1. High Thermal Conductivity Polymer Composites
PI: Asegun Henry, Ph.D.
Co-PI: Kyriaki Kalaitzidou, Ph.D.
Graduate Students: Wei Lv, Sanzida Sultana
Intel Update Meeting: 7/11/2014

2. Objective and Approach
Objective – Higher TC chassis
Polymer chain alignment in fibers
High thermal conductivity fillers
Approach – Experiments + Modeling
Sintered fibers
High TC matrix
Mechanical
Incorporate fillers
Measure composite TC
Use modeling to understand experiments
Use modeling to evaluate alternatives AH

3. Overview of Experimental Approach
Melt spinning of fiber
Step 1
Zylon
Fiber stretching modulus measurement
Spectra
High thermal conductivity composite
Sinter fibers and xGnP layers
Single fiber coating
Thermoset (Epoxy)
Thermoplastic (PP)
xGnP Film (lab)
Step 2
XG leaf
(commercial) AH
Fiber winding automation
Guide and tension application for better fiber alignment
Step 3
Scale up

4. Sintering of Zylon Polybenzobisoxazole (PBO)KK
Not sure what cahill is
Thermal conductivity of high modulus polymer fibers 1
Thermoset – no melting point
Doesn’t sinter
Attainable highest temperature is 343o C while decomposition temperature of zylon is 650 o C .
Sintering attempt of zylon fiber
1. Wang, X, Ho, V., Segalman, R. A., Cahill, D. G. dx.doi.org/ /ma400612y | Macromolecules 2013, 46, 4937−4943.

5. Graphite Film Fabrication
Epoxy (low viscosity, casting)
20% loading  agglomeration
PP (compression molding)
PP film coating  agglomeration
Move to xG leaf
xGnP having thermal conductivity of W/mK KK
Discontinuous deposition of 1 μm xGnP on PP film

6. Graphite Films xGnP film XG leaf Price: $500 /kg 50 µm thickness
11 inch
1.69 inch
Move to slide 6
Price: $500 /kg
50 µm thickness
Tensile strength 10 MPa
Thermal conductivity
In-plane: 500 W/mK
Through: 3 W/mK
Price: $199/kg
140 µm thickness
Thermal conductivity2
In-plane: 178±12 W/mk
Through: 1.28±0.12 W/mk
2.Thermal conductivity of exfoliated graphite nano-platelet paper, Jinglei Xiang, Lawrence T. Drzal, Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI , USA

7. Spectra Fiber Sintering
Fiber Characteristics:
Modulus: 70±18 GPa (based on DMA)
113 GPa (based on MSDS)
Melting point: 147 o C
Sintering Conditions:
115 o C, 250, 350 psi,
varied sintering time with thickness
40 layer & 5 layer sample
50 μm
Sintered fiber (5 layer) on flat Aluminum mandrel
50 μm KK
1 cm
incised sample (40 layer) for graphene layer insertion
SEM micrograph of 5 layer sample cross-section 7

8. Samples for TC Measurement
Types of Sample:
Spectra
2% xGnP/Spectra
7% xGnP/Spectra
21% xGnP/Spectra
Dimensions:
5.4cm X 2.9 cm X 4.3 mm
Surface Roughness:
0.365 µm
Top KK
Bottom

9. Sample Architecture
Z direction : fibers are aligned, in-plane direction of graphite layer Y direction : transverse to fiber layers and graphite layer X direction : Transverse to fiber alignment, another in-plane direction of graphite layer. kz > kx > ky
Move to slide 9 Y Z X
3D view of sample

10. Sintering Effects Sintering condition Melting Peak, Tm oC
Crystallization Peak, Tcr oC
Melting Enthalpy, J/g
Crystallinity, %
0 hour
149
119
210±16
71±5
3 hours
220±9
75±3
6 hours
231±8
80±1
9 hours
236±10
80±3
Sintering  No significant effect on crystallinity KK
Crsytallinity calculated using the enthalpy of fusion of HDPE with 100% Crystallinity as J/g 3.
3. Wunderlich, B. Thermal Analysis. Academic Press: San Diego, 1990.
*Results based on 3 data points.

11. Scaled Up Fabrication Setup
Fiber winded on the mandrel
Mandrel motor
Motor for linear motion
Actuator for graphite layer
tensioner
Guide
Mandrel AH
Linear actuator
tensioner
Fiber spool

12. Procedure Feed the fiber and tie one end on the mandrel
Manual rotation of mandrel
Adjust Tensioner
Pause & Add Graphite Layer
Wind Fibers
N cycles to build thickness
Cut the sample from mandrel
Sinter the sample in hot press AH
Sinter to
adhere edges
Measure thermal conductivity (1D Fin)

13. Speed of Different Components
Graphite Deposition
10-30 min intervals
Rotational motion: 400 rpm AH
Linear motion 0.55 rpm
Every 2 min

14. Cost Analysis Description Quantity Unit price
Teknic stepper motor ( mandrel ) 2
$324
Raptor RTX Gearbox 1
$675
Linear actuator
$838
Teknic stepper motor (linear motion)
Power supply
$199
Controller
$1079
Total
$3439 AH

15. Cost Analysis Description Quantity Unit price 8718M_mandrel motor 1
$220
R1025
$401
Controller
$200
4118S-04S motor
$55
R256 controller
$215
Linear system
$950
Total
$2041 AH

16. Timeline Tasks Component ordering Thermal conductivity measurements
07/14
08/14
09/14
10/14
11/14
12/14
01/15
02/15
03/15
04/15
05/15
Component ordering
Thermal conductivity measurements
Scale-up assembly
Automation tests
Winding tests
Composites manufacture
Refinement of the process
Fit model to experiments
Predictions of alternative materials