UV protective properties of cotton and flax fabrics dyed with multifunctional plant extracts

Abstract

Ultraviolet radiation (UVR) blocking properties of textiles depend on fibre type, fabric construction and nature of finishing chemicals. Natural dyes can provide vegetable fibres with strong colours if mordants are used.In this study UV protection properties of dyeing extracts from Mediterranean flora (Helichrysum italicum Roth, Rubia peregrina L., Daphne gnidium L., Lavandula stoechas L., Cynara scolymus L.) were tested in combination with fabrics made of vegetable fibres (cotton and flax) and different types of mordants (potassium alum and chestnuts tannins). Pre- and post-dyeing solutions were analyzed quali-quantitatively by HPLC/DAD/ESI-MS in order to calculate the dye uptake on fabrics during the dyeing process.UVR transmittance of fabrics was measured using a spectrophotometer equipped with an integrating sphere. After the dyeing process only flax fabrics mordanted with alum and dyed with Lavandula and Rubia, and flax fabrics mordanted with tannin and dyed with Rubia and Helychrysum reached the minimum protection level. A very good protection level was reached by flax mordanted with alum and dyed with Helychrysum. Chestnut tannins provided a slight support in phenols uptake for Lavandula and Helichrysum plant dyes with respect to potassium alum, but without an improvement of the fabrics UV protection properties; flax samples dyed with Helichrysum extract showed an improvement in UV protection properties when mordanted with potassium alum instead of tannins. Colour fastness and the persistence of UV protection characteristics were also tested after light/sun exposure and after several washes.