Polymer Nanocomposites for Inflatable Space Structure

Applications

PROJECT WORK

Submitted by

P.L. Amarnath

Arathi M. Sharma

G. Rajyalakshmi

G.C. Shri manikandan

Guided by Dr. S.S. Bhagawan Mr. K. Jayanarayanan

Professor Assistant Professor

Department of Polymer Engineering Department of Polymer Engineering

DEPARTMENT OF POLYMER ENGINEERINGAMRITA SCHOOL OF ENGINEERINGAMRITA VISHWA VIDYAPEETHAM

COIMBATORE 641 105MAY 2008

AGENDAAGENDA

IntroductionPolymer NanocompositesInflatable Space Structures

Scope & Objectives Experimental Material Specification Preparation of nanocomposites Laminate preparation Design of Experiments Box Behnken Design T-peel test and Lap shear test Results and Discussions Conclusion

Introduction

Introduction to Introduction to Polymer Polymer NanocompositesNanocomposites

Contain reinforcing particles (layered silicates) with at least one Contain reinforcing particles (layered silicates) with at least one dimension in the nanosize range [1-100nm]dimension in the nanosize range [1-100nm]

Increase in mechanical, thermo-mechanical, barrier, optical, fire Increase in mechanical, thermo-mechanical, barrier, optical, fire retardant properties at low filler loading (<5%)retardant properties at low filler loading (<5%)

2 types of structures formed in PNC : Intercalated & Exfoliated2 types of structures formed in PNC : Intercalated & Exfoliated

Intercalated PNC : A well ordered multilayered nanocomposite Intercalated PNC : A well ordered multilayered nanocomposite with alternating polymer/mineral layer structure having a repeat with alternating polymer/mineral layer structure having a repeat distance of a few nmdistance of a few nm

Exfoliated nanocomposites : Individual delaminated mineral Exfoliated nanocomposites : Individual delaminated mineral layers randomly dispersed in the polymer matrix.layers randomly dispersed in the polymer matrix.

Two types of Two types of NanocompositesNanocomposites Intercalated & Exfoliated Intercalated & Exfoliated

Advantages of PNCAdvantages of PNC

Efficiently reinforced without loss of ductilityEfficiently reinforced without loss of ductility

Increase in modulus by factor of 3Increase in modulus by factor of 3

Improved impact strengthImproved impact strength

Reduction in permeability by 2 orders of magnitudeReduction in permeability by 2 orders of magnitude

Increase in heat deflection temperature Increase in heat deflection temperature

Reduction in flammabilityReduction in flammability

Layered Silicates Layered Silicates Montmorrilonite ClayMontmorrilonite Clay

AlSiONa+, Li+

1 nm

20 nm – 1μm

Tetrahedral sheet(SiO4)

Octahedral sheet(AlO6)

Layered silicates : Montmorillonite Layered silicates : Montmorillonite clayclay(cont)(cont)

They have platy structure with thickness of < 1nm with They have platy structure with thickness of < 1nm with lateral dimensions of layers varying from 300 A° to lateral dimensions of layers varying from 300 A° to several microns . several microns .

Crystal lattice consists of 2 D layers. A central octahedral Crystal lattice consists of 2 D layers. A central octahedral sheet of alumina or magnesia is fused to two external silica sheet of alumina or magnesia is fused to two external silica tetrahedron by the tip so that the oxygen ions of the tetrahedron by the tip so that the oxygen ions of the octahedral sheet do also belong to the tetrahedral sheets.octahedral sheet do also belong to the tetrahedral sheets.

These layers organize themselves to form stacks with a These layers organize themselves to form stacks with a regular Van der Waals gap in between them called the regular Van der Waals gap in between them called the interlayer or the galleryinterlayer or the gallery

Introduction to Inflatable Introduction to Inflatable StructuresStructures

Inflatable structures becoming popular in Civil, Inflatable structures becoming popular in Civil, Architecture & Aerospace Engg.Architecture & Aerospace Engg.

Gossamer structures finds applications in space as thin Gossamer structures finds applications in space as thin film solar arrays, antennas, solar sails, sunshields, air film solar arrays, antennas, solar sails, sunshields, air ships & large membrane reflectors.ships & large membrane reflectors.

Rigidizable materials : Initially flexible to facilitate Rigidizable materials : Initially flexible to facilitate inflation (or) deployment, and become rigid when inflation (or) deployment, and become rigid when exposed to an external influenceexposed to an external influence

ECHO-IIISRSSOLAR SAIL BOOM

INFLATABLE REFLECTOR

REFLECTOR ANTENNA

PARABOLIC REFLECTOR

Scope & Objectives

To prepare Polyester (PBT) / Nanoclay (MMT) composite cast films by melt extrusion.

To characterize the Intercalated and Exfoliated behaviour of the nanocomposites using XRD technique.

To compare the properties of nanocomposites prepared using Single Screw Extruder and Twin Screw Extruder (Haake Rheocord).

To prepare laminates based on PBT/MMT cast film/ PU adhesive / UHMWPE fabric

Main Objective: To develop Polymer Nanocomposites which

serve as structural gas envelopes for inflatable space structures.

Objectives Objectives (contd)

To Study the peel resistance and lap shear strength of PBT To Study the peel resistance and lap shear strength of PBT

and UHMWPE Laminates. and UHMWPE Laminates.

To optimize the nanoclay content in PBT film and To optimize the nanoclay content in PBT film and

Polyurethane based adhesive using Design of Experiments. Polyurethane based adhesive using Design of Experiments.

[Box Behnken Design][Box Behnken Design]

To generate quadratic equations based on regression analysis To generate quadratic equations based on regression analysis

for the properties of interest.for the properties of interest.

To generate contour plots for peel strength and shear strength To generate contour plots for peel strength and shear strength

data.data.

Validation of the prediction of properties by conducting a Validation of the prediction of properties by conducting a

verification experiment.verification experiment.

Experimental Aspects

Material Material SpecificationSpecification

Polyester (PBT) Resin Polyester (PBT) Resin

Grade : Valox® PBT Resin 315Grade : Valox® PBT Resin 315

Supplier: GE Advanced MaterialsSupplier: GE Advanced Materials

Unreinforced, for extrusion/ compounding only.Unreinforced, for extrusion/ compounding only. High viscosity. FDA and USP Class VI compliant.High viscosity. FDA and USP Class VI compliant. Melt viscosity between 7500 and 9500 poise.Melt viscosity between 7500 and 9500 poise.

NanofillNanofillererGrade : Cloisite® 20AGrade : Cloisite® 20A

Supplier: Southern Clay Products IncSupplier: Southern Clay Products Inc

Cloisite® 20A : A natural montmorillonite modified with aCloisite® 20A : A natural montmorillonite modified with a

quaternary ammonium saltquaternary ammonium salt

Physical propertiesPhysical properties

Color: Off whiteColor: Off white

X ray Results: dX ray Results: d001.001. = 24.2A = 24.2A

Density: 1.77 (g/cc)Density: 1.77 (g/cc)

UHMWPE FabricUHMWPE FabricGrade : Dyneema SK75 1760 dtexGrade : Dyneema SK75 1760 dtex

Supplier: DSM.Supplier: DSM.

Melting Temperature: 144-152°C Melting Temperature: 144-152°C Specific gravity: 0.975 g/cm3Specific gravity: 0.975 g/cm3

Polyurethane Polyurethane AdhesiveAdhesive

Name: Name: CAC SF11/CAC SF11A (Solvent-Free Adhesive System)CAC SF11/CAC SF11A (Solvent-Free Adhesive System)

Supplier:Supplier: Henkel CAC Pvt. Ltd, Chennai Henkel CAC Pvt. Ltd, Chennai

DescriptionDescription

CAC SF11/CAC SF11A is a solvent free two component CAC SF11/CAC SF11A is a solvent free two component adhesive system consisting of polyurethane based adhesive CAC adhesive system consisting of polyurethane based adhesive CAC SF11 and a polyester based additive CAC SF11A.SF11 and a polyester based additive CAC SF11A.

Preparation of nanocompositesPreparation of nanocomposites

Using Single Screw ExtruderUsing Single Screw Extruder

Nanoclay masterbatch used : 2%, 4% NC filled PBTNanoclay masterbatch used : 2%, 4% NC filled PBT

Preparation of 0.1%, 0.2%, 0.3%, 0.4%, 0.5% filled PBTPreparation of 0.1%, 0.2%, 0.3%, 0.4%, 0.5% filled PBT from the master batchesfrom the master batches

Processing parameters set at 200° C, 210° C, 230° C, 240° Processing parameters set at 200° C, 210° C, 230° C, 240° C, 250° C at various zones and 260 ° C at the die zone with C, 250° C at various zones and 260 ° C at the die zone with a screw speed of 50 rpma screw speed of 50 rpm

Using Twin Screw Using Twin Screw ExtruderExtruder

1 Kg of nanoclay masterbatch (4% NC filled PBT) extruded 1 Kg of nanoclay masterbatch (4% NC filled PBT) extruded in single screw extruderin single screw extruder

Preparation of 0.25%, 0.50%, 0.75%, 1.0%, 1.25% filled Preparation of 0.25%, 0.50%, 0.75%, 1.0%, 1.25% filled PBT from masterbatchPBT from masterbatch

Extrusion process carried out using HAAKE extruder & Extrusion process carried out using HAAKE extruder & extrudates obtained in sheet form using a Sheet die.extrudates obtained in sheet form using a Sheet die.

Processing parameters set at 220° C, 230° C, 230° C at Processing parameters set at 220° C, 230° C, 230° C at various zones and 235 ° C at the die zone with a screw speed various zones and 235 ° C at the die zone with a screw speed of 8-10 rpm.of 8-10 rpm.

Laminate Laminate PreparationPreparation

Hand lay-up technique was followedHand lay-up technique was followed

UHMWPE fabric and nanoclay filled PBT films are cut to UHMWPE fabric and nanoclay filled PBT films are cut to dimensions specified in the T-peel and lap shear test standardsdimensions specified in the T-peel and lap shear test standards

The two substrates are bonded using nanoclay modified PU adhesive as per the Box-Behnken design

The adhesive in the bonded areas is allowed to cure for 24 hrs before testing

Design of Experiments

Design of Design of ExperimentsExperiments

Design of Experiments (DoE) is a structured technique, based Design of Experiments (DoE) is a structured technique, based

in statistics, for analyzing the behaviour of a product, process, in statistics, for analyzing the behaviour of a product, process,

or simulation by changing multiple design parameters in a or simulation by changing multiple design parameters in a

specific manner and recording the response. specific manner and recording the response.

Box-Behnken Box-Behnken DesignDesign

The Box-Behnken design is an independent quadratic design in that it The Box-Behnken design is an independent quadratic design in that it does not contain an embedded factorial or fractional factorial design. does not contain an embedded factorial or fractional factorial design.

In this design the treatment combinations are at the midpoints of In this design the treatment combinations are at the midpoints of edges of the process space and at the center. edges of the process space and at the center.

Coded formCoded formTrialTrial XX YY ZZ

11 +1+1 +1+1 00

22 +1+1 -1-1 00

33 -1-1 +1+1 00

44 -1-1 -1-1 00

55 +1+1 00 +1+1

66 +1+1 00 -1-1

77 -1-1 00 +1+1

88 -1-1 00 -1-1

99 00 +1+1 +1+1

1010 00 +1+1 -1-1

1111 00 -1-1 -1-1

1212 00 -1-1 +1+1

1313 00 00 00

Variables used in DesignVariables used in Design

Variation of nanoclay content in the PBT film (X)Variation of nanoclay content in the PBT film (X)

NCO/OH ratio in the polyurethane adhesive (Y)NCO/OH ratio in the polyurethane adhesive (Y)

Variation of nanoclay content in the adhesive (Z)Variation of nanoclay content in the adhesive (Z)

Un-coded Un-coded FormForm

TrialTrialWt PBT/MMTWt PBT/MMT NCO/OHNCO/OH MMT in AdhesiveMMT in Adhesive

PercentagePercentage RatioRatio PercentagePercentage

11 1.251.25 75/2575/25 2.52.5

22 1.251.25 55/4555/45 2.52.5

33 00 75/2575/25 2.52.5

44 00 55/4555/45 2.52.5

55 1.251.25 65-3565-35 55

66 1.251.25 65/3565/35 00

77 00 65/3565/35 55

88 00 65/3565/35 00

99 0.750.75 75/2575/25 55

1010 0.750.75 75/2575/25 00

1111 0.750.75 55/4555/45 00

1212 0.750.75 55/4555/45 55

1313 0.750.75 65/3565/35 2.52.5

T-Peel TestT-Peel Test

The strength required to pull apart The strength required to pull apart a bonded surfacea bonded surface

Two substrates, each 16cm x 2.5cm Two substrates, each 16cm x 2.5cm are bonded by adhesive, with a are bonded by adhesive, with a bonded length of 12cm & bonded bonded length of 12cm & bonded width of 2.5cmwidth of 2.5cm

Peel angle = 180 degPeel angle = 180 deg Specimen is pulled at 200mm/min Specimen is pulled at 200mm/min Failure : Adhesive, Cohesive or Failure : Adhesive, Cohesive or

Substrate failureSubstrate failure

Lap Shear TestLap Shear Test

Determines the shear strength of Determines the shear strength of adhesivesadhesives

Two substrates each 2.5cm x Two substrates each 2.5cm x 10cm are bonded by adhesive 10cm are bonded by adhesive with a bonding area of 2.5cm x with a bonding area of 2.5cm x 1cm 1cm

Specimen is pulled at 50mm/min Specimen is pulled at 50mm/min Failure: Adhesive, Cohesive or Failure: Adhesive, Cohesive or

Substrate failureSubstrate failure

Results and Results and DiscussionsDiscussions

0.2% Filled PBT

0

1

2

3

4

5

6

Angle 13.557 24.66 34.671 45.07 55.276 65.458 76.22

Angle 2 Theta

Inte

nsity

Cou

nt

0.4% Filled PBT

0

1

2

3

4

5

6

Angle 13.053 22.969 33.434 43.789 53.97 64.273 74.58

Angle 2 Theta

Inte

nsit

y C

ou

nt

0.1% Filled PBT

0

1

2

3

4

5

6

Angle 12.693 23.17 33.46 43.64 54.087 64.992 76.338

Angle 2Theta

Inte

nsit

y C

ou

nt

0.3% Filled PBT

0

1

2

3

4

5

6

Angle 13.244 23.309 34.192 44.19 54.296 65.037 76.2

Angle 2 Theta

Inte

nsit

y C

ou

nt

XRD Plots

0.2% Filled PBT

0

1

2

3

4

5

6

Angle 13.557 24.66 34.671 45.07 55.276 65.458 76.22

Angle 2 Theta

Inte

nsity

Cou

nt

0.1% Filled PBT

0

1

2

3

4

5

6

Angle 12.693 23.17 33.46 43.64 54.087 64.992 76.338

Angle 2Theta

Inte

nsit

y C

ou

nt

0.3% Filled PBT

0

1

2

3

4

5

6

Angle 13.244 23.309 34.192 44.19 54.296 65.037 76.2

Angle 2 Theta

Inte

nsit

y C

ou

nt

0.2% Filled PBT

0

1

2

3

4

5

6

Angle 13.557 24.66 34.671 45.07 55.276 65.458 76.22

Angle 2 Theta

Inte

nsity

Cou

nt

0.1% Filled PBT

0

1

2

3

4

5

6

Angle 12.693 23.17 33.46 43.64 54.087 64.992 76.338

Angle 2Theta

Inte

nsit

y C

ou

nt

0.4% Filled PBT

0

1

2

3

4

5

6

Angle 13.053 22.969 33.434 43.789 53.97 64.273 74.58

Angle 2 Theta

Inte

nsit

y C

ou

nt

0.3% Filled PBT

0

1

2

3

4

5

6

Angle 13.244 23.309 34.192 44.19 54.296 65.037 76.2

Angle 2 Theta

Inte

nsit

y C

ou

nt

0.2% Filled PBT

0

1

2

3

4

5

6

Angle 13.557 24.66 34.671 45.07 55.276 65.458 76.22

Angle 2 Theta

Inte

nsity

Cou

nt

0.1% Filled PBT

0

1

2

3

4

5

6

Angle 12.693 23.17 33.46 43.64 54.087 64.992 76.338

Angle 2Theta

Inte

nsit

y C

ou

nt

Tensile Test Tensile Test ResultsResults

MMT loadings(Wt. %)

UltimateStress(M Pa)

Young’s Modulus(M Pa)

Elongation at break

(%)

0% 28.6 61 71

0.1% 33.7 73.7 62

0.2% 30.5 62 73.9

0.3% 26.8 57.3 64

0.4% 29.1 64.3 69

0.5% 33.4 75.8 60

Wt Wt PBT/MMTPBT/MMT

NCO/OHNCO/OHMMT in MMT in AdhesiveAdhesive

T-PEEL T-PEEL STRENGTHSTRENGTH

LAP SHEAR LAP SHEAR STRENGTHSTRENGTH

PercentagePercentage RatioRatio PercentagePercentage N/mN/m kN/sq.mkN/sq.m

1.251.25 75/2575/25 2.52.5 10441044 879879

1.251.25 55/4555/45 2.52.5 11691169 434434

00 75/2575/25 2.52.5 973973 782782

00 55/4555/45 2.52.5 965965 526526

1.251.25 65-3565-35 55 510510 482482

1.251.25 65/3565/35 00 832832 670670

00 65/3565/35 55 12711271 502502

00 65/3565/35 00 612612 440440

0.750.75 75/2575/25 55 957957 670670

0.750.75 75/2575/25 00 722722 565565

0.750.75 55/4555/45 00 10281028 414414

0.750.75 55/4555/45 55 706706 670670

0.750.75 65/3565/35 2.52.5 761761 662662

T-Peel and Lapshear Test Results

Regression Regression AnalysisAnalysis

A statistical procedure used to predict the value of A statistical procedure used to predict the value of an unknown variable (dependent variable) from the an unknown variable (dependent variable) from the values of one or more known variables values of one or more known variables (independent variables). (independent variables).

It measures the relationship between each of the It measures the relationship between each of the independent variables and the dependent variable.independent variables and the dependent variable.

Regression Regression EquationEquation

General form of Regression equationGeneral form of Regression equation

aa11+a+a22XX11+a+a33XX22+a+a44XX33+a+a55XX11

22+a+a66XX2222+a+a77XX33

22+a+a88XX11XX22+a+a99XX22XX

33+a+a1010XX33XX11

aa11, a, a2 2 …a…a10 10 - coefficients obtained from contour plots - coefficients obtained from contour plots

XX1 1 ,, XX2 2 ,, XX3 3 – coded X, Y & Z of Box-Behnken design– coded X, Y & Z of Box-Behnken design

Regression equationRegression equation (cont)(cont)

T-PEEL STRENGTH (N/m)T-PEEL STRENGTH (N/m)

761.26 – 33.35X761.26 – 33.35X11 – 21.58X – 21.58X11 + 31.39X + 31.39X33 + 114.78X + 114.78X1122 + +

161.87X161.87X2222 – 69.65X – 69.65X33

22 – 33.35X – 33.35X11XX22 – 245.25X – 245.25X22XX33 + +

139.3X139.3X33XX11

LAP SHEAR STRENGTH (kN/sq m)LAP SHEAR STRENGTH (kN/sq m)

662 + 269X662 + 269X11 + 107X + 107X22 + 294X + 294X33 – 319X – 319X1122 + 246X + 246X22

22 – 107X – 107X3322

+ 473X+ 473X11XX22 – 628X – 628X22XX33 – 377X – 377X33XX11

Contour plot of T-Peel testContour plot of T-Peel test

Coded Y

Coded Z

1.00.50.0-0.5-1.0

1.0

0.5

0.0

-0.5

-1.0

Coded X 0Hold Values

> – – – < 700

700 800800 900900 1000

1000

T-Peel

Contour Plot of T-Peel vs Coded Z, Coded Y

Contour plot of lap shear Contour plot of lap shear testtest

Coded Y

Coded Z

1.00.50.0-0.5-1.0

1.0

0.5

0.0

-0.5

-1.0

Coded X 0Hold Values

> – – – – – – < 450000

450000 500000500000 550000550000 600000600000 650000650000 700000700000 750000

750000

Lapshear

Contour Plot of Lapshear vs Coded Z, Coded Y

Coded X

Coded Z

1.00.50.0-0.5-1.0

1.0

0.5

0.0

-0.5

-1.0

Coded Y 0Hold Values

8001300

T-Peel

550000900000

Lapshear

Contour Plot of T-Peel, Lapshear

Overlaid Contour Plot

Verification Verification ExperimentsExperiments

Mechanical Mechanical propertiesproperties

X=0.5% Y=65/35 X=0.5% Y=65/35 Z=2.5%Z=2.5%

X=0.75% Y=65/35 X=0.75% Y=65/35 Z=1.25%Z=1.25%

PredictedPredicted ExperimentalExperimental PredictedPredicted ExperimentalExperimental

T-Peel T-Peel StrengthStrength (N/m)(N/m)

806806 832832 728728 738738

Lap Shear Lap Shear Strength Strength (kN/m(kN/m22))

641641 644644 621621 627627

Conclusion Melt mixing using TSE showed a better dispersion of MMT in PBT than using SSE, which can be depicted from XRD data

The optimization process was carried out by using DoE technique and factors affecting the properties of the laminates were identified and studied

In accordance with the design, laminates prepared and tested for mechanical properties and data obtained were used to generate models by linear regression analysis.

Verification experiments were carried out to validate the prediction from the equations and the results showed a fair match between the experimental and predicted values.

Future workFuture work

The barrier properties of the laminates prepared maybe studied. The barrier properties of the laminates prepared maybe studied.

The nanocomposites may be prepared using PET instead of PBTThe nanocomposites may be prepared using PET instead of PBT

Carbon Nanotubes maybe used as reinforcing members instead Carbon Nanotubes maybe used as reinforcing members instead of MMTof MMT

Epoxy/polyester based adhesives maybe used in laminate Epoxy/polyester based adhesives maybe used in laminate preparation instead of Polyurethane based adhesives.preparation instead of Polyurethane based adhesives.

Surface treatment of PBT film and UHMWPE fabric (corona Surface treatment of PBT film and UHMWPE fabric (corona and plasma treatments) and plasma treatments)

Thank youThank you