Manufacturing and Characterisation of Conductive and Piezoelectric Textile Fibres
Doktorsavhandling, 2014

This thesis explores the manufacturing and characterisation of melt spun electrically conductive polymer nanocomposites and piezoelectric textile fibres. Potential applications of these fibres are for example textiles with heating and sensor capabilities. Melt spinning is a uniaxial deformation process of a polymer melt, commonly used for production of polymeric textile fibres. The quality of the produced material depends to a large extent on the rheological behaviour of the polymer melt. A relevant characterisation of the composite properties is of great importance for the understanding of the processing issues encountered in fibre spinning, including the effect of the spinning on the properties of the final fibres. Several combinations of polymers and fillers were prepared by different melt mixing methods and the rheological and electrical properties were evaluated complemented by morphological and thermal analysis to investigate the dispersion and agglomeration of the filler particles. Graphite nanoplatelets (GNP) and a low-structured and a high-structured carbon black (CB) were incorporated as fillers into a polymer matrix. It was found that the melt elasticity, fibre-forming properties and the electrical conductivity were greatly influenced by the mixing route and filler morphology. Bicomponent fibres with an insulating polymer sheath and the conductive composite in the core were produced. The orientation of the material imposed during melt spinning and cold drawing reduced the conductivity, which in case of GNP-containing fibres probably was caused by the plate-like particles being separated during the spinning. The comparison of low- and high structured CB in HDPE revealed the best trade-off between processability and final conductivity when the low structured filler was used and fibres with a conductivity of 1.5 S/cm was produced. The polarisation and characterisation of piezoelectric poly(vinylidene fluoride) (PVDF) bicomponent fibres were also treated in this thesis. Polarization of the melt spun fibres was performed in order to produce structures adequate piezoelectric properties. A high poling voltage at an elevated temperature was favourable for obtaining a high piezoelectric activity. The fibres were very sensitive and even small mechanical deformations could be registered; for example a sensor prepared from woven textile could be employed in order to detect the heart beats of a human. In order to achieve an efficient high piezoelectric response from of PVDF, the amount of β-phase crystallinity should be as high as possible. This can be improved by adding different nanofillers to the polymer. In the present study, a small amount of carbon nanotubes (CNT) was incorporated into PVDF. It was evident that this addition of CNTs could enhance the total amount of β-phase in the melt spun fibres.

electrical conductivity

polyethylene

polypropylene

Graphite nanoplatelets

smart textiles.

melt spinning

piezoelectric fibres

rheology

conductive fibres

carbon black

graphene

PVDF

VDL-room
Opponent: Ulf Gedde

Författare

Erik Nilsson

Chalmers, Material- och tillverkningsteknik, Polymera material och kompositer

Electrically conductive textile fibres with hybridized graphite nanoplatelets and carbon balack fillers

Proc Nordic Polymer Days 2012, Copenhagen,; (2012)p. 1.7-

Paper i proceeding

Melt spinning of conductive textile fibers with hybridized graphite nanoplatelets and carbon black filler

Journal of Applied Polymer Science,; Vol. 130(2013)p. 2579-2587

Artikel i vetenskaplig tidskrift

Poling and characterization of piezoelectric polymer fibers for use in textile sensor

Sensors and Actuators, A: Physical,; (2013)p. 477-486

Artikel i vetenskaplig tidskrift

Denna avhandling beskriver tillverkning och karakterisering av smält spunna elektriskt ledande och piezoelektriska textilfibrer. Möjliga tillämpningar av dessa fibrer är till exempel textilier med värme- eller sensor-egenskaper. Resultaten visar att smältans elasticitet och den elektriska ledningsförmågan i hög grad påverkades av blandningsmetoden och fyllmedlets morfologi. Bikomponentfibrer med ett isolerande polymerhölje och ledande komposit i kärnan har producerats. Den bästa balansen mellan processbarhet och slutlig ledningsförmåga erhölls då låg-strukturerad kimrök användes och en fiber med en konduktivitet på 1.5 S/cm tillverkades.Polarisering och karakterisering av piezoelektriska polyvinylidenfluorid (PVDF) bikomponentfibrer har också studerats i denna avhandling. Polarisering av de smältspunna fibrerna genomfördes i syfte att tillverka strukturer med fullgoda piezoelektriska egenskaper. Fibrerna är väldigt känsliga och även den minsta mekaniska deformationen kan mätas; exempelvis en människas hjärtslag. För att uppnå en hög effektivitet i piezoelektrisk respons i PVDF skall andelen kristallin β fas vara så hög som möjligt, vilken kan ökas genom tillsats av nanofyllmedel. Bevisligen gör tillsats av kolnanorör att den totala andelen β fas i de smältspunna fibrerna ökade.

This thesis explores the manufacturing and characterisation of melt spun electrically conductive polymer nanocomposites and piezoelectric textile fibres. Potential applications of these fibres are for example textiles with heating and sensor capabilities. It was found that the melt elasticity, fibre-forming properties and the electrical conductivity were greatly influenced by the mixing route and filler morphology. Bicomponent fibres with an insulating polymer sheath and the conductive composite in the core were produced. The best trade-off between processability and final conductivity when the low structured filler was used and fibres with a conductivity of 1.5 S/cm was produced. The polarisation and characterisation of piezoelectric poly(vinylidene fluoride) (PVDF) bicomponent fibres were also treated in this thesis. Polarization of the melt spun fibres was performed in order to produce structures adequate piezoelectric properties. The fibres were very sensitive and even small mechanical deformations could be registered; for example a sensor prepared from woven textile could be employed in order to detect the heart beats of a human. In order to achieve an efficient high piezoelectric response from of PVDF, the amount of β-phase crystallinity should be as high as possible. This can be improved by adding different nanofillers to the polymer. It was evident that the addition of CNTs could enhance the total amount of β-phase in the melt spun fibres.

Ämneskategorier

Polymerkemi

Textil-, gummi- och polymermaterial

Nanoteknik

Kompositmaterial och -teknik

Styrkeområden

Nanovetenskap och nanoteknik

Materialvetenskap

ISBN

978-91-7597-107-0

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 3778

VDL-room

Opponent: Ulf Gedde