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Polypropylene Based Nanocomposites with Synthetic Clay
Polypropylene Based
Nanocomposites with
Synthetic Clay
J. Li and L. A. Utracki
Industrial Materials Institute
Outline
Objectives
Method of compounding
Preliminary results
XRD measurements
DSC
SEM and TEM
Mechanical behavior
FTIR measurements
Objective
The main purpose of this work has been the
evaluation of dispersion and mechanical
behavior of polypropylene (PP) based
Mineral clays (abundant and inexpensive)
Welded platelets Small grit particles Amorphous silicates
Thus resulting the variability of ultimate PNC.
Synthetic clays
Clarity, transparence (no inherent coloration)
Well controlled physical and chemical properties PNC containing synthetic clay is expected to
have consistent and desirable properties and
Why Synthetic Clay?
Characteristics of TOPY Synthetic Clays
Clay Intercalant Wt % d001 (nm) Aspect ratio Organic
content (meq/g) 4C-Ts Sodium magnesium fluoride silicate 3MOD
Stearyl trimethyl ammonium chloride 25.5* 2.43* (2.32)** 1000-5000** 0.827** 4CD-Ts Sodium magnesium fluoride silicate 2M2OD
Di-hydrogenated tallow di-methyl ammonium chloride
39.5* 3.38*
(3.18)**
1000-5000** 0.352**
* Measured at IMI
Materials and compositions
The following materials were used:
Two-step compounding was used:
First a master batch (MB) was prepared by compounding in a mini-extruder PP-MA with mineral or synthetic clay (mineral content = 18.7-wt%).
In the second step MB was diluted with PP to inorganic content of 1.1-wt%. Trade name Mw (Kg/mol) Density (g/mL at 25OC) Tm (OC) MA content (%) Supplier PROFAX-PDC1274 (PP) 250 0.902 ~161 --- Basell
Epolene-3015 (PP-MA) 47 0.91 ~162 1.31 Eastman
Polybond 3150 (PP-MA) 330 0.91 ~164 1.0 Crompton
4C-Ts --- 2.80 --- --- Topy Ind. 4CD-Ts --- 2.80 --- --- Topy Ind. C15A --- 1.66 --- --- Southern Clay Prd. C20A --- 1.66 --- --- Southern Clay Prd.
Method of compounding
Masterbatch Preparation
Dry blending of PB3150 +
EP3015 with mineral or synthetic clay
Compounding condition: co - or counter rotation,
T = 190oC, speed = 100rpm and
t = 5 min with dry N2 blanket.
PNC Preparation
Dry blending of a masterbatch with PP
The compounding conditions were the same as for the
masterbatch preparation.
Illustration of Minicompounder used for sample preparation
Co- and counter
– rotating
configurations
Mini-injection molding
Chamber temperature: 200oC
Molder temperature: 100oC
Sample dimension (mm):
Mini-injection molding machine
35 12
Mechanical testing
Flexural behavior was tested using an
INSTRON 1125 tester
with 500 kg-range
transducer
Crosshead speed: 5 mm/min
C PS 0 20x103 40x103 60x103 80x103 100x103 4C-Ts; d001 = 2.43 nm 4CD-Ts; d001 = 3.38 nm C15A; d001 = 3.21nm C20A; d001 = 2.50 nm
XRD Patterns for Synthetic
and Mineral Clay
Synthetic clay 4CD –Ts contains less intercalant than 4C – Ts (0.352
meq/g vs. 0.827 meq/g). Synthetic clay 4CD -Ts seems to possess much more ordered structure than 4C-Ts.
2 1 2 3 4 5 6 7 8 9 10 CPS 0 2000 4000 6000 8000 NPS1 NPS2 NPM1 NPM2
XRD Patterns for NPS1, NPS2,
NPM1 and NPM2 (
Co-rotating
)
Clay Type d001 PNC d001 d001 4C-Ts 2.43 NPS1 3.92 1.49 4CD-Ts 3.38 NPS2 4.05 0.67 C15A 3.21 NPM1 3.66 0.45 C20A 2.50 NPM2 3.83 1.33 4C-Ts in NPS1 and C20A in NPM2 show significant intercalation by polymer during melt compounding.1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 CPS 0 2000 4000 6000 8000 10000 NPS1B NPS2B NPM1B NPM2B
XRD Patterns for NPS1B, NPS2B,
NPM1B and NPM2B (
Counter-rotating
)
Clay Type d001 PNC d001 d001 4C-Ts 2.43 NPS1B 3.95 1.52 4CD-Ts 3.38 NPS2B 3.98 0.60 C15A 3.21 NPM1B 3.75 0.54 C20A 2.50 NPM2B 3.75 1.25 Comparing d001 of PNC’s prepared using different extruder configurations, it isD D S C
DSC Thermograms
Addition of PP-MA into PP matrix increased the PNC crystallinity. No effect of clay on PNC crystallinity was observed (considering
Temperature (oC)
80 100 120 140 160 180
Norm
alized Heat Flow
(m w/g) 1 2 3 4 PP PP-PPMA NPS1 NPS2 NPM1 NPM2 Sample Xc% PP 41.8 PP-PPMA 44.5 NPS1 45.8 NPS2 44.2 NPM1 46.0 NPM2 45.2
NPM1 NPM2
NPS1 NPS2
FEGSEM (Co-rotating)
Big aggregates
Big aggregates are observed in PNC either containing synthetic clay
NPS1B NPS2B
NPM1B NPM2B
FEGSEM (Counter-rotating)
Fewer aggregates are observed
Better clay dispersion was obtained using counter-rotating screw configuration except NPM2B
TEM Observation (1)
NPS1 Co-rotating NPS1B Counter-rotating
200 nm 50nm 200 nm
50 nm
TEM Observation (2)
Co-rotating Counter-rotating
NPS2 NPS2B
200 nm 50 nm 200 nm 50 nm
Partially exfoliated structure was observed in both NPS2 and NPS2B. In terms of dispersion, NPS2B seems to be better than NPS2.
TEM Observation (3)
PNC with C15A was prepared in a TSE.
A partial exfoliation was accompanied by the presence of tightly
packed stacks (dispersion accompanied by the thermal degradation of Stacks observed by TEM
50 nm 200 nm
Flexural Behavior
PP PP-PPMA NPS1 NPS2 NPM1 NPM2 Flexural strength (Mpa) 40 45 50 55 60 65 70 75 Flexural m odulus ( M pa) 1600 1800 2000 2200 2400 2600 Flexural strength Flexural modulus PP PP-PPMA NPS1B NPS2B NPM1B NPM2B Flexua l strength ( M pa) 40 45 50 55 60 65 70 75 Flexural mo dulus (Mpa) 1600 1800 2000 2200 2400 2600 Flexural strength Flexral modulus Co-rotating Counter-rotatingUsing counter-rotating configuration NPS1B showed best flexural performance in terms of modulus and strength.
IR Spectra
Pressed films in transmission. Difference spectra obtained by subtracting spectrum of neat PP. Matrices without clay show
anhydride peak at 1781 cm-1 and
acid peak at 1714 cm-1 (probably
arising from hydrogen-bonded dimer).
In nanocomposites, acid peak maximum shifts to 1723 cm-1,
indicating interaction with clay (possibly as hydrogen-bonded Ab so rb a n ce NPL1B NPLS1B PP + PB3200 NPLS2B PP + EP3015 + PB3150 NPL02B NPL2B
Anhydride Acid dimer? Acid monomer?
Conclusions (1)
Melt intercalation of synthetic and mineral clay in PNC does not depend on extruder configuration.
No significant clay effect on the crystallinity of PNC was observed during melt compounding.
PNC’s with synthetic clay show a better mechanical performance than their counterparts with mineral clay though the dispersion was poorer than expected.
From the loose stack structure of synthetic clay (shown by HRTEM), obtained under poor mixing
conditions, one may expect better results from tests using full compounding lines (e.g., TSE or SSE + EFM).
Conclusions (
2)
Comparing results obtained for PNC’s prepared using two mixing screw configurations, co- and
counter-rotating, the latter gave better dispersion and
mechanical properties for PNC with synthetic clay. An interaction between PP-MA and synthetic clay during melt compounding was found by FTIR. The interaction between organoclay and matrix could facilitate intercalation and exfoliation.
