The Effect of Combined Atmospheric Plasma/UV Treatments on Improving the Durability of Flame Retardants Applied to Cotton

Application of a combined atmospheric plasma/UV laser to cotton fabrics impregnated with selected non-durable flame retardants (FRs) has shown evidence of covalent grafting of the latter species on to cotton fibre surfaces. As a result, an increase in their durability to water-soaking for 30 min at 40 degrees C has been recorded. Based on previous research plasma gases comprising Ar-80%/CO220% or N-2(80%)/O-2(20%) were used to pre-expose cotton fabric prior to or after FR impregnation to promote the formation of radical species and increased -COOH groups on surface cellulosic chains, which would encourage formation of FR-cellulose bonds. Analysis by scanning electron microscopy (SEM/EDX), X-ray photoelectron spectroscopy (XPS) and thermal analysis (TGA) suggested that organophosphorus- and nitrogen- containing flame retarding species in the presence of the silicon-containing molecules such as 3-aminopropyltriethoxy silane (APTS) resulted in formation of FR-S-O-cellulose links, which gave rise to post-water-soaking FR retentions > 10%. Similarly, the organophosphorus FR, diethyl N, N bis (2-hydroxyethyl) aminomethylphosphonate (DBAP), after plasma/UV exposure produced similar percentage retention values possibly via (PO).O.cellulose bond formation, While none of the plasmas/UV-treated, FR-impregnated fabrics showed self-extinction behaviour, although burning rates reduced and significant char formation was evident, it has been shown that FR durability may be increased using plasma/UV treatments.

Automated summary

Application of a combined atmospheric plasma/UV laser to cotton fabrics impregnated with flame retardants (FRs) has demonstrated the covalent grafting of FRs onto cotton fiber surfaces, resulting in increased durability to water. Analysis by scanning electron microscopy, X-ray photoelectron spectroscopy, and thermal analysis revealed the formation of FR-cellulose bonds through plasma/UV exposure. The use of certain organophosphorus and nitrogen-containing FRs in the presence of silicon-containing molecules further enhanced the FR retention after water-soaking. Although the treated fabrics did not exhibit self-extinction behavior, the burning rates reduced and significant char formation was observed.