Clay dispersion using Extensional Flow Mixer for polymer nanocomposites

(1)

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Clay dispersion using Extensional Flow Mixer for polymer nanocomposites

Tokihisa, M.; Yakemoto, K.; Sakai, T.; Utracki, L. A.; Sepehr, M.; Li, J.; Simard, Y.

(2)

Clay dispersion using

Extensional Flow Mixer for

polymer nanocomposites

M. Tokihisa

1

_{, K. Yakemoto}

1

_{, T. Sakai}

2

_,

L.A. Utracki

3

_{, M. Sepehr}

3

_{, J. Li}

3

_{and Y. Simard}

3

1 _{The Japan Steel Works, Ltd. (Japan)}

2 _{Fellow of The Japan Steel Works, Ltd. (Japan)}

(3)

Introduction 1

The main methods of PNC manufacture are:

¾

Co-solvent method (co-dissolution)

z

Cumbersom, hazardous, expensive, …

¾

Reactive (by polymerization or co-polymerization)

¾

Melt compounding

z

Limited to several type of polymeric matrices

z

Slow – usually requires several hours

z

Applicable to a low nano-filler concentration range

z

Available only to resin manufactures

z

Universal – might be used with a single-phase polymer, or

a multiphase polymeric system (blend, composite, or foam)

z

Rapid – residence time < 15 min

z

Applicable to a wide range of nano-filler concentrations

z

Inexpensive and environmentally friendly

(4)

3

Introduction 2

Polymer processing involves laminar flow in fields:

¾

Rotational = shear

z

Large energy consumption and

temperature increase (measured:

∆T ≤ 90 ºC) resulting high degree

of degradation

z

Inefficient for dispersing the minor

phase, e.g., drops in blends, clay

stacks in PNC (rotation of viscous

drops; compression of aggregates)

Fig. Clay stack behavior during

shear flow field

¾

Irrotational = elongational

z

Small energy consumption that leads

to small temperature increase (∆T

≤

1 to 3

_{ºC) and low degradation}

z

Facilitates dispersion of the

dispersed phase, e.g., drops in

blends, clay stacks in PNC

z

Engenders orientation of the

dispersed phase

Fig. Clay stack behavior during

elongational flow field

(5)

Introduction

Melt flow from extruder

To die

Extensional Flow Mixer, EFM-3

(Designed for polymer blend)

Spiral pipes Spiral mandrel Upper flow channel Lower flow channel Seal bushing Flange to die Extensional flow zone Outer wall End cap Flange onto extruder

Redesigned EFM, EFM-N

Designed for dispersing

nanoparticles

Orient organoclay

Peel off organoclay

Randomize the flow

(6)

Objectives

Investigation of the effect of EFM with new C-D

geometry for dispersing the clay (EFM-N) on

compounding conditions compared with the

commercial EFM (EFM-3)

Investigation of the effects of single screw extruder

(SSE) + EFM-N on clay dispersion compared with

SSE + EFM-3 and twin screw extruder (TSE)

Investigation of the effects of SSE + EFM-N on

mechanical performances compared with SSE +

EFM-3 and TSE

(7)

Materials

PA-6 (UBE1015B, M

_W

= 21.7 kg/mol, Ube Industries) dried

for 48h at 80ºC, without stabilizers.

PP (Profax-PDC1274, M

_W

= 250 kg/mol, Basell

Polyolefins), without stabilizers.

PP-MA1 (Epolene 3015, 1.31wt% MAH, M

_W

= 47kg/mol,

Eastman Chemicals)

PP-MA2 (Polybond 3150, 0.5wt% MAH, M

_W

= 330kg/mol,

Crompton)

Cloisite 15A (C15A, MMT di-methyl di-hydrogenated

tallow ammonium, Southern Clay Products) dried for 24h

at 100ºC

(8)

Method of compounding

Single screw extruder (SSE)

EFM-3 or EFM-N

Masterbatches (MB) were prepared using co-rotation

intermeshing twin screw extruder (N = 200rpm, Q = 5kg/h)

under dry N

₂

:

(1)

PA-6 + 4wt% C15A (T=240ºC)

(2)

PP + 20wt% PP-MA + 10wt% C15A (T=240ºC)

PNC was prepared by diluting MB with the matrix polymer in a

TSE, SSE or SSE + EFM (EFM-3 or EFM-N). The C-D gap: h

= 15, 30, 100, 300 (±3)µm.

(9)

Characterization of PNC

X-ray diffraction (XRD)

The mean interlayer spacing, d

₀₀₁

(Bragg)

The number of platelets per stack, N (Scherer)

The relative amount of clay platelets absent in stacks, X

_E

(%)

High resolution transmission electron microscopy

(HRTEM)

Mechanical properties

Tensile properties (strength, modulus and elongation)

Flexural properties (strength and modulus)

(10)

Figure 1: The relationship between the gap and the pressure at the inlet of C-D plate. 0 5 10 15 20 25 30 35 40 45 1 10 100 1000 （60）（48）（35）（23）（25）（31）（34） (19） SSE+EFM-N SSE+EFM-3 EFM gap (µm)

Pressure and temperature vs. EFM gap on PP based PNC

Figure 2: The relationship between the gap and the polymer

temperature at the die exit.

180 185 190 195 200 205 210 1 10 100 1000 （60）（48）（35）（23）（34）（25） EFM gap (µm) SSE+EFM-3 SSE+EFM-N ( ): screw rotation speed

Pressure at the inle

t of C-D plate (MPa)

Polymer temper

ature at the die exit (

°

C)

Barrel temperature: 180℃ Throughput: 10kg/h

The compounding conditions using EFM-N were more

severe than those using EFM-N on PP based PNC

(11)

Pressure and temperature vs. EFM gap on PA6 based PNC

215 220 225 230 235 240 245 250 255 1 10 100 1000 0 5 10 15 20 25 30 35 40 45 1 10 100 1000

Figure : The relationship between the gap and the pressure at the inlet of C-D plate. Barrel temperature: 235ºC(15µm), 240ºC Throughput: 5kg/h SSE+EFM-N SSE+EFM-3 EFM gap (µm)

Pressure at the inle

t of C-D plate (MPa)

Figure : The relationship between the gap and the polymer

temperature at the die exit.

EFM gap (µm)

Polymer temper

ature at the die exit (

°

C) SSE+EFM-3 SSE+EFM-N （101）（82）（60）（44）（45）（25）（14）（8） Barrel temperature guessed to be 240℃ at 15μm gap ( ): screw rotation speed

The compounding conditions using EFM-N were more

severe than those using EFM-N on PA6 based PNC

(12)

11

Effect on the polymeric matrix

9 9.5 10 10.5 11 11.5 12 12.5 1 2 3 4 (60) (34) (48) (31) (35) (25) ₍₁₈₎ SSE+EFM-N SSE+EFM-3 15μm 30μm 100μm PP+PP-MA1+PP-MA2+C15A ( ) screw rotation speed

SSE SSE+EFM

Melt flow rate, MFR (dg/min)

Figure The comparison of the effects of the compounding condition and compounding line on melt flow rate (MFR)

MFR of PP extruded at 180°C through SSE + EFM-N with the EFM gap of 15µm gave the MFR = 11.94 (11.72 to 12.13) dg/min, which is the almost

same as the data of Basell data sheet (MFR=12).

Addition of organoclay and

compatibilizing mixture of PP-MA’s caused a decrease to MFR = 10.3 ± 0.2 in SSE alone or in SSE + EFM-3. The use of SSE + EFM-N increases the MFR to about 10.6 ± 0.2 dg/min even at the most severe compounding conditions (15µm)

EFM-N has benign effect on the polymeric matrix due to the

absence of shear degradation, although it made

(13)

Figure . The XRD scan for PP based PNC (SSE, SSE+EFM-3) 0 2000 4000 6000 8000 10000 12000 1 2 3 4 5 6 7 8 9 10 0 2000 4000 6000 8000 10000 12000 1 2 3 4 5 6 7 8 9 10 SSE SSE+EFM-3 (gap=15µm) SSE+EFM-3 (gap=30µm) SSE+EFM-3 (gap=100µm) SSE+EFM-3 (gap=300µm)

2 θ (degree)

Intensity

(CPS)

Intensity

(CPS)

SSE SSE+EFM-N (gap=15µm) SSE+EFM-N (gap=30µm) SSE+EFM-N (gap=100µm) SSE+EFM-N (gap=300µm)

Figure . The XRD scan for PP based PNC (SSE, SSE+EFM-N)

Barrel temperature: 180°C Throughput: 10kg/h

XRD measurement of PP based PNC

Compounding PP based PNC in SSE+EFM-N did not significantly

(14)

13

3 3.2 3.4

0.0001 0.001 0.01 0.1

Figure : Gap effect on interlayer

spacing (d

₀₀₁

).

Figure 3: Gap effect on incremental

exfoliation (Ext), and number

of platelets per stack (N).

0 10 20 30 0.0001 0.001 0.01 0.1 1 2 3 4 Degree of exfoliation, X E (%) Inverse gap, 1/h (µm-1₎

Number of platelet per

s tack, N (-) EFM-3: N EFM-N: N EFM-3: Exf EFM-N: Exf Interlayer spacing, d 001 (% ) Inverse gap, 1/h (µm-1₎ EFM-3 EFM-N Barrel temperature: 180℃ Throughput: 10kg/h

Results of XRD: d001, X

_E

and N v.s. gap

d

₀₀₁

and N were not correlate with the compounding

conditions. However, X

_E

systematically increases with

(15)

Figure TEM micrographs of PP based PNC

(a) SSE (b) SSE + EFM-3

(EFM gap=15µm)

(c) SSE + EFM-N (EFM gap=15µm)

TEM observation ( × 50k)

Large and long

aggregates with 10

to 20 clay platelets

in stack

Few short stacks

Large but shorter and

looser aggregates

Stacks with 3 to 4

layers

Higher particle density

Large and tight but

shorter aggregates

Few short stacks

(16)

TEM observation (× 400k, × 500k)

Figure TEM micrographs of PP based PNC on high magnification

(a) SSE ( ×400k) (b) SSE + EFM-3 (EFM gap=15µm, ×500k) 50nm _50nm _50nm (c) SSE + EFM-N (EFM gap=15µm, ×400k)

Tight stack

Loose stack

Tight stack

(17)

0 2000 4000 6000 8000 10000 12000 14000 1 2 3 4 5 6 7 8 9 10 0 2000 4000 6000 8000 10000 12000 14000 1 2 3 4 5 6 7 8 9 10 SSE SSE+EFM-N (gap=15µm) SSE+EFM-N (gap=30µm) SSE+EFM-N (gap=100µm) SSE+EFM-N (gap=300µm) SSE SSE+EFM-3 (gap=15µm) SSE+EFM-3 (gap=30µm) SSE+EFM-3 (gap=100µm) SSE+EFM-3 (gap=300µm) 2θ (degree) 2θ (degree) Intensity (CPS) Intensity (CPS)

XRD measurement of PA6 based PNC

Figure . The XRD scan for PA6 based PNC (SSE, SSE+EFM-3)

Figure . The XRD scan for PA6 based PNC (SSE, SSE+EFM-N)

Barrel temperature: 235°C, 240°C Throughput: 10kg/h

Compounding PA6 based PNC in SSE+EFM significantly modified the clay

dispersion. At the small EFM gap (15µm, 30µm), the diffraction peaks did

(18)

17

XRD measurement of PA6 based PNC

Figure The XRD scan for PA6 based PNC using various kind of

compounding methods

2θ (degree)

Intensity

(CPS)

Dilution of PA6 MB to 2% C15A in SSE+EFM-N (gap=30µm) resulted in

full exfoliation – the diffractgram is similar to that of the commercial PA6

based PNC, UBE1015C2 (PA6 grafted on to MMT)

(19)

18 d₀₀₁(UBE1015C2)=5.33nm TSE(d₀₀₁=4.44nm) UBE1015C2(X_E=80.8) N(UBE1015C2 )=2.44 TSE(N=2.79) TSE (X_E =50.7)

Figure . Gap effect on interlayer spacing (d₀₀₁)

Figure . Gap effect on incremental

exfoliation (X_E), and number of platelets per stack (N)

Compounding PA6 based PNC in SSE+ EFM-N with progressively reduced EFM gap resulted in expansion of d₀₀₁, while in SSE+EFM-3, d₀₀₁ was about constant

The degree of clay dispersion using SSE+EFM-N is better than that using TSE Comparable tests of the commercial UBE1015C2 (PA6 grafted onto MMT)

(20)

19

50nm 50nm 50nm

TEM observations (× 300k)

(a) SSE

(b) SSE + EFM-3

(C-D gap=30µm)

(c) SSE + EFM-N

(C-D gap=30µm)

Several large

aggregates with 10 to 12 clay platelets in stack Short stacks with 3 to 4 platelets may be seen

No large aggregate

Stacks with 2 to 3 layers Many single layer stacks Oriented stacks

Higher particle density Many single layer stacks Twisted clay platelets Absence of triplets

(21)

TEM observations (× 200k, × 300k)

50nm 50nm

(a) TSE

(b) SSE + EFM-N (C-D gap=30µm)

Figure TEM micrographs of PA6 based PNC

Clay dispersion using SSE+EFM-N with 30µm EFM gap is

better than that using TSE

(22)

21

Tensile test results (PP based PNC)

30 31 32 33 34 35 36 37 0 20 40 60 80 100

Figure 4 : The relationship between

EFM gap and tensile modulus.

Figure : The relationship between EFM

gap and tensile strength.

1600 1700 1800 1900 2000 2100 2200 0 20 40 60 80 100 EFM gap (µm)

Tensile modulus (MPa)

SSE+EFM-3 (PP+PP-MA1+PP-MA2+C15A) SSE+EFM-N (PP+PP-MA1+PP-MA2+C15A) (60) (48) (35) (25) (34) (31) (48) SSE+EFM-N (PP) TSE (PP+PP-MA1+PP-MA2+C15A)

Tensile strength (MPa)

EFM gap (µm) SSE+EFM-N (PP+PP-MA1+PP-MA2+C15A) SSE+EFM-3 (PP+PP-MA1+PP-MA2+C15A) (35) (25) (48) (31) (60) (34) (48) SSE+EFM-N (PP) TSE (PP+PP-MA1+PP-MA2+C15A)

The modulus and the strength of PP based PNC were higher than those of pure PP – 21.8 to 25.9% higher (the modulus), 13.1 to 14.3% higher (the strength) For most EFM gaps the modulus and the strength obtained using SSE+EFM-N were higher than those obtained using SSE+EFM-3

(23)

Flexural test results (PP Based PNC)

1500 1600 1700 1800 1900 2000 2100 2200 0 20 40 60 80 100 48 50 52 54 56 58 60 62 0 20 40 60 80 100

Figure :The relationship between EFM

gap and flexural modulus.

Figure :The relationship between EFM

gap and flexural strength.

EFM gap (µm)

Flexural modulus (MPa)

SSE+EFM-3 (PP+PP-MA1+PP-MA2+C15A) SSE+EFM-N (PP+PP-MA1+PP-MA2+C15A) (60) (48) (35) (25) (34) (31) (48) SSE+EFM-N (PP) TSE (PP+PP-MA1+PP-MA2+C15A)

Flexural strength (MPa)

EFM gap (µm) SSE+EFM-N (PP+PP-MA1+PP-MA2+C15A) SSE+EFM-3 (PP+PP-MA1+PP-MA2+C15A) (35) (25) (48) (31) (60) (34) (48) SSE+EFM-N (PP) TSE (PP+PP-MA1+PP-MA2+C15A)

The modulus and the strength of PP based PNC were higher than those of pure PP – 32.9 to 34.2% higher (the modulus), 17.1 to 19.9 % higher (the strength) For most EFM gaps the modulus and the strength obtained using SSE+EFM-N were higher than those obtained using SSE+EFM-3

(24)

18 20 22 24 26 28 30 32 34 36 38 0 20 40 60 80 100

Figure :The relationship between EFM

gap and impact strength.

EFM gap (µm) Impact strength (J/m) SSE+EFM-3 (PP+PP-MA1+PP-MA2+C15A) (60) (48) (35) (25) (34) ₍₃₁₎ (48) SSE+EFM-N (PP) TSE (PP+PP-MA1+PP-MA2+C15A) SSE+EFM-N (PP+PP-MA1+PP-MA2+C15A)

Impact result (PP based PNC)

The impact strength of PP based PNC were higher than those of pure PP – 18.3 to 26.2% higher

The impact strength obtained using SSE+EFM was higher than that obtained using TSE

(25)

Conclusions

EFM-N had benign effect on the polymer matrix due to the

absence of shear degradation, although it made

compounding conditions more severe.

Clay dispersion obtained by using SSE + EFM-N were

better than that obtained by using SSE + EFM-3 and TSE.

The best dispersions were obtained for small EFM gaps at

15 or 30µm with compounding PA6/C15A in SSE + EFM-N

resulted in full exfoliation.

TEM micrographs show a better dispersion in PNC from

SSE + EFM-N than from SSE + EFM-3, or TSE.

Clay dispersion of compounded PA6/C15A in SSE + EFM-N

was comparable to that of commercial UBE1015C2.

Most of the mechanical performance compounded using

SSE + EFM-N were higher or comparable to those

compounded using SSE + EFM-3, or TSE due to superior

clay dispersion of SSE + EFM-N.

(26)

Acknowledgments

Florence Perrin

Manon Plourde

(form National Research Council Canada,

Industrial Materials Institute)

(27)

Experimental conditions (PA-6 based PNC)

Material Composition (wt%) Test No. PA-6 C15A 5.5±0.1 1163 PA-1 SSE+EFM-3 60 6.0±0.3 PA-2 SSE+EFM-N 101 5.1±0.5 PA-4 SSE+EFM-N 82 4.6±0.3 PA-5 SSE+EFM-3 25 5.3±0.4 1071 PA-7 SSE+EFM-3 8 4.8±0.1 PA-8 SSE+EFM-N 300 14 5.2±0.2 1147 100 1108 15 235 1138 5.1±0.4 5.1±0.6 6 44 45 2 EFM gap h(μm) PA-0 SSE - 240 PA-3 SSE+EFM-3 30 PA-6 SSE+EFM-N 240 98

Compounding equipments SSE and EFM _{temperature (}

℃ ) Screw speed (rpm) Measured _throughput (kg/h) Residence time (s)

(28)

Experimental conditions (PP based PNC)

Material Composition(wt%) Test No. PP PP-MA1 PP-MA2 2 2 C15A 10.1 1163 PP-1 SSE+ EFM-3 34 10.1±0.1 PP-2 _EFM-NSSE+ 60 9.9±0.1 PP-4 SSE+ EFM-N 48 10.1±0.2 PP-5 SSE+ EFM-3 25 9.9±0.2 1071 PP-7 SSE+ EFM-3 19 9.9 PP-8 SSE+ EFM-N 23 10.1±0.1 1147 300 100 1108 15 1138 10.0±0.2 10.1 18 31 35 2 EFM gap h(μm) PP-0 SSE -PP-3 _EFM-3SSE+ 30 PP-6 SSE+ EFM-N 180 94

Compounding equipments _{SSE and EFM}

temperature ( ℃ ) Screw speed (rpm) Measur ed throughput (kg/h) Residence time (s)

(29)

80 82 84 86 88 90 92 94 96 98 100 0 10 20 30 40 50 60 70 80 90 100 110 2800 2900 3000 3100 3200 3300 3400 3500 3600 3700 3800 3900 0 10 20 30 40 50 60 70 80 90 100 110

Figure : The relationship between EFM

gap and tensile modulus.

Figure: The relationship between EFM

gap and tensile strength.

EFM gap (µm)

Tensile modulus (MPa)

SSE+EFM-3 (PA6+C15A) (101) (82) (45) (25) (60) (44) (101) SSE+EFM-N (PA6) TSE (PA6+C15A)

Tensile strength (MPa)

EFM gap (µm) SSE+EFM-N (PA6+C15A) SSE+EFM-3 (PA6+C15A) (101) (82) (45) (25) (60) (44) (101) SSE+EFM-N (PA6) TSE (PA6+C15A) SSE+EFM-N (PA6+C15A)

Tensile results (PA6 based PNC)

The modulus and the strength of PA6 based PNC were higher than those of pure PA6 – 19.0 to 24.1% higher (the modulus), 8.4 to 11.4% higher (the strength)

For most EFM gaps the modulus obtained using SSE+EFM-N were higher than those obtained using SSE+EFM-3

(30)

Flexural results (PA6 based PNC)

134 136 138 140 142 144 146 148 150 152 154 156 158 160 162 164 166 0 10 20 30 40 50 60 70 80 90 100 110 2800 2900 3000 3100 3200 3300 3400 3500 3600 3700 3800 3900 4000 0 10 20 30 40 50 60 70 80 90 10 0 11 0

Figure : The relationship between EFM

gap and flexural modulus.

Figure: The relationship between EFM

gap and flexural strength.

EFM gap (µm)

Flexural modulus (MPa)

SSE+EFM-3 (PA6+C15A) (101) (82) (45) (25) (60) (44) (101) SSE+EFM-N (PA6) TSE (PA6+C15A)

Flexural strength (MPa)

EFM gap (µm) SSE+EFM-N (PA6+C15A) SSE+EFM-3 (PA6+C15A) (101) ₍₈₂₎ ₍₄₅₎ (25) (60) (44) (101) SSE+EFM-N (PA6) TSE (PA6+C15A) SSE+EFM-N (PA6+C15A)

The modulus and the strength of PA6 based PNC were higher than those of pure PA6 – 16.2 to 20.4% higher (the modulus), 10.1 to 11.7% higher (the strength) The modulus obtained using SSE+EFM were higher than that obtained using TSE

(31)

Impact results (PA6 based PNC)

20 22 24 26 28 30 32 34 36 38 40 0 10 20 30 40 50 60 70 80 90 100 110

Figure: The relationship between EFM

gap and impact strength.

Impact strength (J/m) EFM gap (µm) SSE+EFM-3 (PA6+C15A) (101) (82) (45) (25) (60) (44) (101) SSE+EFM-N (PA6) TSE (PA6+C15A) SSE+EFM-N (PA6+C15A)

The impact strength of PA based PNC obtained using

SSE+EFM-N at 15µm gap was comparable to that of pure PA6 The impact strength obtained using SSE+EFM was higher than