Question

What are the principal polymers used in fiber-reinforced polymers?

Answer 1

Fibre-reinforced plastics are best suited for any design program that demands weight savings, precision engineering, finite tolerances, and the simplification of parts in both production and operation.

The principal polymers used in fibre reinforced polymers:

1.Carbon-fibre-reinforced polymers

2.Glass-fibre-reinforced polymers

1.Carbon-fibre-reinforced polymers:

Advantages over a traditional rudder made from sheet aluminium are:

• 25% reduction in weight
• 95% reduction in components by combining parts and forms into simpler moulded parts.
• Overall reduction in production and operational costs, economy of parts results in lower production costs and the weight savings create fuel savings that lower the operational costs of flying the aeroplane.

• Advantages this has over cast aluminium manifolds are:
  • Up to a 60% reduction in weight
  • Improved surface quality and aerodynamics
  • Reduction in components by combining parts and forms into simpler moulded shapes.

2.Glass-fibre-reinforced polymers

• Advantages over stamped aluminium are:
  • Pedals can be moulded as single units combining both pedals and mechanical linkages simplifying the production and operation of the design.
  • Fibres can be oriented to reinforce against specific stresses, increasing the durability and safety.

Fibre materials:

Glass fibre:

"Fibreglass reinforced plastics" or FRPs (commonly referred to simply as fibreglass) use textile grade glass fibres. These textile fibres are different from other forms of glass fibres used to deliberately trap air, for insulating applications (see glass wool). Textile glass fibres begin as varying combinations of SiO₂, Al₂O₃, B₂O₃, CaO, or MgO in powder form. These mixtures are then heated through direct melting to temperatures around 1300 degrees Celsius, after which dies are used to extrude filaments of glass fibre in diameter ranging from 9 to 17 µm. These filaments are then wound into larger threads and spun onto bobbins for transportation and further processing. Glass fibre is by far the most popular means to reinforce plastic and thus enjoys a wealth of production processes, some of which are applicable to aramid and carbon fibres as well owing to their shared fibrous qualities.

Roving is a process where filaments are spun into larger diameter threads. These threads are then commonly used for woven reinforcing glass fabrics and mats, and in spray applications.

Fibre fabrics are web-form fabric reinforcing material that has both warp and weft directions. Fibre mats are web-form non-woven mats of glass fibres. Mats are manufactured in cut dimensions with chopped fibres, or in continuous mats using continuous fibres. Chopped fibre glass is used in processes where lengths of glass threads are cut between 3 and 26 mm, threads are then used in plastics most commonly intended for moulding processes. Glass fibre short strands are short 0.2–0.3 mm strands of glass fibres that are used to reinforce thermoplastics most commonly for injection moulding.

Carbon fibre:

Carbon fibres are created when polyacrylonitrile fibres (PAN), Pitch resins, or Rayon are carbonized (through oxidation and thermal pyrolysis) at high temperatures. Through further processes of graphitizing or stretching, the fibres strength or elasticity can be enhanced respectively. Carbon fibres are manufactured in diameters analogous to glass fibres with diameters ranging from 4 to 17 µm. These fibres wound into larger threads for transportation and further production processes.Further production processes include weaving or braiding into carbon fabrics, cloths and mats analogous to those described for glass that can then be used in actual reinforcements.

3.Aramid fibre

Aramid fibres are most commonly known as Kevlar, Nomex and Technora. Aramids are generally prepared by the reaction between an amine group and a carboxylic acid halide group (aramid);.Commonly, this occurs when an aromatic polyamide is spun from a liquid concentration of sulphuric acid into a crystallized fibre. Fibres are then spun into larger threads in order to weave into large ropes or woven fabrics (Aramid).Aramid fibres are manufactured with varying grades to based on varying qualities for strength and rigidity, so that the material can be somewhat tailored to specific design needs concerns, such as cutting the tough material during manufacture.