شیرین شکوهی

Melt free-radical grafting reactions between ethylene-propylene-diene terpolymer (EPDM) and glycidyl methacrylate (GMA) were inves tigated in the presence and absence of s tyrene (S t) comonomer in a batch mixer (170°C, 60rpm). Effect of dicumyl peroxide (DCP) initiator, GMA and s tyrene concentrations were s tudied on the grafted EPDM characteris tics. Titration results indicated an increase in the graft degree (GD) and gel content (GC) values with increasing DCP concentration. Whereas, introduction of S t led to 132 % increase in GD and 39 % decrease in GC which might be ascribed to its effect on res tricting crosslinking side-reaction. FTIR spectrums confirmed that GMA has been successfully grafted onto EPDM.

In this research, quinoa starch samples were evaluated in 9 treatments with different proportions of adipic acid and acetic anhydride mixture (ratio 1 to 30), along with a control sample in terms of physicochemical and functional characteristics and determining the optimal conditions for chemical modification. The mentioned treatments were designed by 3 independent variables affecting chemical modification, including chemical modifier concentration (2%, 4% and 6%), suspension pH (8, 8.5 and 9) and reaction time (60, 90, 120 minutes) by Taguchi method. became The swelling power and water absorption capacity of sample T2 (modifier concentration 2%, suspension pH 9 and reaction time 120 minutes) significantly increased compared to the control sample, which is a sign of the formation of crosslinks along with the formation of stable three-dimensional gel networks. Spectroscopy results showed that except for T2 sample, the rest of the samples had a slight tendency to retrogradation, which was a sign of the high stability of the said sample during the retention period to syneresis (p<0.05). Acetylation significantly improved the solubility characteristics compared to the control sample due to the better dispersion of starch in the aqueous medium. With the increase in the modifier concentration, the stability of the samples against the freeze-thaw cycle decreased significantly (p<0.05). The investigated parameters in measuring the thermal characteristics of modified quinoa starch were evaluated with a significant difference more than the control sample. The apparent viscosity of the T2 sample at the shear speed of 20, 50 and 100 rpm increased significantly compared to the control sample, but the other samples showed a lower viscosity. Also, using Taguchi analysis, the optimal treatment of modified quinoa starch with 2% modifier concentration, suspension pH 9 and reaction time 120 minutes was determined.

This study aimed to investigate the effect of chemical modification with adipic acid/acetic anhydride mixture (1:30) on the physicochemical and functional properties of amaranth starch and also to determine the optimal conditions for amaranth starch chemical modification with the mentioned mixture. Amaranth starch was isolated and then modified under nine different treatments designed by the Taguchi method using three main chemical modification factors, including the mixture of adipic acid /acetic anhydride concentration (4%, 6%, and 8%), reaction time (60, 90 and 120 min) and suspension pH (8, 8.5 and 9). Swelling power, solubility, color, paste clarity, thermal properties, freeze-thaw stability, and apparent viscosity of starch samples were investigated. Modification optimal conditions were determined using Taguchi analysis and the related percentage deviation (RPD) method. The result obtained from this study showed that the chemical modification significantly changed the physicochemical and functional properties of amaranth starch. Adipic acid/ acetic anhydride mixture improved the swelling power, solubility, viscosity, and paste clarity of modified starch than native. Modified starch powders showed more lightness, less yellowness, and redness in color. Chemical modification reduced gelatinization temperatures, gelatinization enthalpy, and freeze-thaw stability. However, since other food components such as sugars, salt, hydrocolloids, etc., influence the freeze-thaw stability of starch, the possibility of modified amaranth starch utilization as a stabilizer, thickener, or fat replacer in food products with the mentioned mixture needs additional research is required to be conducted. The optimum modification conditions were a concentration of 6%, a reaction time of 120 minutes, and a pH of 9.

In recent years, legumes have been highly considered as a good source of protein, fibers, minerals and other bioactive compounds in order to develop novel foods with improved nutritional properties. There is some evidence that legume consumption reduces the risk of diabetes, cardiovascular disease and some cancers. Vicia faba has about twice protein content as cereals and can be a good alternative to meat and protein-rich ingredients. It should also be noted that the amount of insoluble fiber is higher than soluble fibers in legume. Vicia faba belongs to the Fabaceae family .Vicia faba contains high protein (21-41% dry content of the bean), carbohydrates (51-68% dry content of the bean), fiber (5-5.8%), B-vitamins and minerals. Recently, the protein function of Vicia faba, especially its protein isolate, has been studied on a laboratory scale for use in food products, due to its good ability in hydration, solubility, emulsification, viscosity, and foam and gel formation. Research has also shown that the protein in Vicia faba has better ability to emulsify water and oil and foaming capacity and foam stability compared to bean and pea flour. The structural and functional properties of the protein isolates and concentrates of legumes such as Vicia faba are strongly influenced by their preparation, extraction and drying methods. One of the ways to improve extraction and optimization of protein properties can be ultrasound and an enzymatic controlled hydrolysis. Due to the importance of dietary fiber, various methods have been developed for their decomposition, many of which are very precise and special, some of which have high-purity enzymes and selectively release oligosaccharides and polysaccharides containing dietary fiber. In this  study, the possibility of using ultrasound and limited enzymatic hydrolysis in order to produce value added product and increase the extraction efficiency and improve the functional properties of protein and fiber of Vicia faba, were evaluated.

In this study, ultrasound and enzymatic hydrolysis were used to optimize extraction and modify physicochemical properties of protein and fiber of VaciaFaba. The proteins were affected by ultrasound at 200, 300 and 400 W for 15, 25 and 35 minutes, and the Alcalase enzyme 2.4 LFG at 0.15, 0.3 and 0.45% doses were extracted at 15, 25 and 35 minutes and the design of the treatments was done by Designer Express software. Solubility, oil absorption capacity, emulsification and zeta potential of protein samples were measured. Vicia faba fiber extraction under alkaline conditions was obtained from solutions of 0.0012, 0.012 and 0.12% sodium hydroxide until reaching pH 12, 11 and 10 and Termamy 2x enzyme was used for enzyme hydrolysis. Water retention capacity and rheological properties of Vicia Faba fiber samples were investigated.

The results showed that the use of ultrasound and enzymatic hydrolysis had a positive effect on solubility, oil absorption capacity and emulsion properties of the protein samples. Zeta potential was also negative for all treatments, which indicates that the Vicia faba protein treatment solution contains more negative amino acids than positive-loaded amino acids. Among the fiber samples of the ViciaFaba, a fiber sample with a pH of 10 had the highest water retention capacity and G-level than the other two samples, indicating a more solid and elastic quality. Also, in all fiber samples, increasing cutting speed reduced the viscosity and the samples showed a dilution action with cutting or pseudoplastic.

Nanocomposites samples based on unplasticized polyvinyl chloride (UPVC) containing polymethyl methacrylate (PMMA) as toughener, graphene nano-platelets (GNP) as reinforcement and di-octylphthalate as plasticizer were prepared with different composition ratios (i.e. 80/20 and 90/10 containing 0, 0.5, 1 and 2 phr GNP) using Haake internal mixer. Nanocomposite samples were analyzed using x-ray diffraction and scanning electron microscopy to investigate the mutual interactions between GNP and PMMA. Mechanical properties (Tensile modulus, elongation at break and impact resistance) of the prepared nanocomposites including tensile modulus, elongation at break and impact strength were also measured. Results showed that increasing nanographene platelets content increases tensile modulus where impact strength, tensile strength and elongation at break are decreased. At constant graphene contents, nanocomposites containing 20% PMMA show higher impact strength and tensile modulus. This was attributed to the higher mixing efficiency due to the interactions established between PMMA and GNP observed through FTIR and also higher miscibility of UPVC/PMMA pair besides the PMMA characteristics. Fracture surface of nanocomposites are significantly rough at the presence of nano-graphene which shows the torturous crack growth path.

Nanocomposites based on butadiene rubber (BR)، (0، 3، 5 and 7 phr) organoclay (Cloisite 15A) and (0، 10، 20، 30، 40 phr) powder coating wastes، i. e.، epoxypolyester hybrid (EPH) were prepared using a laboratory-scale internal mixer in order to study the effect of organoclay and EPH content on the mechanical and morphological properties of the nanocomposite samples. Cure characteristics of the prepared compounds including optimum cure time (t90) and scorch time (t5) depicted a decrease in both mentioned factors with increasing nanoclay content and EPH loading. Intercalation of elastomer chains into the silicate layers was determined by d-spacing values calculated according to the results of X-ray diffraction (XRD) patterns. X-ray diffraction (XRD) results reveal the intercalation of elastomer chains into the clay galleries. This phenomenon was also confirmed according to the scanning electron microscopy (SEM) micrographs and mechanical properties of the nanocomposite samples which were observed to be improved with addition of nanoclay and EPH content.

Nanocomposite samples based on elastomer blends of butyl rubber (IIR) and ethylene propylene diene monomer (EPDM) were prepared using a laboratory scale two-roll mill in order to study the effect of Cloisite 15A organoclay content (i.e., 1, 3, 5 and 7 wt%) on the mechanical and morphological properties of IIR/EPDM/Cloisite 15A nanocomposites compared to the unflled EPDM/IIR blends. Rheometer (RPA), X-ray diffraction (XRD) and scanning electron microscope (SEM) were utilized for relevant characterization of cure behavior and microstructural properties of the prepared samples. Cure characteristics of the prepared compounds including optimum cure time (t90) and scorch time (t5), depicted a decrease in these two parameters with increasing nanoclay content; where the cure time was prolonged with EPDM increasing content. In fact, nanoclay not only acts as a reinforcing agent in nanocomposites but also accelerates the cure process of IIR/EPDM elastomer compounds. Intercalation of elastomer chains into the organoclay silicate layers was determined by d-spacing values calculated according to the results of X-ray diffraction patterns. XRD results of all the nanocomposites samples prepared here showed a leftward shift towards lower diffraction angles in the organoclay characteristic peak, indicating an increase in the d-spacing values compared to the pure organoclay which emphasizes the intercalation of elastomer chains into the clay galleries. This phenomenon was also confrmed according to the direct observation of the cryogenically fracture surfaces of the samples by SEM micrographs depicting a combination of intercalated and exfoliated microstructures. However, there appeared incrementally slowed down rate in higher clay contents. With addition of nanoclay, mechanical properties of the nanocomposite samples including hardness, fatigue strength, tensile modulus and tensile strength were observed to be improved. Elongation-at-break and resilience of the nanocomposites were decreased as expected.