Carbon Fibers and Lignocellulosics

Transcription

1 Carbon Fibers and Lignocellulosics Clive Liu, Huibin Chang, Satish Kumar School of Materials Science and Engineering Georgia Institute of Technology Atlanta, GA IPST Executive Conference March 13,

2 Carbon Fibers Carbon fiber research began ~1960. Initially carbon fibers were made from cellulose. Carbon fibers are also made from petroleum pitch. From pitch, carbon fibers with tensile modulus (stiffness) >90% of the theoretical modulus, and high electrical and thermal conductivity can be made. However, pitch based carbon fibers have low compressive strength. Currently, carbon fibers are predominantly made from poly(acrylonitrile) co-polymer. PAN was first made ~1950. Tensile strength of initial carbon fibers made in 1960s was <1 GPa and tensile modulus was <100 GPa. These values represent ~15% and ~10% of the best tensile strength and modulus values achieved today, respectively. 2 Attempts are being made to make carbon fibers from other polymers and materials. This is done in an attempt to make carbon fibers cheaper and more renewable. 2 2

3 PAN based Carbon Fiber Processing Poly(acrylonitrile) (PAN) is polymerized from acrylonitrile. Acrylonitrile is a product of the petroleum industry. Therefore its price fluctuates with the price of oil. PAN polymer is extruded into fiber form from solution. PAN fiber is oxidized in air typically between 200 to 300 ºC, and the oxidation time can be between 1 to 2 hours. Oxidized fiber is then carbonized to a temperature of ºC. This is the carbon fiber used in most structural applications today. Carbonized fiber can be graphitized to ºC for specialized applications. Applications in aerospace and defense systems began in 1980s and in large scale civilian structures ~2010 (e.g. Boeing 787)

4 Carbon Fibers PAN based carbon fiber Carbon Nanotubes Science, 273, 483 (1996) Diameter: 5 µm Tensile strength: 3.1 N/tex (5.6 GPa) Tensile modulus: 155 N/tex (280 GPa) Diameter: 1 nm Tensile strength: N/tex ( GPa) Tensile modulus: 467 N/tex (1060 GPa) 4 4 4

5 40 ºC increase in Tan δ peak temperature at 10 wt% CNT Solvent resistance PAN fiber in the left vial dissolved while PAN/CNT fiber containing 1 wt% CNT did not dissolve even after 30 days 5 5 5

6 Interphase Comparison between composite and nanocomposite Carbon fiber CNT Diameter 5 µm 1 nm Interphase layer thickness Interphase/filler volume ratio 5 nm 5 nm 0.004/1 99/1 Interphase Bulk polymer For creating interphase, a nano material can be times more effective than a conventional reinforcement such as carbon fiber. Carbon Nanotubes act as a template for polymer orientation and nucleating agent for polymer crystallization

7 PAN/Carbon Nanotube Fibers PAN PAN/SWNT (99/1) Stabilized Carbonized 7 HG Chae, ML Minus, A Rasheed, S Kumar, Polymer, 48(13), 3781 (2007). 7 7

8 Fiber spinning system 8 8 8

9 Fiber drawing system Unwinding stand Water rinse Drawing stands stand Drying stand Take-up winder 9 9 9

10 Continuous carbonization line 10 10

11 PAN and PAN/CNT precursor fibers manufactured at Georgia Tech

12 Carbon fiber processed at Georgia Tech

13 Carbon Fibers: Current Challenges After nearly 50 years of development, carbon fiber technology now appears mature Both cost and performance appears to have reached a plateau. Performance: Tensile strength is about 5% of the theoretical value Tensile modulus of the high strength fiber is about 26% of the theoretical value Cost: Energy (1/3) + infrastructure (1/3) + material (1/3) Density: Density of current high strength commercial carbon fibers is about 1.76 g/cc. Recently carbon fibers with density of about 1.2 g/cc have been demonstrated. Scale up of this fiber is expected to require significant effort

14 PAN/Lignin/MWNT Composite Carbon Fiber March 13 th 2014 Hsiang-Hao (Clive) Liu Adviser: Dr. Satish Kumar School of Materials Science and Engineering Institute of Paper Science and Technology 14

15 Why Lignin? Abundant renewable resource: Lignin is the second most available biomacromolecule on earth Second only to cellulose. Low cost: Lignin is mostly regarded as the by-product of the paper manufacturing industry. Department of Energy Targets: Goal: $5/lb Strength: 1.75 GPa Modulus: 175 GPa 15 15

16 Precursor Spinning/Drawing Precursor spinning/drawing conditions PAN/Lignin (PL) PAN/Lignin/CNT (PLC) Solid Content Ratio (PAN/Lignin/CNT) Spin DR x Cold DR x Hot DR 70/30/0 1 x 1.8 x 7.5 = /30/3 1 x 2 x 6.75 = 13.5 PLC composite fiber PL composite fiber 16 16

17 From precursor to carbon fiber Oxidative Stabilization Trial Stabilization of precursor fibers with constant heating rate in temperature range between 250 ºC and 320 ºC with residence time from 150 minutes to 450 minutes. Carbonization Stabilized fibers purged with nitrogen for 40 minutes before heating. Constant heating rate to temperature ranging from 1000 ºC to 1200 ºC. Stabilization/Carbonization Setup 17 17

18 Comparison of Lignin and PAN/Lignin Carbon Fiber properties Carbon Fiber Composition Stream Explosion Lignin (Hydrogenlysis) Stream Explosion Lignin (Phenilysis) Diameter (µm) Tensile Strength (MPa) Tensile Modulus (GPa) Elongation at break (%) Reference 7.6± (Sudo et al., 1992) (Sudo et al., 1993) Acetesolv Lignin (Uraki et al., 1995) Alcell Lignin 31± (Kadla et al., 2002) Hardwood Kraft Lignin 46± (Kadla et al., 2002, 2005) Softwood Kraft Lignin (with Hardwood lignin permeate) Modified Technical (Hardwood) Lignin Zoltek PAN/Lignin (65/35) PAN/Lignin* 36± (Nordström et al., 2012) (Warren, 2012 ORNL Review) (Zoltek,2012) This work PAN/Lignin/CNT* This work *Batch carbonization 18 18

19 Conclusions Successful production of the PAN/Lignin and PAN/Lignin/CNT carbon fibers. Future works Partially replace PAN with lignin in composite fibers. Continuous process of carbonization

20 Carbon Fibers from Polyacrylonitrile(PAN) and Cellulose Nanocrystals (CNC) Huibin Chang Advisor: Dr. Satish Kumar School of Materials Science and Engineering Institute of Paper Science and Technology 20 20

21 Why Cellulose Nanocrystals (CNC)? PAN CNC Tensile strength (GPa) ~ Elastic modulus in axial direction (GPa) ~ Crystallinity (%) The most abundant renewable polymer in the biosphere 21 Objective: Polyacrylonitrile (PAN)/Cellulose nanocrystals (CNCs) composite fibers will be gel spun using dimethyl formamide (DMF) as the solvent. Moon, Robert J., et al. Chemical Society Reviews 40.7 (2011):

22 Solution preparation and spinning PAN/CNC fibers 1. CNCs were dispersed in DMF (dimethyl formamide) 2. PAN was separately dissolved in DMF 3. CNC/DMF solution was added into the PAN/DMF solution 4. Excess solvent was evaporated 5. PAN/CNC/DMF solutions were spun into precursor fiber (Solid Content Ratio: CNC/PAN = 1/99) 6. Control PAN solution was also prepared and spun into precursor fiber 22 22

23 Conclusions The tensile strength, modulus and elongation at break of PAN/CNC fibers at highest draw ratio are increased by 20%, 9% and 16%, respectively when 1wt% CNC is added into the PAN matrix

24 Future Work Characterize the thermal and dynamic mechanical properties Stabilize and carbonize fibers Characterize the mechanical and structural properties of carbonized fibers

25 Functional Fibers, Paper, and Materials

26 Current staff and students Dr. Han Gi Chae Senior Research Engineer Dr. Kishor Gupta Research Scientist II Dr. Yaodong Liu Research Scientist II Dr. Prabhakar Gulgunje Research Engineer II Dr. M. G. Kamath Research Engineer II Dr. Sushanta Ghoshal Postdoctoral Fellow Dr. Vijay Raghavan Postdoctoral Fellow Dr. Chandrani Pramanik Postdoctoral Fellow Dr. Ashok Singh Postdoctoral Fellow An-Ting Chien Graduate Student Brad Newcomb Graduate Student Clive Liu Graduate Student IPST Fellow Amir Davijani Graduate Student Po-Hsiang Wang Graduate Student Huibin Chang Graduate Student IPST Fellow Current and past support and collaborations DARPA AFOSR IPST ONR NSF NIST AFRL Boeing Rice University UIUC G. P. Peterson, B. Feng CNI, Unidym, CCNI Applied Sciences Inc Collaborators and former group members