Khaled El-Tahlawy

Synthesis and characterization of starch citrate-chitosan foam with superior water and saline absorbance properties.

The objective of this research was to synthesize and characterize high-value foam gel materials with unique absorptive and mechanical properties from starch citrate-chitosan. The effects of starch citrate concentration, pH, solid to liquid ratio, reaction time, and temperature on absorbency, weight loss in water, and strength were determined. The cross-linked starch citrate-chitosan foam is flexible and elastic and has significantly increased absorbance and strength and decreased weight loss in water compared to starch-chitosan foam. A unique characteristic of the starch citrate-chitosan foam is that it absorbs more saline solution than pure water, which is the opposite of current commercial super absorbents. An increased strength, increased degradation temperature, increased storage modulus, and decreased weight loss in water for starch citrate-chitosan relative to starch-chitosan are in agreement with amide bonds formed between the carboxyl group of starch citrate and the amino group of chitosan.

Chitosan: A new route for increasing the efficiency of stannate/phosphate flame retardants on cotton

Abstract Sodium stannate/phosphate is an ideal eco-friendly flame retardant agent for cotton fabric. Development of this technique is an essential way to overcome some of its disadvantages such as the harsh feeling as a result of using high concentration of sodium stannate. Chitosan is added in the phosphorylation bath as a nitrogen source and to facilitate the phosphorylation process. Incorporation of 1% chitosan could decrease the sodium stannate concentration to the one-third of the amount that is used in the conventional method. Increasing the stannate concentration in the finishing bath from 10 to 30% could enhance the flame retardancy of the cotton fabric. Thermogravimetric analysis of the treated cotton fabric shows an increase in the residual percent of the fabric and decrease in both thermal degradation onset point (TDOP) and maximum degradation rate point as a function of stannate concentration. Increasing diammonium hydrogen phosphate (DAHP) from 2 to 10% in the finishing bath shows an increase in the residue at 500°C to 39.24%. Phosphorus and nitrogen percentages show an increase in their values till reaches to 1.39 and 1.72, respectively. The effect of curing temperature and time, chitosan concentration, and the sequence of treatment are studied in detail.