Urethane Knowledge Center

Abrasion Resistance

There are two types of abrasion: sliding and impingement. Sliding is the passing of an adjacent surface across the elastomer…

Adhesion of Elastomers

In the rubber and urethane industry, it is common to adhere an elastomer to a rigid component. Some examples include…

Chemical and Environmental Resistance Properties

These charts compare the physical, chemical resistance, and environmental resistance properties of elastomers.

Comparative Physical, Mechanical and Thermal Properties

This chart compares the physical, mechanical, and thermal properties of elastomers.

Compression and Shape Factor

When a load is applied to an elastomer, it "flows" in accordance with the force exerted on it, and also…

Compression Set

Compression set tests, described in ASTM D-395, are of two main types: Method A, compression set under constant load; and…

Concentricity Versus Runout

Concentricity is the relationship of two or more cylindrical features that have a common center. The center of one feature…

Cost Comparison

The following cost comparison shows the ratio of prices for selected materials to the lowest cost elastomers: EPDM, SBR, and…

Creep and Stress Relaxation

When subjected to load, all elastomers exhibit an increasing deformation with time, known as creep. This occurs at any stress…

Durometer / Hardness

Hardness, as applied to elastomers, is defined as the relative resistance of a surface to indention by an indenter of…

Electrical Properties

The electrical properties of elastomers that are most commonly measured are: Resistivity Dielectric Strength Dielectric Constant Power Factor Materials suitable…

Flash Extension

In the thermoplastic injection molding process, a common part specification is “no flash allowed.” With plastic, however, mold cavity vents…

Frictional Characteristics

Figure 1 Friction of urethane polymers against non-lubricated surfaces decreases with increasing hardness of the polymer, as shown in Figure…

Material Selection Process

At Molded Dimensions Group, we know it's not always easy to pick an elastomer—there are many factors to take into…

PU Selection Guidelines

This chart lays out the PU selection guidelines.

Resilience / Rebound

Resilience is defined as the ratio of energy given up in recovery from deformation to the energy required to produce…

Shelf Life Comparison

The shelf life of molded parts assumes storage in controlled environmental conditions, both in terms of temperature and humidity. The…

Static and Dynamic Load Deflection

Rubber and urethane provide greater deflection for applied forces than do rigid materials such as metals or ceramics. Most uses…

Surface Finish and Appearance

When considering the finish and appearance of molded products, several factors are important to take into account. Machined Finish of…

Tear Resistance

Tear resistance is a complex result of other basic properties, such as modulus and tensile strength. Many laboratory methods have…

Temperature Capabilities

Rubber and urethane temperature capabilities / Temperature capabilities of basic elastomers

Tensile

Tensile strength and ultimate elongation, while extremely useful for compound development and control, are of lesser importance to the design…

Urethanes in Compression

Urethane elastomers have a higher load-bearing capacity than do conventional elastomers of comparable hardnesses. This permits the design of smaller…