Most of our articles discuss NF-400 as a reinforcement compounded into thermoplastic pellets. But nanofiber mats are also directly usable in thermoset composite manufacturing — the same wet layup, vacuum bagging, and compression molding processes that composite fabricators already use with glass and carbon fabrics. The difference is that nanofiber mats are much thinner, much lighter per ply, and produce panels with distinctive mechanical properties that neither glass nor carbon can replicate at equivalent thickness.
Why Thermoset Rather Than Thermoplastic
Thermoplastic compounding (melt mixing CNC or nanofiber into a polymer) is our primary business because it integrates into injection molding workflows that dominate high-volume manufacturing. But thermoset composites — fiber reinforcement impregnated with a liquid resin that cures into a rigid solid — remain the standard for large flat panels, complex curved structures, and applications where the part geometry cannot be injection molded.
Thermoset processing also avoids the thermal degradation concern. In thermoplastic compounding, the nanofibers must survive melt temperatures of 250-280°C for several minutes. In thermoset processing, the nanofiber mat is wet with liquid resin at room temperature and cured at 80-150°C. PAN nanofibers are perfectly stable at those temperatures. The lower processing temperature also means that CNC-based reinforcements, which begin degrading above 270°C, can be used in thermoset applications where they cannot survive thermoplastic melt processing.
Mat Preparation and Resin System Selection
We supply NF-400 mats for thermoset applications on rolls, 1.2 meters wide, at basis weights from 5 GSM to 30 GSM. For structural panel applications, we recommend 12-20 GSM mats. Thinner mats (5 GSM) are used as interleaf layers between conventional glass or carbon plies to improve interlaminar fracture toughness — a specific application we will cover in a future article.
The resin system should be low viscosity at infusion temperature. Nanofiber mats have very small pore sizes (1-5 microns depending on basis weight) that resist impregnation by high-viscosity resins. For hand layup or vacuum infusion, use a resin system with mixed viscosity below 500 mPa·s at the infusion temperature. Most room-temperature cure epoxy systems meet this requirement. Vinyl ester and polyester laminating resins also work.
We have tested compatibility with three specific resin systems: Hexion EPON 862 / Lindride 6K (elevated-temperature cure epoxy), West System 105/205 (room-temperature cure epoxy), and Ashland Derakane 411-350 (vinyl ester). All three produce void-free laminates when processed correctly. Higher-viscosity resin systems — structural adhesive epoxies, filled systems, or BMI resins — may require higher pressure or elevated-temperature infusion to achieve full wetting.
Layup Procedure for a Flat Panel
The following procedure produces a 300mm x 300mm flat panel with 10 plies of NF-400 at 12 GSM in an epoxy matrix. This is our standard characterization layup for mechanical testing.
Step 1: Cut 10 plies of NF-400 mat to 300mm x 300mm using a rotary cutter. Handle the mat carefully — at 12 GSM, the mat is extremely delicate and tears easily if handled by the edges. Use gloves and support the mat flat on a rigid sheet during handling. Mark the machine direction on each ply with a small corner notch if fiber orientation matters for your application.
Step 2: Mix the epoxy resin system. For EPON 862 / Lindride 6K, mix at 100:26 ratio by weight. Degas the mixed resin under vacuum for 10 minutes to remove entrained air from mixing. The degassed resin should be bubble-free and clear.
Step 3: Apply a thin coat of resin to the mold surface (flat steel platen coated with release agent — Frekote 770NC works well). Place the first NF-400 ply onto the wet resin. Using a squeegee or roller, work resin through the mat from center to edges, expelling air. Add resin to the top surface of the ply until the mat appears translucent, indicating full wet-out. Typical resin application per ply: 15-20 grams for a 300mm x 300mm piece at 12 GSM.
Step 4: Repeat for each subsequent ply. Ensure each ply is fully wet before placing the next. Total resin consumption for a 10-ply layup: approximately 150-200 grams. The fiber volume fraction will be approximately 8-12% — low compared to conventional composites (typically 40-60% fiber) because nanofiber mats are much thinner and lighter than woven fabrics.
Step 5: Place release film and a steel caul plate on top of the layup. Transfer to the compression press.
Compression Molding Parameters
Press temperature: for EPON 862 / Lindride 6K, ramp to 120°C at 2°C/minute. Hold at 120°C for 2 hours. Cool to room temperature at 2°C/minute. The slow ramp rates are important — rapid heating causes resin viscosity to drop before the mat is fully constrained, allowing resin to flow laterally and creating dry spots. Slow cooling prevents thermal stress cracking in thick panels.
Press pressure: 0.5-1.0 MPa (approximately 75-150 psi). This is significantly lower than conventional glass or carbon fiber compression molding, which typically uses 3-10 MPa. High pressure squeezes resin out of the nanofiber mat and creates resin-starved areas. The goal is just enough pressure to hold the plies in contact and ensure consistent thickness — not to compact the reinforcement.
Resulting panel thickness for a 10-ply NF-400 at 12 GSM layup: approximately 1.8-2.2mm, depending on resin content. This is thin by composite panel standards, but the flexural modulus per unit thickness is competitive with glass fiber laminates because the nanofiber reinforcement contributes stiffness more efficiently per gram than glass.
Mechanical Properties of the Finished Panel
Flexural testing per ASTM D790 on specimens cut from our standard 10-ply NF-400/epoxy panel: flexural modulus 3.8 GPa, flexural strength 95 MPa. For context, a similar-thickness neat epoxy panel (no reinforcement) measures approximately 2.9 GPa modulus and 110 MPa strength. The nanofiber reinforcement increases modulus by 31% while slightly reducing strength.
The strength reduction is attributed to the low fiber volume fraction. At 8-12% fiber volume, the nanofiber phase introduces potential stress concentration sites (fiber ends, mat-resin interface defects) without providing enough continuous reinforcement to offset them. At higher fiber volume fractions — achievable with thicker mats or more plies at tighter stacking — the strength deficit diminishes. Our 20-ply panels at 20 GSM per ply show both higher modulus (4.6 GPa) and flexural strength above the neat epoxy baseline (118 MPa).
The most interesting property of nanofiber-reinforced thermoset panels is their impact behavior. In drop-weight impact testing (ASTM D7136), our 10-ply panels absorbed 35% more energy before penetration than equivalent-thickness neat epoxy panels. The nanofiber network acts as a distributed crack arrest mechanism — propagating cracks encounter thousands of fiber-matrix interfaces per millimeter of travel, each of which absorbs a small amount of energy through fiber debonding and pullout.
Applications and Ordering
Compression-molded nanofiber-thermoset panels are currently in evaluation for protective enclosures (instrument housings, equipment covers), interior aircraft panels (where weight is critical and flame retardancy is managed through resin selection), and sporting goods (paddle blades, helmet shells). The panels are lightweight — a 10-ply NF-400/epoxy panel weighs approximately 2.4 kg/m² — and can be post-formed by CNC machining or waterjet cutting.
We supply NF-400 mats for thermoset applications by the roll. Standard roll is 1.2m x 100m at 12 GSM. Custom basis weights (5-30 GSM) are available with minimum order of 50 square meters. Resin compatibility data sheets are available on request. Contact info@soarceusa.org for technical data or to discuss your specific layup requirements.