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Kristiina Oksmanand
Aji Mathew
Department of Engineering Design and MaterialsNTNU
Biopolymer Based Nanocomposites
Biocomposite group
Outline
• Introduction to Nanocomposites� Definition of nanocomposites� Processing� Applications
• Bio Nanocomposites� Why?� Raw materials� PLA nanocomposites� Problems� Conclusion
PLA/CLAY
Definition of nanocomposite:
1D, Layered silicates 2D, Carbon nanotubesCellulose whiskers
3D, Gold particles, Inorganic oxides
Composite materials where at least one dimension of the reinforcement is in the range of 1-100 nm
Nanocomposites applications on the market
• Automotive exterior claddings
• Barrier layers in beer bottles
• Pipe and wire coatings
Süd-Chemie
GM side step
Amcor
Processing methods
• In-situ polymerisation� Clay based composites with nylon (Toyota) � Used for preparation of thermoset polymers and elastomer clay
nanocomposites
• Solution casting� Most common used processing method� Many different materials are used� Thin films
• Melt blending� New method� Can be implemented in industry� Clay based nanocomposites with PS, nylon, PP, PLA
Bio-Nanocomposites, Why?
• Improve the following biopolymer properties:� Mechanical� Thermal stability� Toughness� Barrier� Biodegradability
• Use renewable raw materials
Nano reinforcements
• Clay (natural and synthetic) are used to enhance: barrier and mechanical properties, fire retardancy and thermal stability(6-44 $/kg)
• Cellulose whiskers can be used: mechanicalproperties, barrier properties, thermalstability, biodegradability(14 $/kg + treatments)
The matrix polymers for commercial applications are: PP, PET and Nylon
Cellulose whiskers and fibrils
Wood fibre: length 2-4 mm, width 20-40 µm
Microfibril: infinite length and width about 10-20 nm
Length of crystalline region 300-600 nm
Wood fiber
3.5 mm
20 µm
10 nm
Other sources: different plants (flax, hemp etc.), root crops, sea animals…
Photo M. Sain, University of Toronto
Biopolymer matrices
• Polylactic Acid (PLA) is a polyester and originates from renewable agricultural raw materials (corn). It is completely biodegradable in natural systems when water and micro-organisms are present, Cargill-Dow, NatureWorks®
• Starch based polymers, are biodegradable polymers based on starch usually from corn, Evercorn™,USA, Novamont, MaterBi, Italy
• Cellulose esters, orginates from cellulose. Cellulose Acetate Butyrate (CAB) and Cellulose Acetate Propionate (CAP), Cellulose Acetate (CA), Eastman Chemicals Company, USA
• Bacteria produced polyester, Polyhydroxy Alkanoate (PHA), obtained from renewable resources, is waterproof and fullybiodegradable, Metabolix, USA
Ongoing activities: PLA nanocomposites
Separation of cellulose whiskers and clay• Chemical treatments and sonification
Solution casting of thin films• Blending of polymer solution and
separated nano whiskers/particles• Casting and drying at RT
Melt blending• Melt extrusion of polymer and nano
whiskers/particles• Compression molding of samples
Ongoing studies on nanocomposites
• Nanostructurecharacterisation� TEM, AFM, SEM� X-ray
• Mechanical testing� Tensile� DMTA
• Transparency• Thermal properties• Barrier properties
Clarity of PLA and PLA-MCC
0 5 10 15 20
Inte
nsity
(a.
u)
2θ (degree)
Bentone 107
PLA
PLA-Bentone 107
PLA-g- Bentone 107
Problems to solve when making bio-nanocomposites
Separation of nano whiskers1. Use of chemicals (swelling agents) 2. Mechanical treatments (steam
explosion, ultra sonification, grinding etc.)
Processing1. Incorporation of nano whiskers in to
the polymer2. Dispersion of nano whiskers in the
polymer (compatibilizers, shear etc)3. Degradation of the biopolymers
Conclusions
• Nano whiskers can be separated from commercially available micro crystallinecellulose.
• We have been able to make nanocompositeswith both solution casting and melt blending using clay and MCC.
• We are expecting to improve biopolymersbarrier- and mechanical properties, ductilityand thermal stability.
• We are collaborating with University of Toronto, Canada and Chalmers Technical University in Sweden in this field.
PLA/MCC nanocomposite
MCC nano whiskers
Acknowledgment
• Asahi Kasei Corp. Tokyo Japan for supplying MCC • Southern Clay Products, Gonzales, Texas, USA for
supplying clays• Cargill-Dow LLC, Minnetonka, MN, USA for supplying
PLA resin• NFR for financial support