Final Report Summary - PREDFIRE-NANO (Predicting Fire Behaviour of Nanocomposites from Intrinsic Properties)
The 'Predicting fire behaviour of nanocomposites from intrinsic properties' (PREDFIRE-NANO) project is developing a methodology to predict the real-scale burning behaviour of polymer nanocomposites from their intrinsic material properties. The development and availability of new fire retardant polymers over the last ten years has been driven by:
(a) the abandonment of halogen based fire retardants due to regulations
(b) the growth of nanotechnology
(c) the application of performance based fire safety engineering and
(d) the adoption of European harmonising tests such as the SBI (Single burning ttem).
Especially promising for their fire retardancy has been the discovery of nanocomposites (nanoclay), which have distinct advantages over traditional fire retardants in production, amount of additive (only 2-5 % compared to 20-70 %) and recycling (simple clays). In addition, concurrent work investigated the use of traditional fire retardants together with nanocomposites to enhance the fire retardancy by promoting char formation during decomposition and thus, reducing the gases that can burn in the fire.
Serious impediments to the development of these materials are the absence of a fundamental methodology and tests to accurately and correctly assess their flammability and burning behaviour in fires. Standards approval tests (such as the limited oxygen index LOI and UL94), that were accepted for halogenated fire retardant polymers, are not capable of realistically assessing the fire behaviour of polymer nanocomposites (or even the large scale behaviour of halogenated fire retardant polymers, e.g. cables).
On the other hand, small-scale fundamental experiments (such as thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) which measures the decomposition kinetics and energetics and FTIR (Fourier transform infrared spectroscopy) are not sufficient to predict the fire behaviour of the materials. This work will combine measurements in these small scale apparatus and measurements in intermediate apparatus (the standard cone calorimeter or the universal flammability apparatus (UFA)) to identify key properties of the pyrolysis chemistry that underpin the fire behaviour of the materials. It has been shown that measurements (at various heat fluxes on the material) in the UFA can provide effective global flammability (i.e. thermal, ignition and pyrolysis) properties that predict the fire growth behaviour of the simple, non-composite materials in real fires). However, further work proposed here will provide the properties needed to predict the burning behaviour and emission of smoke and toxic products from nanocomposite materials in real fires.
The project has been extended in 2007 by an additional partner from Russia (FIRE RAS Lab of spectroscopy and millimetre wave measurements) with work related to:
a) examining the monodispersity of nanocomposite polymers by measuring their dielectric properties through mm wave radiation and
b) measuring surface temperature by reflection of mm wave radiation.
The work and the budget for which Swintex was responsible was reassigned to CDCMP and ENSCL with the approval of the commission.
Project objectives
This project has developed a methodology for the evaluation of flammability and safe design of fire materials. To achieve this aim, the plan was to:
a) relate the intrinsic flammability properties to the nanodispersion of the base material modified by nanoparticles and / or fire retardants
b) relate and predict the real fire behaviour of polymeric materials using intrinsic properties measured in small scale apparatus such as the TGA, DSC combined with EGA (evolved gas analysis such as FTIR) as well as in intermediate scale apparatus such as the cone calorimeter and tube furnace
c) explore the design of new fire safe materials.
These objectives expand beyond the current state of the art of fire retarded materials which is based on trial formulations that can only be evaluated doing large scale fire tests.
Overall self-assessment
PREDFIRE-NANO made significant progress in:
a) quantitatively modelling the fire retarding action of nanoparticles regarding their shielding action on the surface of the pyrolysing nanocomposite polymer
b) modelling microscale measurements to mesoscale fire behaviour
c) modelling mesoscale to large scale behaviour and
d) proposing promising combinations of nanoparticles, chemical (phosphinated based) fire retardant and intumescent paints.
Researchers were also invited by Springer Verlag to write a book on nanocomposite polymers and suggested to the EC could fund the writing of this book as they have run out of time in this project given also the fact that there will be about EUR 100,000 surplus in the funding of the project owing to the variability of the exchange rate.
Major results and impact on industry
1. An impressive wealth of data has been collected for six different fire retarded polymers PA6, PP, PBT, EVA, Flaxboard + intumescent Char17, and PP +Flax fiber. The data include measurements for the characterisation for monodispersity (XRD, TEM, NMR, rheometry), data for intrinsic flammability properties (TGA, DSC, MDSC, ATR, char strength, smoke point), data in intermediate scale pyrolysis and flame (tube furnace, cone calorimeters) and large scale fire data (SBI test, 1/3 scale ISO room tests with different openings). All these data included in an edited CD provided to the commission are recommended that they should be published in a book.
2. Monodispesrsity of the nanocomposites can be characterised well by increased dynamic viscosity via rheometry which gives consistent results with the other techniques, i.e. XRD, TEM, NMR. The Russian partner also demonstrated that nonodispersity and uniformity can be measured using millimetre wavelength determination of eth dielectric properties of the nanocomposite polymer.
3. Microscale to mesoscale modelling for nanocomposite polymers in fire. An important achievement was the development and demonstration of a methodology to relate microscale (intrinsic) properties to mesoscale (cone calorimeter) pyrolysis and burning.
4. Mesoscale to large scale modelling: a methodology was developed to model the large scale behaviour from mesoscale and microscale properties using CFD modelling. However, it has not been completely successful because the FDS code has deficiencies not previously known. Namely, it predicts lower flame temperatures and soot and hence lower heat fluxes to the pyrolysing material which do not allow the fire to spread as the experiments show. The use of a combination nanofillers and phosphinates would provide the optimum fire retardant solution both for large scale fires as well as for the small questionable flammability tests.
5. Formulations of fire retardant plus nanocomposite: combinations of fire retardant chemical and nanocomposite have been shown to provide a product that reduces flammability (fire growth), tendency to dripping and allows processability from raw or recyclable materials.
Two areas that have not completely been resolved in this work are related to the ease of ignition and smoke production. The only polymer formulation that is superb is EVA+MH (orATH) and nanofiller. However, to make other nanocomposite polymer (NCP) formulations suitable substitutes for brominated fire retardants, ignition must be delayed. The phosphinate fire retardant causes earlier ignition than the NCP and produces twice as much smoke per unit mass pyrolysed. One approach resulting from this programme is to apply on the surface of NCP a intumescent coating such Char 17 which has been provided by a partner in this project.
(a) the abandonment of halogen based fire retardants due to regulations
(b) the growth of nanotechnology
(c) the application of performance based fire safety engineering and
(d) the adoption of European harmonising tests such as the SBI (Single burning ttem).
Especially promising for their fire retardancy has been the discovery of nanocomposites (nanoclay), which have distinct advantages over traditional fire retardants in production, amount of additive (only 2-5 % compared to 20-70 %) and recycling (simple clays). In addition, concurrent work investigated the use of traditional fire retardants together with nanocomposites to enhance the fire retardancy by promoting char formation during decomposition and thus, reducing the gases that can burn in the fire.
Serious impediments to the development of these materials are the absence of a fundamental methodology and tests to accurately and correctly assess their flammability and burning behaviour in fires. Standards approval tests (such as the limited oxygen index LOI and UL94), that were accepted for halogenated fire retardant polymers, are not capable of realistically assessing the fire behaviour of polymer nanocomposites (or even the large scale behaviour of halogenated fire retardant polymers, e.g. cables).
On the other hand, small-scale fundamental experiments (such as thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) which measures the decomposition kinetics and energetics and FTIR (Fourier transform infrared spectroscopy) are not sufficient to predict the fire behaviour of the materials. This work will combine measurements in these small scale apparatus and measurements in intermediate apparatus (the standard cone calorimeter or the universal flammability apparatus (UFA)) to identify key properties of the pyrolysis chemistry that underpin the fire behaviour of the materials. It has been shown that measurements (at various heat fluxes on the material) in the UFA can provide effective global flammability (i.e. thermal, ignition and pyrolysis) properties that predict the fire growth behaviour of the simple, non-composite materials in real fires). However, further work proposed here will provide the properties needed to predict the burning behaviour and emission of smoke and toxic products from nanocomposite materials in real fires.
The project has been extended in 2007 by an additional partner from Russia (FIRE RAS Lab of spectroscopy and millimetre wave measurements) with work related to:
a) examining the monodispersity of nanocomposite polymers by measuring their dielectric properties through mm wave radiation and
b) measuring surface temperature by reflection of mm wave radiation.
The work and the budget for which Swintex was responsible was reassigned to CDCMP and ENSCL with the approval of the commission.
Project objectives
This project has developed a methodology for the evaluation of flammability and safe design of fire materials. To achieve this aim, the plan was to:
a) relate the intrinsic flammability properties to the nanodispersion of the base material modified by nanoparticles and / or fire retardants
b) relate and predict the real fire behaviour of polymeric materials using intrinsic properties measured in small scale apparatus such as the TGA, DSC combined with EGA (evolved gas analysis such as FTIR) as well as in intermediate scale apparatus such as the cone calorimeter and tube furnace
c) explore the design of new fire safe materials.
These objectives expand beyond the current state of the art of fire retarded materials which is based on trial formulations that can only be evaluated doing large scale fire tests.
Overall self-assessment
PREDFIRE-NANO made significant progress in:
a) quantitatively modelling the fire retarding action of nanoparticles regarding their shielding action on the surface of the pyrolysing nanocomposite polymer
b) modelling microscale measurements to mesoscale fire behaviour
c) modelling mesoscale to large scale behaviour and
d) proposing promising combinations of nanoparticles, chemical (phosphinated based) fire retardant and intumescent paints.
Researchers were also invited by Springer Verlag to write a book on nanocomposite polymers and suggested to the EC could fund the writing of this book as they have run out of time in this project given also the fact that there will be about EUR 100,000 surplus in the funding of the project owing to the variability of the exchange rate.
Major results and impact on industry
1. An impressive wealth of data has been collected for six different fire retarded polymers PA6, PP, PBT, EVA, Flaxboard + intumescent Char17, and PP +Flax fiber. The data include measurements for the characterisation for monodispersity (XRD, TEM, NMR, rheometry), data for intrinsic flammability properties (TGA, DSC, MDSC, ATR, char strength, smoke point), data in intermediate scale pyrolysis and flame (tube furnace, cone calorimeters) and large scale fire data (SBI test, 1/3 scale ISO room tests with different openings). All these data included in an edited CD provided to the commission are recommended that they should be published in a book.
2. Monodispesrsity of the nanocomposites can be characterised well by increased dynamic viscosity via rheometry which gives consistent results with the other techniques, i.e. XRD, TEM, NMR. The Russian partner also demonstrated that nonodispersity and uniformity can be measured using millimetre wavelength determination of eth dielectric properties of the nanocomposite polymer.
3. Microscale to mesoscale modelling for nanocomposite polymers in fire. An important achievement was the development and demonstration of a methodology to relate microscale (intrinsic) properties to mesoscale (cone calorimeter) pyrolysis and burning.
4. Mesoscale to large scale modelling: a methodology was developed to model the large scale behaviour from mesoscale and microscale properties using CFD modelling. However, it has not been completely successful because the FDS code has deficiencies not previously known. Namely, it predicts lower flame temperatures and soot and hence lower heat fluxes to the pyrolysing material which do not allow the fire to spread as the experiments show. The use of a combination nanofillers and phosphinates would provide the optimum fire retardant solution both for large scale fires as well as for the small questionable flammability tests.
5. Formulations of fire retardant plus nanocomposite: combinations of fire retardant chemical and nanocomposite have been shown to provide a product that reduces flammability (fire growth), tendency to dripping and allows processability from raw or recyclable materials.
Two areas that have not completely been resolved in this work are related to the ease of ignition and smoke production. The only polymer formulation that is superb is EVA+MH (orATH) and nanofiller. However, to make other nanocomposite polymer (NCP) formulations suitable substitutes for brominated fire retardants, ignition must be delayed. The phosphinate fire retardant causes earlier ignition than the NCP and produces twice as much smoke per unit mass pyrolysed. One approach resulting from this programme is to apply on the surface of NCP a intumescent coating such Char 17 which has been provided by a partner in this project.
