Oxidation and cross-linking to improve stability and sizing properties of cassava starch with ammonium persulfate-assisted hexamethylenetetramine

Abstract

An oxidation cross-linking modified cassava starch (AHS) with high thermal viscosity stability and good film-forming property was synthesized by oxidation cross-linking and amidation reaction，which used ammonium persulfate (APS) as the oxidant, hexamethylenetetramine (HMT) as the cross-linking agent and urea as an assistant. The results of Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (1H NMR) showed that compared with cassava starch, the strength of the hydroxyl peak on the AHS structure changed, and the strength of the intramolecular hydrogen bond decreased. The crosslinking agent HMT releases formaldehyde under heating conditions to crosslink oxidized starch. The auxiliary urea undergoes an amidation reaction to form amide bonds while adsorbing residual formaldehyde, improving the toughness of the AHS sizing film. When the APS usage is 0.4% (carboxyl content is 0.3024%), the HMT usage is 0.35% (sedimentation volume is 7.8mL), and urea usage exceeds 3%, the viscosity thermal stability of the AHS sizing agent is well (97.12%), and the elongation of the sizing film can reach 2.97%. Finally, The AHS sizing agent can improve the tensile properties and wear resistance of cotton yarn. This study overcomes the toxic substance emissions caused by traditional aldehyde crosslinking agents, improves the viscosity stability of the starch sizing agent, and provides a new approach to improving the viscosity thermal stability and film-forming properties of starch sizing agents.