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