Flame Retardant Polymer Nanocomposites

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<ul><li><p>Jeffrey W. GilmanGroup Leader</p><p>Materials and Products GroupNIST</p><p>Flame Retardant Polymer Nanocomposites </p></li><li><p>General Flame Retardant Approaches for Polymers</p><p>I- Gas Phase Flame Retardants- Reduce Heat of Combustion (Hc ) resulting in incomplete combustion.- Inherent Drawbacks: Negative Public Perception! </p><p>II- Endothermic Flame Retardants- Function in Gas Phase and Condensed Phase- Via endothermic release of H2 O, polymer cooled and gas phase diluted.- Inherent Drawback: High loadings (30-50%) degrade mechanical properties.</p><p>III- Char Forming Flame Retardants- Operate in Condensed Phase- Provides thermal insulation for underlying polymer and a mass transport </p><p>barrier, preventing or delaying escape of fuel into the gas phase.- Inherent Drawback: High loadings (20-50%) degrade mechanical properties.</p><p>Goal: develop cost effective, environmentally friendly approacheGoal: develop cost effective, environmentally friendly approaches to s to reduce flammability reduce flammability andand improve physical propertiesimprove physical properties</p></li><li><p>Polymer clay NanocompositePolymer clay NanocompositeMaterials:Layered silicates, organic modifier, polymer matrix</p><p>Processing Techniques:Solution mixing and film castingMelt mixing (extrusion, injection molding)In situ polymerization</p><p>Morphologies (Simplified picture):</p><p>Properties:Flame resistanceImproved gas permeabilityHigher stiffnessScratch resistanceHigher glass transitionImproved thermo-mechanical response</p><p>Usuki et al. 2001, Nano LettersL. F. Drummy -AFRL</p></li><li><p>PPPP--clay Nanocomposite: TEMclay Nanocomposite: TEM</p><p>Gilman, et al, Chemistry of Materials; 2000; 12; 1866-1873</p></li><li><p>0200</p><p>400</p><p>600</p><p>800</p><p>1000</p><p>1200</p><p>1400</p><p>1600</p><p>0 120 240 360 480 600</p><p> PP intercalated + delaminated (mass fraction 2 % silicate) PP-g-MA (mass fraction 0.4 % MA)</p><p>PP intercalated + delaminated (mass fraction 4 % silicate) </p><p>H</p><p>e</p><p>a</p><p>t</p><p>R</p><p>e</p><p>l</p><p>e</p><p>a</p><p>s</p><p>e</p><p>R</p><p>a</p><p>t</p><p>e</p><p>(</p><p>k</p><p>W</p><p>/</p><p>m</p><p>2</p><p>)</p><p>Time (seconds)</p><p>Flux = 35 kW/m 2</p><p>PPPP--clay Nanocomposite: Cone Calorimetryclay Nanocomposite: Cone Calorimetry</p></li><li><p>Gasification of Polystyrene LayeredGasification of Polystyrene Layered--silicate Nanocompositessilicate Nanocomposites</p><p>Char or </p><p>Coke Formation </p></li><li><p>Critical criteria for formation of homogeneous char</p><p>Kashiwagi et al., Polymer, 2004</p><p>Homogeneous clay dispersion in polymer</p><p>Unstable and inhomogeneous clay dispersion in polymer</p><p>Pyrolysis and phase separation</p><p>homogeneous char:thermal barrier</p><p>discontinuous char:Poor thermal protection</p><p>Depends on: clay loading, dispersion, polymer Mw, viscosity, degradation mechanisms, carbonaceous char formation</p></li><li><p>Nanocomposite + Conventional Flame Retardant Approach</p><p>zz Nanocomposites + additional flame retardants have resulted in fiNanocomposites + additional flame retardants have resulted in final nal materials that pass regulatory tests and have superior balances materials that pass regulatory tests and have superior balances of of properties. properties. zz Successful commercial approaches remove some of existing FR Successful commercial approaches remove some of existing FR </p><p>package, replace with nanocomposite. package, replace with nanocomposite. </p><p>zz DupontDupont 1980s 1980s PBT + PBT + OMMtOMMt + + OrganoOrgano BrBr-- UL94 V0UL94 V0zz Showa Denko Showa Denko PBT PBT SynMicaSynMica + + MealmineCYMealmineCY-- UL94V0UL94V0zz KabelwerkKabelwerk EupenEupen: EVA + : EVA + OrganomontmorilloniteOrganomontmorillonite + Al(OH)+ Al(OH)33. . </p><p>UL1666UL1666zz PolyOne: (polyolefin nanocomposite PolyOne: (polyolefin nanocomposite ULUL--94 V94 V--0 @ 3.0mm) 0 @ 3.0mm) zz StrathclydeStrathclyde PU Foam + PU Foam + OMMtOMMt + FR + FR pass cribpass crib--5 5 zz NanocorNanocor PhosPhos. Clay . Clay -- UL94 V0UL94 V0zz U mass Lowell U mass Lowell ClayClay-- ELO as substitute for ELO as substitute for PbPb in PVCin PVC</p></li><li><p>ChallengesChallenges1)1) Furniture and mattress firesFurniture and mattress fires</p><p>still causestill cause~1000 deaths/yr and cost $ 500 M/yr~1000 deaths/yr and cost $ 500 M/yr</p><p>1)1)</p><p>Objective:Objective:</p><p>to evaluate the effectiveness of to evaluate the effectiveness of nanoadditive based flame retardantsnanoadditive based flame retardants</p><p>in reducing in reducing the flammability of flexible foams.the flammability of flexible foams.</p><p>2)2)</p><p>Objective :Objective :</p><p>To improve the ability of barrier To improve the ability of barrier fabrics to prevent flame spread in mattresses and fabrics to prevent flame spread in mattresses and furniture using furniture using nanoadditivesnanoadditives..</p></li><li><p>Melt Pool Fires During Foam Burning </p><p>240 kW in 540 sec240 kW in 540 sec</p><p>0</p><p>100</p><p>200</p><p>300</p><p>400</p><p>500</p><p>600</p><p>0 100 200 300 400 500 600 7000</p><p>100</p><p>200</p><p>300</p><p>400</p><p>500</p><p>600</p><p>Time Since Start of Ignition (s)</p><p>Polypropylene fabric</p><p>Cotton fabric</p><p>Cal 117 PU Foam</p><p>550 kW in 280 sec550 kW in 280 sec</p></li><li><p>Nano-additives</p><p>Layered Double Hydroxide </p><p>Mg(OH)64-</p><p>Al(OH)63-</p><p>POSSCarbon nanotubes</p><p>Coughlin-U MassBellayer - NIST</p><p>Zammerano-Chimteclab</p><p>Layered Silicates</p><p>Nano silica</p><p>Kashiwagi - NIST</p></li><li><p>Flame Retardant MechanismHigh aspect ratio nanoadditives (e.g. CNF) properly dispersed in the polymeric matrix form a percolated jammed structure, due to particle- particle interactions, so that the melt behaves rheologically like a gel</p><p>-</p><p>Inhibition of dripping </p><p>1 10 100 10001</p><p>10</p><p>100</p><p>R</p><p>e</p><p>l</p><p>a</p><p>t</p><p>i</p><p>v</p><p>e</p><p>v</p><p>i</p><p>s</p><p>c</p><p>o</p><p>s</p><p>i</p><p>t</p><p>y</p><p>Shear Rate (1/s)</p><p> C30B CNF POSS</p></li><li><p>6.6 parts of Br-P FR in the standard formulation are replaced by 6.6 parts inorganic additive (e.g., CNF, Na+ MMT, LDH and Boehmite)</p><p>When organo-modified additive are used (e.g., OMMT) the amount of additive is increased in order to keep constant the inorganic fraction of the additive.</p><p>Modified/Nano Formulations</p><p>Br-P FR (wt.%)</p><p>Nano-additive (wt.%)</p><p>Br-P FR (Control 1) 6.2 0Talc (Control 2) 2.3 3.9CNF 2.3 3.9Boehmite 2.3 3.9LDH 2.3 3.9OMMT (C30B) 2.3 5.1POSS 2.3 5.1</p></li><li><p>Foam Processing Optimization</p><p>Control POSSFire-</p><p> quench Boehmite C30B</p><p>Non-optimized foam samples with various additives. </p><p>Each formulation needsto be individually tuned to match the control formulation.</p><p>1. Adjustment of the polyol nanoparticle dispersion viscosity by coupling agents.</p><p>2. Optimization of the curing and blowing reaction through suitable catalysis ratios.</p><p>3. Prevention of collapse and shrinkage by appropriate surfactants and cell openers.</p><p>4. Monitoring of the foam rise and curing with a FOAMAT foam qualification system.</p><p>5. Evaluation of the foam quality by optical analysis, density and air flow measurements. </p></li><li><p>Characterization of Nanoparticles Dispersions</p><p>0 1 2 3 4 5</p><p>2.0 nm</p><p>1.9 nm4.0 nm</p><p>3.8 nm</p><p>I</p><p>(</p><p>q</p><p>)</p><p>q (nm-1)</p><p> Cloisite 30B in liquid polyol Cloisite 30B Foam</p><p>Median Size (m)</p><p>Cloisite</p><p>30B 100Boehmite 0.2POSS 8CNF -</p><p>Small Angle X-Ray ScatteringAggregate size estimation by means of Static Laser Scattering</p></li><li><p>Foam Characterization</p><p>POLYOL</p><p>FOAM</p><p>OPTICAL MICROSCOPY</p><p>SEM</p><p>Talc OM-Clay CNF</p><p>Br-P FR OM-Clay CNF</p><p>CNF</p></li><li><p>Cloisite 30B FoamCNF Foam</p><p>Modified Cone Calorimetry</p></li><li><p>Nanoadditive Flame Retardants for Polyurethane Foam </p><p>Tom Ohlemiller, Richard Harris, J. Randy Shields, Tom Ohlemiller, Richard Harris, J. Randy Shields, Mauro Mauro ZammaranoZammarano (GR), Roland (GR), Roland KrKrmermer (GR)(GR)</p><p>PoolPool--fire fire </p><p>PU FRPU FR--foam controlfoam controlnono</p><p>PoolPool--fire fire </p><p>PU FRPU FR--foam + 4% Carbon Nanofoam + 4% Carbon Nano--Fibers:Fibers:</p><p>Catch Pan</p><p>ViscosityNano-Graphite</p></li><li><p>HRR by Modified Cone Calorimetetry</p><p>0 50 100 150 200</p><p>0</p><p>1000</p><p>2000</p><p>3000</p><p>4000</p><p>5000</p><p>6000</p><p>H</p><p>R</p><p>R</p><p>(</p><p>W</p><p>)</p><p>Time (s)</p><p> Cloisite 30B POSS Talc</p><p>35% reduction in PHRR with CNF</p><p>External Heat Flux: 11 kW/m2</p><p>0 50 100 150 200</p><p>0</p><p>1000</p><p>2000</p><p>3000</p><p>4000</p><p>5000</p><p>6000</p><p>H</p><p>R</p><p>R</p><p>(</p><p>W</p><p>)</p><p>Time (s)</p><p> Talc Br-P FR CNF</p></li><li><p>Flame Retardant Mechanism of CNF</p><p>*Takashi Kashiwagi, BFRL, NIST </p><p>High aspect ratio nanoadditives (e.g. CNF) properly dispersed in the polymeric matrix form a percolated jammed structure, due to particle- particle interactions, so that the melt behaves rheologically like a gel*.</p><p>-</p><p>Inhibition of dripping-</p><p>Heat shield effects of network structured protective layer</p><p>1 mm1 mm1 mm</p><p>Residue of CNF foam after Cone</p><p>1 10 100 10001</p><p>10</p><p>100</p><p>R</p><p>e</p><p>l</p><p>a</p><p>t</p><p>i</p><p>v</p><p>e</p><p>v</p><p>i</p><p>s</p><p>c</p><p>o</p><p>s</p><p>i</p><p>t</p><p>y</p><p>Shear Rate (1/s)</p><p> C30B CNF POSS</p></li><li><p>CNF Foam Residue - SEM</p><p>1 mm1 mm1 mm</p><p>Residue of CNF foam after Cone</p><p>b) 4 m</p><p>10 mc)</p></li><li><p>Environmentally Friendly, Nano-based Polyurethane Fire Retardant Systems</p><p>Professor Richard A. Pethrick,</p><p>Department of Pure and Applied Chemistry, University of Strathclyde, Thomas Graham </p><p>Building, 295 Cathedral Street Glasgow G1 1XL.</p><p>"Pollution Prevention through Nanotechnology" September 25-26, 2007, in Arlington , VA</p></li><li><p>1 10 100 1000</p><p>0.1</p><p>1</p><p>10</p><p>Shear thinning of sonicated glycol blends of Strath A / Strath B</p><p> 1% Strath B 2% Strath B 3% Strath B 1% Strath A 2% Strath A 3% Strath A</p><p>V</p><p>i</p><p>s</p><p>c</p><p>o</p><p>s</p><p>i</p><p>t</p><p>y</p><p>(</p><p>P</p><p>a</p><p>.</p><p>s</p><p>)</p><p>Shear Rate (1/s)</p><p>Effect of dispersion methods -study of PU monomers</p></li><li><p>Alignment of Platelets Due to Shear</p><p>Applied Shear</p><p>Alignment of the platelets in the shear field leadsto a lowering of the viscosity.</p></li><li><p>Flame Retardancy in Polymer Foams.</p><p>Nano platlets compositestructures within cellwalls to inhibit volatilediffusion and enhancethe viscoelasticity ofthe melt phase .</p></li><li><p>Flexible Foam Systems</p><p> A series of flexiblefoam system have beenproduced with therequired flexibilityand incorporatingnanocompositeorganically modifiedclay materials.{Patents have beenapplied for thesesystems} </p></li><li><p>What do the materials look like?</p><p> Electron microscopy has been performed and they show the nano material is present in the foam walls and has effected the rheology in the foam formation</p><p> The materials have comparable mechanical properties to current flexible foam formulations</p></li><li><p>Electron Micrograph of PU foam</p></li><li><p>Electron Micrography of PU Foam Structure</p></li><li><p>CL592 CL594</p><p>Daly, Lewicki, Liggat, McCulloch, MacRitchie, Pethrick, Rhoney</p><p>The Challenge:</p><p>The Process:Formulation design</p><p>Toavoid this</p><p>Obtain this</p><p>Escalating Self-extinguishing</p><p>Crib 5 Testing</p><p>From these</p></li><li><p>Nano Composites</p><p>I hope this short presentation has shown that by recognising the natural nano dimensions which exist in natural materials it is possible to enhance the properties of conventional materials which we produce and achieve a greater use of these materials.</p><p>Nano composites are not all about new exotic materials but can be about using traditional materials more effectively. </p></li><li><p>Acknowledgements</p><p> Dr J.J. Liggat, Dr John Daly, Dr Ian Rhoney, Dr Sharon Ingram, EPSRC. Scottish Enterprise. Southern Clay. </p></li><li><p>Layer by layer assembly of nanoparticles</p><p>Collaborator: Jaime Grunlan, Texas A&amp;M </p><p>University</p><p>Deposition of nanoparticles using layer by layer assembly technique.</p><p>Coated Control Foam: 2 wt. % coating</p><p>Movie Speed: 10x</p></li><li><p>Amphipholis squamata Common echinoderm Diet consists of particles Bioluminescence under </p><p>nervous control, and produced only under stimulation</p><p> Commonly used in the Deheyn lab to assess sub- lethal effect</p><p>Dimitri D. Deheyn, Ph.D. Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego</p><p>Methodologies to Determine Health and Methodologies to Determine Health and Environmental effects of Environmental effects of NanoNano--particlesparticles</p></li><li><p>Experimental setup in aquariums</p><p>Nanoparticles* Concentration (ppm) Abbreviations</p><p>Single-Wall Carbon Nanotubes 1 and 10 SNT</p><p>Multi-Wall Carbon Nanotubes 10 MNT</p><p>Surfactant: Carboxymethyl cellulose 0.1 CMC</p><p>Layered Double Hydroxide Colloidal 1 and 10 CLD</p><p>Micro Layered Double Hydroxide 10 MLD</p><p>Surfactant: Sodium acetate ~10 SA</p><p>* Received from Jeff Gilman group at NIST, National Institute for Standard and Technology</p></li><li><p>Time variation of the spontaneous light Nanoparticles</p></li><li><p>Time variation of the spontaneous light Nanoparticles</p></li><li><p>Parameter Space for Polymer Nanocomposites</p><p>Polymer Nano-additive </p><p>Organic Treatment </p><p>Processing Conditions </p><p>Other additives </p><p>Flame Retardant </p><p> PE PP PS </p><p>PA6 PU </p><p>PVC PC PEO </p><p>PMMA EVA </p><p>Epoxy . . </p><p>clay POSS </p><p>Carbon Silica LDH </p><p>. </p><p>. </p><p>. </p><p>. </p><p>. </p><p>. </p><p>. </p><p>. </p><p>AlkylammoniumImidazolium </p><p>Chelates Silated Alkyl </p><p>Carboxylate . . . . . . . </p><p>Temperature Shear </p><p>Residence time sonication </p><p>. </p><p>. </p><p>. </p><p>. </p><p>. </p><p>. </p><p>. </p><p>. </p><p>. </p><p>Stabilizers Processing </p><p>UV Antioxidant</p><p>Fillers Pigments </p><p>. </p><p>. </p><p>. </p><p>. </p><p>. </p><p>. </p><p>. </p><p>Phosphate Halogenated Silicon Based</p><p>. </p><p>. </p><p>. </p><p>. </p><p>. </p><p>. </p><p>. </p><p>. </p><p>. </p><p>. </p></li><li><p> We will use a small-scale automated high throughput liquid handling equipment with the capability of mixing dozens of polyol, nanoadditive combinations to screen for nanoscale mixing with polyols. </p><p>NanoNano--dispersiondispersion</p></li><li><p>Conclusionszz An An important applicationimportant application of polymer clay nanocomposites is of polymer clay nanocomposites is </p><p>as a flame retardant in polymers. as a flame retardant in polymers. </p><p>zz flame retardant mechanism of polymer clay nanocomposites flame retardant mechanism of polymer clay nanocomposites appears to be the maintenance of a appears to be the maintenance of a homogeneous homogeneous dispersiondispersion</p><p>zz StrathclydeStrathclyde -- Clay in Foam passes crib 5Clay in Foam passes crib 5 test for UK test for UK upholstered furnitureupholstered furniture</p><p>zz Carbon Carbon NanoNano FibersFibers inhibit melt dripping and reduce the inhibit melt dripping and reduce the flammabilityflammability</p><p>zz GrunlanGrunlan -- LBLLBL Coating can be used to remove dripping in Coating can be used to remove dripping in foamsfoams</p><p>zz DeheynDeheyn/Scripps preliminary data show /Scripps preliminary data show possiblepossible toxic effects toxic effects from surfactants and from surfactants and nanotubesnanotubes</p></li><li><p>Acknowledgments</p><p>Dimitri</p><p>D. Deheyn, Marine Biology Research Division, </p><p>Scripps Institution of Oceanography, University of California, San DiegoRoland Krmer</p><p>School of Chemical Science and Engineering, Fibre and Polymer Technology,Royal Institute of Technology, SE-100 44 Stockholm, Sweden</p><p>Jeffrey W. Gilman, Richard Harris, Jr., Thomas J. Ohlemiller, Sameer</p><p>S. Rahatekar, John R. Shields, Takashi Kashiwagi</p><p>Building and Fire Research Laboratory, NIST, Fire Research Division, Gaithersburg, MD</p><p>Jaime C. GrunlanDepartment of Mechanical Engineering &amp; Polymer Technology Center (PTC) </p><p>Texas A&amp;M University, College Station, TX</p><p>Professor Richard A. PethrickDepartment of Pure and Applied Chemistry, University of Strathclyde, Thomas </p><p>Graham Building, 295 Cathedral Street Glasgow G1 1XL</p></li><li><p>Methane ice burning http://http://www.geomar.dewww.geomar.de</p><p>Thank you</p><p>Flame Retardant Polymer Nanocomposites General Flame Retardant Approaches for PolymersSlide Number 3Slide Number 4Slide Number 5Gasification of Polystyrene Layered-silicate NanocompositesCritical criteria for formation of homogeneous charNanocomposite + Conventional Flame Retardant ApproachChallengesMelt Pool Fires During Foam Burning Slide Number 11Slide Number 12Slide Number 13Slide Number 14Characterization of Nanoparticles DispersionsFoam CharacterizationModified Cone CalorimetryNanoadditive Flame Retardants for Polyurethane Foam HRR by Modified Cone CalorimetetrySlide Number 20Slide Number 21Slide Number 22Slide Number 23Alignment of Platelets Due to ShearFlame Retardancy in Polymer Foams.Flexible Foam SystemsWhat do the materials look like?Slide Number 28Slide Number 29Slide Number 30Nano CompositesAcknowledgementsSlide Number 33Amphipholis squamataExperimental setup in aquariumsTime variation of the spontaneous lightNanoparticlesTime variation of the spontaneous lightNanoparticlesParameter Space for Polymer NanocompositesSlide Number 39ConclusionsAcknowledgmentsMethane ice burning</p></li></ul>