Cellulose Reinforced High Density Polyethylene Presented by

Velu Palaniyandi M.S. Thesis Defense Advisors: Dr.John Simonsen Dr.Ralph Busch

Contents Background Introduction Objectives Materials and Methods Results Conclusions Acknowledgements

Background Natural Fiber Reinforced Composites (NFRP) applications in Car Interiors

Source : Reinforced Plastics, Feb 2004

Some More Applications Heat deflection temperature Gas barrier / permeability Packaging materials Electrical conductivity Electronics ,Housing appliances Flame retardancy

Source :Plastic technology ,Feb 2004

C

C oi r

ot to na no n cr ys D t ou al gl P as on de Fi r ro sa P in e

ce llu lo se

S is al

Ju te

Fl ax

em p

140

H

E -g la ss

Stiffness/Specifi Stiffness(Gpa)

Property Comparison Among the Commonly Used Reinforced Fibers 160

Stiffness Specific Stiffness

120

100

80

60

40

20

0

Introduction Why cellulose-reinforced thermoplastics? Property enhancement at lower density and cost than synthetic fiber materials (glass, carbon) Non-abrasive and easily recyclable compared to inorganic fillers High strength to weight ratio Sound abatement capability Low energy for processing (6500 BTU/lb of kenaf ; 23,500BTU/lb of glass fiber)

Role of fiber and Matrix in FRP σ1

σ1

Fiber

σ1

Composite decreases ε, increases E

Fiber High stiffness

Matrix

Brittle Matrix

εm

εf =εc strain,ε

Medium for stress transfer Stress-Strain curve

Binds the fiber together

Fiber Reinforced Composite - Issues Fiber dispersion Dispersing agent

Interfacial adhesion Compatabilizer or coupling agents Surface modification of fibers

Effect of filler on the crystallization behavior of polymer

Compatabilizer – Function and Mechanism Matrix H O H O H O

lo

H O

llu Ce

H O

se

Objectives To prepare nanocrystalline cellulose with high aspect ratio To investigate the material properties of nanocrystalline cellulose (NCC) filled high density polyethylene (HDPE) To use microcrystalline cellulose (MCC) as a model filler for NCC To disperse MCC using a coupling agent system To study the non-isothermal crystallization kinetics of the filled composites

Materials Matrix: High Density Polyethylene Filler Cellulose nanocrystal from Cotton Microcrystalline cellulose (FMC Corp, NJ) Coupling agent: MAPE (Optipak 210)

Developed by Kaichang Li’s lab AKD (Aquapel 364) PMDI (Rubinate 1840)

Experimental Methods Crystalline regions

Amorphous region

Individual cellulose microfibrils

Acid hydrolysis Individual crystallites

Schematic of acid hydrolysis of cellulose

Composite Preparation Method Brabender Plasticorder Melt mixing HDPE and NCC/MCC at 180 oC for 10 min MAPE (0.4 wt%) and AKD-PMDI (1.0 wt%) was added during mixing

Carver Hot press Compression molding at 185 oC at 348.5 kPa for 10 min

Composite Characterization Techniques Mechanical testing –Sintech 1G, Universal testing machine Flexural strength (MOR) and Flexural modulus (MOE) were measured according to ASTM D 790-02

Thermal Analysis Differential Scanning Calorimetry, TA Instruments DSC 2920 -Temperature range – 20-200oC - Heating/cooling rate – 5, 10, 12.5, 15oC/min Thermo gravimetric analysis , TA Instruments, Q500

- Temperature range – 40-600oC - Heating rate –10oC/min

Results – TEM Characterization/ Mechanical Testing

Transmission Electron Micrograph From Cellulose Nanocrystal Suspension Negatively Stained With Ammonium Molybdate

Mag -100,000X

L d

Aspect ratio =L/d

Mag -100,000X

Diameter – 4nm Length – 120 – 160 nm Aspect ratio – 30-40

Flexural Strength (MOR) 38

MOR (MPa) MOR (MPa) MOR (MPa)

36 34 36 34 34 32 32 32

30 30

30

28 28 28

26 26

MCC-HDPE

26

24

MCC-HDPE MCC-AKD-PMDIHDPE MCC_MAPE_HDPE 5%NCC-HDPE MCC-HDPE

24 24

22

22 22

20 20 -5 -5 -5

20

0 0

0

55 1010 15 15 5 10 15 Wt %Wt M% CC/NCC conte MCC/NCC contentnt Wt % M CC/NCC conte nt

20 20 20

25 25 25

Flexural Stiffness 1.600

MCC-HDPE MCC-MAPE-HDPE MCC-AKD-PMDI-HDPE 5%NCC-HDPE

1.500 1.400

MOE(GPa)

1.300 1.200 1.100 1.000 0.900 0.800 0.700 0.600 -5

0

5

10

15

Wt % M CC/NCC CONTENT

20

25

4.0 Aspect ratio (L/D)

Aspect ratio with No MAPE

3.5

Aspect ratio with MAPE

3.0 2.5 2.0 1.5 1.0 0

5

10 15 Wt % of MCC

20

25

Low aspect ratio due to agglomeration

Light Microscopy Image of the Cross Section Perpendicular to the Length of the Samples

Mag-10x

Mag-20x

Agglomerated cellulose fibers in 5%NCC-HDPE composite

Light Microscopy Image of the Cross Section Perpendicular to the Length of the Samples

Mag-20x Dispersed cellulose fibers in 5%MCC-AKD— PMDI-HDPE sample

THERMAL ANALYSIS Differential Scanning Calorimetry/ Thermal Gravimetric Analysis

Polymer Crystallization Isothermal Crystallization Constant temperature process Avrami, Ozawa,Kissinger

Non- Isothermal crystallization Constant cooling rate process Simulates real processing conditions Modified Avrami, Kissinger

Kissinger Method – Activation Energy (Ea) d (ln ϕ/Tp2) /d(1/Tp) = -∆E/R ϕ– Cooling rate (ok/min) Tp – Crystallization peak temperature (k) ∆E – Activation energy (kJ/mole) R- Universal gas constant (= 8.314 j/mol k)

Melting

Endothermic

Matrix Crystallinity= ∆Hc/∆Hoc

Exothermic

dQ/dT

Heating

Low temp

High temp

Low temp

High temp

Cooling Crystallization Tp

RESULTS Thermal Analysis

Crystallization Peak Temperature CCr ryys st taal ll li izzaattiioo nn pp e a kk tt e mp mp ee rr aa t uurr ee aatt 1100 ppe m inn e rr mi

C r y s t a l l i z a t i o n p e a k t e mp e r a t ur e a t 1 0 p e r mi n

3 9309. 15 3 91

39 0. 5 390 3 90 3 90 3 89. 5 3 38 8 9 9. 5

3 89 389

M C C -H D P E M C C - HD P E A K D - P MMDCI -CH-DHPDEP E M C C - M A P E - H DP E

3 88 38 8. 5

3 88. 5 3 88 3 87

38 7. 5 388 3 87 3 86 3 87. 5 38 6. 5 3 85 3 86 387

00 0

55 5

10 15 10 1515 10 %M C CC %M %MCC C

20 2 0 20

25 2 5 25

Percent Matrix Crystallinity

Percent crystallinity(%) Percent Crystallinity Percent Crystallinity (%)(%)

85 75

80 80 7075 75

6570 70

65 60 65

MCC_HDPE MCC_HDPE

60 60

MCC_HDPE MCC-AKD-PMDIMCC-MAPEHDPE

55

55 55

HDPE

50

50 50

45 45

45 40 4040 -5

-5-5

0

00

5

55

10

15

1010 1515 Wt % MCC Wt W% t %MCC MCC

20

20 20

25 25

25

Activation Energy MCC-HDP E

Activation Energy (kj/mole) Activation Energy (kj/mole)

190

190 170

MCC-HDPE MCC-HDPE MCC-MAPE-HDPE MCC-AKD-PMDI-HDPE MCC-HDPE

170 150 150 130 130 110 110 90 90

7070 -5 -5

0 0

5 5

10 15 10 15 % MCC content % MCC content

20 20

25 25

Avrami Exponent 1.60

Avrami exponent,n

1.50

1.40

MCC-MAPE-HDPE

1.30

AKD-PMDI-HDPE

1.20

1.10

1.00 -5

0

5

10 Wt %MCC

15

20

25

Derivative Thermogravimetric (DTG) Curves 16

20% MC C -HD PE 14

20% MC C -AKD -PMD I-HD PE

Weight loss rate (%/min)

12

10

8

6

4

2

0 0

50

100

150

200

250

300

350 o

Te mp e ratu r e ( C)

400

450

500

550

600

650

Derivative Thermogravimetric (DTG) Curves 12

Pure Cellulose

10

Weight loss rate (%/min)

Ea=153.1kj/mole 8

Cellulose nanocrystal Ea=113.53kj/mole

6

Sulfate groups

decrease onset degradation temperature

4

2

0 20

70

120

170

220

270

320

Temp(oC)

370

420

470

520

570

Conclusions Coupling agents increase strength. Fillers alter nucleation behavior PMDI-AKD increases crystallinity. PMDI-AKD changes the activation energy and peak crystallization temperature Degradation behavior of the composite is not altered in the presence of compatabilizer. Grafted sulfate groups decreases the activation energy and onset degradation temperature The concept of compatabilizer systems can be extended to nanocomposites

Acknowledgements This project was funded by a grant from the USDA National Research Initiative Competitive Grants Program

Advisors Dr.John Simonsen Dr.Ralph Busch

Committee members Dr.Joe Karchesy Dr.Sundar V.Atre Dr.Jeffrey K.Stone

Thanks to my colleagues in my group and to folks in WSE dept