Frontier Applications | Exploring the Large-Scale Substitution Potential of Bio-Based Materials: Low-Field NMR Accelerates Complex Process Evaluation

Background

In late 2021, UPM-Kymmene, a Nordic-based biobased materials and bioenergy company, announced the launch of UPM BioMotion™ RFF—a “new to the world” renewable filler technology. According to its patent^[1], the technology separates lignocellulose particles and lignin particles from crude lignin. The lignocellulose can be used to produce bioethanol (see article: “LF-NMR Technology for Evaluating Bioethanol Production Process”), while the lignin is subjected to hydrothermal carbonization to obtain lignin-derived materials^[2]. These materials are rich in carbon and functional groups, allowing them to enhance the performance of rubber-based products such as tires—serving as a sustainable alternative to traditional carbon black.

On June 27, 2024, UPM announced on its official website that it had partnered with Finnish tire manufacturer Nokian Tyres to replace 30% of the reinforcing carbon black in tire sidewalls with UPM’s lignin-based filler material using RFF technology. This marks a significant step toward replacing fossil-based materials with biobased alternatives, reducing carbon emissions and lowering the carbon footprint of industrial manufacturing.

The Significance of Replacing Carbon Black with Lignin

Carbon black is a common reinforcing agent used in tires to improve the mechanical strength and wear resistance of rubber and other elastomers. It is one of the most widely used filler materials in the rubber industry, typically accounting for around 15% of material costs. However, carbon black production contributes to environmental issues such as greenhouse gas emissions, air pollution, water contamination, and solid waste. A new national standard, GB 29449-2024 “Energy Consumption Limits per Unit Product for Tires and Carbon Black,” will take effect on May 1, 2025, further restricting carbon emissions.

Amid growing environmental pressures and evolving regulations, lignin has emerged as a highly promising biobased alternative to carbon black in sustainable rubber manufacturing.

LF-NMR for Performance Characterization of Rubber and Other Polymers

Large-scale replacement of carbon black with lignin will inevitably lead to changes in rubber processing techniques.

Crosslink density is one of the most critical parameters for evaluating the performance of rubber and other polymer materials. It is widely used in process control and formulation studies, including optimizing vulcanization time, temperature, and curing agent selection. In this context, LF-NMR provides real-time support for adjusting curing conditions when replacing carbon black with fillers like silica or lignin—or even blended systems.

During vulcanization, the rubber transforms from a 2D linear molecular structure to a 3D network. As a result, its crosslink density changes significantly. Nuclear magnetic resonance (NMR) is capable of capturing the microstructural changes associated with this transition and offers advantages such as fast measurement cycles and high repeatability.

Conclusion

As a renewable, biodegradable, and biocompatible biobased material, lignin plays a critical role in reducing environmental impact. However, large-scale adoption also calls for improved process control. Low-field NMR offers a green, rapid, and non-destructive solution for measuring rubber crosslink density—making it a valuable tool for optimizing vulcanization processes and ensuring high-performance, sustainable rubber production.

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References

[1] Miettinen, Mauno. “METHOD AND APPARATUS FOR SEPARATING LIGNOCELLULOSE PARTICLE FRACTION AND LIGNIN PARTICLE FRACTION, LIGNIN PARTICLE COMPOSITION, LIGNOCELLULOSE PARTICLE COMPOSITION AND THEIR USE.” U.S. Patent No. US11,066,525B2, July 20, 2021.

[2] Lahtinen, Mika et al. “TYRE COMPRISING HYDROTHERMALLY CARBONIZED LIGNIN.” U.S. Patent No. US10,428,218B2, October 1, 2019.