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Here, we report the continuous peroxide-initiated grafting of vinyltrimethoxysilane (VTMS) onto a standard polyolefin by means of reactive extrusion to produce a functionalized liquid ethylene propylene copolymer (EPM). The effects of the process parameters governing the grafting reaction and their synergistic interactions are identified, quantified and used in a mathematical model of the extrusion process. As process variables the VTMS and peroxide concentrations and the extruder temperature setting were systematically studied for their influence on the grafting and the relative grafting degree using a face-centered central composite design (FCD). The grafting degree was quantified by 1H NMR spectroscopy. Response surface methodology (RSM) was used to calculate the most efficient grafting process in terms of chemical usage and graft yield. With the defined processing window, it was possible to make precise predictions about the grafting degree with at the same time highest possible relative degree of grafting.
Die kontinuierliche Erfassung von Qualitätsparametern ist eine zunehmende Anforderung in der Polymerextrusion. Die optische Spektroskopie kann diese Anforderung erfüllen, da sie neben der Farbe weitere Parameter wie beispielsweise chemische Eigenschaften, Trübungsgrad oder Partikelgröße erfasst. Dabei werden für Inline-Messungen im Extruder optische Sonden eingesetzt. Im laufenden Betrieb bilden sich Ablagerungen auf den Sondenfenstern. Dieser Beitrag präsentiert ein neues Cleaning in Place Konzept, mit dessen Hilfe die Fenster auch während der Produktion ohne Unterbrechung gereinigt werden können. Auch die Kalibrierung der Messtechnik ist dabei möglich. Das verhindert Rüstzeiten und sichert eine kontinuierliche Inline-Messung.
Polyurethane thermosets have a wide range of applications. In this study, alternative raw materials were used to enhance sustainability. In two newly developed biobased polyurethanes (PUs), the cross-linker content was varied, which caused phase separation and therefore affected the turbidity. To investigate this phenomenon, UV–Vis–NIR spectroscopy was utilized. Spectra were recorded from 200 to 2500 nm in transmittance mode, and multivariate data analysis was applied to the three UV, Vis, and NIR sections separately. For the two different PU classes, each with five different cross-linker contents, classification by principal component analysis combined with linear or quadratic discriminant analysis was possible with an accuracy between 93% and nearly 100%. The best separation was achieved in the NIR range. Partial least-squares regression models were determined to predict the cross-linker content. As mentioned, the model for the NIR range is the most suitable, with the highest R2 (validation) of 0.99 for PU1 and 0.98 for PU2. The corresponding root-mean-square error of prediction values of the external validation was the lowest, with 0.82% (PU1) and 1.25% (PU2). Therefore, UV–Vis–NIR absorbance spectroscopy, especially NIR, is a suitable tool for monitoring the appropriate material composition of turbid PU thermosets in line.