Modern NMR analytics for the plastics, fiber, and materials industries

Companies in the plastics, fiber, and materials industries are continuously working on higher-quality, higher-performance materials that meet complex requirements: sustainable plastics, functionalized polymer blends, high-performance and bio-based fibers.

“The performance of a polymer material is determined to a great extent by its molecular and supramolecular structure,” explains Dr. Melanie Bartel, a scientist in the Polymer Engineering department at Fraunhofer IAP. “Anyone who wants to develop new materials or optimize existing products must understand the relationships between the process, the structure, and the resulting material properties. This is exactly where NMR analytics provides highly precise, quantifiable structural information that is often only available qualitatively or in combination with other analytical methods,” Bartel says.

The new NMR equipment at Fraunhofer IAP makes it possible to analyze polymer systems in solution, as gels, and as solids at the molecular level. This allows both changes in chemical structure and molecular arrangement to be tracked—for example, during the conversion of carbon fiber precursor materials into carbon fibers or during the modification of bio-based polymers.

 

NMR infrastructure for materials research, process understanding, and quality control

At the heart of the infrastructure is a 500 MHz NMR spectrometer with three additional sample heads. Liquids, gels, and solids can thus be analyzed on a single spectrometer. This expands the possibilities for quality control, the examination of process intermediates, and the analysis of structural changes along the entire process chain.

“Our partners receive sample preparation, measurement conditions, and answers tailored specifically to their questions,” Bartel emphasizes. She adds: “We can show which structural changes occur during synthesis or processing and how these correlate with material properties. This helps identify undesirable developments early on and control optimization processes in a more targeted way.” In addition, NMR analytics makes it possible to determine the composition of unknown materials and the additives they contain.

 

Diffusion NMR for analyzing complex mixtures and formulations

Diffusion NMR adds another tool for characterizing complex mixtures in solution and diffusion processes far more comprehensively than before. The method distinguishes polymers, oligomers, and monomers based on their mobility in the solvent, thereby providing additional information about molecular sizes, the specific transport of active substances, and dynamics. For companies, this is particularly relevant when complex formulations or intermediate products need to be evaluated—for example, resins, coatings, or fiber precursors. Diffusion processes in individual process steps can also be assessed more effectively, since the diffusion coefficients of individual components can be detected and insights into the mobility and interactions of molecules can be gained.

 

NMR measurements under realistic temperature conditions

An expanded temperature control unit enables measurements in a range from minus 150 to plus 150 degrees Celsius. Reactions can therefore be monitored directly under practical conditions in the NMR spectrometer. Companies gain insights into reaction kinetics, temperature windows, and process stability. This information can flow directly into the design and improvement of industrial processes—for example, for thermally sensitive materials, reactive resin systems, or temperature-dependent conversion processes.

 

Microplastics analysis in soils and environmental samples

NMR also opens up new possibilities for analyzing soil samples. Microplastic contamination in various soils can be examined quickly and efficiently. The method enables characterization of polymer components in complex soil matrices as well as determination of the chemical composition of microplastic particles. In this way, NMR analytics supports the differentiation of various polymer types and creates a reliable analytical data basis for environmental assessments, input analyses, and material flow studies. Whether humus, forest soil, agricultural soil, or seabed: solid-state NMR provides valuable insights into the type and extent of plastic contamination in different ecosystems.

 

Optimizing carbon fibers and understanding processes better

Carbon fiber precursors, that is, the polymer precursor materials, pass through several intermediate stages during thermal conversion into carbon fibers, which can hardly be studied with conventional analytical methods. This is where solid-state NMR demonstrates its particular strengths. The new equipment makes chemical structural changes visible in these phases and creates a solid basis for targeted optimization of manufacturing processes. “For the development of high-performance carbon fibers, it is crucial to understand which molecular and supramolecular changes occur during processing,” Bartel explains. “With the expanded solid-state NMR, we can investigate these processes in much greater detail and systematically clarify process-structure-property relationships.”

 

NMR analytics supports current carbon fiber projects

Researchers at Fraunhofer IAP are already using powerful NMR analytics successfully in various carbon fiber projects. Within the CarbonLabFactory Brandenburg initiative, a project funded by the BMWE STARK program, the focus is on novel ultrahigh-molecular-weight polyacrylonitrile (PAN) copolymers that are particularly suitable for producing high-strength carbon fiber types. In the ComCarbon project, scientists developed melt-spinnable PAN copolymers that can make carbon fiber production significantly more economical.

 

Analytics and innovation from one source

Companies and research institutions receive a comprehensive analytics and development offering from a single source at Fraunhofer IAP—from sample preparation and the development of customized measurement strategies to the interpretation of results. The institute’s experts support their partners in efficiently answering specific questions from research, development, and quality control. The new NMR infrastructure is available for joint development projects, industrial collaborations on structure elucidation, and long-term research and innovation partnerships.

 

Read more about NMR analysis at Fraunhofer IAP