Ville Klar

Doctoral Candidate

Aalto University, School of Engineering

Department of Engineering Design and Production

2.0

Machine Design in DWOC2.0Production machine design for new

cellulose-based products

Why filaments?

• Strong form

• Building block for other shapes and structures

• Many established processes

• Filaments or fibre yarn

3

Raw materials

Machine elements

Applications

Process parameters

Raw materials

• New processes required in spinning from fibre suspensions

– Development of sections of the spinning line required

• Established solution spinning technologies not directly applicable

– Multiphase fibre suspension different rheological properties

– Forming (drawing) and axial alignment of fibres

– Drying & dewatering

Raw materials

• Fibre properties

• Stiffness comparable to Kevlar [1]

• Tenacity comparable to glass fibres [2]

• Fibre properties and yarn properties

not directly comparable (fibre network)

• Native wood cellulose structure

• Cellulose I structure is 50 % stiffer than the

Cellulose II structure [1]

• Cost and raw material efficient processes

• Development required in production of raw materials

Helicoidal structure[3]

[1] Sakurada, Ichiro, Yasuhiko Nukushina, and Taisuke Ito. "Experimental determination of the elastic modulus of

crystalline regions in oriented polymers." Journal of Polymer Science 57.165 (1962): 651-660.’

[2] Saito, Tsuguyuki, et al. "An ultrastrong nanofibrillar biomaterial: the strength of single cellulose nanofibrils revealed via

sonication-induced fragmentation." Biomacromolecules 14.1 (2012): 248-253.

[3] Emons, Anne Mie C., and Bela M. Mulder. "How the deposition of cellulose microfibrils builds cell wall architecture."

Trends in plant science 5.1 (2000): 35-40.

Machine elements

Dry spinning [4]

[4] Dry spinning, http://www.tikp.co.uk/knowledge/technology/fibre-and-filament-production/dry-spinning/

[5] Introduction to solution spinning, http://nptel.ac.in/courses/116102010/18

Wet spinning [5]

Dry-jet wet spinning [5]

Machine elements

Pump Spinneret Bath Forming Drying Spooling

Rheology of the

suspension Filament geometry

Efficiency

Wet strength

Axial alignment of fibres

Drawing

Machine elements: Spinneret

• ”Headbox” of spinning

• Iterative prototyping

• Phenomenological study of a coaxial spinneret

Process parameters

Pump Spinneret Bath Forming Drying Spooling

Flow rates (ml/min)

Agitation of suspension

(thermal, ultrasound, mechanical)

Spinneret diameter (mm)

Air gap (mm)

Spinneret geometry / type

(cylindrical, conical, double

conical, hyperbolical, etc.)

Bath liquid

Bath temperature

Drawing ratio

Drawing sequence

Compression / twisting

Roll / godet geometry, surface, configuration

Conductive/convective/radiation

Air flow / pressure

Drying time

Drying temperatures

Plying

Coating

Post-treatment

Process parameters

Raw material properties

Suspension parameters

Spinneret geometry

Timescales

Forming parameters

Drying parameters

Filament properties

Production rates

Analysis of the effect of spinning parameters

Process parameters

• Prototype coaxial spinning line

• Different parameters measured and controlled

• Efficient testing of different spinning parameters in a fume hood with sufficient

production rates

Applications

Textiles

Composites

NonwovensFilaments Design

Applications

Applications

Weft-knitted sample

Sufficient production capability

Sufficient filament properties

Sufficient lengths of filaments

Applications

• Filaments are the first step…

• Additive manufacturing

• Combined processes

• New processes based on native wood fibres can be greatly improved by developing new machinery

• Effects of spinning parameters can be efficiently studied through automation and control

• Scalability can be studied through prototype spinning lines

• Development of spinning leads to different processes for new applications

Conclusions