N12 makes carbon nanotubes, one of the strongest materials in the universe.
N12 aligns the carbon nanotubes into a vertical array to ensure that they are all working together.
N12 places the carbon nanotubes only where they are needed—in the weakest part of the composite—the polymer-rich interlaminar region.
NanoStitch® technology “stitches” the plies together, toughening the interlaminar region and preventing delamination. NanoStitch locates trillions of precisely-aligned nano-reinforcements between fiber plies, increasing laminate shear strength and toughness, without adding weight, thickness, or porosity.
Fiber-reinforced polymer composites are commonly made of sheets of polymer reinforced with strong carbon fibers. The fiber direction of each layer is optimized for the application. However, the layers are held together by thin layers of polymer with no fiber reinforcement—the interlaminar region—thereby creating a common location for damage when the structure is stressed. Cracks can rapidly run along these interfaces – weakening and delaminating the structure and leading to structural failure.
N12 NanoStitch® is added to the surface of the prepreg to reinforce the interlaminar region. Aligned in the z-direction, the trillions of carbon nanotubes in NanoStitch® prevent crack propagation and improve the adhesive and cohesive properties of the interlaminar layer. NanoStitch allows fabricators to make composite structures that are tougher, lighter, and more durable without requiring any adjustments to their manufacturing processes.
N12 Technologies’ products for nano-enhancement of composite systems are industrial-scale, but the benefits of the underlying technology are discovered in the lab. Nanostitch, Fuzzy Fiber, and SLS have been extensively studied in the literature. A selection of journal and conference papers are referenced here. N12’s research focus today is on applying these products to new composite systems and markets to help our customers do more with their composite systems.
Presented at SAMPE Baltimore May 2015
ABSTRACT: Quasi isotropic carbon fiber epoxy laminates were fabricated for fatigue testing using a modified ASTM D2344 short beam shear (SBS) strength testing to quantify the effect of vertically-aligned carbon nanotubes (VACNTs) on fatigue life. Parts were globally reinforced with VACNTs grown in-house using a continuous chemical vapor deposition process on metallic ribbon substrate. VACNTs were then transferred onto prepreg and laminated using industry standard practices for composite manufacturing. Short beam shear fatigue testing revealed that globally reinforced laminates using VACNTs survived longer under a given cyclic load than baseline samples, resulting in a fatigue life over two orders of magnitude longer than conventional carbon fiber composite laminates.
ABSTRACT: Unidirectional symmetric ply-dropped test specimens were fabricated with vertically-aligned carbon nanotube (VACNT) forests (“nano-reinforcement”) located at specific ply interfaces to improve interlaminar mechanical properties of the structure. A second, baseline set of specimens were fabricated without nano-reinforcement for comparison. The nano-reinforced specimens exhibited 5% higher useful strength and failure modes that were distinct from the baseline set, with no change in overall mass, thickness, porosity or stiffness owing to the inclusion of VACNTs. Nano-reinforcement of the interlaminar region local to ply drops prevented crack propagation along those ply interfaces, with failures instead due to intra-ply cracking or fiber breakage, indicating nano-reinforcement mitigates weakness at ply interfaces.
ABSTRACT: Baseline and vertically aligned carbon nanotube (VACNT)-reinforced quasi-isotropic carbon fiber epoxy laminates were fabricated in parallel using out-of-autoclave (OOA) resin systems. The composite parts were tested for interlaminar shear strength (ILSS) and open hole compression (OHC) strength. High-resolution large-area maps for cross-section views of entire ILSS specimens are obtained by stitching images taken in secondary electron and backscattered electron imaging modes simultaneously to reveal the global void distribution and crack propagation. Image analysis and X-ray micro-CT were employed to assess void content. Results show VACNT-reinforcement greatly reduces void content in OOA parts. Nearly void-free OOA laminates incorporating VACNTs can be produced with less-stringent and shorter processes than otherwise required. ILSS and OHC strength are improved for up to 33% and 7%, respectively, for cross-ply epoxy laminates, through a combination of direct crack-arresting and reduced porosity. This novel design of hierarchical composite structure with interlaminar VACNT reinforcement has been successfully applied to multiple resin systems, and can be implemented within industry-standard composite manufacturing processes and requires no special tools.
ABSTRACT: Laminated carbon fiber composites are susceptible to delamination and fiber breakage when subject to impact, which in turn reduces their residual strength. This can severely reduce the service life of composite components in many industries, from aerospace to sporting goods, and cause designers to add part thickness and weight in areas of the structure where impacts are likely. Vertically aligned carbon nanotube (VACNT) forests are added to conventional unidirectional prepregs to: reinforce the interlaminar region between plies; reduce propagation of impact damage at ply interfaces; and increase compression strength post impact. Three composite systems, Newport 34-700/NCT301, Tencate IM7/TC350-1, and Hexcel IM7/8552, underwent ASTM D7136  and D7137  impact and compression testing. In all cases, VACNT reinforcement improved the residual strength of the composite after severe impacts by 11 – 16%. Characteristic impact damage of conventional fiber-reinforced polymer (FRP) composites and VACNT-toughened FRPs are compared.