PROCESSING OF THERMOSET AND THERMOPLASTIC COMPOSITE MATERIALS school presentations... · PROCESSING...

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PROCESSING OF THERMOSET AND THERMOPLASTIC COMPOSITE MATERIALS

Prof. J.F. GERARD

Ingénierie des Matériaux Polymères IMP UMR CNRS#5223 Université de Lyon - INSA Lyon, Villeurbanne (France) [email protected]

ALPLAST Summer School - 2013 New Trends in Plastic Enginering - Oyonnax (France)

mailto:[email protected]





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CONTENTS

1.- INTRODUCTION 2.- REINFORCING FIBERS 3.- WETTABILITY OF FIBERS AND INTERFACE GENERATION AS KEY STEPS 4.- THERMOPLASTIC (NON-REACTIVE) –BASED COMPOSITES 5.- REACTIVE PROCESSING OF FIBER-BASED COMPOSITES

EPF 6th Summer School – Gargnano May 2013 Polymers & Energy: Polymers for Future Energy Challenges

INTRODUCTION Composite materials = polymer matrix + filler or fiber

CONTENTS 1.- INTRODUCTION 2.- REINFORCING FIBERS 2.1. – Glass fibers 2.2..- Carbon fibers 2.3.- Aramid fibers 2.4.- Natural fibers 3.- WETTABILITY OF FIBERS AS A KEY ISSUE 4.- THERMOPLASTIC (NON-REACTIVE) –BASED COMPOSITES 5.- REACTIVE PROCESSING OF FIBER-BASED COMPOSITES

Processing fiber-based composite materials

3 ALPLAST Summer School - 2013 New Trends in Plastic Enginering - Oyonnax (France)

Molten polymer: thermoplastic

Reactive system: thermoset or thermoplastic

INTRODUCTION

Not only the combinaison between fibers and a polymer matrix…


Interface vs. interphase


INTRODUCTION Glass fibers


Processing glass fibers

Different types of glass fibers according to the chemical composition


from GlassFibreEurope.eu

FIBERS

Glass fibers


Chemical composition vs. physical properties


FIBERS Glass fibers

xxxxxx



Glass fibers

Glass fiber sizing

Water Film former Coupling agent Antistatic agent Lubricant Dry extract. 1 wt. %


from Micelman Co.

FIBERS CONTENTS 1.- INTRODUCTION 2.- REINFORCING FIBERS 2.1. – Glass fibers 2.2..- Carbon fibers 2.3.- Aramid fibers 2.4.- Natural fibers 3.- WETTABILITY OF FIBERS AS A KEY ISSUE 4.- THERMOPLASTIC (NON-REACTIVE) –BASED COMPOSITES 5.- REACTIVE PROCESSING OF FIBER-BASED COMPOSITES

Glass fibers Glass fiber sizing

Film former


from Michelman Co.



Coupling agent = organosilanes



Glass fibers



Fiber-matrix interface

Fiber-matrix interfacial

shear strength

Epoxy-glass fiber Polyester UP-glass fiber



Carbon fibers

Different processes available



Carbon fibers

ex-PAN

Precursor: PAN

First step from polyacrylonitrile fibers to crosslinked fibers



Carbon fibers


ex-PAN

Precursor: PAN

Second step


Carbon fibers

From PAN fibers to sized CF



Carbon fibers

Layered and isotropic

microstructure of the CF fibers

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Carbon fibers

ex-PAN CF

Graphite layers along the z-axis of the fiber Graphite edges on the surface (polar groups)



Carbon fibers

Activation of the surface via oxidization step



Aramic fibers


Aramid fiber

(lyotropic LCP)


Cellulose fibers

Multi-scale architecture of the fibers



Cellulose fibers

Highly hydrophilic

surface and

bulk structure

• Water uptake • Water swelling • Incompatible with non-polar polymer matrices



UHMWPE fibers

Gel spinning of PE

solutions



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UHMWPE fibers FIBERS CONTENTS

1.- INTRODUCTION 2.- REINFORCING FIBERS 2.1. – Glass fibers 2.2..- Carbon fibers 2.3.- Aramid fibers 2.4.- Natural fibers 3.- WETTABILITY OF FIBERS AS A KEY ISSUE 4.- THERMOPLASTIC (NON-REACTIVE) –BASED COMPOSITES 5.- REACTIVE PROCESSING OF FIBER-BASED COMPOSITES

Fragmentation Microdroplet

IFSS proportional to 1/ lc

Fragmentation and decohesion processes

Interfacial adhesion – How to test ?


28

FIBERS

Microdroplet

Fiber

Blades

Load

Friction force

Max force

Displacement

Recording max load

vs. embedded length

(embedded surface = 2.p.rf2.Le)

Fiber / matrix interfacial adhesion

29


FIBERS

Colloque Matériaux 2002 - Coll. 6

- 24 Octobre 2002

Greszczuk’s analysis

e

f

max

max L.coth..r..2

F

ff

int

E.r.b

G.2

* Conventional analysis demonstrate as funcyion of Le ( moy = Fmax / 2..rf

2.Le)

Max. shear stress

f

e2

ficff

max

r

L.nhcsc1

E.G.rr.2F

Analyse Penn & Lee

33

2

3

s33

2

s3

s33

2

s33f

ic

s33

s3

dC

D

C

D

C

T

Cr

G2

C

TD

Analyse Sheer & Nairn

• Description of interfacial nature ? Interface contributions: initiation of fracture ? fissure suivie par rupture catastrophique ou propagation fissure stable

Fiber-Matrix interfacial adhesion

FIBERS

THERMOPLASTIC COMPOSITES

Thermoplastic-based composites - Analysis



Benefits

Unique properties

Vibration

dampening

Light weight

Potent. low cost

Shelf life

Recyclable

Durability

Fatigue

Corrosion

Toughness

Limitations

Cost

Materials

Manufacturing

Tooling

Design know-how

Manufacturing know-how

Use temperature


Thermoplastic-based composites – Matrices



Chemical nature

Polyethylenes

Polypropylenes

Nylons

Polycarbonates

Acrylics

Polyesters

Polyimides

Polysulfones

Polyketones

Polyurethanes

the list continues

Properties

ultimate strain > 100%

no microcracking

no delamination

dampening

no water uptake

low dielectric properties

melt formable

weldable

elastomeric - plastic - elastic behavior

the list continues

THERMOPLASTIC COMPOSITES TP- composite B-Stage Commercial Products




TP- composite B-Stage Commercial Products



Thermoplastics)

Pultruded Products

LFT (Long Fiber Reinforced Thermoplastics)

CFT (Continuous Fiber Reinforced Thermopastics)

Wire coated products

Commingled fibers

Powder coated materials

Film sticking

Slurry processes

GMT (Glass Mat Reinforced Thermoplastics)

Pultruded Products

LFT (Long Fiber Reinforced Thermoplastics)

CFT (Continuous Fiber Reinforced Thermopastics)

Wire coated products

Commingled fibers

Powder coated materials

Film sticking

Slurry processes


TP B-stage products


Long fiber thermoplastic composites



TP B-stage products


Short Fiber, Long Fiber and Continuous Fiber Composites


Typical short fiber

thermoplastic material,

granules with fiber length

of approx. 2 to 4 mm,

resulting fiber length in a

part of approx. 0.4 mm

Long fiber thermoplastic

material, pellets of ½” and 1 “

fiber length, resulting fiber

length in a part of approx. 4-6

mm in injection molding and

approx. 20 mm in

compression molding

Continuous reinforced

thermoplastic material,

tape used for woven

sheets (thermoforming),

filament winding or

pultrusion


TP B-stage products


Pultruded TP prepregs


Fiber:

E-glass, S-glass, Carbon, Aramid, polymer fibers

Matrix:

PE, PP, PA (6, 6/66, 12, …), PET, PBT, PC, PEI,

PPS, SMA, …

Fiber content:

20% - 60% standard, some up to 84%

Product forms:

Tape, pellets (0.5”, 1”), woven tapes

more complex textile structures in development

THERMOPLASTIC COMPOSITES TP B-stage products


TWINTEX prepreg

xxxxxx


Twintex®

prepreg

Consolidated

composite

Temperature

+ Pressure

Source: Vetrotex


TP B-stage products


Twintex processing


Glass TP

Commingling

Roving

Extruder Bushing

Fiber/matrix combinations:

E-glass/PP, E-glass/PET

Fiber content:

60 % and 75 % by weight

Product forms:

Roving, fabric, pellets


TP B-stage products




Processing routes of TP-based composites



Process Type of Application

Injection Molding

Compression

Molding

Thermoforming

Hand Lay Up /

Vacuum Bag /

Autoclave

Low-Structural

Components

Semi-Structural

Components

Structural Components


TP –based composite materials


Effect of reinforcing fiber length


0,0

0,2

0,4

0,6

0,8

1,0

1,2

0,1 1 10 100Length (mm)

Rel

ativ

e P

rop

erty

Lev

el

Modulus

Strength

Impact

Processibility





Low volume manufacturing processes

Discontinuous processes

Thermoforming

Thermoplastic S-RIM, RTM and VARTM

Thermoplastic filament winding

Vacuum bag molding

Net shape preforming (modified P4)

THERMOPLASTIC COMPOSITES TP –based composite materials


Thermoforming

Process


Heat in Oven Thermoforming Operation

Finished Product





Weight performance: Good weight/performance ratio for fabric reinforced sheets

due to continuous fibers

Reduced weight/performance ratio for extruded sheets

depending on the resulting fiber length

Design flexibility: Limited, especially for complex geometries

Simulation tools available

Processability: Stabilization against oxidation necessary

Fiber disalignments with continuous fibers possible depen-

ding on geometry, material, tooling and process conditions

Recyclability: High rate of production scrap (fixation)

No direct recyclability

Use in other processes like plastication of regranulation





TP S-RIM, RTM, VARTM

Weight/performance: Excellent

Design flexibility: Limited to preforming capability, flow length and flow behavior

of the resin

Processability: Reaction can be sensitive to moisture and fiber sizing

Recyclability: Production scrap due to preforming step depending on

preforming method

No direct recyclability; can be used in other processes





TP Filament Winding

Weight/performance: Excellent

Design flexibility: Limited to symmetric parts that can be wound on a mandrel

Processability: Higher oxidative stabilization required

Recyclability: Low rate of production scrap


Scrap can be used in other processes




Vaccum Bag/ Hand Lay-Up

Weight/performance Excellent due to continuous fiber reinforcement

Design flexibility Limited to drapability and to the posibility of manually lay up

Processability Higher void content due to low pressure consolidation

Using autoclave to reduce void content

Often fiber disalignments

Recyclability High rate of production scrap possible depending

on the size of the material sheets and the part geometry


Scrap can be reused in other processes




High volume manufacturing processes

Discontinuous processes

Injection molding with

Compression molding

Stamp forming Preheated preforms

Matched metal tools

Potential to manufacture very thin sections (0.5 to 1 mm)

Drapable material required

Continuous processes

Pultrusion

LFT-extrusion





LFT-Injection Molding

Weight/Performance

Lower end of thermoplastic composites due to reduced

fiber length in the final part

Improvements possible by using local reinforcements

(using pultruded sections, sheets or tapes of continuous

composites localized strengthening and stiffening,

reduction of warpage)

Design Flexibility High

Flow channels and positions of gates have to be carefully designed

Processability

Recyclability Low production scrap rate

Can be re-used in the same process




Compression Molding

Weight/Performance Medium

Retaining fiber length gives excellent properties for a

random oriented material, but is lower than using a fabric

Local reinforcement or fabric reinforced GMT improve it

(using pultruded sections, sheets or tapes of continuous

composites localized strengthening and stiffening,

reduction of warpage)

Design flexibility High

Special simulation tools available

Processability Very stable process

Recyclability Some production scrap due to trim operations

Scrap can be added and reused in the same process (GMT

only sheets can be reused in the same process)




Curv

Self-reinforced polypropylene

Consists of “hot compacted” polypropylene fiber or tape Surface of tape or fiber melts during compaction to form the

“matrix” that binds the directional elements together

Oriented morphology contributed to the Le Tour de France

over six-fold increase :

Nearly doubles tensile strength of 40% random mat short

glass polypropylene, with comparable modulus and

22% weight savings: Increased recyclability

Reduced weight

Lower temperatures and pressures for thermoforming

Reduced irritation in the workplace

High strain to failure, with good impact strengthzzz

Data from “A New Self-Reinforced Polypropylene Composite” Jones, Renita S. and Derek E. Riley





Pultrusion

Weight/performance

Good to excellent due to continuous reinforcement

Design flexibility

Low design flexibility

Limited to constant cross sections, but can be shaped (pull/press)

Processability

Only limited experience available

Depends on stabilization of the material as well as used

material form

Recyclability

Low rate of production scrap expected


Can be used in other processes





LFT-Extrusion

Weight/performance Medium weight performance

Depends on retaining fiber length

Design flexibility Low design flexibility

Limited to constant cross sections

Can be post shaped or pull formed

Processability Not a lot of experience

A stable process is expected using the right die design

Recyclability Low rate of production scrap

Can be reused in the same process


XXXXXXX


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Process Cycle Time Tooling Costs Scrap Rate Overall Economics

Thermoforming Medium Low High Good for low volume production with no

or limited thickness variation

TP S-RIM, RTM,

VARTM

Medium to long, up to several minutes VARTM: low, single

sited tool

RTM: low to medium

S-RIM: Medium

Depends on

preforming

technique; often

high for

complex shaped

parts

Good for low volume production

TP Filament Winding Medium to long, depending on number

of tapes and heating system

Low to medium Low Good for symmetrical parts in low to

medium volume production

Vacuum Bag/

Hand Lay-up

Long; manual preparation can be hours

for a part

Low, single sided

tool

Medium to high Good for prototyping. Not recommended

for production scale.

Injection Molding

-LFT

-ILC

Short cycle times; typically 50 – 80 sec. High; steel tools with

ejector pins and slides

Very low Excellent for high volume production

Compression Molding

-GMT

-LFT

-ILC

Short cycle times; typically 35 – 60 sec. High; steel tools with

ejector pins and slides

Low – medium

depends on cut

outs. Scrap can

be reused

Excellent for high volume production of

large components

Pultrusion Continuous process; not enough

experience on throughput

Medium Low Limited experience available

Extrusion Continuous process; throughput mainly

limited by cooling capacity of calibration

die

Medium to high Low Expected to be cost

effective for profiles

REACTIVE PROCESSING OF COMPOSITES

Rheology (chemiorheology) is the most important parameter



Viscosity

Modulus

Temps de réaction

wsol

REACTIVE PROCESSING OF COMPOSITES Rheology (chemiorheology) is the most important parameter


Time-Temperature-transformation diagram Isothermal cure


REACTIVE PROCESSING OF COMPOSITES TS –based composite materials


B-Stage products

baed on

unsaturated

polyester resin




B-Stage products

baed on

unsaturated

polyester resin

Magnesia MgO as thickener




Curing unsaturated polyester resin

Heterogeneous curec network


Conversion



B-Stage products

baed on

unsaturated

polyester resin PVAc for shrinking Compensation Low Shrink Additive Low Profile Additive




B-Stage products


REACTIVE PROCESSING OF COMPOSITES CONTENTS 1.- INTRODUCTION 2.- REINFORCING FIBERS 2.1. – Glass fibers 2.2..- Carbon fibers 2.3.- Aramid fibers 2.4.- Natural fibers 3.- WETTABILITY OF FIBERS AS A KEY ISSUE 4.- THERMOPLASTIC (NON-REACTIVE) –BASED COMPOSITES 5.- REACTIVE PROCESSING OF FIBER-BASED COMPOSITES


TS –based composite materials

B-Stage products




Pre-pregs and compounds



Open mold processes :

• contact molding

• simultaneous projection molding

• continuous layering / stratification

• filament winding

• pultrusion

• centrifugation

Low pressure closed mold processes

• low pressure compression (hot/cold)

• RTM (Resin Transfer Molding)

• moulage au sac

High pressure closed mold processes

• compression : SMC and BMC

• BMC injection

• RIM (Reaction Injection Molding)


Numerous processes




Pultrusion



Filament winding



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Rotational molding /centrifugation



Low pressure - Closed mold TS –based composite materials

Autoclave


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Bag Molding (pressure/temperature)


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Low pressure injection molding

REACTIVE PROCESSING OF COMPOSITES

High pressure –

Closed mold




Hot compression / BMC




Compression / SMC




Injection / BMC




BMC injection

Feeding process




ZMC injection




Reinforced Reaction Injection Molding

THERMOPLASTIC COMPOSITES REACTIVE PROCESSING



Materials used for liquid molding processes

Cyclics

Reactive nylon

Fulcrum

Requirement for these materials

Viscosity less than 3000 mPa.s (cP)

(better less than 1000 mPa.s (cP))

TP–based composite materials




Nylon 6 (Nyrim)


170°C

env. 45

min

N C

O

C

O

H3C N C

OMgBr

NC

O

H3C CH2 5 C

O

N C

O

NC

O

H3C CH2 5 C

O

N C

O

N C

OH

N C

OH

NC

O

H3C CH2 5 C

O

N C

O

N C

OH

N C

OMgBr

CH3CH2MgBr

(CH

2)5

(CH

2)5 (CH2

)5

Polymérisation anionique




Nylon 12






85

Cyclics Corp.

CBT100 190-240°C CBT200 170-240°C 1 or 2 parts

Catalysts

185 à 205°C

50% crystallinity Molar masses from 30 to 60 000 g.mol-1

Tripathy, Macromolecules (2005)





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Cyclic oligomers of polycarbonate

http://www.cyclics.com/





87

Physical phenomena occuring during cure/processing

Tg Tg

Tg Tg

Tc

Tc

Tc

Tcure < Tg : Vitrification diffusion

Glass transition temperature Tg = f(conversion)





88

Vitrification Crystallization

Liquid polymer

Solid

monomer

Phase

separation

Tmelting

polymer

Tm monomer

Liquid

monomer

PA12

Melting of monomer / crystallization / phase separation





89

Processability window …. + viscosities = f(x)

PA12

Establishment by isomelting points of the times

where the melting point of the polymerreached the

polymerization temperature





90

Processability window …. + viscosities = f(x)

PA12



Cyclics


Cyclic form of PBT, PET, PC and others

Only PBT commercial available

Based on a ring shaped cyclical form

One or two part systems

Solid at room temperature – low viscosity resin at

elevated temperature (approx. 150 cP)

Polymerize into the Polymer using a catalyst

Isothermal process

Typical process temperature: 180 – 200 oC




Fulcrum


ISOPLAST matrix (Dow proprietary engineering thermoplastic polyurethane)

Thermoplastic viscosity issues addressed by ability to reverse polymerization in the melt stage, reducing viscosity to ensure good impregnation

Repolymerizes upon cooling, retaining traditional thermoplastic composite advantages

High impact resistance

Recyclability

High elongation to failure (~2.5%, versus ~1-1.5% for thermosets)

Zero-emissions processing

Fulcrum is the combination of ISOPLAST and pultrusion, with specific hardware design

Provides 10-fold line speed improvement over typical thermoset pultrusion lines

Allows thermoforming, welding, and overmolding of finished pieces

Figures from “Fulcrum Thermoplastic

Technology;

Making High-Performance Composite via

Thermoplastic Pultrusion” Dow Plastics,

January 2000




Fulcrum


Figures from “Fulcrum Thermoplastic Technology;

Making High-Performance Composite via

Thermoplastic Pultrusion” Dow Plastics, January 2000

Thermoformed Fulcrum Components





Reactive Thermoplastic VARTM/RTM/S-RIM

Similar the thermoset process

Reaction of at least two components creates

a thermoplastic resin that can be melted,

pre-shaped, welded, …

Low viscosity is required

Possible materials: Nylon, TPU, C-PBT (Cyclics)


PROCESSING OF THERMOSET AND THERMOPLASTIC COMPOSITE MATERIALS school presentations... · PROCESSING...

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Transcript of PROCESSING OF THERMOSET AND THERMOPLASTIC COMPOSITE MATERIALS school presentations... · PROCESSING...