MAGNETISABLE MELT-SPUN FIBRES PRODUCED AS LIQUID-CORE HOLLOW FIBRES: DEVELOPMENT OF FIBRES AND EFFECTS OF MAGNETISABILITY

Magnetisable fibres, among others, can be used for targeted fibrearrangement or fixing by use of a magnetic fields, antistatic properties or shielding against electromagnetic fields. In some cases the application requires to keep the functional, magnetic component separate from the environment. Liquid-filled hollow fibres are a promising candidate for this purpose, as the fibre hull material can be chosen to keep optimal interaction with the surrounding environment, while the liquid-phase allows for introduction of large fractions of fillers. In this study, a novel strategy to achieve magnetisable fibres was investigated. By melt spinning, hollow polyethylene fibres were produced and in situ filled with a liquid containing iron oxide particles. As reference, polypropylene monofilaments were melt spun, where the iron oxide particles were compounded into the polymer prior to melt spinning. Both processes were successfully implemented, however in the first strategy the ferrofluid caused deficient process robustness due to nozzle clogging and thermal instability. For rough access of the achievable magnetisability, hollow fibres were filled manually with a ferrofluid. To evaluate magnetic functionality, a custom-built measurement unit was developed for quantifying the magnetic attraction force of fibre samples. The measured magnetic detachment forces of the ferrofluid-filled samples were 17.0 ±0.8 mN and therefore in the range of the monofilaments, where values from 11.4 ±0.7 mN to 26.6 ±1.8 mN were measured, depending on fibre diameter and iron content.