Characterization of additivated recycled plastics

Objective. To test physicochemical properties before and after reprocessing.

Our customer, a company that develops additivated plastic materials, wants to test whether these plastics maintain their physicochemical properties when reprocessed.

Solution. We characterize composition, thermogravimetric profile and processing quality.

The first step was to learn from our customer about the material and the reprocessing process. During the study we analyzed pieces before and after reprocessing, as well as pieces of virgin plastic.

We selected as characterization techniques infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential calorimetry and the scanning yellowing test (DSC).

In order to study whether the addition of additives or the application of recycling processes affected the chemical composition of the original plastic, we carried out a study of the chemical groups of the samples by FTIR. After that, after verifying that in some cases signs of degradation of the material appeared such as the appearance of oxidized groups, we evaluated the behavior of the samples when subjected to high temperatures, by means of TGA and DSC. This allowed us to check whether the additivation and recycling processes had been carried out correctly and how they affected the heat capacity of the starting materials. Finally, in a complementary way, we analyzed whether the post-processing of the plastic materials and the different dosages of the additives modify the aesthetics of the final product, quantifying by colorimetry how the yellowing index of the samples was modified.

Thanks to the study we carried out, we were able to recommend to our client which additives improve the properties of the plastics and which conditions are ideal to carry out their recycling, affecting, as little as possible, their aesthetic appearance.