C ASE S TUDIES: R EDUCTION OF T HERMAL C ONDUCTIVITY & I - - PowerPoint PPT Presentation
13-14 MAY- VIENNA, AUSTRIA C ASE S TUDIES: R EDUCTION OF T HERMAL C ONDUCTIVITY & I MPROVEMENT OF M ECHANICAL P ERFORMANCE OF P OLYMERIC F OAMS BY U SING N ANOSTRATEGIES Cristina Saiz-Arroyo 1 , Alberto Lpez-Gil 2 , Josas Tirado 2 , Sergio
Technology and Innovation for Cellular Materials at Industry Service
Cristina Saiz-Arroyo1, Alberto López-Gil2, Josías Tirado2, Sergio Estravís2, Javier Escudero2, Miguel Angel Rodríguez-Pérez2
1 CellMat Technologies SL, Valladolid-Spain 2 CellMat Laboratory-University of Valladolid, Valladolid- Spain
13-14 MAY- VIENNA, AUSTRIA
CELLULAR MATERIALS LABORATORY UNIVERSITY OF VALLADOLID- SPAIN
∼ ∼ ∼145 scientific papers
Established in 1999. International recognized laboratory in the area of cellular materials.
technology on cellular materials to industrial partners.
manufacturing better and cheaper materials using specific know-how.
formulations for foaming applications Established in October 2012. Spin-off company of the University of Valladolid.
SPECIFIC AND NOVEL KNOW-HOW AND TECHNOLOGIES ON ADVANCED CELLULAR MATERIALS
LICENSES TRANSFER AGREEMENTS
FLAME RETARDANCY
SOLID PLASTIC PARTS PRODUCERS
PROCESS & PRODUCT
BY BIOPLASTICS
FLAME RETARDANCY
FOAM PRODUCERS
CLASSIC APPROACH: OBTENTION OF TAILORED POLYMERIC FOAMS WITH IMPROVED PROPERTIES FOR A CERTAIN APPLICATION
PROCESSING PARAMETERS CELLULAR STRUCTURE MORPHOLOGY POLYMERIC MATRIX PHYSICAL PROPERTIES MARKET, APPLICATION MODIFICATIONS POLYMERIC MATRIX
MICROSCOPIC LEVEL MACROSCOPIC LEVEL
WHY NANOPARTICLES?
PROCESSING PARAMETERS CELLULAR STRUCTURE MORPHOLOGY POLYMERIC MATRIX PHYSICAL PROPERTIES MARKET, APPLICATION MODIFICATIONS POLYMERIC MATRIX MICROSCOPIC LEVEL MACROSCOPIC LEVEL
NANOPARTICLES
matrix
IMPROVEMENTS IN THE SOLID POLYMERIC MATRIX, (Solid Nanocomposite in Cell Walls)
MULTIFUNCTIONAL ROLE OF NANOPARTICLES IN CELLULAR POLYMERS
CASE STUDY # # # #1: RIGID POLYURETHANE FOAMS/NANOCLAYS
PROCESSING PARAMETERS CELLULAR STRUCTURE MORPHOLOGY POLYMERIC MATRIX PHYSICAL PROPERTIES MARKET, APPLICATION MODIFICATIONS POLYMERIC MATRIX MICROSCOPIC LEVEL MACROSCOPIC LEVEL
PUR FOAMS WITH IMPROVED INSULATION PROPERTIES FOAMING MECHANISMS
formulation blown with water
NANOFILLER/POLYURETHANE REACTIVE FOAMING
POLYOL ADDITIVES WATER NANOFILLERS (Nanoclays)
STEP 1: NANOFILLERS ADDITION/DISPERSION
Dispersion / exfoliation (mechanical stirring)
STEP 2: FOAMING PROCESS
Mechanical stirring to activate/promote the reaction ISOCYANATE Reactive foaming expansion
1 2 3 4 5 24 25 26 27 28 29
Therm al Conductivity (m W /m ·K) Nanoclays Concentration (wt% ) Therm al Conductivity
1 2 3 4 5 1 2 3 4 5 6 7 8 9 10
Reduction Therm al Conductivity (% ) Nanoclays Concentration (wt% )
RESULTS: THERMAL CONDUCTIVITY Effective reduction of λ λ λ λ due to the introduction of nanoclays. Optimum content- Minimum in λ λ λ λ- 1wt%- 8% Reduction
1 2 3 4 5 24 26 28 30 32 34 36 38
Therm al Conductivity (m W /m ·K) Nanoclays Concentration (wt% ) λ- 2 Days After Production λ- 40 Days After Production
1 2 3 4 5 24 26 28 30 32 34 36 38
Therm al Conductivity (m W /m ·K) Nanoclays Concentration (wt% ) λ- 2 Days After Production λ- 40 Days After Production
DIFFUSION OF BLOWING AGENT
λ- Air: 25.3 mW/m·K λ- CO2: 14.5 mW/m·K
1 2 3 4 5 1 2 3 4 5 6 7 8 9 10
Reduction Therm al Conductivity (% ) Nanoclays Concentration (wt% ) Reduction λ- 2 Days After Production Reduction λ- 40 Days After Production
RESULTS: THERMAL CONDUCTIVITY Effective reduction of λ λ λ λ due to the introduction of nanoclays. Optimum content- Minimum in λ λ λ λ- 1wt%- 8% Reduction
λ λ λ λs: Conduction through solid phase λ λ λ λg: Conduction through gas phase λ λ λ λr: Thermal radiation λ λ λ λc: Convection within the cells, negligible φ φ φ φ < 4mm.
3
3 , , !, ",
, #$
Science Part B: Polymer Physics 38:993-1004, (2000). R.A. Campo-Arnaiz, M.A. Rodríguez-Pérez, B. Calvo, J.A. de Saja. Extinction coefficient of polyolefin foams. Journal of Polymer Science, Part B: Polymer Physics 43: 1608- 1617, (2005).
PHYSICS IN POLYMER FOAMS: NANOPARTICLES COULD ACT IN MOST OF THE MECHANISMS TAKING PLACE
COALESCENCE DRAINAGE NUCLEATION SOLIDIFICATION MELTING DIFFUSION COARSENING
Microfocus X-Ray source
Source: 5 µm Spot 20-100KV 0-200µA
ANALYSIS OF THE FOAMING PROCESS: X-RAY RADIOSCOPY SET UP
Flat panel detector
Detector: 2240x2344 12bits 9fps max 50 µ µ µ µm
%&'())*&+),( -..
CONE BEAM SEQUENCE OF RADIOGRAPHIES ADQUIRED ON REAL TIME
FOAMING PROCESS: NEAT PU VS PU + 3wt% NANOCLAYS NEAT PU PU + 3wt% NANOCLAYS Qualitative analysis: Cell size reduction due to the addition of nanoclays
NUCLEATING EFFECT OF NANOCLAYS: QUANTITATIVE ANALYSIS (X-RAY + IMAGE ANALYSIS)
3 4 5 6 7 8 9 1 2 3 4 10 20 30 40 50 60 70 80 90 100
Relative density /% Tim e /s
neat PU 0.5% clays 1% clays 3% clays 5% clays
3 4 5 6 7 8 9 1 1 2 3 4 5 50 100 150 200 250 300 350 400 450 neat PU 0.5% clays 1% clays 3% clays 5% clays
Cell size /µ
µ µ µm
Tim e /s
DENSITY EVOLUTION CELL SIZE EVOLUTION
CELL DENSITY, (Nc , cells/cm3)
50 100 150 200 250 300 350 400 450 0.0 4.0x10
6
8.0x10
6
1.2x10
7
1.6x10
7
2.0x10
7
Cell density /cm
3
Tim e /s
neat PU 0,5% clays 1% clays 3% clays 5% clays
NUCLEATING EFFECT OF NANOCLAYS: QUANTITATIVE ANALYSIS (X-RAY + IMAGE ANALYSIS)
Nc = 6 πφ 3 ρsolid ρ foam −1
MEAN CELL SIZE AS A FUNCTION OF NANOCLAYS CONTENT AND REPRESENTATIVE AVERAGE CELL, (Obtained by Tomography)
1 2 3 4 5 300 400 500 600 700 800 900
cell size /µ µ µ µm nanoclays content /%
CELL WALL THICKNESS
STRUTS MASS FRACTION, (fs) & CELL WALL THICKNESS (δ δ δ δ)
2D Slice of a single cell after having applied the struts identification methodology
1 2 3 4 5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
cell wall thickness /µ µ µ µm Nanoclays content /%
Nanoclays Content (wt%) fs 0.66 0.5 0.62 1 0.66 3 0.78 5 0.76
0 1 2 3 1 4 567
The presence of the nanoparticles seems to affect the kinetics of polyurethane formation reaction.
FTIR evidences of a delay in the gelling reaction leading to an increase of the time at which the material is in a non- crosslinking stage favoring drainage and hence leading to a reduction of cell wall thickness to values lower than expected.
CELL WALL THICKNESS
STRUTS MASS FRACTION, (fs) & CELL WALL THICKNESS (δ δ δ δ)
2D Slice of a single cell after having applied the struts identification methodology
1 2 3 4 5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
cell wall thickness /µ µ µ µm Nanoclays content /%
Nanoclays Content (wt%) fs 0.66 0.5 0.62 1 0.66 3 0.78 5 0.76
0 1 2 3 1 4 567
LOWER ATTENUATION OF RADIATION
EXPERIMENTAL DETERMINATION OF EXTINCTION COEFFICIENT (K)
FTIR Espectrometer, Transmission Mode. Ke,λ
λ λ λ
e n , ,
λ λ
λ λ λ
n
, ,
0.8 1.8 2.8 1 2 3 4 5 L (mm) Ln € € € €
Beer-Lambert Law Samples with different thicknesses
Experimental determination of Ke,λ
λ λ λ
R.A. Campo-Arnaiz, M.A. Rodríguez-Pérez, B. Calvo, J.A. de Saja. Extinction coefficient of polyolefin foams. Journal of Polymer Science, Part B: Polymer Physics 43: 1608-1617, (200
EXPERIMENTAL DETERMINATION OF EXTINCTION COEFFICIENT (K)
λ λ
b b e R e
∞ , , ,
2 2,2 2,4 2,6 2,8 3 3,2 3,4 3,6 400 900 1400 1900 2400 2900 3400 3900 Wave Number (cm-1) Ke, λ (m-1)
K e,λ
λ λ λ AS A FUNCTION OF WAVE NUMBER
ROSSELAND MEAN EXTINCTION COEFFICIENT
89,: : Spectral black body emissive power. λ: Wavelength
position being considered).
enough, considered optically thick, radiative flux, Rossland equation.
R.A. Campo-Arnaiz, M.A. Rodríguez-Pérez, B. Calvo, J.A. de Saja. Extinction coefficient of polyolefin foams. Journal of Polymer Science, Part B: Polymer Physics 43: 1608-1617, (200
EXTINCTION COEFFICIENT: COMPARISON WITH THEORETICAL MODEL, (GLICKSMAN MODEL)
15,00 20,00 25,00 30,00 35,00 0,00 0,50 1,00 3,00 5,00 nanoclays concentration (wt %) K (cm-1) Experimental Glicksman
Sample (nanoclays con. %wt.) K (exp.) (cm-1) K Gliks. (cm-1) Variation % Kω (m-1) exp. 23.18 25.40 9.56 46266 0.5 25.47 28.53 11.99 42946 1 30.42 28.91
68945 3 33.68 29.59
97505 5 27.31 28.93 5.95 46488
THEORETICAL EXPRESSION FOR K, GLICKSMAN MODEL
Differences between experimental and theoretical values: CHANGES IN Kw Kw increases up to 3wt%
; <=> ?# ; 4.10
1
$
good level of dispersion and exfoliation.)
nanoparticles in the struts as the cell wall thickness is reduced. NO ATTENUATION OF RADIATION, NANOCLAYS CONCENTRATION >3
R.A. Campo-Arnaiz, M.A. Rodríguez-Pérez, B. Calvo, J.A. de Saja. Extinction coefficient of polyolefin foams. Journal of Polymer Science, Part B: Polymer Physics 43: 1608-1617, (200
COALESCENCE DRAINAGE NUCLEATION SOLIDIFICATION DIFFUSION COARSENING REDUCED CELL SIZE: Heterogeneous
Nucleation (Increase in the number of cell per unit volume) & Coalescence Absence (constant cell density). REDUCTION OF RADIATION
CONTRIBUTION. Clays are “correctly” distributed until 3wt%, INCREASING THE EXTINCTION COEFFICIENT OF THE POLYMERIC MATRIX (Kw). REDUCTION OF THE RADIATION CONTRIBUTION INCREASE IN fs as the nanoclays concentration
attenuate thermal radiation. HIGHER
CONTRIBUTION TO RADIATION THERM.
The CONDUCTIVITY OF SOLID PHASE
INCREASES and this has a negative influence. It
is more important at high filler content.
HIGHER CONTRIBUTION OF CONDUCTION THROUGH SOLID PHASE RESULTS FOR λ λ λ λ A COMBINATION OF POSSITIVE AND NEGATIVE EFFECTS MELTING
CASE STUDY # # # #2: HIGH DENSITY LDPE/SiO2 FOAMS
PROCESSING PARAMETERS CELLULAR STRUCTURE MORPHOLOGY POLYMERIC MATRIX PHYSICAL PROPERTIES MARKET, APPLICATION MODIFICATIONS POLYMERIC MATRIX MICROSCOPIC LEVEL MACROSCOPIC LEVEL
HIGH DENSITY LDPE FOAMS WITH IMPROVED MECHANICAL PERFORMANCE DISPERSION/COMPATIBILIZATION
Surface treated with dimethyldichlorosilane
dissolution, pressure quench method
ρ ρ ρr=0.6
SOLID NANOCOMPOSITES
VS
SYNERGISTIC EFFECTS
MICROGRAPHS: CELLULAR STRUCTURE OF LDPE/SiO2 FOAMS
WITH LLDPE-g-MA WITHOUT LLDPE-g-MA
NEAT LDPE
CHEMICAL COMPOSITION VERSUS NUCLEATING EFFECT
1 2 3 4 5 6 7 8 9 10 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
Nucleation Ratio Contenido de Silice (wt% )
W ITHOUT LLDPE-g-MA W ITH LLDPE LLDPE-g-MA
Optim um SiO
2
concentration: 1wt%
CD*E8&+),( F&+), G8EEDE&H .8(I)+J C&(,*,KL,I)+8 M,&K G8EEDE&H .8(I)+J C8&+ N,EJK8H M,&K
WITH LLDPE-g-MA: Values around 2 for
concentrations, worst results than for neat LDPE. WITHOUT LLDPE-g-MA: Values of nucleation ratio higher than 1.4 in any case
MECHANICAL PROPERTIES. SOLID VERSUS NANOCOMPOSITES: SYNERGISTIC EFFECTS
1 2 3 4 5 6 7 8 9 10
5 10 15 20 25 30 35 40
15.5% ∆
∆ ∆ ∆ E-FOAM
ED NANOCOM POSITES ∆
∆ ∆ ∆ E-SOLID NANOCOM
POSITES
∆ E-LDPE / E-NS (%
) Silica Content (% ) 39.8% 19.8%
1 2 3 4 5 6 7 8 9 10 5 10 15 20 25 ∆
∆ ∆ ∆ E-FOAM
ED NANOCOM POSITES ∆
∆ ∆ ∆ E-SOLID NANOCOM
POSITES
∆ E-LDPE / E-NC (%
) Silica Content (wt% ) 10.6% 18.2%
WITH LLDPE-g-MA WITHOUT LLDPE-g-MA ∆P
PQRSP/UVWXYPQRSP PQRSP
x100
SYNERGISTIC EFFECTS due to the combination of nanoparticles and foaming processes. LOWER SILICA CONTENT TO ACHIVE HIGHER LEVELS OF IMPROVEMENT. Higher reinforcement in the solids. Better compatibilization (bonding) polymer/particle
RIGID POLYURETHANE FOAM/NANOCLAYS: THE NUMBERS PUR: 4 €/kg Nanoclays: 7 €/kg PUR + 1wt% Nano: 4.03 €/kg 1wt% Nanoclays→ → → →8 % reduction in λ λ λ λ 10 mm Neat PU 9.25 mm PU + 1wt% Nanoclays Wall- PUR: 10m x 2.5 m x 10 mm Wall- PUR + 1wt% Nano: 10 m x 2.5 x 9.25 Density-PUR: 53.1 kg/m3 Density-PUR + 1wt% Nano: 54.07 kg/m3 Wall- PUR: 53.10 € Wall- PUR + 1wt% Nano: 50.11 €
FULL OF BUILDINGS? …
LDPE/SiO2 FOAMS: THE NUMBERS Z
~
GIBSON & ASHBY MODEL
Ef: Elastic modulus foam Es: Elastic modulus solid ρf: Density foam ρs: Density solid
LDPE + 3 wt% SiO2,
<] <^ 0.5619
Corresponds to a ρ ρ ρ ρr: 0.749 LDPE + 3 wt% SiO2: r: 0.649
LDPE: 1.5 €/kg SiO2: 5 €/kg LDPE + 3 wt% SiO2: 1.60 €/kg FOAMED PART- Volume 0.1 m3 LDPE: 68.9 kg LDPE + 3 wt% SiO2: 61.4 kg LDPE: 103.44 € LDPE + 3 wt% SiO2: 98.33 €
LET’S THINK… ABOUT CARS….
CELLMAT TECHNOLOGIES S.L. CENTRO DE TRANSFERENCIAS Y TECNOLOGÍAS APLICADAS (CTTA) PASEO DE BELÉN 9A OFFICE 105 47011, VALLADOLID-SPAIN Phone:+34 983 189 197 c.saiz@cellmattechnologies.com www.cellmattechnologies.com
ACKNOWLEDGEMENTS