Polymer Processing

Crane Engineering has the capability to detect molding impurities in plastic injection molded parts by utilizing both the expertise of the analysts in the metallurgy and chemistry laboratories. Fracturing, cross-sectioning, and stereomicroscope evaluation are conducted to detect the presence of an impurity. Both the bulk phase and the impurity region of the sample can be analyzed on our Varian Excalibur FT-IR using the slide-on ATR attachment. The resulting spectra are compared to an extensive database for identification.

For example, a manufacturing client that produces custom plastic injection molded parts was finding defined impurities in small, clear, polyurethane molded parts they produced. The part was fragmented and cut to allow access of a cross section containing the impurity, which was found to be another plastic material with a slightly different refractive index, making it visible inside the clear intact part. A stereomicroscope was used to image and document the presence of this impurity.

The cross-section of the sample was analyzed on Crane Engineering’s Varian Excalibur FT-IR using the slide-on ATR. Both the bulk phase and the impurity region were analyzed, with the resulting spectra compared to an extensive database for identification. The molding impurity was found to be polysulfone, and it was determined that a small number of polysulfone injection molding pellets had contaminated the polyurethane pellets used to mold this part.