Hesam Omrani Fard; Mohammad Hossein Abaspour fard; Mehdi Khojastehpour; Ali Dashti
Abstract
Introduction: One of the new methods for improving the mechanical properties of bioplastics is the production of blending based bioplastics. Recent studies show that proteins, in combination with starch, form a strong network of hydrogen bonds and intermolecular interactions that resulted stable 3-D ...
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Introduction: One of the new methods for improving the mechanical properties of bioplastics is the production of blending based bioplastics. Recent studies show that proteins, in combination with starch, form a strong network of hydrogen bonds and intermolecular interactions that resulted stable 3-D materials. The big problem in the commercialization of blending based bioplastics is the lack of industrial machinery for the continuous production of bioplastics with the direct use of biopolymers. Industrial production of bioplastics is accompanied by increasing heat along with applying the pressure. It is necessary to know the kinetics of thermal degradation of bioplastics to study thermal behavior at different temperatures in order to design bioplastics processing devices and molding machines, software modeling of processes, mass and energy equilibrium, and optimizing energy consumption in the production process along with improving the thermal properties of the bioplastics.
Materials and methods: In this study, the dynamics thermal decomposition of bioplastics prepared from a mixture of potato whole flour-gelatin and glycerol with a control sample consisting of potato whole flour and glycerol was investigated and compared. The gelatin was extracted from chicken feet using chemical methods. In this research, two isoconversional models including Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) models were considered. Using each of these models, thermal decomposition kinetic parameters were calculated for bioplastic samples.
Result and discussion: The results showed that the maximum activation energy of the mixed bioplastics determined 162 and 150 kJ/mol by FWO method at the conversion ratio of 0.9 and 0.5 respectively, while it was 217 kJ/mol at the ratio of 0.6 for control bioplastics. The amounts of kinetic parameters calculated in this study, were able to determine the thermal behavior at different temperatures and the thermal decomposition process. Also, it can help to redesign and optimize the methods of molding and shaping of potato-gelatin based bioplastics by the use of existing machinery in the industry.
Adieh Anvar; Behzad Nasehi; Mohammad Noshad; Hassan Barzegar
Abstract
In this study, microwave drying conditions of quince pomace optimized with respect to quality attributes (moisture content, color change and consumer acceptance). Response surface methodology (RSM) technique was used to develop models to respond to the microwave power (100, 2000, 300 W), and microwave ...
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In this study, microwave drying conditions of quince pomace optimized with respect to quality attributes (moisture content, color change and consumer acceptance). Response surface methodology (RSM) technique was used to develop models to respond to the microwave power (100, 2000, 300 W), and microwave time (5, 10, 15 min). The models obtained from the responses were adequate and acceptable because the coefficient of determination R2 of the models was relatively high. Microwave power of 200W and microwave time of 8 minutes were concluded as the optimum conditions prior to air-drying at 50°C. To describe the drying process, the experimental data for moisture loss was converted to moisture ratios. The effective moisture diffusivity increased with increase in microwave power and its values varied from 1.83-4.87×10-9 m2/s. Using an exponential expression based on Arrhenius equation the activation energy and was found to be 16.41 W/mm.
Ladan Rahimi; Babak Ghanbarzadeh; Jalal Dehghan nia
Abstract
Introduction:Polyethylene terphthalate (PET) is one of the materials that are widely used for packaging of beverages and edible oils. In this study, the migration of di(2- ethylhexyl) phthalate (DEHP), dimethyl phthalate (DMP), diethyl phthalate (DEP), di-iso-butylphthalate (DIBP) and di-n-butylphthalate ...
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Introduction:Polyethylene terphthalate (PET) is one of the materials that are widely used for packaging of beverages and edible oils. In this study, the migration of di(2- ethylhexyl) phthalate (DEHP), dimethyl phthalate (DMP), diethyl phthalate (DEP), di-iso-butylphthalate (DIBP) and di-n-butylphthalate (DBP) from PET bottles into the lemon juice was investigated. Material and methods:According to European Commission regulations, 3% acetic acid (w/v) was chosen as simulant. The acetic acid samples were stored at 5, 25, and 40°C for three months and analyzed periodically by gas chromatography. Results and discussion: It was concluded that the storage temperature and time had a large effect on the migration of phthalet ester. The concentrations of migrating substance were more than its specific migration limit. The release kinetics of phthalet ester from PET bottle was described using Fick’s second law of diffusion coefficient, and crank model. The diffusion coefficients (D) determined for DEHP have most migration than other, were 0.084, 0.109, and 0.159 ×10-9 cm2/s at 5, 25, and 40°C, respectively. The diffusion coefficients (D) determined for DBP have most migration than other, were 0.084, 0.105, and 0.138 ×10-9 cm2/s at 5, 25, and 40°C, respectively. The diffusion coefficients (D) determined for DIBP have most migration than other, were 0.084, 0.177, and 0.125 ×10-9 cm2/s at 25, and 40°C, respectively. The temperature dependence of D, Arrhenius equation giving values of activation energy (Ea) for DIBP, DBP and DEHP are 2.82, 2.06 and 1.302 J mol-1 respectively.
Farideh Tabatabaei Yazdi; Mohebbat Mohebbi; Seyed Ali Mortazavi; Arash Ghaitaranpour; Behrooz Alizadeh Behbahani
Abstract
The effects of a couple of factors (cooking period of wheat: 0, 1 and 3.5 h and temperature of drying 70, 80 and 90 ْC) on drying behavior of Tarkhineh during hot-air drying has been investigated. Tarkhineh pill samples with 8 cm diameter and 11 mm thickness were dried to 0.64(d.b). Results showed that ...
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The effects of a couple of factors (cooking period of wheat: 0, 1 and 3.5 h and temperature of drying 70, 80 and 90 ْC) on drying behavior of Tarkhineh during hot-air drying has been investigated. Tarkhineh pill samples with 8 cm diameter and 11 mm thickness were dried to 0.64(d.b). Results showed that cooking of wheat led to higher water absorption of Tarkhineh dough, while increased drying rate. On the other hand, increasing drying temperature resulted in higher drying rate of samples. The effects of temperature on drying rate was pronounced in raw samples compared to cooked ones, which could be attributed to the cracking in the cooked samples during drying . Drying kinetics of Tarkhineh in raw samples unlike cooked samples presented a falling rate period followed by a constant rate period. The effective moisture diffusion coefficient of Tarkhineh varied between 1.611E-10 & 7.822E-10 (m2/s)) for the given temperature range) and corresponding activation energy was between 37.928 and 17.941(kJ/mol) respectively.
