Home>Testing Services>Long Term Relaxation and Creep>Relaxation and Thermal Recovery Sequence

Relaxation and Thermal Recovery Sequence

Introduction

A one day physical testing sequence has been developed to provide insight into the early effects of elevated temperature on compressed elastomers. By compressing an elastomeric material specimen (or actual elastomeric part) and holding it at a constant strain, the effects of time and temperature on the reaction force are measured. In particular, the reaction force at sub-ambient temperatures after first being subjected to an elevated temperature can be indicative of the changes that occur in the elastomer while at the earlier elevated temperature.

Applicable Technical Downloads

The Effects of Large Temperature Changes on Elastomer Seal Performance

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Instrument Scematic for the Relaxation and Thermal Recovery Sequence

Home>Testing Services>Long Term Relaxation and Creep>Long Term Stress Relaxation

Long Term Stress Relaxation

Introduction

When a constant strain is applied to a rubber sample, the force necessary to maintain that strain is not constant but decreases with time, this behavior is called stress relaxation. Conversely, when a rubber sample is subjected to a constant stress, an increase in the deformation takes place with time, this behavior is called creep. The processes causing stress relaxation may be physical or chemical in nature, and under all normal conditions both types of process will occur simultaneously. However, at normal or low temperatures, stress relaxation is dominated by physical processes. At high temperatures or long times, chemical processes are dominant.

Applicable Technical Downloads

Long Term Creep and Long Term Stress Relaxation Experiments for Rubber and Plastic Materials

Stress Relaxation Tests, Technical Report 98/1, by Mr.Göran Spetz

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Continuous measurement

One type of relaxation instrument measures the reaction stress continuously and consists of a small rig with a load cell. When testing at elevated temperature the rig is placed in a cell oven. The rigs are connected to a data acquisition box connected to a computer, storing the force and temperature data over time. The Elastocon system used at Axel Products is a continous measurement system.

Home>Testing Services>Long Term Relaxation and Creep>Long Term Creep

Long Term Creep

Introduction

When a constant stress is applied to a plastic, rubber, solder or other sample, the strain created by the stress is not constant but increases with time. This behavior is called creep. The processes causing creep may be physical or chemical in nature, and under all normal conditions both types of process will occur simultaneously. However, at normal or low temperatures, creep is dominated by physical processes. At high temperatures or long times, chemical processes are dominant.

Experiments can be performed in tension and compression with automated continuous measurements.

Applicable Technical Downloads

Long Term Creep and Long Term Stress Relaxation Experiments for Rubber and Plastic Materials

Stress Relaxation Tests, Technical Report 98/1, by Mr.Göran Spetz

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