Composites Part A: Applied Science and Manufacturing
Effect of resin type and glass content on the reaction to fire characteristics of typical FRP composites
Introduction
Traditionally, the manufacture of composites is largely a guess and check operation with regards to fire characteristics. The original design composite is tested via standard fire tests but the composite would need to be re-tested if the resin type or glass content was changed, possibly without knowing if the change will positively affect the test results. The testing cycle can be time consuming and expensive. However, if the manufacturer had an idea of how changing the resin type or glass content would affect the results, this would provide a guideline to ease the time and financial commitment of manufacturing fire-safe composites. The current work aims to provide a beginning to systematic research into how changing the resin type and glass content affects the fire characteristics of typical fiber reinforced polymer composites.
Bench-scale apparatuses such as the Fire Propagation Apparatus (FPA, ASTM E 2058 [1]) and the Cone Calorimeter (ASTM E 1354 [2]) are used in this study to provide useful data which can be used in a fire model to simulate burning. In the fire community, using data similar to that which will be developed in this study as parameters in a fire model in order to simulate the end use of the material is the long-term goal [3]. Significant steps were taken toward this goal with the development of the Fire Dynamics Simulator (FDS) developed at the National Institute for Standards and Technology [4] and other computational fluid dynamics (CFD) based fire models [5], [6]. A subset of these more comprehensive models is the pyrolysis model, which describes the heating and decomposition of the material. A good review of pyrolysis models is available in the literature [7]. From the composites literature [8], [9], [10], [11], there is a significant amount of work on the temperature profile of composites with regards to thermo-mechanical stability. These studies incorporate a comprehensive pyrolysis model but focus more on temperatures at depth instead of temperatures at or close to the surface, which are more important for reaction to fire characteristics.
The current work aims to obtain data from bench-scale test apparatuses that can be used to both differentiate the composites according to resin type and glass content as well as provide a good data set for calibration of pyrolysis models such as that being developed at the University of California, Berkeley [12]. While traditional bench-scale measurements such as heat release rate and mass loss rate were used, measuring surface and in-depth temperatures as well as changing the environment to which the sample is exposed give additional insight into the behavior of the composites and provide the beginning of a data set useful for modelling purposes. The minimum heat flux for proper ignition, a common fire engineering “property,” was determined for all of the composites by varying the applied heat flux to the material. Following the homogeneous material paradigm currently used in fire engineering, a simple parameter estimation to determine the thermal diffusivity, thermal conductivity and specific heat was completed in an attempt to further differentiate the composites.
Section snippets
Composite systems
In the following discussion, the term “system” will be used to differentiate between resin types (e.g. System 1 is a polyester). The term “sample” will be used to differentiate between glass contents (e.g. sample 1A has a lower glass content than sample 1B). Lastly, the term “specimen” will be used to represent one individual composite from the sample that will be tested.
Eleven different fiber reinforced polymer (FRP) samples were tested for the current work. There was a total of four different
Proper and improper ignition
The concept of proper ignition that was used in this study is an extension of the concept of “sustained flaming” that was developed in ASTM E 2058 [1]. The standard defines sustained flaming as the “existence of flame on or over most of the specimen surface for at least a 4 s duration” [1]. Since one of the goals of this study is to produce useful data for the development of pyrolysis models, a fully developed flame cone is necessary to make the simplifying assumption of one-dimensional burning.
Results
Many aspects of the composites were studied through the use of an extensive testing matrix geared toward calibration of a pyrolysis model and comparing glass content and resin type of the different composites. As discussed in the previous section, tests were also done with 1A and 3C in the FPA at 50 kW/m2 under air, nitrogen and 40% oxygen enhanced air. Since no difference in the temperature profile was determined and this is not the main focus of the current study, these results will not be
Parameter estimation
The current paradigm in fire engineering for estimation of pyrolysis parameters is to consider all materials to be homogeneous with constant properties. The parameters estimated are then effective values that have the heterogeneous nature of any given material implicitly incorporated. In particular the thermal diffusivity, thermal conductivity and specific heat are commonly estimated assuming an inert homogeneous solid with constant properties and thermally thick behaviour (semi-infinite) with
Conclusions and future work
The results of this study can be important to the composites industry because it is the beginning of systematic research into how the resin type and the glass content affect the overall fire performance of composites. The resin type was found to affect the resultant fire performance, however the effect of glass content was a little more subtle. For example, there was a difference in the peak heat release rate (see Fig. 1) with glass content for the System 1 composites but there was no
Acknowledgements
The significant support for this project from FM Global Research (FM Global Fellow Avila and FM Global Scholar Dembsey) is greatly appreciated. The technical support of Patricia Beaulieu, Steve Ogden, Dana Capron and Lawney Crudup at FM Global throughout this project was very helpful. Discussions with Chris Lautenberger at the University of California, Berkeley regarding data useful for pyrolysis modelling was instrumental in creating the testing matrix. The authors greatly appreciate the
References (24)
- Standard methods of test for measurement of synthetic polymer material flammability using a fire propagation apparatus...
- Standard test method for heat and visible smoke release rates for materials and products using an oxygen consumption...
- Bill RG, Croce PA. The international FORUM of fire research directors: a position paper on small-scale measurements for...
- McGrattan KB, Forney GP. Fire dynamics simulator (Version 4), User’s guide, NIST special publication 1019, National...
- et al.
An updated international survey of computer models for fire and smoke
J Fire Protect Eng
(2003) - Cox G, Kumar S. Chapter 3–8: modeling enclosure fires using CFD. The SFPE handbook of fire protection engineering....
- Lautenberger C, Fernandez-Pello C. Pyrolysis modeling, thermal decomposition, and transport processes in combustible...
- et al.
Sensitivity and uncertainty analyses for FE thermal model of FRP panel exposed to fire
Composites A
(2006) - et al.
Polymer composites in fire
Composites A
(2006) - et al.
Properties of composite materials for thermal analysis involving fires
Composites A
(2006)
Finite element modeling of fire degraded FRP composite panels using a rate dependent constitutive model
Composites A
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