حامد عزیزی

School is one of the contributing environmental factors to the psychological development of adolescents. School is the most important place to promote health among children and adolescents. In this regard, those in charge of education, seek to improve the welfare of students by providing appropriate conditions in schools. The purpose of this study is to predict school well-being based on perceived affective support and Education Resilience Orientation. The statistical population of this research was made up of 821 high school female students of secondary grade in Baneh. Due to the covid-19 pandemic and the absence of students in school, school welfare questionnaires, perceived affective support and Education Resilience Orientation were provided to students as an internet link. After completing the questionnaire, their data were collected and entered into EXCEL and SPSS software for analysis. The results of school welfare skewness with perceived affective support and Education Resilience Orientation showed that the distributions of variables in this study were normal. The results showed that the values of Pearson correlation coefficient for school well-being with perceived affective support and Education Resilience Orientation at level of 1% had a significant positive relationship.

School is one of the contributing environmental factors to the psychological development of adolescents. School is the most important place to promote health among children and adolescents. In this regard, those in charge of education, seek to improve the welfare of students by providing appropriate conditions in schools. The purpose of this study is to predict school well-being based on educational optimism and education resilience orientation. The statistical population of this research was made up of 821 high school female students of secondary grade in Baneh. Due to the covid-19 pandemic and the absence of students in school, school welfare questionnaires, academic resilience (ARI) and educational optimism were provided to students as an internet link. After completing the questionnaire, their data were collected and entered into EXCEL and SPSS software for analysis. The results of school welfare skewness with academic resilience and educational optimism showed that the distributions of variables in this study were normal. The results showed that the values of Pearson correlation coefficient for school well-being with educational optimism at level of 1% had a negative significant relationship and for school well-being with educational resilience at level of 1% had a significant positive relationship.

Demand for the use of polymers in different industries with different properties is increasing. However, pure polymer does not have the ability to create a wide range of desired features. To solve this problem, various additives are used, many of which are minerals. The polar nature of these additives has made them impossible to use in non-polar polymers, such as polyolefins, due to the incompatibility and poor interface adhesion. Various methods are used to increase compatibility, one of which is the use of compatibilizers. Functionalized waxes are among the materials that researchers have studied over the years. The backbone of functional waxes is miscible with a polymer, and the functional groups on the wax surface can interact with the groups present on the additive surface. Therefore, their use improves the dispersion and distribution of additive particles in the polymer. Also, due to their low molecular weight, these waxes can penetrate the pores and capillaries on the additive surface and act as a successful co-compatibilizer. In this study, first, the methods of increasing compatibility and the cases used for this purpose are briefly reviewed. Then, the performance of functionalized waxes as a compatibilizer and co-compatibilizer and their effect on the physical, mechanical, and thermal properties of the polymer composites are investigated in details.

Having a reliable, low-cost, and always available energy production system has announced the energy storage systems as an important candidate. There are different methods to store renewable energies, which the storage of latent heat energy is more important one because of its ability to generate high energy storage density at constant temperature (phase change phase). Organic or inorganic compounds that are capable of absorbing and storing large amounts of heat energy are called phase-change materials. Due to the high efficiency and high capicity of phase-change materials in energy storage systems, the use of these materials in recent years has attracted many developed countries. The purpose of this paper is to review the various types of phase-change materials, the application systems and the other researches on these materials.

Hypothesis: Biodegradable polymer blends in comparison to petroleum-based polymers consume less energy in the production process, and do not produce environmental pollution due to their renewable sources. One of these biodegradable blends is polyolefin elastomer/starch (POE/S) blend. In this study, the effect of composition ratio of polyolefin elastomer/starch on properties such as mechanical, morphology, rheology and biodegradability properties of the blend were investigated. Because of non-polar microstructures of POE and polar starch, a polyolefin elastomer/maleic anhydride copolymer (POE-g-MAH) was used to improve their compatibility.
Blends of polyolefin elastomer and starch were prepared in presence of POE-g-MAH as synthetic compatibilizer with a Brabender internal mixer. The concentration of POE-g-MAH was fixed at 10 wt% and the content of starch in both binary and ternary blends was varied between 0 wt% and 55 wt%.
Findings: The results showed changes in the tensile, hardness, SEM micrographs, and void increasing after exposing the blends to fungi for three months at room temperature. To examine the compatibility of the blends, Fourier transform infrared spectroscopy (FTIR) was used. The observations of the scanning electron micrographs of polymer blends showed that by increasing the amount of starch from 15 to 55 wt%, the size of the dispersion phase increased; though it was reduced by adding 10 wt% of POE-g-MAH in the polymer blends. The rheology tests were carried out using rheometrics mechanical spectrometry (RMS) and the results indicated an increase in the complex viscosity, loss modulus and storage modulus after the addition of the compatibilizer into the blend. By adding starch to POE in the blend, the tensile strength and elongation-at-break decreased. The comparison between the blends with and without compatibilizer showed higher tensile strength and elongation-at-break for the blends with compatibilizer. The biodegradation experiments for the blend with 15 wt% of starch showed that the degradation of blend composition was negligible, but with higher starch content, the degradation rate increased and the blend with compatibilizer showed less degradation than the blend without compatibilizer.

The importance of maintenance and supply fresh fish instead of frozen due to the consumers interested in fresh fish is highly regarded. Titanium dioxide is a non-toxic nanoparticle that the American Food and Drug Administration approve its using at levels that are in contact with food. The antimicrobial and anti-fungal effects of this nanoparticle have been proven in a wide range of microorganisms (Saito et al, 1999).The use of titanium dioxide nanoparticles in polyethylene and polypropylene coatings has been investigated. The results showed that this nanoparticle, in addition to reducing the oxidation content of the package, could be effective in reducing silicone recovery of polyethylene and polypropylene in nature (Manangan et al, 2010). Rainbow trout is one of the most widely consumed breeding fish in Iran. Due to the high production and consumption of this fish, it is vital to take the necessary measures to maintain quality and increase its shelf-life. Therefore, this research was conducted to investigate the effect of titanium dioxide nanoparticle polyethylene packaging on quality and shelf-life of rainbow trout fillets during storage in a refrigerator.
Material and Chemical (Peroxide value (PV) )Pearson,1997(., Tiobarbioritic acid (TBA) (Egan et al., 1997(, total volatile basic-nitrogen (TVB-N) (Pearson, 1997), pH), microbial (Total viable, Total viable counts, psychrophilic counts, lactic acid bacteria and Enterobacteriaceae) and Sensory analysis of samples was calculated and determined. The results of ANOVA using SPSS 16 software analysis and comparison of data using Duncan's multiple range test was 0.05 Sensory evaluation and analysis of non-parametric Mann-Whitney U test was used to test.
Result and The process of microbial changes in the rainbow trout fillet was increased, except for the psychrophilic bacteria that were in the packaged nanocomposite treatment until the 4th day of the growing trend and then until the end of the period was reduced. Nanocomposites containing titanium dioxide containing nanoparticles prevent the growth of pseudomonas. (Bodaghi et al, 2013).The total amount of all chemical factors during the storage period showed an increasing trend in both treatments except for the factor observed in the packed sample. The results showed that in the control sample, the sensitivity rating on the day 8 was kept to a limit of less than 4, while in the sample packed with the nanocomposite until the 16th day, the points were less than the limit and the color score on day 12 Limiting receipts. Fat oxidation and microbial decomposition, and the production of esophagus combustion agents and fish tissue were changed. The antioxidant and antimicrobial effects of the packaged sample resulted in prolonging the shelf life and maintaining the quality of the fillets until the 16th day. Sensory, chemical and microbiological analysis results showed that the rainbow trout shelf life in nanocomposite packaging is suitable for 16-18 days.

Toxicities of water sources due to the discharge of industrial effluents is a worldwide environmental problem. Industrial wastewater often contains a considerable amount of heavy metal ions and organic pollutants, which would endanger public health and the environment.Cadmium Cd(II) is a toxic heavy metal, normally found in industrial wastewater, especially from metal plating industries, Cd–Ni batteries, phosphate fertilizer, mining, pigments, stabilizers, and alloys. Cd(II) adversely effects human health because of serious damage to the kidney, renal disturbances, and bones lesions. In this work, heavy metal ions were removed using biodegradable polymer based on chitosan and functionalized graphene with amine groups. Nanocomposite Samples containing 0.5, 1, 2, 5 wt.% of functionalized graphene were obtained via solution method. At first, graphene was oxidized with sulphuric and nitric acid then triethylenetetramine was grafted on the graphene surface. Functionalized graphene was characterized by Fourier Transform Infra-Red (FT-IR) spectroscopy, Thermal Gravimetric Analysis (TGA) and Scanning Electron Microscopy (SEM). Results showed functionalization of graphene was successfully accomplished. The morphology of nanocomposite was monitored by SEM. Adsorbing heavy metal ions (Cadmium) was investigated with Flame Atomic Absorption Spectrometry (FAAS) and results revealed that the nanocomposite samples have a higher potential for ion metals adsorption than that of neat chitosan. The adsorption of nano samples for cadmium was increased around 20% in comparing to neat chitosan. The effect of sorbent concentration, pH, mixing time and heavy metal ion concentration was studied on the adsorption behavior and it was found that the optimum adsorption occurs at pH=7, 50 ppm ion metal concentration, 2h contact time and 25 mg of sorbent.

The method by which a polymer structure develops during polymer processing has important effects on the quality of final product. Among the structural development methods, crystallization process is of the highest interest. In this study, isothermal crystallization behavior of poly(lactic acid) (PLA) and its nanocomposites with graphene was investigated under quiescent and shear conditions. Neat PLA and its noncomposites containing 0.5, 1, 2 and 3 wt% graphene were prepared via melt mixing method in an internal mixer. Structural analysis and crystallization behavior of the nanocomposites before and after applying shear stress were investigated by differential scanning calorimetric (DSC) analyses. The effect of shear rate, shear time and concentration of nano-graphene on the progress of crystallization process was studied at 135°C using rheometic method. The preshear rates of 0.1, 0.3, 0.5, 1.1 and 1.8 s-1 were applied at temperature of 200°C for 60 s. The increase of storage modulus indicated to the formation of crystalline structure. Results showed that by increasing nano-graphene content the storage modulus was rapidly reached its ultimate value and the induction time of crystallization was decreased. The crystallization process was enhanced by applying preshear stress, particularly in high concentration of nano-graphene platelets. Increasing the shear time to 300 and 600 s, the induction time was decreased. DSC analysis results showed that degree of crystallization increased after applying preshear stress.

The effect of modified starch on the properties of poly(styrene-ethylenepropylene- styrene) tri-block copolymer was studied. Chemical treatment of starch with maleic anhydride was accomplished in an internal mixer in the presence of glycerol. The reaction was confirmed using Fourier infrared spectroscopy (FTIR) and titration. The blend samples containing 10, 20, 30 and 50 wt% were obtained by melt blending and their mechanical, morphological and dynamic-mechanical properties were studied. Scanning electron microscopy (SEM) images displayed droplet-matrix morphology and with increases in modified starch up to 50 wt% some partial co-continuous morphology was also observed. With increase of modified starch in the compound, the size of dispersed phase increased. DMTA results revealed that the partial compatibility was obtained because of slight difference between glass transition temperatures of two phases in the presence of modified starch. The peak of modified starch shifted to higher values and the differences between the two peaks decreased, indicating partial compatibility. Mechanical properties including tensile, elongation-at-break and modulus were also determined and the results showed that the mechanical properties of the sample were higher than those of neat TPS because of the higher compatibility. Tensile strength was decreased with increase in modified starch content due to the absence of strong interfacial adhesion. Moduli of the samples were increased with increase in modified starch content due to higher stiffness of starch. Biodegradability of the samples was evaluated by weight loss percentage using compost test. A rapid degradation was observed in the first 45 days and with increase of the modified starch content the degree of degradation was increased.

In this article، the correlation between molecular microstructure and rheological behavior for three different grades of high density polyethylene with broad molecular weight distribution have been investigated. Structural parameters such as Mn، Mw، Mz، molecular weight distribution (MWD) and branching index were characterized by high temperature Gel Permeation Chromatography (GPC) test. GPC results showed that BL4 and EX3 have bigger weight average molecular weight and narrower molecular weight distribution، respectively. Furthermore،it was found from GPC results that all three HDPE has a broad MWD and EX3 has more short chain branches than two other samples. Rheological characterization was done in a Mechanical Compact Rheometer (MCR) in rotational and dynamic modes at both linear and nonlinear viscoelastic region. From rheological characterization the zero shear viscosity (η0)، relaxation time and relaxation time distribution، stress relaxation modulus and damping factor were obtained and by utilizing relaxation time spectrum function (h(τ))، molecular weight distribution was calculated for each sample and compared with GPC results. The relationship between zero shear viscosity with molecular weight and MWD at 180 ºC obtained. After calculating molecular weight distribution function and average molecular weights using different mixing parameters (β)، by choosing β=0. 73، a good correlation between molecular parameters obtained from rheological data with those of GPC results was obtained. After calculating stress relaxation modulus and consequently damping factor for each sample، comparing to Doi-Edwards model، it was found that the damping function type C is an appropriate damping function type for selected polyethylenes.

Crystallization behavior of nanocomposite based on semicrystalline polymers and graphene nanoplatelets (GNp) has been considered due to its critical effect on the performance of the final product. In this study، nanocomposite based on poly (lactic acid) /graphene nanoplatelets (PLA/GNp، 0. 5 and 1 wt %) was prepared via solution method using dimethylformamide as a solvent. PLA has the largest contribution in the current biopolymer research. To present time، it is well accepted that nanoparticles would be recognized as efficient heterogeneous nucleating agents for various semicrystalline polymers. To improve the dispersion of graphene in the matrix، functionalization using acid treatment and acylation reaction was accomplished. Characterization of functionalization reaction and grafting reaction between PLA and functionalized graphene (FGNp) was tracked by Fourier transform infrared spectroscopy، elemental analysis، and thermogravimetry analysis. Scanning electron microscopy results demonstrated that a relatively fine dispersion of FGNp is achieved in the PLLA matrix. Non-isothermal and isothermal crystallization behavior was studied using differential scanning calorimetry. The isothermal tests were conducted at test temperatures 130°C، 125°C، 120°C and 115°C. The results indicated that crystallization percentage for the samples containing FGNp nanoparticles were higher than those of pristine-containing samples. With increase of temperature in isothermal test onset time for crystallization decreased due to higher mobility of polymeric chains in the samples. It seems that the presence of functionalized nanoparticles facilitated formation of β format of crystals.

A new generation of shape-memory materials includes those that have found many applications in domestic life as well as in industry. The use of these materials lies in response to external stimuli such as temperature, light, electric or magnetic fields-aligned or changing the pH of a new technique in engineering. Physical properties of the materials, such as changes in shape, color and refractive index are dependent on the use of external stimuli. The materials with shape memory properties in their molecular structure can store their original structure. Materials that exhibit shape memory effect have the ability to change in shape and stay in shape retrieval of temporary and permanent forms towards external stimuli. The shape memory materials find specific applications as smart fibers, heat shrinkable pipes, packaging and medical applications such as self-adjust wires and stents to open the blood vessels. In this paper, an overview is given on the structure and properties of nanoparticle-containing shape memory polymeric materials towards external stimuli.

The growing interest in using natural fibers as reinforcing agents of polymer-based composites is mainly due to their advantages such as lower cost, lower density, ease of preparation, lower energy requirements for processing, biodegradability, wide availability and relative non-abrasiveness over traditional reinforcing fibers such as glass and carbon. In this study, wood-plastic composite (WPC) containing 40 wt % of wood was prepared using an intermeshing co-rotating twin screw extruder. The effect of wood particle size in three levels (100, 250, and 400 μm) was studied on the physicalmechanical properties of WPC such as: tensile properties, heat distortion temperature (HDT), melt flow index (MFI) and notched Izod impact resistance. In addition, the rheological behaviors were studied as function of wood particle size. The data showed an increase in the modulus and a decrease in the tensile strength with increase of wood particle size while there was no considerable change in the elongation-at-break. The results also showed that MFI decreased and impact resistance increased with decreases of wood particle size. HDT was independent from variation of wood particle size. Complex viscosity and storage modulus increased with decrease of wood particle size while Tan δ did not change with variation of particle size.