Modification of biological starch macromolecule with phosphate and dimethylammonium chloride acyloxylate substituents confers good desizability, film properties, paste stability and adhesion.

This study revealed the influence of phosphorylation-dimethylammonium chloride acyloxylation (PDACA) on the desizability, film properties, paste stability, and adhesion of biological starch macromolecules. A new starch-based sizing agent, phosphorylated-dimethylammonium chloride acyloxylated starch (PDACAS), was synthesized with degrees of substitution (DS) ranging from 0.033 to 0.065. Compared to control phosphorylated-quaternized starch (PQS, 87.4 %), the desizing efficiency of cotton yarns sized with PDACAS was ~94 %, exceeding the industrial minimum requirement of 90 %. The PDACAS film tensile properties were as follows: elongation at break of 3.31 %-3.78 %, bending endurance of 1131-1537 cycles, and tensile strength of 35.83-28.31 MPa, compared with those of acid-thinned starch (ATS) film (2.74 %, 957 cycles, and 38.12 MPa). The PDACAS had paste stability of ~92 %, compared with 83.3 % for ATS. The bonding forces (an indicator of adhesion to fibers) ranged from 107.1 N to 125.3 N for cotton roving, and 128.3 N to 148.7 N for polyester/cotton roving, which were significantly better than those of ATS (95 N for cotton and 117.9 N for polyester/cotton roving). Overall, PDACA treatment effectively avoided the adverse effect of high DS quaternization on the desizability of PQS and imparted good film properties, paste stability, and adhesion to starch.

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 ≥ 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.

Investigating the relationship between structure of itaconylated starch and its sizing properties: Viscosity stability, adhesion and film properties for wool warp sizing.

The purpose of this work was to evaluate the effect of itaconation on sizing properties (such as viscosity stability, adhesion and film properties) of biological macromolecule (corn starch) for developing a new bio-based sizing agent [itaconylated starch (IS)]. Granular IS samples were characterized by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) techniques. The adhesion of IS to wool fibers was investigated by a standard method (FZ/T 15001-2008). And film properties of IS samples were also studied in terms of tensile strength, breaking elongation, bending endurance and degree of crystallinity, etc. Compared with control acid-converted starch (ACS), stronger bonding forces to wool fibers for IS as well as higher breaking elongation and lower tensile strength for IS film were displayed. Increasing the degrees of substitution (DS) of IS samples from 0 to 0.052 was able to achieve gradually enhanced bonding forces, breaking elongation and bending endurance, which implied that increasing the number of itaconate substituents could play a significantly positive role in overcoming the shortcomings (insufficient adhesion and film brittleness) of starch. These experimental results denoted that the granular IS exhibited potential for the use as a new starch-based size in the sizing of wool warp yarns.