Karsten Kretschmer

Terahertz-Forschung begegnet Kunststofftechnik (Terahertz Research Meets Polymer Technology)

Die Terahertz-Messtechnik kann in Zukunft vermehrt Einzug in die Prozess- und Qualitätskontrolle der Kunststofftechnik halten. Zeitbereichsspektroskopie und ein neuer Algorithmus zur äußerst genauen Datenauswertung ermöglichen es, den Gehalt von Zusatzstoffen präzise inline zu überwachen oder Kunststoffbauteile zerstörungsfrei zu prüfen. Im Gegenzug versprechen aber auch Funktionswerkstoffe auf Polymerbasis Mehrwert als THz-Systemkomponenten. Terahertz technology might soon be introduced into the process and quality control for the polymer processing industry. Time-domain spectroscopy and a new algorithm for highly accurate data evaluation enable the precise in-line monitoring of additive content or the non-destructive testing of polymeric components. In return, materials on polymeric basis can provide valuable terahertz system components.

A mathematical model describing the solid conveying and melting behavior of planetary roller extruders

Due to increased quality requirements and the trend to cost reduction by process optimization, the modeling of plastic processing by means of simulation software becomes more and more important to predict process behavior. Most tools are based on a physical analysis of the process conditions and a reflection of those in a mathematical model, either based on FE methods or an approach to approximation or complete analytical models. First models were published for planetary roller extruders. However, these models deal primarily with the melt conveying behavior and have not yet been developed for the melting process which in many cases is critical to address homogenization features of such machines in the melt phase. This paper presents an approach to calculate the melting degree along the barrel of a planetary roller extruder. Therefore, models that are used to describe the melting process of single and twin screw extruders are adjusted to the conditions in the planetary roller extruder. At first the relevan...

Terahertz Time-Domain Spectroscopy on Polymeric Compounds

We present terahertz time-domain spectroscopy measurements on compounds based on standard polymers. Concentrations of various additives are clearly distinguished. The results are encouraging for the industrial application of terahertz time-domain spectroscopy for polymer science, the control of compounding processes and for quality assurance.

Wie sind beste Langzeiteigenschaften erreichbar

Holz-Kunststoff-Verbundwerkstoffen, bekannt unter dem Kürzel WPC (Wood-Plastic-Composites), wird ein wachsendes Einsatzpotenzial prognostiziert – Grund genug zu untersuchen, welche Vorbehandlungsmethoden und Klebstoffe zu langzeitbeständigen Holz-Kunststoff-Verbundwerkstoffen für Außenanwendungen führen. Nach der Ermittlung der mechanischen Kurzzeit-Eigenschaften folgte die Bestimmung der am besten geeigneten Werkstoff-Vorbehandlung-Substrat-Kombinationen.

THz spectroscopy for the inline control of polymeric compounding processes

We present non-destructive and contactless inline measurements on the molten polymer polypropylene and on the polymeric compound polypropylene-CaCO3 carried out with a THz spectrometer. The effect of temperature and pressure on the THz properties of the molten polymeric material is investigated. Additionally, we analyze the additive content of the compound during the extrusion processing and compare this data with offline results. Further measurements on wood plastic composites demonstrate the capability of detecting the degree of dispersion of compounds with THz-spectroscopy.