Key Findings
The optimized hybrid silicone sealant (Experimental Group 4) achieved a tensile strength of 41 kgf/cm², representing a 46.43 percent improvement over the control group’s 28 kgf/cm². Adhesion strength in Group 4 rose to 30 kgf/cm², an increase of approximately 15.38 percent. In standardized fire testing following KS F 2845, the material satisfied both integrity and insulation criteria for more than 60 minutes, while the control group failed after 40 minutes due to flame penetration.
Technical Details
The formulation utilizes two complementary nanomaterials to create a sequential defense mechanism:
- Silica Aerogel: A nanoporous solid with thermal conductivity of approximately 0.013 W/(m·K) that suppresses temperature rise on the unexposed side of joints.
- Nanographene Flakes: Two-dimensional platelets that act as physical barriers to gas and heat migration and promote a dense char layer.
To prevent agglomeration, researchers used atmospheric-pressure plasma treatment, followed by immersion of silica aerogel in an aqueous ammonium phosphate solution and nanographene flakes in a silane emulsion. The formulation also included boron-treated titanium for a vitreous protective layer and Pigment Yellow 181 as a radical scavenger. In thermogravimetric analysis, Experimental Group 3 showed the lowest additional mass loss during high-temperature decomposition, while Group 4 exhibited the shortest after-flame time of about 5 seconds and retained over 85 percent of its initial tensile strength after four weeks of thermal aging at 200 °C.
Background & Context
Fire engineers have struggled with sealant lines in high-rise building joints. Conventional fire-resistant sealants use large quantities of inorganic fillers like aluminum hydroxide and iron oxide; however, these often degrade the elasticity and adhesion necessary for long-term aging and building movement.
Significance & Outlook
The material functions through a tiered response: aerogel shields the matrix below 200 °C, aluminum hydroxide releases cooling water vapor above 220 °C, and nanographene flakes build a char skeleton between 300 and 600 °C to prevent the aerogel framework from collapsing. These laboratory-scale results demonstrate a balance of tensile properties and thermal durability.
Source: https://bioengineer.org/hybrid-silicone-sealant-withstands-fire-for-over-an-hour-in-building-joints/
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