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The supramolecular structure in pipe walls of isotactic PP‐R is a function of compound composition and processing parameters, which both influence the mechanical properties of the pipes. µFTIR shows a gradient of the crystallinity across the pipe wall, with a lower‐crystalline outer layer, and a higher‐crystalline core layer. The rate of extrusion has an influence on the thickness of the outer layer. The nucleating effect on the morphological profile throughout the pipe wall can be visualised. µFTIR shows a homogeneous distribution of the primary antioxidant in the pipe wall. Both the spectral crystallinity and the antioxidant concentration distribution are calculated.magnified image

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Moisture-induced stresses in amorphous thermoplastics are studied in detail using the finite element method (FEM). The approach is based on the coefficient of moisture expansion which is derived from the sorption behavior (i.e., changes of mass, density and elastic properties). The required model parameters were obtained by isothermal diffusion and swelling experiments at different levels of relative humidity at room temperature. In the analysis, the evolutions of moisture-induced stresses in a model system have been analyzed, i.e., drying sheets of poly(- methyl methacrylate). The calculated stresses during drying are discussed with regards to the sorption models. Results indicate that these computational models are essential in capturing the accurate moisture-induced stress. Finally, the simulation results were verified by three-point bending. The implemented method shows the potential to predict environmental stress cracking due to humidity by FEM. This is important for the improved design of plastics parts

We present a confocal Raman depth profiling technique combined with multivariate spectral decomposition. The method allows for non-invasive layer structure and chemical composition determination on polymer multilayer films with micrometer accuracy.

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The edge-seal is the most important part of an insulating glass unit regarding the loss of insulating gases from the inter-pane space. Its long-term behavior is mainly defined by climate loads. Here, increasing stresses on the polymer sealants lead to chainorientation. This introduces anisotropic materials properties. The strain causes macroscopic deformation of the edge-seal. Both effects might enhance the permeation rate, yet are not considered by the established testing standards. Therefore, the standard test to measure the gas loss rate under climate conditions has to be refined and extended. In this work, a new test setup is introduced which correlates the stress-strain behavior within the edge-seal with the gas loss rate of insulating glass units. Three different concepts are evaluated by means of the stress-strain state within the edge-seal as well as the needed dimensions and the manufacturing complexity of the test stand. As a result, the internal pressure controlled permeation test method appears to be the most suited. Finally, the measurement setup is realized as a prototype and optimized.

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