Quaternization-butyrylation to improve the viscosity stability, adhesion to fibers, film properties and desizability of starch for warp sizing

The influence of the quaternization and butyrylation on the sizing properties of biological starch macromolecule was evaluated for acquiring a new starch bio-based size [quaternized-butyrylated starch (QBS)]. The sizing properties of granular QBS samples were investigated in comparison with acid-thinned starch (ATS) and quaternized starch (QS). The QBS samples with a DS range of 0.029-0.0779 exhibited bonding strengths of 17.0-18.3 cN/tex to cotton fibers [15.5 cN/tex (ATS, DS = 0) and 16.6 cN/tex (QS, DS = 0.0240)] and 31.0-34.3 cN/tex to polyester fibers [28.0 cN/tex (ATS) and 30.1 cN/tex (QS)], and their films showed breaking elongations of 2.99-3.51% [2.59% (ATS) and 2.81% (QS)] and tensile strengths of 36.5-32.1 MPa [38.1 MPa (ATS) and 37.3 MPa (QS)]. Compared with QS, significantly increased bonding strengths as well as obviously decreased strengths and increased elongations of the films for the QBS samples with the total DS & GE; 0.0635 were exhibited. As increasing the modification levels from 0.029 to 0.0779, QBS presented paste stabilities from 90.4% to 85.7% which met with the requirement in warp sizing, and displayed higher desizing efficiencies (93.2-93.8%) than ATS (91.5%) and QS (90.2%). Based on these results, the amphiphilic quaternization-butyrylation was a good means for starch to acquire good sizing properties.