Creep is a type of deformation dependent on time and load, which occurs after instant deformation, when a constant stress is applied.
(For thermoplastics, temperature also plays an important role).
In practice, the deformation is recorded over time in tension or compression for various stress levels.
To compare products with each other creep values are given under a given stress.
The tests are long and the results obtained are strongly influences by environmental conditions during the test, such as temperature, humidity etc.