Dialdehyde Starch And Its Crosslinking Efficiency

Dialdehyde starch is a multifunctional, highly reactive carbonyl compound. It is generally accepted that dialdehyde starch has its very low toxicity, renewability and degradability compared with low molecular weight cross-linkers such as glyoxal and glutaraldehyde. Dialdehyde starch has found broad potential applications in various industries. Dialdehyde starch is scarcely produced and applied in China. Though its production has been commercialized in some countries, as yet, dialdehyde starch has not found any important application on large scale. On the one hand, the cost of dialdehyde starch is high. On the other hand, dialdehyde starch has low cross-linking efficiency. Starch resources are very abundant in China and no literature is available on the mechanism of low cross-linking efficiency. So we study the preparation, properties of dialdehyde starch and investigate the factors that influence the cross-linking efficiency of dialdehyde starch and hope to find the theories to improve the applications of dialdehyde starch.1. The factors that influence the aldehyde content in dialdehyde starch included reaction time, reaction temperature, concentrations of sodium periodate, reaction PH, and the ratio of sodium periodate to starch. A four-factor homogeneous experiment was designed with fixed ratio of sodium periodate to starch at 1.1:1. It was found that the optimal conditions were reaction time 3.47 hours, reaction temperature 36.46 C, reaction concentration of sodium periodate 0.63mol/L, reaction pH 1.83.2. Dialdehyde starch of known aldehyde content were subjected to various heat treatments in aqueous suspensions at different pHvalues. Acid product was determined by continuous titration with sodium hydroxide. The amount of reactive aldehydes ((CHO) T 掳xime) was calculated by measuring the oxime formation upon addition of hydroxylamine. The amount of reactive aldehydes is lower than the actual amount of aldehydes.3. The study of the stability and Theological properties shown that the dialdehyde starch with high aldehyde content didn't easily swell, the absolute viscosity was lower than that of dialdehyde starch with low aldehyde content and the dialdehyde starch swelled easily in alkaline medium.4. The study of interaction of dialdehyde starch and chitosan shown that two main factors influenced the cross-linking efficiency of dialdehyde starch. One was thealdehyde content. The other was the molecular weight of dialdehyde starch.5. The study of interaction of dialdehyde starch and gelatin shown that the order of the cross-linking efficiency was: glutaraldehyde > dialdehyde starch > glyoxal.