Introduction to Plastic Foams - Trinity College, Dublinfoams/PRESENTATIONS/Wednesday11/... · Introduction to Plastic Foams André Moreira Polymer Physics, BASF AG Ludwigshafen, Germany

Introduction Introduction to to Plastic FoamsPlastic Foams

AndrAndréé MoreiraMoreiraPolymer Polymer PhysicsPhysics, BASF AG, BASF AG

Ludwigshafen, GermanyLudwigshafen, Germany

Les Les HouchesHouches, Jan. 2006, Jan. 2006

AcknowlegmentsAcknowlegments::

H.H. WeiWeißß V. V. SchSchäädlerdlerP. P. MMüüllerller M. M. RRüüllmannllmannE. E. WaWaßßnerner H. H. SchuchSchuchK. HahnK. Hahn C. C. ExnerExnerM. M. AllmendingerAllmendinger P. LopesP. LopesB. B. SowartSowart A. A. AlteheldAlteheldD. LongoD. Longo K.K.--H. H. WaWaßßmermerT. FrancisT. Francis F. F. HeilmannHeilmannM. M. RRüüllmannllmann M. M. BotheBothe

Dr. AndrDr. Andréé MoreiraMoreira, BASF AG, BASF AG

Global summaryGlobal summary

Introduction

Plastic foams: Physics and Chemistry

Plastic foams: industrial processes

Mechanical properties

Acoustic properties

Thermal properties

Nanoporous foams: the future?

Part I

Part II


Summary: Part ISummary: Part I

IntroductionWhat are polymers?What are plastic foams?Open and closed cell foamsApplications and Markets

Plastic foams: Physics and ChemistryNucleationBubble growthStabilization (solidification)

Plastic foams: industrial processesExtrusion process (XPS)Expandable beads (EPS)Reactive foams (PUR)

IntroductionIntroduction


What are polymers?What are polymers?






Some usual monomersSome usual monomers

Source: Cowie, Polymers: Chemistry & Physics of modern materials. , Blackie (1991)


Mechanical behavior Mechanical behavior of polymersof polymers

Source: Gibson & Ashby, Cellular solids , 2nd Ed., Cambridge (1997)


World polymers marketWorld polymers market

World plastics production

1

10

100

1000

1950 1960 1970 1980 1990 2000 2010 2020

year

mill

. to

ns


Plastic consumption worldwidePlastic consumption worldwide


What are foams & cellular materials?What are foams & cellular materials?


What are foams & cellular materials?What are foams & cellular materials?


Closed and open foam-structures

cork sponge

cakecrisp

Natural cellular structuresNatural cellular structures


Styrodur®(XPS) closed-cell polystyrene foam

Basotect®open cell Melamine polycondensate

Closed and open foam-structures

Artificial cellular structuresArtificial cellular structures


Polyurethane foams Styropor® (EPS)Polystyrene (closed-cell)

Neopolen®

Polypropylen (closed-cell )

Foams@BASFFoams@BASF

Styrodur®(XPS) polystyrene (closed-cell)

Neopor® (EPS)Polystyrene (closed-cell)

Basotect®Melamine (open cell)


ApplicationsApplications……


Savings after

50 years93 100 l

oil

Energy and Material needed to production of EPS (equivalent in oil)

670 loil

Foams and the environmentFoams and the environment


Foams and the environmentFoams and the environment

IR Camera

Plastic foamsPlastic foams::Physics Physics and and ChemistryChemistry


Bubbles growFluid is initially sturated with a blowing agent. Bubbles nucleate.

Bubbles touch each other: "Polyhedralfoam„, closed cells - 100-600 µm.Exs.: XPS (Styrodur), EPS (Styropor), some PUR foams

Open cellsEx.: MF foam(Basotect)

Cell w

alls b

reak

up

The making ofThe making of…… cellular plasticscellular plastics


Phase diagram PS-CO2 (T=150 C)

0

150

300

450

600

750

0 0.05 0.1 0.15 0.2

w-fraction CO2

P (

bar

)

liquid-gas

single phase

Thermodynamics of bubblingThermodynamics of bubbling


σππ 23 4)(3

4RPPRG ei +−−=∆

ei PPR

−=

σ2*

2

3*

)(316

eiB PPTkG

−=

∆ σπ

∆−=

TkG

JJB

*

0 exp

0 0.5 1 1.5 2RêR*

-200

-100

0

100

DG

êkT

0 200 400 600 800 1000DPêk T

0

0.20.40.6

0.81

JêJ 0

Classical nucleation theory (homogeneous)Classical nucleation theory (homogeneous)

0 5 10 15 20gêk T

00.20.40.60.8

1

JêJ 0σ/ k T


With η~5x103 Pa s and a pressure difference of 200 bar. This means that this characteristic time is of the order of τη~10-3 s

Bubble growthBubble growth

BEB

B

B RPP

dtdR

Rση 24

−−=

1) Viscosity-dominated regime

−

−−+= )(

4exp)( 00 tt

PPRRRR EB

crcrB η

EB PP −=

ητη

4ητDlc ≈

tDFRR mB 220 +≈

)( inf sE

gm cc

P

TRF −=

2) Diffusion-dominated regime

Doelder, Sammler, Koopmans, Paquet, Cellular Polymers 21, 99 (2002)


Bubble coalescenceBubble coalescence


Bubble coalescenceBubble coalescence


n Up to a gas volume of ~ 64% (random packing of spheres), bubbles are still spherical.

n Thereafter bubbles are deformed into polyhedron structures and cell lamellae and struts.

Polyhedron foamPolyhedron foam

Pentagondodekaeder Tetrakaidekaeder


Stabilization of polymer foamsStabilization of polymer foams

1) Viscoelastic stabilization (self healing)

Entropic force (chains stretched)

< 1 due to extrudateswelling

Melt strength

Dra

wab

ilityfo

rce

F

Draw down ratio v / v0(~1 / thickness)

1

Filament break

with:

v0 ... average velocity at die exit

v ... velocity at draw down wheels

F ... forceConstant accelaration of wheels

v0

v

F

Extrudate strand

Rheotens MACCARONE effect


Stabilization of polymer foamsStabilization of polymer foams

1) “Anti-Plasticizer” effect

The blowing agent molecules

(when also plasticizers) leave

the thinner parts faster than the

thicker ones, contributing to

hardening in those areas!

Effect of a plasticizer/blowing agent over PS (fixed shear rate)

100

1000

10000

0 2 4 6 8 10

weight% blowing agent

η (

Pa

s)

M. Rüllmann, BASF


If it survives all that, one getsIf it survives all that, one getssomething like thissomething like this……

Plastic foamsPlastic foams::Industrial Industrial processesprocesses


Melting

Mix blowing agent

Pressurize

Melt mixed with blowing agent

III. IV. V. I. II.

Foam

Extrusion foams (XExtrusion foams (X--Foams, XPS)Foams, XPS)


Phase diagram PS-CO2 (T=150 C)

0

150

300

450

600

750

0 0.05 0.1 0.15 0.2

w-fraction CO2

P (

bar

)

liquid-gas

single phase

Adiabatic expansion of an ideal gas:

5/2

=

I

F

I

F

PP

TT

Ex. (lower limit):TI=150 CPI=150 barPF=1 bar

TF=20 C

Thermodynamics of XPSThermodynamics of XPS


StyrolStyrol

WasserWasser

AdditiveAdditive

StyrolStyrol

WasserWasser

AdditiveAdditive

Styrol/Polystyrol-Perlen + Treibmittel Pentan

Styrol/Polystyrol-Perlen + Treibmittel Pentan

Expandable foams (EExpandable foams (E--Foams, EPS)Foams, EPS)


PackagingBlocks Parts

Raw material (Ø 1 mm) Pre foaming Storage Fusion

EPSEPS


Phase diagram PS-n pentane (P=1 bar)

-20

0

20

40

60

80

100

120

140

160

0 0.2 0.4 0.6 0.8 1

w-fraction pentane

T (C

)

"liquid"-gas

liquid-liquid

single phase(glas/gel)

Thermodynamics of EPSThermodynamics of EPS


• unlimited variety of structural building blocks

• wide range of different properties adjustable ⇒ tailor-made polymers

catalyst, blowing agent

Difunctional or polyfunctional aromatic, (cyclo)aliphatic residue

Polyether/polyester of different functionality, molecular weight, reactivity

OO

NH

OO

NH

+ OH OHOCN NCO

Polyurethane foamsPolyurethane foams


Polyurethane foamsPolyurethane foams

Iso Polyol

Air


PU70 %

XPS5 %

EPS23 %

Others2 %

n 40 Mill. tons polymeric materials

n 3.6 Mill. tons polymer foams

Market in western Europe (2004)Market in western Europe (2004)

Documents

Introduction to Plastic Foams - Trinity College, Dublinfoams/PRESENTATIONS/Wednesday11/... · Introduction to Plastic Foams André Moreira Polymer Physics, BASF AG Ludwigshafen, Germany