Abstract
New hybrid sol–gel coatings based on tetraethoxysilane (TEOS) and phytic acid (PA) were designed and applied to cotton; the flame-retardant properties of the treated fabrics were thoroughly investigated by means of flame-spread and forced-combustion tests. The first goal was to identify the TEOS:PA weight ratio that allowed the achievement of the best flame-retardant properties, with the lowest final dry add-on on the fabrics. Therefore, different TEOS:PA sols were prepared and applied to cotton, and the resulting coated fabrics were thoroughly investigated. In particular, solid-state NMR spectroscopy was exploited for assessing the condensation degree during the sol–gel process, even for evaluating the occurrence of possible reactions between phytic acid and the cellulosic substrate or the alkoxy precursor. It was found that a total dry add-on of 16 wt % together with 70:30 TEOS:PA weight ratio provided cotton with self-extinction, as clearly indicated by flame-spread tests. This formulation was further investigated in forced-combustion tests: a significant reduction of heat release rate (HRR), of the peak of HRR, and of total heat release (THR) was found, together with a remarkable increase of the residues after the test. Unfortunately, the treated fabrics were not resistant to washing cycles, as they significantly lost their flame-retardant properties, consequently to the partial removal of the deposited hybrid coatings.
Highlights
In the last century, polymers and cellulosic textiles became two of the most universally used and the most combustible materials [1,2]
The effectiveness of the deposition of the sol–gel coatings on the cotton fabrics was assessed through FTIR–attenuated total reflection (ATR) spectroscopy
The FTIR–ATR spectrum of cotton treated with the hybrid coating still shows the presence of some typical vibrational modes of cellulose, though these signals are less intense and defined because of the presence the sol–gel coating
Summary
Polymers and cellulosic textiles became two of the most universally used and the most combustible materials [1,2]. A possible solution to enhance the level of fire safety of combustible fibers and fabrics refers to the use of flame-retardant (FR) chemicals, designed to minimize the rate of flame spread and to prevent sustained combustion [3,4] In this context, in the last decades, different FRs were developed; these compounds may contain halogens (chlorine and bromine), phosphorus, magnesium, nitrogen, aluminum, antimony, molybdenum, or quite recently developed nanofiller-based systems [5,6,7]. Its structure consists of phosphate groups that, a flame or a heat flux, may give rise to the formation of phosphoric acid; this latter can act in condensed upon flame or a heat flux, may give rise to the of phosphoric acid; protective this latter phase,exposure favoring to thea dehydration of the cellulosic substrate andformation subsequently forming a stable can act in condensed phase, favoring the dehydration of the cellulosic substrate and subsequently char, effectively affecting combustion processes [28].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
