Liquid Silicone Rubber Foamed with Thermoplastic Expandable Microspheres

Area of Science:

• Materials Science
• Polymer Engineering
• Foam Technology

Background:

• Liquid Silicone Rubber (LSR) is a versatile elastomer.
• Reducing material costs and density of LSR is desirable for various applications.
• LSR foams can be produced via injection molding using expandable microspheres as blowing agents.

Purpose of the Study:

• To analyze the cell structure of LSR foams produced with varying proportions of expandable thermoplastic microspheres.
• To determine the density of the resulting LSR foam samples.
• To understand the influence of microsphere content on foam morphology and properties.

Main Methods:

• Injection molding of cylindrical LSR disks with different microsphere contents.
• Scanning electron microscopy (SEM) for detailed cell structure analysis.
• Density measurements of the manufactured LSR foam samples.

Main Results:

• A highly homogeneous cell structure was achieved in the LSR foams.
• Heat transport significantly impacts the expansion behavior of the microspheres during processing.
• The formation of a filler network effectively limits microsphere expansion at higher blowing agent concentrations.

Conclusions:

• Injection molding with expandable microspheres is an effective method for producing homogeneous LSR foams.
• Controlling heat transport is crucial for optimizing microsphere expansion and foam properties.
• The filler network acts as a limiting factor for expansion, influencing achievable foam densities.