composites flame retardant

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Flame Retardant Nanocomposites Christophe Swistak Valentin Chapuis Alexandre Durussel Composites technology 16.12.2008

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The flame-retardant mechanisms involved in the polymer-clay nano-composites are described.

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Page 1: Composites Flame Retardant

Flame Retardant Nanocomposites

Christophe Swistak

Valentin Chapuis

Alexandre Durussel

Composites technology 16.12.2008

Page 2: Composites Flame Retardant

Outline

• Applications

• Introduction– Fire hazards

– Combustion of polymers

• Flame-Retardant composites

• Nanofillers

• Flame retardancy mechanism

• Processing

Page 3: Composites Flame Retardant

Applications

• Flame retardant wall panels

• Flame retardant doors

• Airplanes & trains

Applications / Introduction / Flame retardant composites / Nanofillers /

Flame retardancy mechanism / Processing

!!! Flame retardant ≠ Fireproof

Page 4: Composites Flame Retardant

Dangers due to fire

• Heat release (HR)– Control intensity and speed of combustion

• « Black » smokes– Difficult orientation of rescue squads and

victims

• Toxic gazes released during combustion– Can lead to death

Applications / Introduction / Flame retardant composites / Nanofillers /

Flame retardancy mechanism / Processing

Page 5: Composites Flame Retardant

Combustion of polymers

• Process in two stages

1. Thermo-oxidative degradation• Heat transfer

• Decomposition leading to generation of flammable volatile products

• Diffusion of gazes through the matrix

2. Normal burning• Combustion involving volatiles products and

oxygen

Applications / Introduction / Flame retardant composites / Nanofillers /

Flame retardancy mechanism / Processing

Page 6: Composites Flame Retardant

Flame-retardant composites (I)

• Conventional composites– Polymer matrix (PP, PE, PA, …)– Fillers

• Aluminium trihydrate AlH3

• Magnesium hydroxide MgOH• Organic brominated compounds

– AdvantagesWell knownNo problem of dispersion of the filler

– DrawbacksX Requires gf ~ 30-60%wt to obtain good flame retardancyX High density, small flexibilityX Toxicity of flame retardant compounds (e.g. Br)

Applications / Introduction / Flame retardant composites / Nanofillers /

Flame retardancy mechanism / Processing

Page 7: Composites Flame Retardant

Flame-retardant composites (II)

• Nanocomposites– Polymer matrix (PP, PE, PA, PS, EVA, epoxy, …)

– Nanofillers• Layered silicates (mostly Monmorillonite (MMT))• Spherical nanoparticles of silica• Carbon nanotube

– AdvantagesSame flame-retardant properties with a smaller volume

fraction of filler (gf~2-10%wt) Easier to process (especially in injection)Better mechanical properties and smaller density

– DrawbacksX Compatibility between matrix and fillerX Dispersion

Applications / Introduction / Flame retardant composites / Nanofillers /

Flame retardancy mechanism / Processing

Page 8: Composites Flame Retardant

Nanofillers (I)• Structure

– Layered structure with thickness ~1nm

– High ratio length/thickness ~ 1000

– “Agglomerated” structure

Applications / Introduction / Flame retardant composites / Nanofillers /

Flame retardancy mechanism / Processing

MMT structure from wikipedia.org

Page 9: Composites Flame Retardant

Nanofillers (II)

• Dispersion– Determine flame-retardant property

Kashiwagi et al., Polymer, 2004

Applications / Introduction / Flame retardant composites / Nanofillers /

Flame retardancy mechanism / Processing

Page 10: Composites Flame Retardant

Nanofillers (III)• Dispersion

– Big challenge

S. Bourbigot et al, 2008, [7]

TEM pictures of PP/clay nanocomposite

Günter Beyer et al, 2002, [1]

Maximization of Matrix/filler interaction Leads to the better flame-retardancy

Applications / Introduction / Flame retardant composites / Nanofillers /

Flame retardancy mechanism / Processing

Page 11: Composites Flame Retardant

Nanofillers (IV)

• Dispersion

– Chemical process1. Expansion2. Compatibilization3. Mixing / Polymerization

– Specific system for each couple of clay and polymer matrix

W.S. Wang et al, 2008, [9]

Applications / Introduction / Flame retardant composites / Nanofillers /

Flame retardancy mechanism / Processing

Page 12: Composites Flame Retardant

Nanofillers (V)• Dispersion

– Mechanical process (separating the layers with a high shear stress)

– Directly in the production process– Addition of a stabilization / compatibilization

agent may be necessary

F. Samyn, S. Bourbigot et al, 2008, [7]

Applications / Introduction / Flame retardant composites / Nanofillers /

Flame retardancy mechanism / Processing

Page 13: Composites Flame Retardant

Flame retardancy mechanism (I)

Applications / Introduction / Flame retardant composites / Nanofillers /

Flame retardancy mechanism / Processing

• Formation of a thermal insulating and low permeability char

• The char acts as a physical and chemical barrier between the polymer and the burning surface

Heat release rate (HRR) decrease

Less smoke/gazes formation

Page 14: Composites Flame Retardant

Flame retardancy mechanism (II)

G. Beyer et al, 2002, [1]

Reduction of the HRR of 47%with only 5%wt of filler

Applications / Introduction / Flame retardant composites / Nanofillers /

Flame retardancy mechanism / Processing

Page 15: Composites Flame Retardant

Flame retardancy mechanism (III)

F. Laoutid et al. 2008, [5]

Reduction of the HRR up to 70 %with 10%wt of filler

Applications / Introduction / Flame retardant composites / Nanofillers /

Flame retardancy mechanism / Processing

Page 16: Composites Flame Retardant

Processing• In-situ Polymerization

• Polymerization in solvent

• Molten processing1. Polymer melting

2. Add fillers

3. Physical dispersion

– Allows injection / extrusion

– Industrial process

Applications / Introduction / Flame retardant composites / Nanofillers /

Flame retardancy mechanism / Processing

Page 17: Composites Flame Retardant

Summary• Important parameters to control

– Heat release rate– Thermal and diffusion barrier

• Nanocomposites (layered silicates)

Same or better flame-retardancy for a lower gf

better mechanical propertiesImprovements in processability and matrix/filler

interactionFillers that are non-toxic

Problems of dispersion and compatibility

Page 18: Composites Flame Retardant

References[1] Nanocomposites : a new class of flame retardants for polymers, in Plastics Additives &

Compounding, October 2002[2] Nanocomposites offer new way forward for flame retardants, in Plastics Additives &

Compounding, September/October 2005[3] Flame retardant mechanism of polymer/clay nanocomposites based on polypropylene, H. Qin

and al., Polymer 46 (2005), pp. 8386-8395[4] Characterization of the dispersion in polymer flame retarded nanocomposites, F. Samyn and

al., European Polymer Journal 44 (2008), pp. 1631-1641[5] New prospects in flame retardant polymer materials: From fundamentals to nanocomposites,

F.Laoutid, et al., Mater. Sci. Eng. R(2008), doi:10.1016/j.mser.2008.09.002[6] Flame retardant mechanism of polyamide 6-clay nanocomposites, T. Kashiwagi and al. Polymer

45, 2004, pp. 881-891.[7] Crossed characterisation of polymer-layered silicat nanocomposite morphology: TEM, X-ray

diffraction, rheology and solid-state nuclear magnetic resonance measurements. F. Samyn, S. Bourbigot and al. European Polymer Journal 44, 2008, pp. 1642-1653

[8] Synergism between flame retardant and modified layered silicate on thermal stability and fire behavior of polyurethane nanocomposite foams, M. Modesti and al., Polymer Degradation and Stability (2008), pp. 1-6

[9] Properties of novel epoxy/clay nanocomposites prepared with reactive phosphorous containing organoclay, W.S. Wang and al., Polymer (2008), pp. 1-11

[10] A novel phosphorus-containing copolyester/monmorillonite nanocomposites with improved flame retardancy, X.G. Ge and al., European Polymer Journal 43 (2007), pp. 2882-2890

[11] http://www.epp.goodrich.com/fyreroc/[12] http://www.cfoam.com/fireproofcore.htm