Chemical Process for Making Dialdehyde Starch

ArticleinStarch - Starke 23(2):42 - 45 · January 1971with33 Reads
DOI: 10.1002/star.19710230203 · Source: OAI
Abstract
A practical, strictly chemical process has been developed for the periodic acid oxidation of starch to dialdehyde starch. In the procedure spent oxidant is converted by alkaline hypochlorite to insoluble sodium paraperiodate, which is recovered in high yield for recycling. The process is suitable for small-scale production of dialdehyde starches of various carbonyl contents.
    • "When the hydroxyl groups in the glucose ring have been oxidized to aldehyde groups, the hydrogen bonds between the individual chains become weaker and result in a thermoplastic behavior and hydrophobia. Although dialdehyde starch (DAS) is the most valuable oxidized starch that has already been used in several industrial applications2526272829 , we know of only a few literature reports of TPS prepared from dialdhyde starch and its properties. When the hydroxyl groups are oxidized to aldehydes, the number of hydrogen bonds of starch should be reduced. "
    [Show abstract] [Hide abstract] ABSTRACT: Dialdehyde sweet potato starch (DASS) with various aldehyde contents was prepared and the properties analyzed in terms of solubility, intrinsic viscosity, scanning electron microscopy (SEM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The results demonstrated that when the aldehyede content of DASS was increased from 20% to 95%, the solubility, molecular weight, crystallizability and thermal stability decreased. Thermoplastic DASS (TPDASS) was prepared by adding glycerol as a plasticizer; the thermal, rheological, hydrophobic and tensile properties of TPDASS were investigated. The results indicated that, for the same glycerol content, with the increase of aldehyde content, the moisture adsorption decreased, while the shear viscosity, glass transition temperature and tensile properties of TPDASS increased significantly. The effects were attributed to the introduction of aldehyde groups reducing the hydrogen bonds and decreasing the hydrophility of the starch. Moreover, the aldehyde and hydroxyl groups of DASS favored a semi-acetal formation with higher aldehyde content and cross-linking of DASS occurred with the increase of aldehyde content. In summary, compared to starch, the thermoplastic properties and hydrophobicity of DASS was improved. In the presence of water (10%,wt), the tensile strength of TPDASS with 95% aldehyde content (TPDASS95) moderately decreased, from 16.7MPa to 14.0 MPa, when the glycerol content increased from 10% to 30%.The TPDASS with improved properties will find their applications in preparing biodegradable plastics.
    Full-text · Article · Mar 2015
    • "The regeneration of the periodate reduction product (i.e., iodate) using both chemical secondary oxidation agents and electrochemical methods has been studied in the context of dialdehyde starch (DAS) production.789 The spent oxidant solution from starch oxidation has been efficiently recovered using ozone [7] and hypochlorite [8] in alkaline and persulfuric acid [10] under acidic conditions. However, the regeneration efficacy of periodate from cellulose oxidation is not well-known. "
    [Show abstract] [Hide abstract] ABSTRACT: The regeneration of aqueous iodate solution from the regioselective periodate oxidation of softwood cellulose pulp to dialdehyde cellulose using hypochlorite as a secondary oxidant was studied. The influence of oxidation time on the pulp dissolution and regeneration efficacy was examined in particular. In addition, the recycling of regenerated periodate solution back to oxidation was clarified. The solutions from the 10 and 15 min oxidations were regenerated with 100% conversion efficacy when 1.2–1.4 times the stoichiometric amounts of hypochlorite were used. However, the regeneration efficacy decreased when the reaction time in the oxidation increased to 30 min because the content of soluble impurities, which consumed the hypochlorite in the side-reactions, increased significantly as the oxidation reaction proceeded. The regenerated solutions possessed good oxidation performance, showing that periodate was successfully regenerated using hypochlorite and supporting the assumption that periodate can be effectively recycled in the process when short oxidation times are used.
    Full-text · Article · Dec 2013
    • "Dialdehyde starch is obtained by oxidation of starch with periodic acid at controlled temperature and pH. Periodic acid is a highly selective oxidizing agent, which cleaves the C-2 – C-3 linkage of anhydroglucose units with the formation of dialdehyde groups123456. The highly reactive dialdehyde groups in starch can be used as crosslinking agents. "
    [Show abstract] [Hide abstract] ABSTRACT: Tapioca starch was oxidized by periodic acid (sodium metaperiodate plus hydrochloric acid) to form dialdehyde tapioca starch (DAS). The influence of periodate concentration (NaIO4, 0.05 N, 0.1 N, 0.2 N and 0.3 N) on the physicochemical properties of DAS such as aldehyde and carboxyl contents, relative crystallinity, thermal properties, pasting properties, swelling power, solubility and molecular weight distribution was investigated. The results indicated that aldehyde and carboxyl contents of DAS increased linearly with the increasing of periodate concentration. X-ray diffraction patterns of DAS remained unchanged after periodate oxidation whereas the relative crystallinity decreased as periodate concentration increased. Furthermore, the gelatinization temperatures (To and Tp) of DAS were also increased, whereas the gelatinization enthalpy decreased. As determined in the Rapid Visco Analyser, the periodate oxidation increased the pasting temperature and peak viscosity as well as breakdown of the tapioca starch. The swelling power of DAS was higher than that of unmodified tapioca starch at 60°C and 70°C, but was lower at 80°C and 90°C. However, the solubility was higher than that of native tapioca starch at all incubation temperatures. Both amylose and amylopectin fractions were degraded during the oxidation reaction as measured by HPSEC. The thermal stability of DAS at boiling temperature was also investigated and depolymerization of the DAS could not be detected at any heating time as demonstrated for the thermal stability of the DAS.
    Article · Apr 2005
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