engleski

Silica precursors in flame retardancy of cotton

Cotton materials, in the case of fire, represent a major risk, since it is flammable and burns strongly and fast. Commercial flame retardants, developed in 1950-1980, significantly improve flame retardancy, but are highly toxic. For that reason, novel flame retardants are researched. Silica compounds have good thermal properties by giving residue after the combustion process. Therefore, in this paper silica precursors were investigated in order to reduce the current high quantities of flame retardants and to reach the full protection. Two silica precursors have been applied by sol-gel treatments on cotton fabrics and compared to conventional flame retardants applied by the pad-dry-cure process. Conventional flame retardant urea and ammonium hydrogen phosphate (Ap3) was applied in full (urea 240g/l and ammonium hydrogen phosphate 115 g/l) and half (urea 120g/l and ammonium hydrogen phosphate 57, 5 g/l) concentration. Silica precursors Tetramethoxysilane (TMOS) and Tetraethoxysilane (TEOS) were applied in concentration of 15 ml/l. Additionally, silica precursor TMOS and TEOS were added to conventional flame retardant. The flame retardancy and burning behaviour were determinated according to standard methods – ISO 15025:2000 Textile fabrics – Burning behaviour – Determination of ease of ignition of vertically oriented specimens, and ISO 4589:1996 – Plastics – Determination of burning behaviour by oxygen index in Limiting Oxygen Index (LOI) Chamber (Dynisco). For better understanding the changes in cotton structure under the heat conditions thermogravimetric method (TGA) on Pyris1 (PerkinElmer) and micro combustion calorimeter (MCC) MCC-2, Govmark, USA were used. For the durability burning behaviour was tested after 1 washing cycle according to ISO 6330:2012 Textiles - Domestic washing and drying procedures for textile testing The mixture of silica precursors with urea and ammonium hydrogen phosphate resulted in higher flame retardancy even when half the concentration of conventional FR was applied. It can be concluded that the silica phase formed by sol-gel process plays a protective role to degradation of the cotton fibers and it is able to modify the thermal and combustion behaviour of cellulose. The best results were achieved with the mixture of flame retardants - silica precursor TEOS, urea and ammonium hydrogen phosphate.

silica precursor TEOS; urea and ammonium hydrogen phosphate; cotton

nije evidentirano