An Eco-Friendly Kenaf–Sisal Hybrid Fibre Reinforced Epoxy Composites as a choice of Conventional Fibre Board for High-Voltage Insulation Applications

Imagine you are trying to build a shield to protect a delicate electronic heart from a lightning storm. For decades, engineers have used heavy, synthetic "armor" made from man-made plastics and fibers to keep high-voltage electricity in check. These materials are tough, but they are also heavy, hard to recycle, and often require a lot of energy to create. Now, picture a different kind of shield: one woven from the very plants that grow in our gardens and fields. This is the world of "natural fiber composites," where scientists mix plant strands with sticky resins to create materials that are strong, light, and kind to the planet. The big question researchers are asking is: Can a shield made of plants actually stand up to the same massive electrical pressures as the heavy, synthetic ones we use today?

This paper dives into that exact question by testing a unique team-up between two powerful plants: Kenaf and Sisal. Think of Kenaf as the stiff, rigid backbone of the team, providing structure, while Sisal acts as the tough, flexible muscle that absorbs shocks. The researchers mixed these two plant fibers together with a special glue called epoxy resin to create a new kind of "hybrid" board. They wanted to see if this plant-based team could outperform the traditional, conventional fiber boards currently used in high-voltage electrical equipment. By treating the plant fibers with a chemical bath (like a tough scrub to make them stick better) and testing them under extreme conditions, the study explores whether nature's own materials can become the new champions of electrical insulation.

The Plant Power-Up: Mixing Kenaf and Sisal

The researchers started with a simple idea: why not combine the best traits of two different plants? Kenaf fibers are known for being lightweight and stiff, while Sisal fibers are famous for their incredible toughness and ability to stretch without breaking. By weaving them together into a single material reinforced with epoxy resin, they hoped to create a "super-material" that was better than either plant could be alone.

However, there was a catch. Plant fibers are naturally a bit slippery and love to soak up water, which makes them hard to bond with the sticky epoxy resin. To fix this, the team gave the fibers a chemical makeover. They soaked the Kenaf and Sisal strands in a sodium hydroxide solution (a type of alkaline liquid) for 24 hours. You can think of this as a deep-cleaning spa day for the fibers; it stripped away the waxy, dirty outer layers and made the surface rough and ready to grab onto the epoxy. This treatment was crucial because it helped the fibers and the resin lock together tightly, preventing water from sneaking in and weakening the structure.

The Great Test: Stress, Shock, and Electricity

Once the "plant-epoxy" boards were created, the team put them through a gauntlet of tests to see how they held up. They made several versions of the material, changing the amount of fiber in the mix. Some had just a little fiber, while others had a lot. They also included a "control group" of plain epoxy (just the glue) and a standard commercial fiber board to see how the new plant mix compared to what is currently used in the real world.

The Muscle Test (Mechanical Strength)
First, they tested how much force the materials could take before breaking. They pulled them apart (tensile strength), bent them (flexural strength), and hit them with a heavy swing (impact strength).
The results were exciting. As they added more fiber to the mix, the material got stronger and stiffer. The sweet spot was found at a 30 wt% fiber loading (meaning 30% fiber and 70% epoxy). At this ratio, the hybrid composite showed off its best performance:

• Tensile Strength: 94.8 MPa
• Young's Modulus (Stiffness): 6.21 GPa
• Flexural Strength: 142.3 MPa
• Flexural Modulus: 6.91 GPa
• Impact Strength: 11.32 KJ/m²

This 30% mix was significantly stronger than both the plain epoxy and the traditional fiber board. However, when they pushed the fiber content to 40 wt%, the performance actually dropped. Why? Because too much fiber caused the strands to clump together like a tangled ball of yarn, creating weak spots and air bubbles that made the material easier to break.

The Lightning Shield Test (Dielectric Properties)
Next, they tested the most important part: could this plant board stop electricity from leaking through? They subjected the materials to high voltages ranging from 33 KV to 132 KV and tested them across a wide range of frequencies from 10² to 10⁶ Hz.

The goal was to keep the "dielectric constant" (how well the material holds an electric charge) stable and the "dissipation factor" (how much energy is wasted as heat) as low as possible.

• The Winner: The 30 wt% hybrid composite again took the crown. It showed the lowest energy loss and the most stable electrical properties.
• The Frequency Effect: Interestingly, as the frequency of the electricity increased, the energy loss in all materials went down. This is a good thing, meaning the materials handle high-speed electrical signals very well.
• The Comparison: The new plant hybrid was much better at insulating than the traditional fiber board, which struggled with moisture and lost more energy. The treated fibers in the hybrid composite created a tight seal that kept the electricity where it belonged.

The Heat and Water Challenge
Finally, they checked how the materials handled heat and water.

• Heat: Using a technique called Thermogravimetric Analysis (TGA), they heated the samples up to 700 °C. The 30 wt% hybrid composite showed improved stability compared to the traditional board, with an onset degradation temperature of 338 °C and a residue of 31.2%. However, the study notes that while these hybrid composites are feasible for electrical insulation, they possess only a moderate degree of thermal stability under these conditions, rather than being exceptionally heat-resistant.
• Water: Natural fibers usually hate water, but the chemical treatment helped. The 30 wt% hybrid absorbed the least amount of water compared to the other samples and the traditional board. Even after being soaked and aged in humid conditions, the plant hybrid kept its strength much better than the old fiber boards, which fell apart quickly.

The Verdict: A Green Alternative

The study concludes that this Kenaf-Sisal hybrid composite, specifically the one with 30 wt% fiber loading, is a serious contender for replacing traditional fiber boards in high-voltage electrical applications. It proved to be stronger, stiffer, and better at blocking electricity than the conventional materials, all while being made from renewable, eco-friendly plants.

The researchers found that the secret sauce was the combination of the two different fibers working together and the chemical treatment that made them stick perfectly to the epoxy. While the material isn't perfect (too much fiber causes clumping) and its thermal stability is moderate, the 30 wt% mix offers a promising, sustainable path forward for the electrical industry. It suggests that we might soon be able to build our power grids and electrical shields using materials that grow in the ground, rather than just relying on heavy, synthetic plastics.