The Functional Chemical Materials Research Laboratory, Institute of Applied Chemistry, Faculty of Chemistry,
Ammonium etidronate, a green product of nontoxic organophosphorus flame retardant, was synthesized from acetic acid, phosphorus oxychloride and phosphorous acid, in which dicyandiamide was used as coupling agent. Moreover, optimum condition for the combination of ammonium etidronate with cotton cellulose was established.
In the first step reaction for the synthesis of ethidronic acid from acetic acid, the optimum acetic acid/oxychloride/phosphorous phosphorous acid molar ratio is 1/1.5/3, condensation reaction temperature 100 °C, condensation reaction time 3h, hydrolysis reaction time 4h, and hydrolysis temperature 100 °C with 80~83% yield.
In the second step for the synthesis of ammonium etidronate, a flame retardant from etidronic acid and urea, optimum etidronic acid/urea molar ratio is 1/3, reaction temperature 100°C, and reaction time 2h, with 87~90% yield.
The mechanical and physical properties of the flame retardant cotton samples were slightly reduced compared to the control samples, but there is no limit in application.
Finding of reaction conditions that can increase the grafting rate of the reaction for the flame retardant treatment of cotton is a step forward in the production of flame retardant cotton fabrics.
In March 2024, the results were published on "Iranian Polymer Journal" as a title of "Preparation and characterization of durable flame retardant cotton fabrics using phosphorylation reaction of cellulose with ammonium etidronate"(https://doi.org/10.1007/s13726-024-01287-9).
