From Handbook of Adhesives and Sealants

13.1 Introduction

The various generic families of sealant materials are reviewed in this chapter. Properties and performance characteristics are presented although they can vary considerably within each family. There are over 15 families of polymers that are used singly or in blends to achieve the storage characteristics, application properties, physical performance, and durability required for each application. Table 13.1 shows some of the strengths and weaknesses of the most popular synthetic based sealant families.

Table 13.1: Characteristics of Popular Sealant Families1

Chemical family and curing type

Strengths

Weaknesses

Silicones, one component (moisture-initiated condensation) and two components (condensation or addition)

Best weathering, highest flexibility good adhesion, heat resistance

High MVTR, low depth of cure, slow curing [b]

Polyurethanes, one component (moisture-initiated condensation) and two components (condensation)

Good weathering, best adhesion, high flexibility

Weak UV resistance, weak heat resistance

Polysulfides, one component (moisture-initiated condensation) and two components (condensation)

Low MVTR [a], fuel resistant, good flexibility

Slow curing [b], low depth of cure

Acrylic latex (water evaporation)

Easy to use

High shrinkage, poor weathering, fair flexibility

Butyls (sulfur vulcanization)

Lowest MVTR, good flexibility

Fair weathering

Anaerobics (metal/peroxide initiated free radical)

Fast curing, chemical resistant, heat resistant

Brittleness, poor gap filling

Vinyl plastisols (heat fusion)

Good adhesion, low cost

Fair flexibility, fair weathering

Asphalts/coal tar resins (cooling oxidation)

Low cost, fuel resistant

Poor weathering

Polypropylene hot melts (cooling)

Low cost, expandable

Limited adhesion, fair flexibility

[b]Two-component version cures faster.

[a]MVTR, moisture vapor transmission rate.

The following sections describe the characteristics...

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Products & Services
Industrial Sealants
Industrial sealants are liquid or viscous compounds used between surfaces to contain fluids, prevent leaks, and prevent infiltration of unwanted material. They may also include compounds for filling gaps or seams.
Adhesive Tapes
Adhesive tapes are used to assemble materials or parts together using a sticky chemical bond.
Silicone Adhesives and Sealants
Silicone adhesives and sealants have a high degree of flexibility and a very high temperature resistance (up to 600° F), but lack the strength of other epoxy or acrylic resins.
Epoxy Adhesives
Epoxy adhesives are chemical compounds for joining components. They require clean surfaces and are valued for their toughness and resistance to chemical and environmental damage.
Industrial Coatings
Industrial coatings are thin films deposited upon materials to add or enhance desired properties, such as color, conductivity, corrosion resistance, etc.

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