Fraunhofer Cluster of Excellence Circular Plastics Economy CCPEEvaluation of effective additives for odor-contaminated materials
Odors from plastics and plastic recyclates pose a major challenge for the circular economy. Additives that act as odor scavengers can provide a remedy. However, selecting the right additive is often difficult. Researchers at Fraunhofer CCPE have developed a new characterisation method that enables the identification of suitable additives for odor control.
The compatibility of additive, odor and plastic is complex. There is no universally effective additive for all types of odor pollution. The effectiveness of an odor protection additive is highly dependent on the material concerned and the various odorants themselves. The search for a suitable additive is currently time-consuming and cost-intensive and involves compounding, the production of test specimens and an olfactory evaluation.
A new characterisation method, developed by researchers from the Fraunhofer CCPE, makes it possible to quickly and easily analyse the suitability of an additive as an odor inhibitor. The effectiveness of an additive in absorbing volatile organic compounds (VOCs) and low-volatility compounds (FOGs), which are released directly from an odor-contaminated material in the test, is measured quickly and easily. In this way, a preselection of additives that are suitable as odor scavengers for a specific material or a specific odor can be determined with little effort.
Using the characterisation method, the emissions are collected from a carrier gas stream that flows in a cascade over an odorous sample and over the additive to be tested. The emissions are absorbed on a porous polymer and then analysed using thermal desorption gas chromatography/mass spectrometry (TD-GC/MS). The analysis and evaluation are carried out in accordance with VDA 278, a method commonly used in the automotive industry for analysing organic emissions from non-metallic vehicle materials. The VOC or FOG value is determined, which represents the sum of the volatile to semi-volatile or semi-volatile substances as toluene or hexadecane equivalents.
Based on the results, efficient odor scavengers can be selected for plastics, recyclates and natural materials in order to significantly improve the quality and circularity of these materials. This is an important step towards a sustainable future.