Investigation and Description of the Weight and Dimension Change of Injection Molded Polyamide Parts by Moisture Absorption

In the scope of this work, the weight and dimensional changes of norm test pieces and technical parts (e.g. cages) of reinforced and unreinforced polyamides due to moisture absorption have been investigated. The diffusion coefficients of the tested polyamides for various conditioning environments were determined on the basis of the test results. The weight change due to moisture absorption as function of conditioning time can be represented within a limited tolerance from the measured results by using the Fick's Diffusion Law and an appropriate geometric factor. Furthermore, the dimensional change in relation to weight increase of tested parts were determined and presented here. Further, the influences of fiber content and orientation on the dimension change of various reinforced test parts were investigated.