The failure of polymer and plastic materials often is caused by the use of the wrong raw materials or the inhomogeneous distribution of the used components inside the polymeric material. Also, contaminations like particles, fibers or inclusions may be the reason for failure. To guarantee the use of the correct raw materials (granules, additives and fillers) their identity and composition easily be controlled by an IR-analysis (view Video).
In case of composite materials, defect layers or a layer made from the wrong material will have a negative impact on the product properties.
The FTIR microscope LUMOS II is a powerful tool for failure analysis of polymer and plastic products: It allows to obtain IR spectra anywhere on the sample with high lateral resolution and thereby to reveal the chemical composition of this particular area of the sample.
Coatings are often applied to modify surfaces for functional reasons, to protect them or to generally enhance the visual appearance of a product. An improper application of a coating can result in failure of the product. As a first step in failure analysis of coated products, it is important to verify the presence of the coating layer on the sample and to check if the right coating material was used. Furthermore, the homogeneity of the layer has to be monitored.
Example: Chemical FT-IR imaging of a cold sealing layer In this example an acrylic coating and an overlying cold seal strip of a packaging foil was examined. The aim of the study was to determine if upon opening of the packaging, the acrylic layer is damaged and to what extent the cold seal is peeled off. The image below shows the distribution of the cold sealing layer superimposed over the visual image. The so called chemical image pictured below shows the color coded distribution of the cold sealing layer and reveals that parts of the layer were indeed damaged.
|See examples of the examination of the homogeneity of coated polymer films in our Application Note M112.|
Example: IR microscopic analysis of a product defect with LUMOS II
A batch of polyethylene pellets contains unwanted brown inclusions. The microscopic visual image of a polyethylene pellet with brown inclusion is shown together with the positions of the IR-analysis:
The IR spectra show clearly different characteristics on the PE pellet matrix (blue spectra) and on the unknown inclusion (red spectra). Search in a spectral library identifies the inclusion to be a polyester (PET):
|Read Aplication Note AN M105 about the IR microscopic identification of particles and inclusions.|
|See example of the identification of a fish eye in a polyurethane in our Application Note AN MIC411.|
|See an example for identification and chemical imaging of inhomogeneity in a rubber material in our Application Note AN M136.|
|Read Application Note AN M102 about the microscopic identification of fibers.|
Multi-layer packaging materials is required for maintaining product integrity, e.g. of food and pharmaceuticals. Different polymer films and other materials are combined to prevent the product from being exposed to oxygen, ultraviolet illumination, or other environmental factors. The design and fabrication of polymer films is typically a complex and costly process that can affect actual and perceived product quality.
IR microanalysis provides insight into the structure of such polymer laminates for quality control and for the analyses of found defects.
Transparent multi layered polymer foils can also be analyzed by Raman spectroscopic depth profiling with a very high depth resolution in the micrometer range. The image below shows Raman spectra of different polymers collected in the course of a depth profiling measurement.
|See examples of the IR-microscopic analysis of individual layers in composite films in our Application Note AN M126|
|Learn more about the non-invasive depth profiling of a multi-layer polymer film in our Application Note AN R527.|