Development of a comparative test methodology to characterize scratch and stickiness of PP-compounds
Research output: Thesis › Master's Thesis
Generally, sticky surfaces are characterized by adhesiveness. However, it is undesirable to touch on sticky surfaces of any products such as automobile instrument panels and interior trims. The major focuses of this present work were on both the development of an objective stickiness measurement and the surface characterization of thermoplastic polyolefin (TPO)-compounds for automotive interior applications. This laboratory stickiness test should complete the current surface characterization tests at BOREALIS Polyolefine Linz GmbH, which includes scratch visibility and gloss measurement. The major elements of this stickiness test are the compression/tension loading, the standardized counterpart (modulus, surface roughness) and the controlled duration of the test. Different model TPO formulations developed and produced by the company partner were used for these investigations. Since the stickiness phenomenon is assumed to be a reason of the degradation of anti-scratch additives (slip agents) after UV irradiation, the model TPOs were formulated with varying amount and type of ready-made anti-scratch additives. The objective of this thesis was to examine the hypothesis that the stickiness occurrence is caused by slip agents with the help of the stickiness test methodology, as well as to verify the correlation of the stickiness test to the human sense of touch. To capture the influence of material conditioning, the materials were tested both in the unconditioned state and after various intervals of UV irradiation in an environmental chamber. The artificial UV irradiation was defined by the Kalahari condition (typical for automotive applications), where the materials were faced to a Xenon arc light source in a dry and hot climate. First of all, it has been shown that the stickiness test is reliable, reproducible, easy to implement and flexible in terms of materials' pretreatment. Based on the results of all experiments, the best material formulation for a balanced stickiness-surface appearance-cost performance was found. Basically, the results of scratch and stickiness characterization indicate that the slip agents are not the main influencing factor for the occurrence of sticky touch on TPO surfaces. It is rather a complex interaction with other additives (e.g., UV stabilizer, antioxidants) during UV irradiation induced degradation of slip agents. The last aspect is to be clarified in further studies.
|Translated title of the contribution||Entwicklung einer vergleichenden Testmethodik für die Charakterisierung der Kratzfestigkeit und Stickiness von PP-Compounds|
|Award date||26 Mar 2010|
|Publication status||Published - 2010|