Energy savings plus mechanical reinforcement and rheology control

One-Component RTV Silicone Construction or DIY Sealant

Adhesives Formulation

Applicable Type

Reactive Adhesives

Applicable Base Polymer

Silicones (Si)

Applicable Industrial Sectors

Buildings & constructions

Applicable Base Polymer Properties

Silicone polymers display an exceptionally wide range of chemistries and physical properties. These polymers can be low viscosity liquids, crosslinkable elastomers, or hard solids. Applications for silicone sealants are extremely broad. Markets include construction, automotive, assembly, maintenance, electrical/electronic, aerospace, and consumer products. Silicone sealants often compete with other materials such as polyurethanes, polysulfides, and acrylics. However, in applications requiring long-term durability to harsh environments, silicones are generally specified.

Typical Formulation Ingredients

Ingredient

Parts by weight

Polymer, polydimethyl siloxane, OH terminated, 50,000 cps

xxxx

Plasticizer, polydimethyl siloxane, trimethyl terminated, 1000 cps

xxxx

Crosslinker methyltrioximinosilane

xxx

Adhesion promoter, aminopropyl triethoxysilane

xxx

Fumed silica, 150 m2/gm surface area

xxx

Catalyst, dibutyltin dilaurate

xxx

(Source: Geltest, Inc.)

Typical Properties

Properties

Elongation, %

xxx

Tensile strength, MPa

xxx

Modulus at 100% elongation, MPa

xxx

Shore A hardness

Skin over time, mins

Tack free time, mins

Through cure, mm in 24 hrs

Processing

Resulting Properties

RTV silicone formulations comprise several different components; some of whch are optional depending on the intended use. The only absolutely essential raw materials are reactive polymer and crosslinkers. However, fillers, adhesion promoters, plasticizers, and catalysts are nearly always added. In addition, many other additives can be used such as pigments, fungicides, flame retardants, and heat stabilizers. The table above provides a starting formulation for a basic medium modulus room temperature vulcanizing (RTV) silicone sealant based on oxime crosslinker. This is an example of one of the oldest and most common RTV silicone sealants. The reaction rate of the moisture cure RTV silicone sealants depends primarily on their formulation, relative humidity, and temperature.

Tips and Tricks

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