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121.
Poly(L ‐lactic acid)‐titanium dioxide nanocomposites (with various loadings of TiO2: 0.5, 1, 2, 5, and 10 wt %) were produced by solution casting method. The influence of TiO2 on thermal properties and crystallinity of PLA was investigated by DSC and FTIR spectroscopy. The TiO2 nano filler has no significant influence on the characteristic temperatures (Tg, Tc, and Tm), but has high impact on the crystallinity of these systems. The degree of crystallinity Xc significantly increases for PLA nanocomposites loaded with up to 5 wt % of TiO2, while for 10 wt % load of TiO2 it drops below Xc of the pure resin. The degradation of the prepared composites was evaluated hydrolytically in 1N NaOH, enzymatically in α‐amylase solutions, and under UV irradiation. The catalytic effect of TiO2 nano particles on the degradation processes under UV light exposure (λ = 365 nm) and hydrolytic degradation was confirmed with the increase of the filler content. The opposite effect was identified in enzymatic degradation experiments. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
122.
Radmila V. Hercigonja Danijela D. Maksin Aleksandra B. Nastasović Snežana S. Trifunović Pavle B. Glodić Antonije E. Onjia 《应用聚合物科学杂志》2012,123(2):1273-1282
The possibility of sorption of technetium‐99 in the form of pertechnetate anion (TcO4?) and the sorption kinetics for removing TcO4? from aqueous solution by chelating polymers based on glycidyl methacrylate (GMA) were investigated. Two samples of macroporous crosslinked poly(glycidyl methacrylate‐co‐ethylene glycol dimethacrylate) (PGME), with different amount of the crosslinker (ethylene glycol dimethacrylate, EGDMA), were synthesized by suspension copolymerization and functionalized with diethylene triamine (deta). We propose that nonspecific sorption of pertechnetate anion via electrostatic interactions takes place at the protonated amino groups of macroporous crosslinked copolymer. The results of batch experiments performed at pH 1–14 showed fast sorption kinetics for removing TcO4? by amino‐functionalized PGME‐deta in a wide range of pH, that is, from 1.0 to 9.0. Almost complete removal of TcO4? (91–98%) was reached within 180 min in the stated pH range (1.0–9.0), with the sorption half‐times of under 25 min. The partitioning coefficients of linear adsorption isotherms, with 180‐min equilibrium time, reach the high values of 2130 mL g?1 and 1698 mL g?1 for the two samples of synthesized PGME‐deta. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
123.
Modeling of kinetics of pertechnetate removal by amino-functionalized glycidyl methacrylate copolymer 总被引:1,自引:1,他引:0
Danijela?D.?MaksinEmail author Radmila?V.?Hercigonja Magdalena??.?Lazarevi? Marija?J.??uni? Aleksandra?B.?Nastasovi? 《Polymer Bulletin》2012,68(2):507-528
Technetium-99 comprises a significant health risk, since edible plants can bioaccumulate and convert it to more lipophilic
species that cannot be excreted through urine. Batch kinetics of pertechnetate removal from aqueous solutions by two samples
of crosslinked poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) functionalized with diethylene triamine (PGME-deta) was investigated at the optimum pH value
of 3.0, and the initial solution activity of 325 MBq dm−3. PGME-deta was characterized by elemental analysis, mercury intrusion porosimetry, and scanning electron microscopy. Five
kinetic models (pseudo-first, pseudo-second order, Elovich, Bangham, and intraparticle diffusion) were used to determine the
best-fit equation for pertechnetate sorption. After 24 h, PGME-deta samples sorbed more than 98% of pertechnetate present,
with maximum sorption capacity of 25.5 MBq g−1, showing good potential for remediation of slightly contaminated groundwater. 相似文献
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Tamara R. Dapčević Hadnađev Ljubica P. Dokić Miroslav S. Hadnađev Milica M. Pojić Aleksandra M. Torbica 《Food and Bioprocess Technology》2014,7(1):235-247
The feasibility of emulsifying starches as bread improvers was investigated by incorporating starch sodium octenyl succinate (OSA-st), pre-gelatinized OSA-st and hydrolysed spray-dried OSA-st at 2.5, 5 and 10 % into wheat flour. Dough rheological properties (creep and recovery measurements; Mixolab, Alveograph) and bread quality parameters (specific loaf volume, crust and crumb colour, crumb moisture, crumb grain features, texture) were evaluated. The substituted flours, except hydrolysed OSA-st, significantly increased water absorption measured by Mixolab. The study on the rheological behaviour of doughs containing emulsifying starches, performed using a rheometer and an Alveograph, showed that OSA-st incorporation yielded strengthened dough, whereas pre-gelatinized and hydrolysed OSA-st addition led to more extensible dough. With regard to the thermal behaviour, investigated in water-limited systems by Mixolab, doughs prepared from pre-gelatinized OSA-st and hydrolysed OSA-st exhibited lower maximum peak torque, whilst all three examined starches increased cooking stability and decreased the setback value. Specific volumes of loaves baked from the substituted flours increased, and the highest effect was observed with pre-gelatinized OSA-st, which consequently produced bread crumbs with the largest mean gas cell area. The bread crumbs baked with octenyl succinate starches were whiter and softer. Although upon 1 day of storage no significant moisture retention capacity of emulsifying starches was noticed, the firmness values of OSA-st and pre-gelatinized OSA-st-supplemented bread crumbs, after 24 h of storage, were similar to or significantly lower than those of the control determined 2 h after baking. The obtained results indicate a requirement for further optimization of the octenyl succinate starch-supplemented doughs in terms of the combination of different types and levels of modified starches in order to obtain maximum bread quality. 相似文献
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Vesna Župunski Mirjana Vasić Jelka Šuštar Vozlič Marko Maras Aleksandra Savić Gordana Petrović Dalibor Živanov 《Food Analytical Methods》2018,11(4):1034-1040
Trypsin inhibitors could limit utilization of legumes in human nutrition, but they could also have beneficial health effects. The objective of this study was to measure trypsin inhibitor activity (TIA) of different legumes using microtiter plate method and to identify factors that contribute to uncertainty of TIA measurement. TIA measurements were performed on seeds of faba bean, pea, common vetch, soybean, and common bean cultivars. The significant effect of legume crop on TIA measurement uncertainty was confirmed with P = 0.045. Certain sources of measurement uncertainty were related with the content of trypsin inhibitors (Tis) in legume seeds. In respect to that, significant effect of level of sample dilution (P ? 0.001) was confirmed. Significant influence of the repeated absorbance measurement of sample reaction mixture on uncertainty of TIA measurement was identified (P ? 0.001), and it took 60% of overall TIA measurement uncertainty for soybean cultivars. TIA of soybean cultivars exceeded 90 TUI/mg. Repeated absorbance measurement of positive control reaction mixture took 70% of TIA measurement uncertainty of cultivars with TIA lesser than 4.5 TUI/mg. Graduated cylinder used for preparation of the final sample solutions took the range from 45 to 90% of overall TIA measurement uncertainty of the cultivars whose TIA were in the middle of previously mentioned. The uncertainty of TIA measurement of legume crops was not studied before; thus, this study pointed out that acquiring insight into factors contributing to uncertainty of TIA measurement could give directions for improvement of TIA testing if microtiter plate method is used. 相似文献
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129.
Monika Makrocka-Rydzyk Aleksandra Wypych Maciej Kozak Haifeng Gao Krzysztof Matyjaszewski 《Polymer》2011,52(24):5513-5520
Structural behavior of miktoarm star polymers comprising poly(butyl acrylate) (PBA) and poly(ethylene oxide) (PEO) arms was studied by means of Differential Scanning Calorimetry (DSC), Wide Angle X-Ray Scattering (WAXS), Polarized Optical Microscopy (POM) and Fourier Transform Infrared Spectroscopy (FTIR) methods. The aim of this study was to correlate changes in the composition of the arms of the PBA/PEO miktoarm star polymers with their structures. As a consequence of increasing PBA content, the decrease in crystallinity of the studied PBA/PEO heteroarm star copolymers was observed. Regardless of the copolymer composition, fraction of oxyethylene units in the crystalline PEO phase was similar in all investigated systems. The POM images showed spherulitic morphology of the materials having low PBA content, while an increase in PBA arms fraction leads to the formation of less ordered structures. The analysis of FTIR vibrational spectrum indicates helical conformation of PEO chains in the crystalline phase. Isothermal crystallization studies carried out using the FTIR technique suggest the existence of isolated domains in the nanoscopic scale of investigated materials. 相似文献
130.