One of our customers was using a certain grade of plastic for injection molding of their top-selling product. However, they had recently switched supplier and wanted to make sure that the material they ordered was exactly the same as they were used to. Therefore they sent us a sample of the product and asked if we could identify the material.
When identifying an organic material, a technique we use regularly is Infrared (IR) spectroscopy. With IR, the sample is irradiated with a beam of infrared light at different wavelengths. Functional groups interact with the infrared light, creating a unique signal. Combining all these signals yields a spectrum that is characteristic for that specific material, comparable to a fingerprint.
We recorded an initial IR spectrum, and it was immediately evident that the sample was some kind of Nylon. However, there are several variations of Nylon that exhibit very similar IR spectra. Therefore, we made a detailed comparison of the IR spectra of the sample (yellow) to many kinds of Nylon from our database, as shown in the figure below. Based on small differences of characteristic peaks, indicated with the coloured arrows, we were able to exclude Nylon 6/6 (blue), Nylon 6/10 (pink) and Nylon 6/12 (green) as possible candidates. The best match was obtained with Nylon 6 (red).
To confirm our IR hit, we used Differential Scanning Calorimetry (DSC) and determined the melting point (Tm) to be around 220°C. To finalize the material identification, we performed thermogravimetric analysis (TGA) to determine whether the Nylon contained any filler. The sample was heated to 900°C to remove the organic material, whilst recording the weight loss in weight percentage (wt%). At 900 °C, the residue was 24 wt%, which can be attributed to inorganic filler material (like glass fibre, which is commonly used to reinforce Nylon 6).
So, by a smart selection of three different techniques and with the help of our extensive database, we were able to determine quickly that the material was indeed Nylon 6 containing an inorganic filler. With this crucial information, the customer was fully reassured and could continue production without interruption.
Interested in our IR analysis? Please contact us via email@example.com, and we will be happy to discuss the possibilities.