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Zhang B.-S.,South China University of Technology | Deng D.-D.,South China University of Technology | Lu H.-F.,Guangzhou Glorystar Chemical Co.
Modern Food Science and Technology | Year: 2014

Corn starch was used to prepare hydroxypropyl starch by ethanol solvent, and then hydroxypropyl starch was modified using epichlorohydrin as cross-linked agent and chloroacetic acid as etherification agent. The microstructures of corn starch, hydroxypropyl starch, cross-linked hydroxypropyl starch, hydroxypropyl carboxymethyl starch, cross-linked hydroxypropyl carboxymethyl starch were analyzed by Fourier transform infrared spectrometer (FT-IR), X-ray diffraction (XRD) and scanning electron microscope (SEM). Modified corn starch showed new absorption peaks at 1287 cm-1 and 1328~1603 cm-1, which indicated that carboxymethyl and hydroxypropyl groups were attached to the native starch. A type X-ray spectra was assigned to modified starch, which confirmed the reaction mainly occurred in the amorphous region. The surface transformation change of starch granules before and after modification was observed, showing that the reaction occurred both inside and outside starch granules. Physical and chemical characteristics of modified corn starch showed that cross-linked hydroxypropyl carboxymethyl starch had good properties of transparency, freeze-thaw stability and rheology.

Xue L.,South China University of Technology | Lin X.,South China University of Technology | Hu X.,Guangzhou Glorystar Chemical Co. | Xu Q.,South China University of Technology
Gaofenzi Cailiao Kexue Yu Gongcheng/Polymeric Materials Science and Engineering | Year: 2015

Octavinyloctasilsesquioxane(OvPOSS) was synthesized with vinyltriethoxysilane under acidic condition. Then through radical thiol-ene addition click reaction, a new multi-vinyl and ethoxy POSS(EV -POSS) was synthesized in the presence of OvPOSS and (γ-mercaptopropyl)triethoxysilane(KH-580). The structure of the products was confirmed by 1H/29Si-NMR, FT-IR, mass spectroscopy and GPC. Then a series of OvPOSS/PMMA and EV-POSS/PMMA nanocomposites were prepared by addition of different kinds of POSS into PMMA. Different morphological features were investigated by XRD and SEM, the results show that OvPOSS crystallizes severely and EV-POSS is well-dispersed in PMMA. Through TGA, EV-POSS is useful to raise the thermal stability because of its good dispersion. The initial degradation temperature can rise by 64.3℃ by adding only 1% EV-POSS. ©, 2015, Chengdu University of Science and Technology. All right reserved.

Zhang B.-S.,Light Technology | Yu H.,Light Technology | Wang J.-P.,Guangzhou Glorystar Chemical Co. | Qu Z.-H.,Guangzhou Glorystar Chemical Co.
Modern Food Science and Technology | Year: 2014

Hydroxybutylated maize starches with different degrees of substitution (DSs) were prepared using 1, 2-epoxybutane, NaOH, and ethanol as the esterifying agent, catalyst, and dispersing agent, respectively. The microstructures of hydroxybutylated starch with different DSs were characterized by Fourier transform infrared spectrometry (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). A new absorption peak, ascribable to the hydroxybutyl group, was found at 1370 cm-1 in the IR spectrum of hydroxybutylated starch, confirming that hydroxybutyl groups were attached to native starch. XRD analysis revealed that hydroxybutylated starch still had an A-type X-ray diffraction pattern, confirming that the reaction mainly occurred in the amorphous region. Changes in the surface morphology of the starch granules before and after modification were observed via SEM, indicating that the reaction occurred on the surface of the starch granules. The result from the Brabender viscometer showed that the pasting temperature and set back values of the modified starches decreased significantly, whereas the peak viscosities increased. Moreover, these changes became more significant with increasing DS. When the DS reached a certain level, the hydroxybutylated starch was soluble in cold water. Thus, on increasing the DS, the transparency and freeze-thaw stability of the starch paste were substantially improved. ©, 2014, South China University of Technology. All right reserved.

Zhang B.-S.,South China University of Technology | Li W.-M.,South China University of Technology | Hou C.-B.,South China University of Technology | Wang J.-P.,Guangzhou Glorystar Chemical Co. | Qu Z.-H.,Guangzhou Glorystar Chemical Co.
Modern Food Science and Technology | Year: 2015

Using corn, cassava, potato, and sago starches as raw materials, high temperature treatment from 100 to 200 ℃ was adopted to investigate changes in the whiteness of original starches and starches treated with physical methods. Scanning electron microscopy (SEM) was used to observe the granular morphology of potato starch, which had the most obvious change in whiteness. Results showed that, after heating at 200 ℃, the whiteness of potato starch decreased from 85.88 to 45.51, which was the largest change; corn starch whiteness reduced from 88.21 to 79.10, which was the smallest change. After purification by ethanol, the resultant and original starches showed similar changes in whiteness under vacuum heating. At 200 ℃, the largest change in whiteness occurred in potato starch and the whiteness of all starches was lowered by 2 to 6 compared to their respective original starches. After heating under acidic or alkaline conditions, changes in whiteness were more obvious in the native starches, especially under alkaline condition. After heating at 200 ℃, whiteness was reduced to a range of 13.67 to 24.76. When starches were pre-gelatinized and heated, the changes in whiteness were roughly the same for the different starches; whiteness was very close to 39 at 200 ℃. These results demonstrate that the proteins and lipids in starch have little influence on the changes in its whiteness; however, variation in the thermostability of the whiteness of different starches might be related to their granular sizes. ©, 2015, South China University of Technology. All right reserved.

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