Production of polymeric foams by extrusion method has found a special important place in plastics processing in recent years. Today the most important polymeric foams which are made by this method are polystyrene and polyethylene foams. Polyethylene because of its low water absorption, easy processability, electrical and weather resistance and ability to produce foams with different densities is specifically important. In this paper, low-density polyethylene (LDPE) foam extrusion process by chemical blowing agent with a die and calibrator design is discussed. The effect of die angle and foam formulation on the expansion ratio and foam morphology is studied. The results show that LDPE foams can be produced in normal polyolefin extruders by changing the die design.

Foaming agents, whether physical or chemical, are substances that reduce the density of polymer products, and they are extensively utilized in the polymer industry. This paper presents a novel method for synthesizing Azodicarbonamide (ADCA), a foaming agent with broad applications across various chemical sectors, including polymer and plastic industries. The process begins with the synthesis of hydrAzodicarbonamide (biurea) through the reaction of urea and hydrazine. Subsequently, Azodicarbonamide is produced via the electrochemical (anodic) oxidation of biurea in the presence of potassium bromide as a catalyst. The resulting compounds were characterized using FTIR and UV-Vis spectroscopies. In the FTIR spectroscopy of ADCA, the -NH peak of biurea at 3300 cm⁻¹ is no longer observed. Meanwhile, in the UV-Vis spectroscopy of ADCA, a peak is detected at λmax = 424 nm. These findings indicate the complete conversion of biurea to ADCA.

Given the significance of bread, it is important to preserve its quality and curb its losses. Nowadays, there are studies focusing on introduction and use of different types of improvers that affect the qualitative properties of baked breads with the outcome of higher quality, longer shelf life, and delay the staling. Ascorbic acid and Azodicarbonamide are oxidative improvers that can enhance dough proofing, density, and the texture of the final product. The objective of this study was to analyze the effect of Lactic acid, Ascorbic acid and Azodicarbonamide on the qualitative properties of Sangak bread. Sangak ingredients (flour, salt and sourdough) and improvers (Lactic acid, Ascorbic acid and Azodicarbonamide) in two levels (0. 25 and 0. 5% of flour weight) were prepared and weighed. Data were analyzed using a completely randomized design with three replications. Means were compared through Duncan’ s multiple range test at a significance level of α ≤ 0. 05 in SPSS, and Excel 2010 was used for plotting charts and diagrams. The results showed that these improvers increased moisture content, ash, acidity, L* color index, and reduced protein content, fat, pH, a* and b* color indices, and fiber content remained unchanged in treated samples as compared to the control samples. The study findings revealed that Azodicarbonamide and Ascorbic acid were capable of improving and modifying the structure of the bread core, and can enhance bread quality and improvers.

Nowadays, there are studies focusing on introduction and use of different types of improvers that affect the qualitative properties of baked goods with the outcome being higher quality, longer shelf life, and delayed staling of breads. The objective of this study was to analyze the effect of lactic acid, ascorbic acid and Azodicarbonamide on some of the qualitative and sensory properties of Sangak bread. Sangak ingredients (flour, salt and sourdough) and improvers (lactic acid, ascorbic acid and Azodicarbonamide) in Concentration of (zero, 0.25 and 0.5% of flour weight) were prepared and weighed. Data were analyzed using a completely randomized design with three replications. Means were compared through Duncan’s multiple range tests at a significance level of α≤0.05. The results showed that these improvers increased sensory properties (including flavor, color, aroma, and texture), energy, correlation and homogeneity, and reduced staling compared to the control samples. The study revealed that Azodicarbonamide and ascorbic acid were capable of improving and modifying the structure of the bread core, and can enhance bread quality and improvers.

The influence of reinforcing fibers (old corrugated container fibers called OCC) and addition of foaming agents (Azodicarbinamide and sodium bicarbonate) on density, strength properties and dimensional stability of OCC fiber/polypropylene composite were investigated. Conten of reinforcing fibers constant at 20% and the content of either foaming agent varied as 3, 5 and 7%. Strength properties including MOR, MOE, maximum tensile strength and modulus as well as izod impact strength were measured. Water absorption after 2 and 24 hours soaking in distilled water at 23±2 oC were measured. Foaming agent decomposition caused some chemical residues in composite and the diffusion and penetration of polymer into the fibers structure led to increase in the density from 839.2 kg/m3 for pure polypropylene to 919.2-947.9kg/m3 for the composite, MOR and MOE also increased by the addition of foaming agent and the reinforcing fiber. The effect of 5 or 7% sodium bicarbonate was statistically significant and it improved the properties of the composite. Similar results were obtained for tensile strength and the modulus.Reinforcing fibers and foaming agent caused higher impact strength of the composite. Water absorption of the composites was higher than pure polypropylene.

This study aimed to evaluate the influence of type and content of chemical foaming agent on the dynamic mechanical properties of high density polyethylene-flax fiber composites. Composites were prepared via melt mixing in an internal mixer, and then foamed using single-stage batch foaming method. Two types of chemical foaming agents including Azodicarbonamide (ADC) and sodium bicarbonate (SB) were considered at three levels of 0, 2 and 4 per hundred resins (phr). The amount of flax fiber and coupling agent for all formulations was fixed at 60% and 2 phr, respectively. Static mechanical tests including flexural and tensile were performed on samples. The dynamic mechanical properties such as storage modulus, loss modulus and damping factor of composites were investigated. Morphology of the samples was also evaluated by scanning electron microscopy (SEM). Results indicate that the chemical foaming agent substantially increased cell size and reduced cell density and mechanical strength of composites. Moreover, the lowest mechanical strength was observed in foamed composites with SB. SEM confirmed that the type and content of chemical foaming agent had significant influence on density reduction of foamed composites. Finally, by an increase in the chemical foaming agent content, the storage modulus and loss modulus of samples decreased. However, by adding the chemical foaming agent to the composites, the damping factor increased. Foamed composites prepared with ADC exhibited inferior storage modulus compared to the SB.

In this research, closed-cell natural rubber foams were produced using a single-step compression molding. The effect of carbon black content on morphology, physical and mechanical properties of the foams were examined. Results showed that in this methodology, the foam density was independent of reinforcement percentage, which is a unique characteristic of single-step foams that contrasts with other previous observations. The study of curing behavior of foam compounds showed that the carbon black increasing from 0 to 30 phr increased the crosslink density (CLD) from 6. 5 to 8. 3*10-5 mol/cm3, the cure rate from 16. 1 to 23. 2 (%/min) and the ultimate torque from 5. 8 to 10. 4 Nm, while, reduced curing time from 9. 2 to 5. 8 min. The scanning electron microscope (SEM) results showed that the reinforcement acted as a nucleation agent increasing the cell density from 8 N/cm3 to 140 N/ cm3 and reducing the cell size from 579μ m to 255μ m. The increase of reinforcing content in the produced foams reduced the cells size and enhanced the properties of the rubber matrix. Accordingly, the modulus and hardness of the foams were increased by 0. 8MPa and 40 shore A, respectively. Results of sound absorption and reflection showed that the rubber foam reflects the sound waves more than 90% and absorbs waves about 10%.

In this study, feasibility of foaming wood plastic composites using injection molding process was investigated. The effect of lignocellulosic raw material (Poplar saw dust and soybean straw flour) on the properties of composites was examined. Wood plastic composite boards with 3.2 mm thickness, 105 mm width and 105 mm length were prepared using high density polyethylene granules. The foaming agent (Azodicarbonamide) at 2 wt % was also used. The scanning electron microscope micrographs confirmed that foaming process has been successfully carried out. The Results showed that all mechanical properties (except the impact strength) decreased while water absorption increased as the microcellular foaming method was used. Adding soybean straw flour to the foam structure led to the decrease in flexural strength, flexural modulus of elasticity and tensile strength. Water absorption and thickness swelling were negatively affected with the addition of soybean straw flour.

Background and Aim: In recent years, has been increased production volume of polystyrene foams. These foams are applicable in food and packaging industries. Growing environmental concerns have created a need to develop biodegradable materials. Starch is a widely available, renewable, low cost, biodegradable and thermoplast (TPS). For this reason, starch generates a great interest at it is considered as promising alternative to synthetic polymers (as polystyrene). But poor mechanical property is a limited parameter to use this polymer. One of the important ways to reduce this limitation, is the improvement of the thermal and mechanical properties using of nanofiber cellulose as reinforcement of foam. But NFC gel is aqueous and it forms irreversible aggregates when dried. High moisture creates big cells in foaming and effect on foam properties. This subject limit using of NFC (nanofiber cellulose) to prepare polymeric composites. The aim of current research is using NFC (nanofibercellulose) to prepare NFC/TPS nanobiocomposite foam by extrusion mixing for better dispersion of NFC in matrix polymer and investigation on thermal and mechanical properties of foam. Materials and Methods: Granules powder of corn starch, glycerol, NFC gel, and Azodicarbonamide have been used to make NFC-TPS nanobiocomposite foam. Glycerol (30 wt %) as plasticizer. NFC (0. 5, 1, 1. 5 wt %) as reinforcing agent and Azodicarbonamide (0. 2 wt %) as blowing agent (BA) were used. Raw materials were mixed in a co-rotating two screw extruder. Then TPS/NFC/ BA granule was prepared. Then by using of these granules, nanobiocomposites foams were prepared under hot press (temperature higher than degradation temp of BA). The morphology of the samples studied by FE-SEM. The tests thermogravimetry (TGA), differential scanning calorymetry (DSC), dynamic-mechanical-thermal analysis (DMTA) were done on TPS/NFC nanobiocomposite foams for determination of the thermal and mechanical properties. Findings: FE-SEM images showed, that TPS/ NFC nanobiocomposite foam has higher and smaller pores in comparison TPS foam. This is due to nucleation effect of NFC. TGA showed thermal stability of TPS/NFC nanobiocomposite foam with increasing of NFC. DSC showed transition glass temperature has been increased with increasing of NFC content. The DMTA showed storage modulus and loss modulus increased with increasing of NFC content but tan delta decreased. The reason of this result is formation microcellular foam and reinforcement of the cell wall of foam by NFC. Conclusion: The results of research showed NFC improved thermal and mechanical properties of TPS/NFC foam. TPS/NFC foam had more unique and smaller in comparison of TPS foam.