research Institute (UDRI) and has been working in the field of fire safe materials for over 18 years. Elias Toubia graduated from the Lebanese University with a B.S. in Civil Engineering, and holds an M.S. in Civil Engineering and a PhD in Materials Engineering from the University of Dayton. He is currently an Assistant Professor of Civil and Environmental Engineering and Engineering Mechanics at the University of Dayton and has over 12 years of experience in structural materials and composites.