Density Gradients, Cellular Structure and Thermal Conductivity of High-Density Polyethylene Foams by Different Amounts of Chemical Blowing Agent

Lobos, Juan; Thirumuruganandham, Saravana Prakash; Rodríguez‐Pérez, Miguel Ángel

doi:10.3390/polym14194082

Cited by 7 publications

(3 citation statements)

References 26 publications

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“…Hence, the choice of blowing agent is particularly important [ 17 ]. Compared with physical blowing agents, chemical blowing agents have obvious advantages in compressive strength [ 18 ], environmental performance [ 17 ], thermal insulation effect [ 19 ], bonding performance [ 20 ], and bubble structure [ 21 ]. Mohamad Saed Hussein et al [ 22 ] discussed the effect of sodium bicarbonate as a blowing agent in epoxy resin.…”

Section: Introductionmentioning

confidence: 99%

Effect of Secondary Foaming on the Structural Properties of Polyurethane Polishing Pad

Chen,

Jiang,

Zhu

et al. 2024

Materials

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Polyurethane polishing pads are important in chemical mechanical polishing (CMP). Thus, understanding how to decrease the density but increase the porosity is a crucial aspect of improving the efficiency of a polyurethane polishing pad. According to the principle of gas generation by thermal decomposition of sodium bicarbonate and ammonium bicarbonate, polyurethane polishing pad was prepared by a secondary foaming method. The influence of adding such an inorganic foaming agent as an auxiliary foaming agent on the structure, physical properties, and mechanical properties of polyurethane polishing pads was discussed. The results showed that compared with the polyurethane polishing pad without an inorganic foaming agent, the open-pore structure increased, the density decreased, and the porosity and water absorption increased significantly. The highest porosity and material removal rate (MRR) with sodium bicarbonate added was 3.3% higher than those without sodium bicarbonate and 33.8% higher than those without sodium bicarbonate. In addition, the highest porosity and MRR with ammonium bicarbonate were 7.2% higher and 47.8% higher than those without ammonium bicarbonate. Therefore, it was finally concluded that the optimum amount of sodium bicarbonate to be added was 3 wt%, and the optimum amount of ammonium bicarbonate to be added was 1 wt%.

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Section: Introductionmentioning

confidence: 99%

Effect of Secondary Foaming on the Structural Properties of Polyurethane Polishing Pad

Chen,

Jiang,

Zhu

et al. 2024

Materials

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“…Among various molecular architectures, low-density PE is recognized for its broader foaming window compared to linear low-density PE and high-density PE. 28 Our study delved into foam extrusion using a blend of commercially accessible PEs (low-density PE and linear low-density PE) to achieve foamed beads amenable to molding at low steam pressure. This was executed using a commercially available extrusion setup.…”

Section: Introductionmentioning

confidence: 99%

Expanded beads of polyethylene moldable at low steam pressure

Tammaro,

Strasser

2024

Journal of Cellular Plastics

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In this study, we explored an innovative approach to extrude expanded polyethylene (ePE) bead foam by utilizing a blend of two types of polyethylene, specifically low-density and linear low-density polyethylene. The intention behind this mixture was to enhance the molding process’s flexibility during steam chest molding. The outcomes of our investigation reveal the adaptability of the devised method and formulation, enabling the production of a broad spectrum of foam densities ranging from 20 to 100 kg/m³. Additionally, we achieved successful molding at remarkably low steam pressures, below 0.6 bar. Our research focuses on the strategic adjustment of processing parameters, including temperature and pressure, along with optimized die geometry for the extrusion foam process. To comprehensively evaluate the foamed molded components, we conducted a comprehensive mechanical and optical analysis. The findings underscore the flexibility and cost-effectiveness of ePE produced through foam extrusion. This method emerges as a promising alternative to expandable polystyrene, especially in applications requiring flexible materials and convenient recyclability without contributing to microplastic pollution in the environment.

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“…Chemical foaming agents are generally solids (powders) generating gases once they reach their thermal decomposition temperature [ 23 ]. Azodicarbonamide (ADC), with a decomposition temperature of around 210 °C (pure ADC), is one of the most famous and versatile chemical foaming agents [ 24 ]. The main reason is due to the possibility of controlling its decomposition temperature using activators (zinc oxide (ZnO) and zinc stearate (ZnSt)) combined with high gas yield efficiency (231 cm 3 of gas per gram) [ 25 , 26 ].…”

Section: Introductionmentioning

confidence: 99%

Experimental and Finite Element Simulation of Polyolefin Elastomer Foams Using Real 3D Structures: Effect of Foaming Agent Content

Rostami‐Tapeh‐Esmaeil

Heydari

Vahidifar

et al. 2022

Polymers

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In this study, polyolefin elastomer (POE) foams were prepared without any curing agent using a single-step foaming technique. The effect of azodicarbonamide (ADC) content as a chemical foaming agent on the foams’ morphology and mechanical properties was studied using scanning electron microscopy (SEM), mechanical properties (tension and compression) and hardness. The results showed that increasing the ADC content from 2 to 3, 4 and 5 phr (parts per hundred rubber) decreased the foam density from 0.75 to 0.71, 0.65 and 0.61 g/cm3, respectively. The morphological analysis revealed that increasing the ADC content from 2 to 4 phr produced smaller cell sizes from 153 to 109 µm (29% lower), but a higher cell density from 103 to 591 cells/mm3 (470% higher). However, using 5 phr of ADC led to a larger cell size (148 µm) and lower cell density (483 cells/mm3) due to cell coalescence. The tensile modulus, strength at break, elongation and hardness properties continuously decreased by 28%, 21%, 16% and 14%, respectively, with increasing ADC content (2 to 5 phr). On the other hand, the compressive properties, including elastic modulus and compressive strength, increased by 20% and 64%, respectively, with increasing ADC content (2 to 5 phr). The tensile and compression tests revealed that the former is more dependent on foam density (foaming ratio), while the latter is mainly controlled by the cellular structure (cell size, cell density and internal gas pressure). In addition, 2D SEM images were used to simulate the foams’ real 3D structure, which was used in finite element methods (FEM) to simulate the stress–strain behavior of the samples at two levels: micro-scale and macro-scale. Finally, the FEM results were compared to the experimental data. Based on the information obtained, a good agreement between the macro-scale stress–strain behavior generated by the FEM simulations and experimental data was obtained. While the FEM results showed that the sample with 3 phr of ADC had the lowest micro-scale stress, the sample with 5 phr had the highest micro-scale stress due to smaller and larger cell sizes, respectively.

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Density Gradients, Cellular Structure and Thermal Conductivity of High-Density Polyethylene Foams by Different Amounts of Chemical Blowing Agent

Cited by 7 publications

References 26 publications

Effect of Secondary Foaming on the Structural Properties of Polyurethane Polishing Pad

Effect of Secondary Foaming on the Structural Properties of Polyurethane Polishing Pad

Expanded beads of polyethylene moldable at low steam pressure

Experimental and Finite Element Simulation of Polyolefin Elastomer Foams Using Real 3D Structures: Effect of Foaming Agent Content

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