Liquid Silicone Rubber Foams Made with Water as Blowing Agent

Marl, Svenja; Rüppel, Annette; Hartung, Michael; Klier, Kevin; Giesen, Ralf-Urs; Heim, Hans-Peter

doi:10.1002/adem.202100382

Cited by 8 publications

(16 citation statements)

References 7 publications

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“…The third conclusion is the very homogeneous cell structure over the entire sample. Compared to other foaming methods, such as water foamed LSR samples in [ 13 ], the size of the pores at different positions is very similar. The homogeneous cell structure results from the nature of the microspheres.…”

Section: Discussionmentioning

confidence: 99%

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Liquid Silicone Rubber Foamed with Thermoplastic Expandable Microspheres

2022

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To reduce the material costs as well as the density of Liquid Silicone Rubber (LSR), LSR foams can be produced in an injection molding process. Expandable thermoplastic microspheres can be used as blowing agents. This publication deals with the analysis of the cell structure of these LSR foams. For this purpose, cylindrical disks are injection molded and examined for their cell structure as a function of different proportions of microspheres using a scanning electron spectroscope. In addition, the density of the samples is determined. It was found that a very homogeneous cell structure is produced in this process, that heat transport has a significant influence on the expansion of the microspheres, and that the formation of a filler network limits the expansion at higher proportions of blowing agent.

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Section: Discussionmentioning

confidence: 99%

“…With other blowing agents such as water (cf. [ 13 ]), multiple nucleation centers can grow together, resulting in very inhomogeneous cell structures. In the case of microspheres, on the other hand, the shells touch each other in the process, but the gas remains separated.…”

Section: Discussionmentioning

confidence: 99%

Liquid Silicone Rubber Foamed with Thermoplastic Expandable Microspheres

2022

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“…In the field of injection molding of LSR, it has been found that with water, an increase in the process temperatures results in a higher weight reduction and an increase in the Shore A hardness. In addition, the number of pores increases, but not the pore size [20].…”

Section: Introductionmentioning

confidence: 94%

“…Here, gases such as carbon dioxide and nitrogen or liquids such as water can be injected into the extrusion process [15]. In the case of water, the blowing agent can also be incorporated into the rubber mixture using a carrier substance such as silica, which means that additional foaming equipment is not required [20]. The alternative to chemical blowing agents is physical blowing agents.…”

Section: Introductionmentioning

confidence: 99%

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High Consistency Silicone Rubber Foams

Hofmann,

Giesen,

Heim

2024

Polymers

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Silicone elastomers are high-performance plastics. In the extrusion process, only high-consistency silicone rubbers were used. In order to reduce the cost and weight, silicone rubbers can be foamed during processing. In this study, high-consistency silicone rubber is processed with different physical and chemical blowing agents. The resulting reaction kinetics, as well as the mechanical and morphological properties, had been investigated and compared with each other. This showed that the chemical blowing agent significantly influenced the crosslinking reaction compared to the microspheres and the water/silica mixture tested, but it also achieved the lowest density compared to the physical blowing agents. When evaluating the foam morphology, it became clear that the largest number of pores was achieved with the microspheres and the largest pores when using the water/silica mixture. Furthermore, it has been shown that the different mechanisms of action of the blowing agents have a major influence on the mechanical properties, such as the micro shore hardness and the foam morphology.

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Improvement of the Cell Structure of Water‐Foamed Liquid Silicone Rubber

Marl,

Hartung,

Klier

et al. 2023

Adv Eng Mater

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This paper shows three different water‐based physical blowing agents for LSR in terms of physical, mechanical, and morphological properties depending on the manufacturing parameters and amounts of blowing agents. The compositions consist of common LSR added with pure water, water‐silicone oil emulsion, and aqueous silicone. The foaming process was initiated in an injection molding process. By sub volumetrically filling the mold, it was possible to foam the LSR during the injection molding process. This publication aims to compare different, water‐based blowing agents for LSR in the injection molding process. The results show, that for all foams porosities between 0.25 and 0.4 are possible. An analysis of the foam structure shows that the aqueous silicone produces a significantly more homogeneous structure than the other two blowing agents. In addition, the mechanical properties were analyzed. For this purpose, tensile tests were carried out and the Shore hardness was determined. The elasticity and mechanical properties decrease slightly. The specific tensile strength also shows a small decrease, although this may be due to either the gradient of the foam structure or chemical reactions between the blowing agents and the LSR.This article is protected by copyright. All rights reserved.

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Liquid Silicone Rubber Foams Made with Water as Blowing Agent

Cited by 8 publications

References 7 publications

Liquid Silicone Rubber Foamed with Thermoplastic Expandable Microspheres

Liquid Silicone Rubber Foamed with Thermoplastic Expandable Microspheres

High Consistency Silicone Rubber Foams

Improvement of the Cell Structure of Water‐Foamed Liquid Silicone Rubber

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