Nelcote V-376C Cyanate Ester Epoxy Prepregs and 7781E + AS4A E-Glass reinforcement are prepregs or fabrics. As a result, we use them with a BPO/BMS resin system. So, these composites help demand airframe applications. So, they require good heat resistance and high performance.
Nelcote V-376C Cyanate Ester Epoxy Prepregs offer an epoxy-based adhesive bond strength of approximately 50 MPa. Additionally, they also offer a unidirectional tensile strength of approximately 38 MPa. Combined with the resin system’s heat resistance and good mechanical properties, these materials are ideal for applications where we need a high-temperature cure.
Nelcote V-376C Cyanate Ester Epoxy Base Resins are thermosetting resins. They cure at elevated temperatures and show broad temperature resistance. Nelcote V-376C Cyanate Ester Epoxy Base Resins are highly resistant to moisture, water vapor, alcohols, acids, and most organic solvents. Additionally, they have good chemical resistance. This includes aromatic solvents, oils, greases, and many food products.
Nelcote V-376C Cyanate Ester Epoxy Prepregs feature;
1). A solvent dissolving resin system that provides good adhesion to and bonding with various materials. They include low-temperature plastic and rubber,
2). An epoxy resin/hardener combination provides excellent tensile and impact strength.
Additionally, the 7781 EB resin system is also compatible with other polyester-based polycarbonate resins such as 3 M’s Rocol and Eskimo. In addition, the 7781 + AS4A E-Glass reinforcement system can also be helpful in the fabrication of composite parts where the heat of repair requirement is high.
3). A high wet out of fabric with no need for “backing” with a release agent and
4). An excellent dielectric strength of 2500 V/mil.
The Nelcote V-376C Cyanate Ester Epoxy Prepregs is suitable for use with the 7781 EB resin system. The 7781 EB resin system is a modified butyl rubber-based epoxy binder. As a result, it allows general-purpose resins to fabric fiberglass-reinforced prepregs and composite parts. In addition, the 7781 EB resin system utilizes chlorinated butamides to lower the viscosity. Therefore, it enables the impregnating of more epoxy and more resin into the fiberglass fabric.
The Nelcote V-376C Cyanate Ester Epoxy Prepregs are suitable for use with the 7781 EB resin system. Additionally, other composite materials, such as ABS and polycarbonate, may also be helpful with the Nelcote V-376C Cyanate Ester Epoxy Prepregs.
V-376C Cyanate Ester Epoxy Prepregs come in widths up to 122 inches (3.15 m) and lengths up to 200 inches (5.08 m).
1). Thickness, nominal, 0.020″ to 0.250″; Specific Gravity, 1.89 ± 0.05;
2). Water Absorption, 24 hours at 23°C (73°F), by weight, ASTM D570
3). Ultimate Tensile Strength at Break and Elongation at Break of Fabric in 8” (20 cm) wide specimens as Tensile Strength, 35%, ±5%;
4). Compressive Stress-at Break, 40% of Specimen width, ±3%; and
5). Apparent Density (Air = 1), g/cm3 at 25°C (77°F), 915 to 945; and a Specific Gravity of 1.895 to 1.915.
The resin-epoxy adhesive on Nelcote V-376C Cyanate Ester Epoxy Prepregs provides a bond strength of approximately 50 MPa. They also offer a unidirectional tensile strength of approximately 38 MPa.
Tensile testing (ASTM D638B Method A) happened on 2”× 2” samples of the fabric in tension at room temperature (23°C ±2°C).
We test the stripping characteristics of the V-376C Cyanate Ester Epoxy Prepregs by placing a 20 gm sample of prepreg in a glass jar. Then, we added distilled water and measured weight after 24 hours at 23°C ±2°C. We do not add any solvent to the water.
We test the adhesion strength of the V-376C Cyanate Ester Epoxy Prepregs by applying ten gms/sq. The prepreg-inch to a steel plate and heat curing at 160°C in an oven for 30 minutes.
Then we conduct functionality testing on the V-376C Cyanate Ester Epoxy Prepregs. We measure dielectric strength, tensile strength, and compression test results.
The variable thicknesses and composition of the fibers in the high-performance BPO/BSS system added flexibility to design alternatives that they could now incorporate into airframe designs.
Then they evaluate three different BPO/BSS resin systems in airframe applications. Additionally, Rayming PCB & Assembly test the first system in a simple, one-piece foam sandwich structure and a two-piece foam sandwich structure.
Secondly, they test the second BPO/BSS system in a one-piece carbon-fiber sandwich structure that incorporated some Nelcote V-376C Cyanate Ester Epoxy Prepregs. Finally, they compare this sandwich
The third BPO/BSS system helped test Nelcote V-376C Cyanate Ester Epoxy Prepregs in an airframe prototype deployed as a “drone.” As a result, we build this prototype with a carbon fiber/epoxy sandwich. They use a Nelcote V-376C Cyanate Ester Epoxy Prepregs in the airframe and the fuselage.
The final prototype, built with BPO/BSS resin systems, had more than 350 pounds (160 kg) and a wingspan of 41.5 feet (12 m). This airframe was also the first to incorporate a one-piece integral air intake duct and an integral, heavily modified Pratt & Whitney JT8D engine.
As with the previous BPO/BSS applications, a five-layer laminate was helpful. The first four layers were fiberglass/epoxy and comprised the pre-engineered structure. We applied the final layer over the engine in a glass/epoxy matrix to dissipate heat from the engine.
The prototype was subject to various testing and evaluation procedures. It includes static and dynamic tests, oil/gas/vapor diffusion testing, LCA studies, and thermal fatigue testing. This testing revealed that the structural integrity of the BPO/BSS airframe design was excellent, with no unexpected failures.
Advantages of BPO/BSS Systems
Using the BPO/BSS system significantly decreased the cost of manufacturing these resulting aircraft. The cost of labor was also considerably reduced. In addition, BPO/BSS did not generate any hazardous waste and could safely work using standard shop tools and skills.
Disadvantages of BPO/BSS Systems:
BPO/BSS systems also had structural limitations, such as poor resistance to crush and vibration. In addition, this application-specific batch design influences the mechanical properties of the resin and fiber. For example, it creates a thermal mismatch between the epoxy and fiberglass layers. However, it presented problems with heat dissipation during flight.
They constructed the simple sandwich design from a 3” “T” shaped fiberglass backplate attached to a 4” × 2” × .125” (10 × five × 3 mm) layer of 1.25 lb/ft2 (86 g/m) BPO-31 epoxy. The laminate was then bonded (I-beam style tooling) onto a backplate. Finally, they bonded the upper portion of the sandwich to a 1” round fiberglass nosecone. They used this BPO/BSS system as a prototype for a mid-size aircraft.
Nelcote V-376 Cyanate Ester Epoxy Prepregs, 7781 E-Glass Reinforced Epoxy Resins, and the BPO/BSS System have met or exceeded all testing and performance requirements aircraft, aerospace, defense, and industrial applications.
The durability of the V-376C Cyanate Ester Epoxy Prepreg remained intact. After exposure to an oil/gas/vapor test, it has no significant degradation. A fuel surrogate was helpful in this test because its results are like those of jet fuel.
The Nelcote 7781 E-Glass Reinforced Epoxy Resins performed as expected in all LCA studies. In addition, it did not produce any negative effects.
The end-user was extremely satisfied with the performance of Nelcote V-376C and the BPO/BSS system. This airframe prototype incorporated a one-piece carbon-fiber sandwich. It was a unique construction in aircraft design at that time, and it performed flawlessly.