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Manufacturing and Characterisation of Conductive and Piezoelectric Textile Fibres

Tillverkning och karakterisering av ledande och piezoelektriska textilfibrer

Erik Nilsson (Institutionen för material- och tillverkningsteknik, Polymera material och kompositer)
Göteborg : Chalmers University of Technology, 2014. ISBN: 978-91-7597-107-0.- 49 s.
[Doktorsavhandling]

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.

Nyckelord: Graphite nanoplatelets, graphene, carbon black, polypropylene, polyethylene, electrical conductivity, rheology, PVDF, piezoelectric fibres, melt spinning, conductive fibres, smart textiles.



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Denna post skapades 2014-11-13. Senast ändrad 2014-11-18.
CPL Pubid: 205755