Lowell, Mass. August 4, 2025 – Specialty Materials, a leading global supplier of chemical vapor deposition (CVD) boron and silicon carbide fibers, recognizes the research team from the Department of Aeronautics at Imperial College London for their innovative research exploring the mechanisms enabling exceptional compression performance in carbon-boron fiber hybrid composites The team of Dr. Gursahib S. Bhatia, Ms. Hwei Linn Khoo, Dr. Torquato Garulli, Dr. Soraia Pimenta, Prof. Paul Robinson, Prof. Emile S. Greenhalgh, and Prof. Silvestre T. Pinho will present their paper, "Localized Hybridization using Boron Fibers: A Route to Improve Open Hole Compressive Performance," in an oral presentation at the 24th International Conference on Composite Materials (ICCM24) this August in Baltimore.

Recent studies by the Imperial College London team have provided significant experimental insights into how 4 mil (100 μm) boron fibers, when used as selective reinforcement in carbon fiber composites, fundamentally alter the failure mechanisms under longitudinal compression. Using digital image correlation combined with in-situ scanning electron microscopy, the researchers discovered that boron fibers not only arrest the propagation of damaging kink bands—a common failure mode in traditional carbon fiber composites—but also promote a novel damage deflection mechanism. This mechanism causes cracks to deflect along the carbon/boron interface, diffusing damage and allowing the composite to withstand loads up to 35% higher even after initial failure events. The research validates the 94-107% improvement in room temperature quasi-isotropic open-hole compression strength compared to current industry-standard carbon fiber systems under ASTM D6484 testing protocols at the National Institute for Aviation Research (NIAR, Wichita, Kansas USA).

Specialty Materials is pleased that its Hy-Bor® prepreg materials, specifically the 52 FPI (fiber per inch) configuration featuring monofilament boron fiber in combination with Toray T1100 carbon fibers and Toray TC275 toughened epoxy system, have enabled this novel study. This research provides a scientific understanding of why Hy-Bor® hybrid composites are uniquely suited for critical lightweight structures in aerospace, space, and high-performance sporting applications where compression strength and damage tolerance are paramount.

"We are delighted to see rigorous scientific validation of the unique micromechanical behavior that boron fiber enables in composite structures," said Monica Rommel, CEO of Specialty Materials. "This work performed at Imperial College London not only deepens the scientific understanding of fiber hybridization mechanisms but also provides critical insights that will guide our ongoing development of next-generation Hy-Bor® materials with tailored property profiles. These findings correlate strongly with the real-world performance advantages we're seeing in aerospace and defense applications."

The research team of Imperial College London adds, "Our research demonstrates that strategic placement of boron fibers creates a hierarchical reinforcement system that fundamentally changes how composites respond to compression loading. The unique diameter and properties of boron fibers provide reinforcement at a scale that effectively bridges the gap between micro and meso-mechanical behavior, offering new design possibilities for ultra-high-performance composite structures."

The full results and further discussion of the mechanisms enabling high compression performance in boron fiber hybrids will be presented by the Imperial College London team at ICCM24 on Friday, August 8, 2025, at 9:55 AM in the Compressive Failure session. Key findings include:

• Detailed characterization of kink band arrest mechanisms at the boron-carbon interface,

• Quantification of stress redistribution effects around boron fibers under compression and how this affects the failure process,

• Comparison of failure initiation and propagation in hybrid and baseline configurations, and

• Correlation between micromechanical observations and macroscopic composite performance.

Specialty Materials has provided materials for this research and recognizes the importance of independent academic investigation in validating and advancing the field of advanced composites. The research was funded by the UK Engineering and Physical Sciences Research Council (EPSRC) programme Grant EP/T011653/1, Next Generation Fibre-Reinforced Composites: a Full Scale Redesign for Compression in collaboration with University of Bristol.

About Specialty Materials
Specialty Materials., founded in 1987, is a certified woman-owned small business (WOSB) based in Lowell, Massachusetts specializing in boron and silicon carbide fibers for advanced composite materials. Its Hy-Bor® portfolio of hybrid composite prepregs is used as selective reinforcement in aerospace, defense, space, and sporting goods applications to deliver unmatched compression performance, stiffness, and damage tolerance. visit www.specmaterials.com.