Plasmagestützte Oberflächenmodifizierung von Polypropen
The use of PP fibres in apparel industry is limited due to the poor dyeability of PP in exhaust-dyeing processes. One reason for the poor dyeing behaviour is the hydrophobic surface of PP, which is only hardly wettable with aqueous dye solutions. Another reason is the low wet fastness, as a result of the minor ability of PP to fix the dyestuff within the fibres. Consequently, a process has to be applied, which increases the surface wettability and additionally, improves the dyestuff-fibre interaction. Suitable environmentally friendly methods to hydrophilise PP surfaces are microwave-induced low temperature plasmas as well as barrier discharges. The aim of this study was to investigate the plasma-induced hydrophilisation of PP fibres for improving their dyeability. The wettability behaviour of both PP foils and fibres are quite comparable. The wettability of the PP surface increases with increasing treatment time in oxygen plasma and barrier discharge, respectively. The influence of different power levels on the resulting contact angle of the fibre surface is negligible. During storage at atmosphere the wettability of the treated PP fibres decreases with proceeding storage time, whereas storage in water does not affect the contact angles. The plasma-induced improvement of the surface wettability is not only due to the insertion of oxygen containing groups, but can also be attributed to the modification of the surface topography, which was investigated by profilometric measurements. The decreasing contact angle of PP fibres with prolonged treatment in an oxygen plasma correlates with an increased surface roughness of the material. The dye-uptake of the disperse dye Resolin Red FB and the solvent dyes Sudan Blue II and Sudan Red B on plasma treated PP fibres was investigated. Dyeing the oxygen plasma treated fibres for 60 min leads to a higher rate of exhaustion of the dyestuffs compared to the untreated material, which is attributed to the plasma-induced surface modification of the fibres. Due to the lower degree of hydrophilisation of the barrier discharge treated fibres, no higher dye uptake was achieved. The diffusion coefficients of fibres treated by oxygen plasma or barrier discharge, calculated by the root-t-law, are increased. The increased dye uptake on the oxygen plasma treated fibres also lead to an enhanced colour strength, compared to the dyed untreated fibre. With an extended treatment time a higher colour strength is detected, which correlates with the improved wettability of the fibre at proceeding exposure duration in oxygen plasma.
info:eu-repo/classification/ddc/660, Technische Chemie
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