Glass Fiber Composites: Properties, Manufacturing and Applications

Last Updated on 19/08/2021

Glass Fiber Composites (GFC)

Moin.S Khan
DKTE’s Textile and Engineering Institute,
Ichalkaranji, Maharashtra, India


Glass fiber composites (GFC) are one kind of fiber reinforced polymer composites. It holds good properties such as low density, high strength, and easy processing, so widely used in aerospace, automotive, and construction. Today, almost any specialization for structural material can be met by combination of glass fiber and plastic resin, which are characterized by many outstanding properties. During 1942 glass fiber reinforced composites were first used in structural aerospace parts. In the early 1960’s high strength glass fibers, S-Glass were first used in joint work between Owens corning textile product and the United States air force later in 1968 S-2 glass began evolving into a variety of commercial application. High strength glass fiber combines high strength, high stability, transparency and resilience at a very reasonable cost-weight performance. The utilities of high strength glass fiber composites are compared by physical, mechanical, electrical, thermal, acoustical, optical and radiation properties.

The glass fiber composites strength/weight ratios are higher than those of most other materials and their impact resistance is phenomenal. Further they possess good electrical properties, resistance to moisture and outdoor weathering and resistance to heat and chemicals. These properties are coupled with ease of fabrication.

Composites are artificially produced multiphase materials having a desirable combination of the best properties of the constituent phases or more precisely these are the materials consist of fibers of high strength and modulus embedded in or bonded to a matrix with distinct interfaces between them.

classification of composites

Properties of glass fibers

  1. Incombustibility
  2. Corrosion resistance
  3. High strength at low densities
  4. Good thermal.
  5. Sound insulation
  6. Special electrical properties.

Typical Properties of Glass Fibers:

Typical Properties of Glass Fibers

Manufacturing of glass fiber:
Glass fibers basically made by,

  • Mixing silica sand, limestone, boric acid and other minor ingredients.
  • The mixture is heated until it melts at about 1260oC/2300oF.
  • Letting the molten glass flow through fine holes. (In a platinum plate)
  • The glass strands are cooled, gathered and wound. (Protective coating may be added.)
  • The fibers are drawn to increase the directional strength.
  • The fibers are woven into various forms for use in composites.

Types of glass fiber:


  • A         Soda-lime glass.
  • E          Electrical type (Borosilicate)
  • C         Chemical resistant type
  • AR      Alkali resistant type
  • S          High performance application


  • General purpose glass fiber
  • Quartz fiber
  • Protective fiber
  • Hollow fiber
  • Conducting/Semi-conducting

Various properties of different glass fibers

Properties E-glass AR-glass S-glass
Tensile Strength (Gpa) 3.5 3.5 4.6
Modulus (Gpa) 73.5 175 86.8
Elongation (%) 4.8 2 5.4
Density (g/cc) 2.57 2.68 2.46
Refractive Index 1.547 1.561
Coefficient of Thermal Expansion (107/0C) 50-52.0 75.0 23-27.0
Dielectric Constant RT, 1010 Hz 6.1-6.3 5.0-5.1


Glass fabric:
This form of glass fiber is particularly suitable for high strength, low weight laminates. Continuous filament glass is preferred in these applications on account of it’s greater strength and low bulk factor. The fabric woven from continuous filament yarn ranges in thickness from 0.002-0.02 inches. In general directional properties of laminates depend on the type of weave and cloth setting employed. (We’ll discuss this later). The example of fabric-reinforced plastic is aircraft radar. In this application, a material is required which will allow the radar rays to go without distortion from the rays sending equipment out of the target and then back to the radar receiving equipment on the plane. It must also stand the air pressure strain of a sonic or supersonic speed. Combination of glass fabric and low-pressure plastic resin provides an excellent answer to these requirements.

Combination of glass fabrics and fire-proofed polyester resin are also used for making high strength flat and shaped laminates for aircraft components such as a ducting, panels, nose, wings tips, rudder parts, covers, dash-boards, shelves, floors.

This material is also used for hollow fishing rods, where unidirectional fabric lends itself to winding round a solid mandrel, for body armor and for the manufacture of large article such as boats by the low pressure technique and for many other products.

Molding techniques
Molding methods are almost legion. At present count more than 22 general molding methods is basic process categories are widely used. These includes:

  1. Hand and spray saturating and mixing.
  2. Continuous impregnation, laminating.
  3. Cure or flat or corrugated panels, solid rods, hollow bar stock.
  4. Compression, transfer and injection molding.
  5. Filament wrapping and winding.
  6. Centrifugal and static casting.
  7. Rotational molding.
  8. Cold forming.
  9. Combination of those above.

Effect of different weaves
The plain weave fabric having square setting i.e. equal number per inch of ends in the warp as picks, is employed where uniformity in strength is desired. Another popular structure is 8-shaft satin weave, in which each weft yarn goes under one and over seven warp yarns. It is mostly used in heavier fabrics when lamination calls for high strength in all direction and where a smooth surface and decorative appearance are desired. Due to lower crimp or ‘weaving take up’ the strength of a satin weave fabric is comparatively greater then of a plain weave fabric.

When maximum strength in one direction is required at a maximum weight, a unidirectional weave is employed. In order to produce such a fabric, usually a large amount of relatively strong warp yarn and fewer weaker weft yarns are employed.

Nonwoven materials from glass fiber are dominated because least labor intensive and most efficient to manufacture.

Different weaves of glass fiber

Glass fiber composites making inroads many markets due to general properties of excellent molded surface finish almost unlimited size, lightness of weight, insulation against heat transfer and electricity and many other attributes. These will become evident in ensuring discussion, build around in nine major markets for GFC which includes following:

  1. Aircraft and Aerospace
  2. Appliances and equipments
  3. Constructions
  4. Consumer goods
  5. Corrosion resistant product
  6. Electrical rods, tubes and components
  7. Marin and Marin accessories
  8. Land transportation
  9. Miscellaneous (Protective gears, Farming, industrial tools, material  handling).

Aircraft and aerospace market
Stability is an important criterion for any material used. Light weight with the ability to withstand heavy loads and provide excellent resistance to bumps and impact. Aerospace and aircraft applications include overhead storage bins, aircraft toilets and helicopter rotor blades. Other benefits from using composites for these applications include cost performance, dimensional stability and corrosion resistance.

Entire external fuselages of smaller planes have been constructed using GFC, interior and commercial plane (Boeing 747) entire exterior of flight vehicle guided missile.

S-glass, which is the more exotic of the current reinforced glass products, has a much higher strength and modulus than E-glass. It also has a high laminate strength-to-weight ratio, high strength retention at elevated temperatures and a high fatigue life. It is very often used for aircraft components such as flight deck armor, and helicopter armor, seats and floors. Apart from their high mechanical performance, S-glass composites are inherently non-conductive and offer low radar thermal profiles, thereby providing the military with the opportunity to see without being seen S-glass fiber has proved itself by performing superbly in hazardous environments. Its strength and reliability have encouraged various manufacturers to use the fiber in fabricating composite blades for different models of helicopter. A new dimension to the applications of glass fibers is the use of hollow S-glass in fiber reinforced composites. In general, the mechanical properties of hollow S-2 glass compare favorably with standard fiber glass composites and show significant weight savings of approximately 16-18%.

Reinforcements commonly used:

  • Preform Rovings
  • Roving for weaving
  • Woven Roving
  • Plied yarns

Construction and Infrastructure
Composites are ideal for use in the construction market because of their dimensional stability, high strength, reduced weight, impact resistance, low flammability, given an appropriate choice of resins and additives, low maintenance and design flexibility.

Use in both interior and exterior building components for residential, commercial industrial and farm construction, tub, and shower units. Corrugated translucent architectural paneling, solar heating elements. Industrial building sky light, yard swimming pool fences and bathroom fixtures. (Resistant to mechanical impact and billing water


  1. Composites for exterior design are present in columns, pediments, domes, cornices
  2. Composites are used for paneling, cladding and covering for protection and insulation panels, shingles, translucent flat or corrugated sheets (facing systems, decorative fascia)
  3. Fascia renovation using glass-cement composites contributes to improving the appearance of buildings, external insulation and coatings of facades where dimensional stability and prevention against cracking is required.
  4. Composites form work and moulds for concrete, easy to make and corrosion-resistant.
  5. Roofing applications include sealing and waterproofing.
  6. Technical glass fabrics are used in the industrial filtration of gases, vapors and smoke.
  7. Doors and windows.


  1. Blinds (against sun or for decoration)
  2. Aesthetic coverings for use on walls, partitions, ceilings, doors and furniture
  3. Glass-reinforced plaster in a wide variety of shapes: columns, ceilings, cornices etc.
  4. Decor and furnishings of reinforced plastics and glass-cement composites
  5. Gypsum boards and partitions
  6. Dry wall tapes
  7. Partitions of glass-cement composites
  8. Composite panels (double-sided insulated, phenolic resins treated)
  9. Sanitary-ware (baths, wash basins, showers, sinks, toilets)
  10. Flooring (flexible flooring, hard flooring
  11. Functional items (letter boxes, meter boxes)
  12. Decorative items.

Glass fiber used in Construction

For rebuilding or creating new infrastructures, composite materials bring a number of benefits to various applications, including high strength, reduced weight, corrosion resistance, lower maintenance, dimensional stability, low installation costs and design flexibility. In bridge construction, for instance, composites provide a high load capacity with low material weight. This low composite weight eliminates the costs of heavy equipment needed to build the bridge, which in turn reduces the installation time. Composites are also very durable; they won’t corrode like steel or rot like wood, so maintenance and replacement costs are reduced.

Consumer goods
Properties –leisure, recreational, basic frames for furniture as well as finished items both traditional and modern, also includes divider screens, decorative and utilities trays, wall plaques, luggage. In sports equipments skis, patio furniture, swimming pool, plays ground equipments, portable tennis courts tennis racquets fishing rods vaulting polls snow mobiles garden tractors skate boards and surf boards.

Consumer goods

Properties: controlled flexibility, high mechanical strength, lightness of weight, easy formability, durability, molded in colors excellent surface and resistant to corrosion and wear.

Corrosion resistant products/equipments
Exhaustive analyses of mechanism of corrosion in fiberglass and their composite structure are available in literature. Engineers and Managers have realized that superior corrosion resistant properties exist in glass fiber composites as compared to traditional material. Composites are ideally suited for corrosive, hostile environments. Applications in this market include all types of pipes, oilfield pipes, fume handling ducts, underground petrol tanks, sucker rods, water, wastewater, drainage and irrigation piping (potable water, sewage, storm drains), cooling towers, component for water and sewage treatment facilities in textile processing, flood control and navigational waterway structures (dam gates, pipes, grating, weirs), energy production structures for oil and gas production (offshore platforms, grating, piping).

Corrosion resistant products

Reinforcements commonly used:

  • Chopped Strand Mat
  • Roving
  • Continuous filament mats
  • Woven Roving
  • Yarns
  • Glass mats

Electrical and Electronics
Substantial incursion of glass fiber composites into field requiring desirable properties for electrical and electronics applications. Mechanical strength and temperature stability were the factors, which favored the use of glass filament technical fabrics in industry as an insulator for electrical conductors. In association with lacquers and coatings, it is used for covering wires and cables. Weather stability, high dielectric strength, high arc resistance and good mechanical toughness were rapid once. These materials were proven in critical areas. They are used in distribution-pole hardware, switchgear, and transformers, telephone equipments, PCB’s, computer parts.

Glass fiber in transformer

Reinforcements commonly used:

  • Continuous Filament Mat
  • Roving for pultrusion
  • Roving for weaving
  • Yarns
  • Plied yarns
  • Technical fabrics
  • Chopped Strands for thermoplastic reinforcement

A major breakthrough in glass fiber application came when the material established its potential for use as optical frequency communication wave guides conveniently known as ‘optical fiber’. Fiber glass is selected for its transparency to a particular wavelength. Glass fibers, suitable for optical transmission materials should not have a transmission loss of more than 20dB/km. In 1970, Owens-Corning produced the first of such fibers which had less than 20dB/km transmission loss. Today, they produce optical fiber with a transmission loss of less than 5dB/km. One of the major application areas for fiber optics is in communications such as the telephone, television networks, in aircraft, aerospace, and satellite communications. It is important to mention here that the current advanced state of the communication industry has only been made possible by the major advances achieved in glass technology, transmission and detection devices and methods of packaging glass fibers. The high mechanical performance of glass is essential to prevent any fiber breakage during the handling and laying of communication cables. Optical fibers are made from extremely pure silica produced under finely-controlled process conditions.

Marine products/Accessories
Properties of fiber glass composites so favorable that approx. 70% of all out board pleasure boats is now constructed with it. The major benefit of using GFC’s in any boat construction are mouldability to almost any boat design or size, seamless construction, high strength and great durability, minimum maintenance, freedom from corrosion, rust, dry rot and water logging.

glass fiber composites in Marine products

Small motorcrafts, water sports surf, ski boats, sailboats of all size and description are being fabricated using GFC’s. Commercial and military hulls including the following fishing boats, lighters (LASH) (saving 40 tons per unit compared to steel construction) submersibles, hovercraft for fast commuter service.

Reinforcements commonly used:

  • Chopped Strand Mats
  • Continuous filament mats
  • Woven Roving
  • Yarns and Glass mats

Land transportation
The first real success splash of glass fiber composites in automotive or land transportation field was the 1953 corvette, which had complete glass fiber body. At the most recent count, more than 154 different automotive applications in GFC existed. The prime contribution of GFC is weight saving and this factor alone will go a long way toward helping automakers satisfy future energy consumption requirements. This is energy effectiveness at it’s best.

glass fiber composites in Land transportation

Reinforcements commonly used:

  • Chopped Strands
  • Chopped Strand Mat
  • Continuous Filament Mat
  • Yarns
  • Rovings for thermoplastic reinforcement
  • Woven Roving
  • Chopped Strands for thermoplastic reinforcement

Glass fibers are used in both radial and bias-ply automotive tyre reinforcement. The Owens-Corning Corporation introduced glass as a tyre cord in a composite impregnated with 15-30% resorcinol-formaldehyde-latex (RFL) resin which coated and protected the individual glass filaments. Glass fiber was first used as a belt in a belted-bias tyre with a nylon carcass. It enables the crown region of the tyre to be reinforced, which in turn increased the trade life by about 1.5 times compared to that of a conventional bias tyre. Compared to the conventional bias-ply and steel reinforced belted-bias tyre, the glass reinforced tyre provides a softer ride, greater resistance to damage, better stability, lower reinforcement cost, ready availability and a superior total performance in long distance driving. Fiber glass is also successfully used in the reinforcement of various other rubber products such as vee-belts, timing belts, and solid tyres. All fiber glass products used for the reinforcement of rubber and elastomers are treated in RFL resin. The RFL content of the fiber is normally between 15-17%.

Glass fiber is also used successfully in railway fishplates. These are produced from a combination of woven fabric and unidirectional nonwoven E-glass reinforcement by using an epoxy resin matrix.

Miscellaneous/Specialty products
The tooling industries are largest single facet making up this final marketing category for GFC parts. A comprehensive list would include such highly serviceable and behind-the-scenes component as temporary or short run forming dies for plastic and metals, checking fixture, hydro forming shapes, hammer forms, stretch dies, foundry patters and many other creative and utilitarian elements.

Orthopedic casts and prosthetic appliances

Orthopedic casts and prosthetic appliances. Prosthetics concerns fabrication of artificial parts for therapeutic treatment of such deformities. Due to their greeter softness, porosity and flexibility. Knitted fiberglass fabrics are frequently used in orthopedic casts. Prosthetic appliances are usually fabricated using fiberglass fabrics with polyester veil mat for surfacing inside and out.

By using their light and image transmission characteristics, optical fibers are also employed in the manufacture of medical instruments such as the gastroscope, in traffic-control signals, in various control instrumentation, in sales-code reading devices and so on.

Other applications are: Screening and filtration. Glass reinforced mortar/cement.

Appliance and equipment
Properties – heat insulation, noise reduction, excellent molded surfaces, dimensional stability, high dielectric strength frames, bases and housing for composites, time-share terminal units, similar appliances

fibreglass composite home appliance products

With this, I want to conclude that these glass fiber composites really taking away the ”market” from conventional materials like metals. With further new technological advancement in fiberglass and resins, their composites always have been able to satisfy the need of any engineering field. At last I want to say that these GFC’s are solution for growing building engineering avenues.


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