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Citric acid crosslinking of cellulose in the presence of zeolite FAU

Polycarboxilyc acids are environmentaly sustainable ester crosslinking agents of cellulose and as the most promising formaldehyde-free agents have been confirmed to impart different durable press finishing properties to cotton [1]. For obtaining the effective crosslinks in cotton fabrics a catalyst is needed. Usually, as also shown in our previous research [2], citric acid is used with sodium hypophosphite (SHP) as a catalyst, while the use of zeolite catalyst should be confirmed as environmentally and economically more acceptable. Esterification of cotton fabrics with CA in the presence of zeolite FAU is presented. Cotton fabric samples were padded to 100% wet pickup with a suspension containing zeolite powder (1.3 wt %) in aqueous solution of CA crosslinking agent (10 wt %). Padded fabrics were dried at 60°C for 10 min to remove the mobile water. Curing was performed at predeterminated temperatures (90 °C -180 °C) at different curing times. Prior to further analyses the cotton samples were first washed to remove the loosely bonded zeolite and the unreacted CA, then treated with a NaOH solution (0, 1 M) with the purpose of quantitatively converting the carboxyl to a carboxylate anion and finally dried. The degree of esterification is evaluated from the FTIR spectra of the samples obtained using the ATR technique. The intensity of the ester carbonyl band at ca. 1730 cm-1 was the basis for semi-quantitative analysis of ester on the cotton fabric. The amount of CA applied to cotton fabric as well as the amount of ester present after the curing process is determined in order to optimize the crosslinking of cotton. The flammability behavior of the samples is valuated from the thermogravimetric analyses. Since a considerable amount of zeolite remains strongly bonded to cotton fabric, as seen from the scanning electron microscopy analyses, the improved flame retarding properties of cotton is obtained.

crosslinking of cellulose; flammability; polycarboxilyc acid; zeolite FAU;

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