Polymer analysis and polymer spectroscopy for plastics analysis

Polymers & Plastics

How Bruker's broad range of analytical systems strongly supports the polymer industry in developing new optimized polymers and efficiently producing plastics with high quality.

Polymer analysis using NMR

Polymer analysis and analysis of plastics can be carried out by using NMR in different states and under a large variety of conditions. Solid state NMR is used to analyze insoluble polymers or those that do not melt. High temperature NMR can be applied for studies of molten polymers or materials in special high temperature solvents and HR-MAS NMR can provide detailed information of polymers in solvent swollen or semi-rigid states.

The high dynamic range of the AVANCE-III system combined with the optimized probe performance makes NMR the ideal tool to study polymer end-groups, branching and other features of the material present only in minute quantities.

Polymer Characterization by Infrared and Raman Spectroscopy

Vibrational spectroscopy (Infrared, Near Infrared and Raman) is widely used for the identification and characterization of polymers. In R&D infrared and Raman spectra of polymers give insight into structures at molecular level as into orientations and conformations of polymer chains.

Furthermore FT-IR spectroscopy is very established for the quality control of industrially manufactured polymers and the used raw materials. A change in the characteristic pattern of absorption bands clearly indicates the change in the composition of the material or its contamination. If a bad spot in a plastic product was found by visible inspection, its origin is typically determined by FT-IR microanalysis as this technique is capable to analyze the chemical composition of even very small areas on the surface. Furthermore FT-IR and Raman microanalysis are used to reveal the chemical structure of multi-layered laminates.

Process Monitoring of Polymers

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 like the MATRIX-F FT-NIR spectrometer.

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.

Polymer Analysis by Mass Spectrometry

Mass Spectrometry (MS) has become an indispensable tool for polymer analysis and has been widely used to study polymer structure, polymer composition, molecular weight and molecular weight distribution, bulk and surface properties, impurity contents, and so on. MS based on accurate mass measurement and/or tandem MS (MS/MS) analysis, can generate rich chemical information that is highly specific for polymer structural analysis. MS is also very sensitive, allowing the detection and identification of minor polymer components or impurities in a composed polymeric material and any by-product of polymerization reaction of a desired polymer or additives. Rapid MS analysis can be done for many polymer samples where no prior sample treatment or extensive separation is needed. MS can potentially provide semi quantitative information required for determination of the number average molecular weight and the weight average molecular weight of an oligomeric distribution of a polymer sample or a characterization of relative amounts of different components of a blend. Some forms of MS can also be used to characterize polymer surfaces.

Matrix assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) MS has opened a new era in mass spectrometric analysis of biomolecules and synthetic polymer. ESI can be particularly useful for analyzing high mass molecules that are easy to form multiply charged gas phase ions and provide structural information for low molecular weight oligomers. In MALDI MS, “weight average” molecular weight and “number average” molecular weight information can be directly obtained for polymers of narrow polydispersity with high precision and speed as well as the determination of end groups. For high PD polymers SEC-MALDI has been established for accurate MW determinations. MALDI MS can also provide structural information and copolymer composition information, if the instrumental resolution is sufficient to resolve oligomers at the molecular weight range of interest.