flame retardant finishing; cotton fleece fabrics; malic acid; succinic acid; solubility and acidity of SUA, MLA and TTA; mole concentration and w/v concentration of the acids and catalysts; fabric bursting-strength measurement; fabric CIE whiteness index measurement; Micro-Scale Combustion Calorimetry (MCC) measurement; bonding of the three bifunctional acids to the cotton; 45° flammability of the cotton fleece treated with 0.54M SUA, MLA and TTA; bursting strength of the cotton fleece