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Fiber Reinforced Plastic: Definition, Properties, Types, and Applications

Fiber reinforced plastic (FRP) is a composite material with a broad range of applications. Its uses extend from everyday life to industrial applications, from terrestrial to space environments.
This article will discuss what fiber reinforced plastic is, its properties, advantages and disadvantages, and applications.

What Is Fiber Reinforced Plastic?

What Is Fiber Reinforced Plastic
Fiber reinforced plastic (FRP) is a composite material composed of a polymer matrix reinforced with fibers. The fibers can be made from various materials including glass, carbon, aramid, or basalt. These fibers enhance the composite’s strength and stiffness. The polymer matrix can be thermosetting or thermoplastic plastics, providing necessary adhesion and protection to the fibers, as well as other properties such as thermal stability and chemical resistance.

What Is the Origin of Fiber Reinforced Plastic?

The origin of fiber reinforced plastic (FRP) dates back to the early 20th century, with the invention of Bakelite by Leo Baekeland, made from phenol and formaldehyde. Significant advancements in FRP occurred in the 1930s with the development of glass fibers and suitable resins. With the introduction of new fibers like carbon and aramid, the exploration and application of glass fiber reinforced plastic in various industries have continued to evolve, enhancing its uses and functionalities.

What Is Another Term for Fiber Reinforced Plastic?

Another term for fiber reinforced plastic (FRP) is glass reinforced plastic (GRP). This terminological difference is mainly due to geographic factors, with FRP being commonly used in North America and GRP in Europe and Asia.

What Is Fiber Reinforced Plastic Made Of?

Fiber reinforced plastic, also known as fiber reinforced polymer, is a composite material made with a polymer matrix reinforced by fibers. The fibers used can be glass, carbon, aramid, or basalt fibers. Occasionally, other fibers such as paper, wood, boron, or asbestos are used. The polymer is usually a thermosetting plastic like epoxy, vinyl ester, or polyester, and more recently, polyurethane systems have also been employed.

How Are Fiber Reinforced Plastics Manufactured?

The manufacturing processes of fiber reinforced plastic (FRP) are diverse, each suitable for different applications and capable of producing materials with varying characteristics. Some common manufacturing methods include:

  1. Hand Lay-up:
    • This is one of the most basic manufacturing techniques for fiberglass. It involves manually placing the fiber-reinforced material into a mold and then applying resin. A roller is used to roll the resin into the fibers to ensure proper saturation and remove air bubbles. This method is suitable for low-volume production and large or complex shapes.
  2. Spraying:
    • Similar to hand lay-up, the spray-up method is an automated technique where chopped fibers and resin are simultaneously sprayed onto a mold. This method is faster than manual lay-up and suitable for large parts with moderate detail.
  3. Fiber Winding:
    • This method is used to manufacture cylindrical or spherical parts by winding resin-saturated fibers onto a rotating mandrel. The fibers are wound in precise geometric patterns to achieve desired strength characteristics. Common applications include pipes and storage tanks.
  4. Pultrusion:
    • Pultrusion is used to manufacture continuous, consistent cross-section profiles such as rods, beams, and channels. Fibers are pulled through a resin bath and then through a heated mold to shape and cure the material. This method is effective for large-scale production of consistent cross-sectional profiles.
  5. Resin Transfer Molding (RTM):
    • Resin transfer molding is a closed mold process that involves injecting resin into a mold containing dry fiber reinforcement. This method is suitable for manufacturing complex shapes with high surface quality and can incorporate various fiber types and resin systems.
  6. Vacuum Infusion:
    • In this process, dry fibers are laid into a mold and resin is drawn into the fibers using a vacuum. This method is suitable for large parts and produces composites with a high fiber-to-resin ratio, resulting in strong, lightweight components.

What Are the Properties of Fiber Reinforced Plastic?

Fiber reinforced plastic (FRP) possesses a range of properties that make it suitable for various industrial applications. The primary properties of fiberglass include:

  • High Tensile Strength: Fiberglass materials are known for their high strength-to-weight ratio, surpassing the strength of many traditional building materials.
  • Corrosion Resistance: Unlike metals, fiberglass does not corrode or rust, thus offering a longer lifespan in corrosive environments.
  • Lightweight: Fiberglass materials are lightweight, facilitating handling and installation, and reducing transportation costs.
  • Impact and Compressive Resistance: Fiberglass exhibits excellent impact and compressive strength, making it durable under various conditions.
  • Fatigue Resistance: Fiberglass materials exhibit good fatigue resistance, beneficial for applications subject to cyclic loads.
  • Electrical Insulation:Generally, fiberglass is non-conductive, making it suitable for electrical insulation applications. However, carbon fiber within fiberglass is an exception due to its conductivity.
  • Thermal Insulation: Fiberglass materials are poor conductors of heat, offering excellent insulation properties.
  • Low Thermal Conductivity: Fiberglass performs well at sub-zero temperatures and in high ambient temperatures, making it suitable for various environmental conditions.
  • Radar Transparency: Most glass fiber-based FRP composites are transparent to radar and radio frequencies, beneficial for applications requiring concealed communication equipment.
  • Dimensional Stability: The coefficient of thermal expansion (CTE) of fiberglass varies with the resin and reinforcement materials used but generally exhibits good dimensional stability with temperature changes.
  • Non-magnetic: Components made from glass fibers and traditional thermosetting resins are non-magnetic, which is crucial for some applications.
  • Design Versatility: Fiberglass can be molded into various shapes, textures, and colors, offering flexible design options that can replicate a wide range of architectural features.

What Are Different Types of Fiber Reinforced Plastic?

Different types of fiber reinforced plastic (FRP) are categorized based on the type of fibers used for reinforcement and the resin matrix that binds these fibers together:

  1. Glass Fiber Reinforced Plastic (GRP): GRP, also known as fiberglass, is a thermosetting plastic matrix reinforced with fine glass fibers. It is renowned for its high strength-to-weight ratio, corrosion resistance, and moldability into various shapes and sizes. GRP is widely used in the automotive, aerospace, maritime, and construction industries.
  2. Carbon Fiber Reinforced Polymer (CFRP): CFRP composites consist of carbon fibers, which, compared to other fiber materials, provide high strength and modulus of elasticity. CFRP is suitable for shear reinforcement of reinforced concrete (RC) components due to its high strength, lightweight, corrosion resistance, and fatigue resistance.
  3. Aramid Fiber Reinforced Polymer (AFRP): AFRP includes fibers like Kevlar, Twaron, Technora, and SVM, known for their high static and impact strength. AFRP is commonly used for wrapping bridge piers to prevent vehicular impact, although its use is limited by long-term strength reduction and sensitivity to ultraviolet radiation.
  4. Basalt Fiber Reinforced Polymer (BFRP): BFRP is made from basalt fibers and exhibits excellent high-temperature resistance, acid resistance, corrosion resistance, radiation resistance, and UV resistance. BFRP has a high tensile strength and good durability but is less commonly used in practical applications.

What Are the Benefits of Using Pultrusion for Manufacturing Fiber Reinforced Plastic?

Pultrusion Manufactured Process

The advantages of using pultrusion for manufacturing fiberglass composites include:

  • Cost-effectiveness: Pultrusion is an economical manufacturing process suitable for large-scale production and manufacturing of long-length products.
  • High Production Efficiency: Pultrusion typically operates at speeds of 0.5-2 meters/minute, allowing for rapid production of profiles.
  • Consistent Quality: Pultrusion produces fiberglass profiles with consistent dimensions and a smooth appearance, ensuring consistency in the final products.

What Are the Limitations of Fiber Reinforced Plastic?

The limitations of fiber reinforced plastic (FRP) include:

  1. Low Modulus of Elasticity: The modulus of elasticity of glass fiber reinforced plastic is significantly lower than that of steel, making it less rigid and more prone to deformation under structural loads. Using high-modulus fibers or steel reinforcement can mitigate this issue to some extent.
  2. Poor Long-Term Temperature Resistance: Glass fiber materials typically cannot withstand high temperatures for extended periods. The strength of polyester-based fiberglass decreases significantly above 50°C, and that of epoxy-based fiberglass also drops noticeably above 60°C. However, high-temperature resistant resins can increase the long-term working temperature to 200-300°C.
  3. Aging: Fiberglass materials are prone to aging, with factors such as UV radiation, wind, rain, snow, chemical media, and mechanical stress causing performance degradation over time.
  4. Low Interlaminar Shear Strength: The interlaminar shear strength of fiberglass is relatively low, as it is primarily borne by the resin. This can be improved by choosing appropriate manufacturing processes and using coupling agents, but interlaminar shear must be considered in design.
  5. Complex Design and Manufacturing: Due to the anisotropy of fiberglass materials, designing components with fiberglass can be very complex. Additionally, the manufacturing and testing of fiberglass components require specialized knowledge and technology.
  6. Strength Perpendicular to Fiber Direction: The strength of fiberglass perpendicular to the fiber direction is much lower than along the fiber direction (up to 5%), which may limit the material’s performance in some applications.
  7. Sensitivity to Notches and Holes: Fiberglass materials are highly sensitive to notches and holes, which can become stress concentration points, significantly reducing the material’s strength, especially in the direction without fibers.
  8. Cost: Although fiberglass materials offer many advantages, their cost may be higher than traditional materials like steel or concrete, especially in applications requiring high-performance resins or fibers.
  9. Recycling and Disposal: Due to the durability and chemical resistance of fiberglass materials, the recycling or disposal of fiberglass products can be challenging, raising environmental concerns.

Compare With Other Material

When comparing Fiber Reinforced Plastic (FRP) with traditional materials such as steel, aluminum, wood, and concrete, each material has clear advantages and disadvantages depending on the application.

Fiberglass vs. Steel

  • Corrosion Resistance: Fiberglass has strong resistance to corrosion, unlike steel which requires protective treatments like galvanizing to prevent rust.
  • Weight: Fiberglass is much lighter than steel, typically reducing weight by 75%, which can lower transportation and installation costs.
  • Strength: Steel generally has higher tensile strength, while fiberglass has a high strength-to-weight ratio, making it sufficiently strong for many applications while being lighter.
  • Maintenance: Fiberglass requires less maintenance compared to steel as it does not corrode and does not need repainting.
  • Thermal and Electrical Performance: Fiberglass is a better thermal and electrical insulator, whereas steel is a conductor.

Fiberglass vs. Aluminum

  • Corrosion Resistance: Both materials are corrosion-resistant, but fiberglass is not affected by galvanic corrosion, whereas aluminum can suffer from galvanic corrosion when in contact with dissimilar metals.
  • Weight: Fiberglass is about 30% lighter than aluminum, which is already known for being lightweight.
  • Strength and Flexibility: Compared to aluminum, fiberglass offers more reliable flexibility and strength in similar applications.
  • Thermal Conductivity: Fiberglass has a lower thermal conductivity, making it a better insulator than aluminum.

Fiberglass vs. Wood

  • Durability: Fiberglass does not rot, warp, or decay, making it more durable in harsh environments than wood, which is prone to these issues.
  • Maintenance: Fiberglass does not require preservatives or coatings for moisture and pest protection like wood does.
  • Strength: Fiberglass generally has higher strength and can be engineered to meet specific load requirements, unlike wood, which has natural variability.

Fiberglass vs. Concrete

  • Weight: Fiberglass is much lighter than concrete, making it easier to handle and install.
  • Installation Speed: Fiberglass can be prefabricated and installed much faster than concrete, which requires curing time.
  • Durability in Harsh Environments: Fiberglass is more resistant to chemical corrosion and environmental conditions than concrete, which can suffer from rebar corrosion and cracking.
  • Design Flexibility: Fiberglass can be molded into complex shapes and sizes, which is more challenging for concrete.

What Are the Different Applications of Fiber Reinforced Plastic?

frp application
Fiber reinforced plastic (FRP), with its unique properties such as high strength-to-weight ratio, corrosion resistance, and design flexibility, is widely used across various industries. Here are some of the key applications of fiberglass discussed in the provided materials:

  1. Automotive Industry: Fiberglass is used as a metal substitute for luxury car bodies, truck and trailer body side panels, and engine components such as intake manifolds. It helps reduce weight, simplify designs, and improve fuel efficiency. Throttle and clutch pedals can also be replaced with glass-fiber reinforced plastic, increasing productivity at a lower cost.
  2. Construction Industry: Over 20% of fiberglass is used in the construction industry to retrofit existing structures, enhancing their load-bearing capacity or repairing damage. Fiberglass is also used in manufacturing highway structures such as guardrails, signboards, drainage systems, bridge decks, as well as in constructing prefabricated homes, office furniture, household appliances, swimming pools, rain gutters, bathroom fixtures, pipe fittings, and covers.
  3. Aerospace Industry: Compared to aluminum, carbon fibers in fiberglass can reduce weight by 25% while ensuring equal or greater strength. Fiberglass is used to produce complex molded parts, significantly reducing the number of parts. Modern aircraft and high-end drones increasingly use fiberglass for manufacturing helicopter rotors.
  4. Sports and Recreation: Fiberglass is used in sports equipment, musical instruments, firearms, camping tents, and camera tripods, benefiting greatly from its lightweight and high-strength characteristics.
  5. Marine and Coastal Environments: Fiberglass is an ideal substitute for wood in marine environments, reducing structural weight and enhancing corrosion resistance. Applications include rolling bridges, floating walkways, and offshore base platforms.
  6. Wastewater and Water Treatment: The anti-corrosion, rust-proof, and corrosion-resistant properties of fiberglass make it suitable for water treatment applications. It is used in structural shapes, walkways, ladders, trough components, parallel plates, and gate guides.
  7. Pedestrian Bridges: Compared to wood and steel, fiberglass composite materials are durable and maintenance-free, making them the material of choice for pedestrian bridges.
  8. Cooling Towers: Fiberglass maintains the integrity of cooling tower structures, offering a cost-effective and low-maintenance material choice.
  9. Military Applications: The high strength, corrosion resistance, and lightweight properties of fiberglass are beneficial for designing walkways, troop seating, and other military applications.
  10. Oil and Gas Industry: Fiberglass has anti-corrosion and saltwater resistance capabilities, making it an ideal material for coastal and offshore operations. It is used for stairs, platforms, walkways, and ladders.
  11. Utility Applications: The non-conductive properties of fiberglass make it suitable for utility applications, reducing impact risks and withstanding chemical tanks and exposure to natural elements.
  12. Chemical Processing Plants: Fiberglass platforms, ladders, and railings are used in corrosive chemical plant environments due to their rust-proof and moisture-resistant properties.
  13. Pulp and Paper Industry: The corrosion resistance and electrical insulation properties of fiberglass make it an ideal material for walkways, ladders, and other industrial applications in the pulp and paper industry.

How Strong is Fiber Reinforced Plastic?

Fiber reinforced plastic (FRP) has considerable strength, with tensile strength and compressive strength close to that of ordinary construction steel Q235. Specifically, the tensile strength of glass fiber reinforced plastic is reported to be 293.75 megapascals, and its compressive strength is 254 megapascals. However, the modulus of elasticity of fiberglass is lower than that of steel, with the modulus of fiberglass being 6,246 megapascals, while steel’s modulus is 200 GPa (2 x 10^5 megapascals). Despite the lower modulus of elasticity, the high strength-to-weight ratio, corrosion resistance, and other advantageous properties of fiberglass make it a viable alternative for many applications traditionally using steel.

What Is the Surface Treatment of Fiber Reinforced Plastic?

Different methods for surface treatment of fiber reinforced plastic, particularly carbon fiber reinforced plastic (CFRP), include:

  1. Plasma Treatment: Utilizes partially or fully ionized gas containing electrons, free radicals, ions, and neutral atoms or molecules to introduce oxygen functional groups on the carbon fiber surface, improving interfacial adhesion.
  2. Acid Oxidation: Involves using acid to oxidize the carbon fiber surface, enhancing its chemical reactivity and bonding capability
  3. Rare Earth Treatment: Uses rare earth elements to modify the carbon fiber surface, thereby improving its mechanical properties and adhesion to the matrix.
  4. Gamma Irradiation: Uses gamma rays to alter the surface properties of carbon fibers, thereby increasing the bond strength between the fibers and the polymer matrix.
  5. Laser Treatment: Involves using laser ablation (including femtosecond laser radiation) to selectively remove contaminants or alter the surface of CFRP composites while minimizing damage to the material.
  6. Chemical Treatment: Uses chemical agents to alter the fiber surface, increasing surface roughness or energy to improve adhesion with the matrix.
  7. Cleaning/De-oiling: Removes organic substances such as grease from the adherent surface, which is crucial for enhancing the adhesion of coating or bonding processes.
  8. Surface Roughening: Uses abrasive materials to remove unwanted layers and roughen the surface texture, thereby improving mechanical interlocking.

Is FRP the Same as Fiberglass?

No, fiberglass is different from glass fiber. Although these two terms are often used interchangeably, there are technical differences between them. Glass fiber refers to the glass fibers themselves, which can be used alone or as reinforcement in various composite materials. When combined with polymers such as plastic, metal, or ceramics, the resulting composite material is stronger than the individual materials and is known as glass fiber reinforced composite. However, if specifically referring to a composite material with a plastic matrix reinforced with glass fibers, it is called glass fiber reinforced plastic (GRP).

FRP, or fiber reinforced polymer, is a broader term that includes composite materials made with a fiber-reinforced polymer matrix, which includes not only glass fibers but also carbon fibers, aramid fibers, basalt fibers, or other types of fibers. Therefore, while all GRP is a type of FRP, not all FRP is GRP, as FRP can use various types of fibers and resins to manufacture materials to meet specific application requirements.

How Durable is FRP?

Fiberglass (fiber reinforced polymer) is highly durable, with durability tests proving that it can be used for over 50 years, significantly extending the lifespan of buildings and structures. This durability is attributed to fiberglass’s ability to withstand wear, tearing, everyday stresses, and common damages sustained by concrete buildings and structures. Fiberglass is more robust and durable than steel, especially in water-exposed conditions where it exhibits significantly better corrosion resistance than steel, which ages under similar conditions. Durability tests conducted in the UK include comprehensive testing of wall samples, a five-layer masonry research building, six-foot diameter columns, and column arch rib joints, all of which emphasize the reliability of fiberglass over extended periods.

How Does FRP Fail?

FRP (fiber reinforced plastic) can fail through various modes, including:

  1. Delamination: This refers to the separation or debonding of the laminate layers within the glass fiber reinforced plastic material. Delamination significantly reduces the panel’s bending stiffness and can occur even if there are no visible defects on the surface or free edges.
  2. Matrix Failure: This includes matrix compression failure and matrix tensile failure, where the former refers to the matrix material failing under compressive load and the latter refers to the matrix cracking under tensile stress. Matrix failure results in a reduction in the load-bearing capacity of fiberglass.
  3. Fiber Failure: Fiber tensile failure is an explosive event that releases a large amount of energy, potentially leading to catastrophic damage, especially in structures where the load cannot be redistributed.
  4. Debonding: This refers to the interface failure between fiberglass and its bonded substrate, such as fiberglass sheets used for reinforcing concrete structures. Debonding can be caused by manufacturing defects or stress concentrations.
  5. Creep Fracture: This is a time-dependent failure that occurs under sustained loads, leading to a gradual decline in mechanical properties and eventual fracture.
  6. Interlaminar Shear Failure: Shear failure occurs between the layers of the composite material, primarily borne by the resin.

Is FRP a Good Insulator?

Yes, FRP (fiber reinforced plastic) is an excellent insulating material. Its low thermal conductivity makes it an effective insulating material, maintaining a constant temperature and cool touch. Glass fiber reinforced plastic also has excellent electrical insulation properties, as it is usually made from multiple layers of glass fibers saturated with various resins, all of which are electrical insulators. These properties make fiberglass suitable for applications requiring thermal or electrical insulation, such as utility poles, circuit boards in electronic products, and structural and electrical components in various industries.

Conclusion

We hope this guide has provided you with a thorough understanding of fiber reinforced plastic.
For more information on all types of fiber reinforced plastic, please contact us immediately.

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