جستجوی مقالات مرتبط با کلیدواژه « starch » در نشریات گروه « شیمی »

Biodegradable films containing poly (lactic acid) (PLA) and starch with three ratios of 90/10, 80/20 and 70/ 30 were prepared and analyzed using FT-IR, FESEM, XRD, EDS and TGA. Results of FT-IR and FESEM indicated that highest amount of starch (30 %) was lead to fragile and less strength of PLA/Starch films. Results indicated that by addition of 5% maleic anhydride (MA) and ZnO NPs to the film formulation, adhesion between the two phases was significantly (p < 0.05) increased Furthermore, by increasing amount of ZnO NPs from 1 to 5% into the film formulation, amorphous structure of the film was significantly (p < 0.05) increased, and the films containing 1 and 5% ZnO NPs had crystal size of 34.14 and 28.4 nm, respectively. Results indicated that by increasing the amount of ZnO NPs in the film formulation from 1 to 5 %, its thermal resistance increased and weight loss decreased from 95.13 to 88.19 %, respectively. Furthermore, degradation percentage of the films decreased from 77.3 to 69.39%, respectively, after one month. Results indicated that film, based on PLA/Starch/MA/ ZnO NPs with ratio of 80/20/5/5 had carbon, oxygen and Zinc with weight percentage of 70.3, 25.1 and 4.6%, respectively.

Silver-iron oxide binary nanocomposites have attracted great attentions due to hybrid unique properties of silver (Ag) and iron oxide (Fe3O4) nanoparticles such as magnetic, optical and antimicrobial properties. Catalytic degradation of organic pollutants, electrochemical sensor and targeted antimicrobial agents are some potential applications of Ag/Fe3O4 nanocomposites. In this study, Ag/Fe3O4 nanocomposites were synthesized using starch as a stabilizer and linker between Ag and Fe3O4 nanoparticles. Their antibacterial and antibiofilm activities against E. coli, P. aeruginosa and S. aureus were evaluated and compared with Ag nanoparticles. The 15–20 nm Ag-nanoparticles adhered as single particles to the agglomerations of 2-10 nm Fe3O4 nanoparticles. MIC and MBEC of the nanocomposites, depending on cell types and producing conditions, were 2-14 ppm and 20-30 ppm, respectively. In the presence of nanocomposites at a half of MIC concentration, Lag phase of growth curve of E. coli and P. aeruginosa increased about 8h and 5h, respectively. Bare Fe3O4 nanoparticles have no significant effect on growth curve of gram positive and negative bacteria, while Ag/Fe3O4 nanocomposites showed more antibacterial activity against gram negative bacteria than Ag nanoparticles. Antibiofilm activity of Ag/Fe3O4 nanocomposites against P. aeruginosa and Methicillin-resistant S. aureus was significantly more than Ag nanoparticles. Unlike Ag nanoparticles, Ag/Fe3O4 nanocomposites at a MBEC concentration inhibited the increase of biofilm biomass. Amount of starch acted an important role on the nanocomposite antibacterial activity. Evaluation of bacterial death time exhibited that Ag nanoparticles killed tested gram- positive and negative species faster than Ag/Fe3O4 nanocomposites that may be attributed to involvement of Ag nanoparticles in the starch matrix and Fe3O4 agglomerations and subsequently, slow release of Ag ions.

Nowadays, the use of polymers is enhancing day by day. Through to not biodegradability in nature, they accumulate and contaminate the environment. One of the recent methods to solve this issue is using biodegradable polymers. Low-density polyethylene was chosen as a symbol and its film was prepared by an extruder in the lab. Starch, Oxo material, polylactic acid, and their mixture were used as biodegradable material and their influence on the physical and mechanical properties of low-density polyethylene were studied. Results indicated that using starch resulted in a significant decrease of mechanical properties for the low-density polyethylene, while Oxo material and polylactic acid caused a low change in the mechanical properties.

Today, polymer-based nanocomposites are used in medicine and drug delivery  Non-toxic and environmentally friendly nanocomposites are very important. In this study, new polyester-based nanocomposites were prepared using silver nanoparticles, starch, and poly(diphenylsulfonyl phthalate). The structure and morphology of the new nanocomposite were investigated using FT-IR, XRD, DLS, and FE- SEM. Swelling and drug release of the new nanocomposite were determined based on different amounts of silver nanoparticles. A polymeric alloy of starch and poly(diphenylsulfonyl phthalate) had the highest swelling. Drug loading and release in nanocomposites decreased approximately with the increasing amount of silver nanoparticles.

This project studies the absorption and removal of copper cations from aqueous solutions by starch-poly (acry-lamide-co-acrylic acid) / graphene oxide hydrogel bio-nanocomposites. The bio-nanocomposite hydrogel was obtained from a radical polymerization of the starch biopolymer with vinyl acrylamide (Am) and acrylic acid (AA) monomers with N,N-methylenebisacrylamide (MBA) in the presence of graphene oxide nanosheets (GO). The bio-nanocomposites were investigated by XRD, FT-IR, FE-SEM, TEM and TGA techniques. The effect of pH on adsorption, effects of time on adsorption, the initial concentration of copper ions and effect of temperature on the adsorption process on copper ions were investigated. The results which obtained from the experiments on the removal and absorption of copper ions were shown the maximum adsorption at pH =5 / 5, the adsorption increased by increasing the time, the equilibrium adsorption process flowed by Langmuir isotherm model and according to thermodynamic parameters, the adsorption of Cu2+ on bio-nanocomposite hydrogels occurred endothermic process and spontaneously, respectively. Also, the amount of adsorption increases proportionally to the amount of GO. Additionally, because of the enthalpy of absorption between 20-80 (KJ / mol), as a result, the process of removal is an electrostatic process

In this study, the nanocomposite films composed of starch/gelatin/nano clay were fabricated and their physiomechanical properties were investigated. The experimental design was done via the RSM method with Design Expert 7.0 software. The gelatin/starch weight ratio and the nanoclay weight percent were selected as independent variables and the tensile strength, Young modulus, elongation at break, and contact angles as dependent ones. The mathematical equations that identify the relationship between the dependent and independent variables were obtained. The results demonstrated that the tensile strength and modulus and the hydrophobicity of the surfacewere increased as nanoclay increased and the portion of gelatin decreased while the elongation at break showed reverse behavior. In the following, the optimization was done and the optimized values for gelatin/starch and nanoclay weight, percent were introduced to have the maximum tensile strength and minimum hydrophilicity. The optimum nanocomposites were fabricated and analyzed via FT-IR, SEM, XRD, and biodegradability tests. The obtained results showed that the nanoclay sheets were intercalated and proper dispersion of nanosheets in the polymeric matrix achieved. The nanocomposite films showed proper degradability and their weight was decreased by 40% after 6 weeks. Overall, this research work confirmed the proper potential of starch/gelatin/nanoclay nanocomposites as biodegradable food packaging films.

Starch-Montmorillonite/polyaniline nanocomposite as a biocompatible and cheap adsorbent was synthesized by chemical oxidative polymerization and was used for removal of Cr (VI) from aqueous solutions.The structure and morphology of as prepared nanocomposite were characterized utilizing Fourier Transform Infrared Spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM).To find out the crystalline structure and the distance between the montmorillonite layers, X-ray diffraction (XRD) analysis was conducted.Different parameters affecting the adsorption efficiency including pH, the initial concentration of Cr (VI) ions, contact time and adsorbent dosage were investigatedand optimized. The result of this study showed that like many adsorption processes, the mechanism of adsorption is influenced by pH. At solution pH=2 while the concentration of Cr is 10 mg/L after 15 min of exposure the removal efficiency is 89.22%.

In this study, the polyamide6/ thermoplastic starch (TPS) blends were prepared. Firstly, the starch became thermoplastic and was chemically modified using glycerol and maleic anhydride, under different conditions. After the preparation of maleated thermoplastic starch (MTPS), polyamide6/ MTPS (or TPS) blends were produced considering three variables; and the effects of various variables were investigated on their bio-degradability. In both steps, the experimental design method of Response Surface Methodology (RSM) was used. In the first step, the effects of Maleic Anhydride (MA) amount, time and temperature of the reaction were evaluated on the “degree of MAgrafted on the starch”. With increasing MA content, the processing time and temperature, higher MA grafting was achieved. While at a higher temperature and longer time, it was constant or slightly decreased. The highest grafting of MA was obtained at 140 ºC, 10 min and 4-6 % MA. In the second step, the influences of polyamide6/starch ratio, degree of MA grafting and degradation time were studied on the bio-degradability of the blends in the active sludge, in 90 days. Samples having TPS, showed some weight losses (or degradation) comparing to the purepolyamide6 which had no degradation. The amount of bio-degradation increased clearly with increasing MA grafted on the starch and MTPS amount. A blend containing 30 % MTPS, reached 45 % weight loss after 75 days. Using RSM, the equations of “degree of MA grafting” and “bio-degradation” versus variables, were obtained with suitable accuracy and low error. Besides, the interactions between the parameters were discussed considering 3D plots and the coefficients of the equations. The predicted results from the equations had a good fitting with the experimental data.