Industrial Process Quality Control
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Infrared spectroscopy (IR) is used for the identification and characterization of polymers. It provides information about the polymer itself, fillers, additives, blends and crystallinity.
In addition, IR spectroscopy is established for quality control of industrially produced polymers and raw materials. Examples are the differentiation between HD-PE and LD-PE or the deformulation of a copolymer or blend into its individual components.
Petrochemical companies were at the top of the field in the early stages of NMR’s adoption into the many industries it has become a key part of. However, these companies are now often branching out into polymers, a huge area in which NMR finds widespread and regular application.
With major polymer manufacturers using NMR for materials analysis, this is making way for research into and development of brand new polymers.
TD-NMR technology has been proven to be a reliable and feasible alternative to replace conventional methods and reduce labor time. The key QC/QA applications in the polymer field include:
The advantages of TD-NMR analysis compared to classical methods are speed and accuracy of analysis. Samples can be either liquid, powder, pellet, film or plate, and the measurement takes only a few seconds. TD-NMR analysis can even be performed in-situ for a wide temperature range, from -100 °C to +200 °C, which is essential for polymer analysis.
Further TD-NMR Applications: Determination of cross-link density in elastomers; plasticizers, additives, and monomer fractions in polymers; Solid content in emulsions and Latex; Soft coatings on polymers; Oil and water content; Fluorine content in polymers; Copolymers and degree of polymerization; Ageing and irradiation induced effects.
Mass spectrometry offers a unique depth of characterization for many diverse polymer classes regarding incoming goods or synthesis QC. This includes bulk material screens, pharmaceutical development, or finished surface analyses.
MALDI-TOF MS offers determination of the mostimportant characteristic values of the polymer, including absolute average molecular weights (Mn and Mw), dispersity Đ, degree of polymerization, and the mass of the combined end groups, may also be automatically calculated in a fast and versatile workflow.
Even similar polymeric components in one sample may be easily distinguished by help of Kendrick Mass Defect plots.
A surface-layer matrix-assisted laser desorption ionization mass spectrometry imaging technique (SL-MALDI-MSI) can be used to study the chemical composition of polymer surfaces with multicomponents.
Synthetic material surfaces with polymer components are important in several industrial and medical processes. These are printing, coatings and biomedical device applications as well as other applications. Consistency of the chemical composition is crucial in these processes. Production can be easily disrupted by the quality of the material which can impart surface defects such as abrasion, degradation, contamination with other materials, and many more.
For the study of these material surfaces MALDI matrices and cationizing salts are applied onto the material for analysis. Surface-specific analysis with a depth resolution of about a few nm can be measured. For instance, surface defects on polystyrene (PS) and poly(methyl methacrylate (PMMA) thin films caused by contamination, masking, scratching/abrasion, and solvation can be analyzed.
Near infrared spectroscopy is used for the quantification of quality relevant parameters in polymers like OH-number, acid or amine value to name a few. As innovative analytical methods are of great economic interest, NIR is becoming more and more established for the monitoring of polymer production processes. Many companies start to replace conventional at-line analysis methods by spectroscopic online tools.
An increased speed of analytical processes and decreased maintenance costs offer a high savings potential. The great amount of information delivered by the NIR spectra allow a simultaneous high-precision analysis of many different components and system parameters such as density, viscosity, degree of cross-linking, stabilizer as well as monomer content and many others.
Photo-curable polymers are widely used in automotive, consumer electronics, printing, and coating industry because of their multifunctional properties.The most important characteristics of curable polymers are the speed of cure and the degree of conversion in the final product.
Time-resolved FTIR spectroscopy is an excellent analytical tool to measure these parameters. The degree of conversion and the speed of cure can be measured within a few seconds using fast scanning spectrometer. Conversion kinetics are easily calculated from the band intensities vs time under lights exposure.
Cost cutting or non-availability of certain components can lead to changes in the supply chain without noticing the customer until a downstream product fails. A simple quality control of incoming goods using a well-established TLC chromatography might not always show the full picture: Spots can overlap and, therefore, cannot be distinguished by simple staining even if 2D-TLC was used. TLC MALDI-TOF mass spectrometry offers an additional dimension to the analysis and can clearly separate all components present on a 1-D- or 2-D-TLC-plate.
The failure of polymer and plastic materials often is caused by the inhomogeneous distribution of the used components inside the polymeric material. Furthermore, contaminations like particles, fibers or inclusions may be the reason for its failure.
As such defects are often extremely small they are hard or even impossible to analyze by a macroscopic measurement. FT-IR microscopy is a powerful tool for failure analysis: It allows to obtain IR-spectra anywhere on the sample with high lateral resolution and thereby reveals the chemical composition of this particular sample area.
A polymer is a macromolecule that is made up of long chains of repeating subunits. The composition, structure, and form of the polymer determine its properties and therefore proper characterization of these parameters is critical. Polymers are often synthesized into fibers, sheets, and other solid forms. The properties of these types of polymers are strongly influenced by their crystallinity, crystal structure, and texture which can be investigated using X-ray diffraction (XRD) and Small Angle X-ray Scattering (SAXS). As these types of polymers typically have large d-spacings, low X-ray absorption, and some preferred orientation (texture), transmission scattering utilizing a 2D detector is an ideal way to characterize these samples.
Polymers are used to create items of all shapes, sizes and intended uses. From the milk jugs to cell phone components created with methods ranging from injection molding to 3D printing, polymers continue to shape the world around us. Ensuring that these components fulfill their intended roles requires access to cutting edge techniques like X-ray Microscopy. XRM allows non-destructive three dimensional imaging of both the interior and exterior structure of polymer components. Whether the task is ensuring the internal/ external part dimensions, checking for voids, or analyzing the mode of failure, XRM plays an essential role in polymer engineering.