Modification of cotton by acrylic acid (AA) in the presence of NaH2PO4 and K2S2O8 as catalysts under thermal treatment

Cotton fabric was modified using acrylic acid (AA) as the finishing agent in the presence of K2S2O8 and NaH2PO4 catalysts separately or in selected combinations, employing a pad-dry-cure technique. Treatment with 8% AA at 30°C and at pH 7 produced optimum effects: a batching time of 30–45 min at 30°C followed by drying of the batched fabric at 95°C for 5 min and curing of the dried fabric at 140°C for 5 min produced most balanced improvements in the textile related properties. NaH2PO4 catalyst allowed esterification of AA with the cellulosic constituent of cotton, and K2S2O8 catalyst allowed radical polymerization of free-AA or cotton bound AA moieties, ultimately leading to some degree of crosslinking of the chain polymers of cotton. Examination of the surface morphology of untreated and treated cotton fabrics by scanning electron microscopy revealed a good degree of masking of the convolutions of the cellulosic fibres and surface crack by a cohesive film of poly(acrylic acid) or its salt, particularly when K2S2O8 was used either alone or in combination with NaH2PO4 as catalyst.