Polymers and composites
Polymers are not only used for the production of plastics and rubber parts but also for fibers, foils, adhesives, paints, coatings and fiber composites.
The increasing universal application of polymers makes sensitive and reliable analytical methods essential for their characterization in various aspects.
In our accredited material laboratories we have a wide range of spectroscopic, chromatographic and thermal analytical methods and we offer you a customer-oriented analysis of polymers, additives and foreign matters (impurities).
Our experts are at your side from product-related analytic for quality assurance through failure analysis of plastics and materials to support in research and development work.
We offer you a comprehensive advice on the selection and preparation of individual test as well as on the obtained results.
Dynamic differential calorimetry ( DSC )
Thermic analysis of polymers with and without filler materials, fibers or reinforcements:
- Examination of the morphologic structure of the tested material
- Examination of plastic types
- Recognition of charge differences of molding materials
- Recognition of additives, filling materials, and the chemical fate of plastics
- Influence of the processing conditions on the material quality
- Characterization of the molded part quality
DSC on CFRP:
- Determination of glass transition temperature (Tg)
- Rest-reactivity [J/g]
- Temperature range of 23-200 °C
- Flushing and inert gas nitrogen
Normen: DIN EN ISO 11357, DIN EN ISO 11357-1, DIN EN ISO 11357-2, DIN EN ISO 11357-3
The TGA is a thermic analysis method that is based on the evaluation of changes of mass in dependence of temperature and time. Changes of mass are caused by e.g. evaporation, decomposition or chemical reactions. The examinations take place in oxidized (air, oxygen) or in inert (nitrogen) atmosphere, in which a temperature range of the ambient temperature up to 1000 °C.
With this method you can draw e.g. conclusions about material composition like amount of softeners and fugitive components, filler material contents e.g. carbon black, chalk, glass fiber in plastics or even decomposition behavior.
With our accredited methods we are specialized on the examination of resin, fiber and pore shares in CFRP. Furthermore tasks like quantification of the composition of the polymers, decomposition speed, drying-time and –temperature, humidity or content of fugitive substances are realizable.
As examination material the most different liquid and solid samples like e.g. rubber mixtures, varnishes, floors, minerals, medicines or even their suspensions are possible.
TGA on CFRP:
- Determination of resin and fiber contents
- Fiber volume [%], Pore volume [%]
- Determination of density previously according to DIN EN ISO 1183-1 method A
Normen: DIN EN ISO 11358, DIN EN ISO 1172, DIN EN 2564
Fourier transform infrared spectroscopy ( FTIR )
The Fourier transform infrared spectroscopy (FT-IR) is a fast and accurate method for the analysis and quality control of industrially produced polymers. It is possible to make statements about the product quality and whether a product moves within the specification. FT-IR spectroscopy also allows the measurement of microscopic small samples such as particles, inclusions and fibers.
For the surface investigation of opaque substances, e.g. coating layers or polymer films, the method of "attenuated total reflection" (ATR) is often used. The samples are brought into contact with a diamond crystal which has a high refractive index. The radiation comes into contact only with the surface of the sample because it is guided by the total reflection at the boundary surface of the ATR crystal. The ATR technique allows the recording of IR spectra for samples which are insoluble in non-aqueous solvents and also do not allow the KBr press technology.
The FTIR microscopy allows a rapid measurement of IR spectra of samples in the micrometer range (measuring spot size up to 10 μm). Microprobes can be precisely positioned and enable the visual observation and the detection of the IR spectrum of the sample section of interest. Samples can be measured both in transmission and in reflection.
The FTIR microscopy allows the analysis of mixtures with several components.
In fact, a single microparticle is sufficient for analysis. IR microscopy is suitable for measurements on all solids (e.g., plastics, metals, coatings). The position of the absorption bands provides information on functional groups of the molecule and can identify these with the help of extensive spectral databases. The chemical compounds can be visualized layer by layer by using the microscopic images. This means that the device measures far smaller than the thickness of a human hair and is therefore suitable both as a recognition method and for quality checks. In addition, this technique is destructive-free and allows the application of further analytical techniques.
The Raman spectroscopy is part of the molecular spectroscopy and provides, complementary to the IR spectroscopy, information on the vibration and rotation states of molecules.
It is based on the inelastic scattering of light on molecules or solids, the so called Raman effect. This effect results from the interaction of electromagnetic radiation and the electron shell of the molecules and is in contrast to IR spectroscopy virtually independent of the wavelength of the excitation radiation.
An intense monochromatic laser radiation is focused on the sample for its excitation. Most of the light is transmitted through the sample and a very small fraction is scattered by the substance in all directions (elastic scattering of the light quanta at the molecules, so-called Rayleigh scattering, same frequency as the laser). On the other hand a much smaller part is inelastic scattered (so-called Raman scattering). The reason for this is the deformability of the electron shell (polarizability) of the molecule during the oscillation process. The frequency and the associated intensity of the spectrum provide information to the properties such as crystallinity, crystal orientation, composition, temperature and relaxation of the material. The Raman spectroscopy is ideal for identifying functional groups in polymers and for revealing details of polymer structures.
Pyrolysis gas chromatography coupled with mass spectrometry (Py-GC/MS)
An excellent method for the analysis and characterization of polymers is the pyrolysis gas chromatography coupled with mass spectrometry. The pyrolysis makes it possible to measure polymers by gas chromatographiy. A mostly complex mixture of volatile components can then be separated and identified using a mass spectrometer.
Py-GC / MS is preferably used when routine methods, such as infrared spectroscopy, reach their limits. The high selectivity and sensitivity of the GC / MS is particularly useful in the case of plastic mixtures with small proportions of individual polymer components or a low starting monomer content in the copolymer or in the presence of additives such as flame retardants or oxidation stabilizers.
With this method very small amounts can be analyzed and valuable additional information can be obtained. The range of applications is broadly diversified, ranging from the production and processing of plastics to the automotive industry, the paper industry, wood analysis and the analysis of resins, paints, coatings and adhesives. The pyrolysis GC / MS has also proved to be a valuable tool for the detection of damage in the automotive industry.
Gel permeation chromatography (GPC)
The gel permeation chromatography (GPC) or size exclusion chromatography (SEC) is the method of choice for the determination of molecular weight and molecular weight distribution of natural and synthetic macromolecules.
The combination of concentration, viscosity and light scattering detectors (triple detection) permits a comprehensive characterization of an unknown polymer sample, independent of the chemical and structural structure of the polymer molecules. In addition to the determination of the absolute molecular weight, it is also possible to determine the distribution of the molecular weight, the intrinsic viscosity and the polymer size (radius) over the entire molecular weight range.
Ion chromatography is a physicochemical separation process for ionic species. The separation is based on the interaction between a liquid mobile phase and a stationary phase. In separation columns are used organic polymers with functional groups as carrier material which can fixed ions by electrostatic forces.
In Cation chromatography the functional groups are, in the simplest case, sulfonic acid groups. In case of Anion chromatography quaternary ammonium groups are used. Depending on the exchanger, anions, cations or ion pairs can be adsorbed.
The sample solution is passed over the chromatographic column at high pressure. For the elution of the ions different electrolytes are used. Depending by their affinity to the stationary phase, for individual ions can be determined specific retention times as a characteristic value. Usually the ions are detected by measuring the electrical conductivity.
Karl Fischer titration is considered an important method for the determination of the water content in solid and liquid samples due to its high selectivity. In many branches of industry such as chemical, petrochemical, pharmaceutical or food companies this technique is routinely applied.
The properties of many plastics are impaired by larger fractions of water in the polymer. High residual water contents in the polymer pellets or granules may lead to streaks or blistering during processing, and consequently affects the quality of the product as well as its chemical and physical properties. For these reasons, the water content of polymer has to be checked to assure the desired quality of the product.
For many polymers the procedure is slightly modified: since most of them are not soluble the water is thermally extracted from the polymer and transferred to a Coulometric cell with dry carrier gas (“oven method”).
Normen: DIN 53715, ASTM D 6869-03, DIN EN ISO 15512