Melt Spinning of Polyacrylonitrile Carbon Fiber Precursors€¦ · · 2014-07-17Melt Spinning of...
Transcript of Melt Spinning of Polyacrylonitrile Carbon Fiber Precursors€¦ · · 2014-07-17Melt Spinning of...
Melt Spinning of Polyacrylonitrile
Carbon Fiber Precursors
1
J. Huang1, D. G. Baird1 , J. E. McGrath2, S. Mecham2, and F. L.
Paulauskas3
1Departments of Chemical Engineering and 2Chemistry, Virginia Tech
3Carbon and Composites Group, Oak Ridge National Laboratory
American Chemical Society-Polymer Chemistry Division: Meeting in
Honor of J. E. McGrath, Cetraro, Italy, June 29 to July 2, 2014
Cooperative Research with Jim
McGrath
2
Title: High Performance Elastomer and Other Multiphase
Organic Composites
Sponsor: Army Research Office
Amount: $800,000 ($160,000 my share)
Duration: September 1, 1980 to February 28, 1984
Title: Lower Cost Carbon Fiber for H2
Storage for Vehicle Fuel Cells
Sponsor: Department of Energy/ORNL
Amount: $785,000
Duration: 10/14/13 to 10/13/16
Total cooperative funding from 1980 to 2016:
$29,580,000
Total number of bottles of wine consumed: ?, ∞ (Not in
resume)
3
Outline of Presentation
•Motivation: Lower cost carbon fiber
•Background: Conversion of PAN fiber to carbon fiber;
solution spinning of precursors; melt spinning of
precursors; water as a plasticizer; patents.
• Reduction of melting point: water; water plus a
miscible substance (azeotrope)
•Rheology of plasticized PAN
•Laboratory spinning process and fiber production
•Precursor fiber properties
•Summary of progress
•Status and future direction
Production of carbon fibers from
PAN precursors
1000 to 1700C in N2
200 to 300C in air
The ideal precursor fibers should have high AN contents (~95 mol% AN),
high strength, high modulus, size of about 10 microns in diameter and free of
voids and other defects.
PAN Precursor Fibers
Carbon Fibers
4
Cost savings by using melt-spun
precursor fibers
Factory cost is the manufacturer’s cost to produce finished CF’s. These cost estimates are
derived primarily from the 2007 Kline reports and are based on petrochemical prices in
CY2007Q1. Estimates based on oil at $60/bbl.
6
Dependence of Melting Point for PAN
Copolymers on Water Content
Frushour, B. G. Polymer Bulletin 7, 1-8 (1982)
Acrylonitrile
(AN)
Vinyl Acetate
(VA)
CH
O
CH2
C
CH3
O
CHCH2
C N
7
8
Melt-spinning of PAN fibers with
water as a plasticizer
Porosoff H., US 4,163,770 (1979)
American Cyanamid Company (ACC)
Kreahling, R.P. et al, US 4,301,107 (1981)
American Cyanamid Company
Steam, 20-32
psiSteam, 40-55
psi
9
Research Objectives
Establish the melting and rheological behavior of
polyacrylonitrile (PAN) copolymers with various plasticizers.
Develop a melt-spinning system and process to generate
precursor fibers from PAN plasticized with water and/or other
plasticizers.
Determine the fiber spinning and drawing conditions.
Evaluate the structure and properties of melt-spun fibers and
compare them with that of commercial wet-spun fibers.
Optimize the MW and AN/MA ratio for best fiber properties.
132.46°C
103.87°C
158.91°C
133.52°C
-1.0
-0.5
0.0
0.5
1.0
1.5
Heat F
low
(W
/g)
-50 0 50 100 150 200 250
Temperature (°C)
PAN-VA-25+25wtpc-water+acn.001––––––– PAN-VA-50-wtpc-water.001–––––––
Exo Down Universal V4.5A TA Instruments
10
DSC of PAN/VA (Vinyl Acetate) with
plasticizers
PAN/VA + H2O +
Acetonitrile
PAN/VA + H2O
11
DSC of PAN/MA (Methyl Acylate)
with plasticizers
PAN/MA+H2O+Acetonitrile
PAN/MA+H2O
167.99°C
135.93°C105.20°C
138.87°C
-1.0
-0.5
0.0
0.5
1.0
1.5
Heat F
low
(W
/g)
-50 0 50 100 150 200 250
Temperature (°C)
pan-ma-50wtpc-water.001––––––– pan-ma-25+25-wtpc-water+ACN.001– – – –
Exo Down Universal V4.5A TA Instruments
Instron Capillary Rheometer
with Pressure ChamberA
B
C
D
E
F
J
I
G
H
A Rheometer plunger with O-ring
B Rheometer barrel
C Polymer melt
D Capillary die
E Pressure chamber assembly
F Capillary sealing block
G Sealing block holding/releasing
mechanism
H Inlet of compressed gas or steam
I Pressure gauge
J Bleeding valve
(a) (b)
(a) The capillary is
sealed until test starts
(b) The sealing block F
is released once test
starts
Rheology data is very useful in fiber
spinning. It is noticed that there is no
such data available for PAN-water
melt in literature and the commercial
rheometer is not applicable to PAN-
water system. So we tried to modify
the rheometer and turn it into one that
can test PAN-water systems.14
Preparation of PAN-H2O Samples
PAN
Sample
P
1 2 3 4
H2O
1. Mix and stir PAN and water with desired ratio
2. Transfer the mixture to rheometer barrel at room temp
3. Compress the mixture with plunger until P=3000 psi
4. Open the barrel bottom and extrude the sample out
15
16
Viscosity of PAN/VA with
Plasticizers
10
100
1000
10000
1 10 100 1000 10000 100000
Vis
cosi
ty (
Pas
)
Shear Rate (s-1)
20%H2O, 180 C
20%H2O, 185 C
20%H2O, 190 C
14%H2O+14%AC, 155 C
Die: D=0.0303”, L/D=33.18, AC = Acetonitrile
The viscosity converges when the shear rate is higher than 1000 s-1
The viscosity of PAN plasticized with water at 190C is about the same as that
plasticized with water and acetonitrile at 155C.
17
VT lab spinning system for
generating melt-spun PAN fibers
Plunger
Barrel
N2
Pressure
Gauge
Pressure Chamber
PAN Fibers
Spinneret
Spool
PAN Melt
VT melt-spun PAN/VA fibers
Inlet for
CO2
Spool
4” SS Tee
19
VT 04-13
Fiber diameter =17.4 m
AN: Acrylonitrile, VA: Vinyl Acetate
Polymer: PAN/VA with 93 mol% AN
Plasticizer: Water and acetonitrile
As spun fiber diameter: ~ 35 micron
Post-spinning stretch:
Heating media: Saturated steam
Steam pressure: 18 psi
Steam temperature: 124C
Draw ratio (second stretch): 5~6
Fiber diameter: 17 m
Filament number: 14
VT PAN/VA drawn fibers
Inlet for
CO2
Spool
4” SS Tee
Fiber diameter =13 m
Polymer: PAN/VA with 93 mol% AN
Plasticizer: Water and acetonitrile
As spun fiber diameter: ~ 35 micron
Heating media: Saturated steam
Steam pressure: 18 psi
Steam temperature: 124C
Draw ratio (second stretch): 6
Fiber diameter: 13 m
Filament number: 8
Filament length: 125’
20
SEM images of PAN fibers
Motor
Present Work
Melt-Spun Fibers after Stretch
Fiber Diameter = 17 µm
Commercial Product
Wet-Spun Fibers
Fiber Diameter = 12 µm
21
22
Mechanical properties of PAN
precursor fibers
Motor
0
100
200
300
400
500
600
700
VT-M Spun GT-M Spun FISIPE-1 FISIPE-2 COMMODITY AEROSPACE
Pe
ak S
tre
ss (
MP
a)
Name Producer Process Component Diameter (µm)
VT-M Spun Virginia Tech Melt-Spun AN/VA 17.4
GT-M Spun* Georgia Tech/BASF Melt-Spun AN/MA 10.9
FISIPE-1/2 FISIPE Wet-Spun AN/VA 14.1/13.7
COMMODITY Industry Wet-spun AN/MA 11.7
AEROSPACE Industry Wet-spun AN/MA 12.9
* From Dale Grove et al., Carbon, 26(3), 1988, pp.403-411.
23
Mechanical properties of PAN
precursor fibers
Motor0
5
10
15
20
VT-M Spun GT-M Spun FISIPE-1 FISIPE-2 COMMODITY AEROSPACE
Mo
du
lus
(GP
a)
24
Mechanical properties of PAN
precursor fibers
Motor0
5
10
15
20
VT-M Spun GT-M Spun FISIPE-1 FISIPE-2 COMMODITY AEROSPACE
Stra
in a
t B
reak
(%
)
Summary
Studied melting behavior of PAN copolymers plasticized with water
and other plasticizers by DSC. The presence of water can lower
the melting point of PAN and make it melt-processable. The use of
second plasticizer can lower the melting point of PAN further.
Measured the viscosity of PAN plasticized with water or water and
second plasticizer with a modified capillary rheometer. The
viscosity of PAN-water at 190C is about the same as that of PAN-
water-acetonitrile at 155C.
Designed and constructed a novel pressurized spinning system
consisting of an Instron capillary rheometer with modified extrusion
die and a pressure chamber with fiber taking-up device.
The SEM images showed that the melt-spun fibers had surfaces
as smooth as those of commercially wet-spun PAN fibers.
25
Summary
Our melt-spun PAN/VA precursor fibers have mechanical
properties similar to that of wet-spun commercial precursors and
higher than that of melt-spun precursors reported in the literature.
The melt-spun PAN/VA precursor has been converted to carbon
fibers at Oak Ridge National Laboratory. The evaluation of the
carbon fibers and optimization of carbonization process are
currently in progress.
Will try PAN copolymers plasticized with water or water and benign
second plasticizer to produce precursor fibers.
Will move to fiber spinning with 5/8” screw extruder to generate
larger quantity of fibers for carbon fiber conversion.
26
Acknowledgements
DOE and Oak Ridge National Laboratory (ORNL) for financial
support
Thank You Jim!
28
132.46°C
103.87°C
158.91°C
133.52°C
-1.0
-0.5
0.0
0.5
1.0
1.5
Heat F
low
(W
/g)
-50 0 50 100 150 200 250
Temperature (°C)
PAN-VA-25+25wtpc-water+acn.001––––––– PAN-VA-50-wtpc-water.001–––––––
Exo Down Universal V4.5A TA Instruments
29
Determination of melting point of
plasticized PAN by DSC
PAN/VA + H2O + Acetonitrile
PAN/VA + H2O
Heating at 10C/min
Cooling at 10C/min
VA: Vinyl Acetate