Polymer composites in 2000: structure, performance, cost and compromise

Polymer matrix composites are based on the combination of stiff, strong reinforcing fibres with either thermosetting or thermoplastic polymer matrices. Since their introduction in the early 1940s, the world market has increased to some 5 million tonnes per annum, and some composites may now be considered commodity materials. The spectrum of fibre-reinforced plastics ranges from very high-performance speciality materials costing more than $1000/kg to these commodity composites, with more modest properties, at less than $10/kg. The performance of composites is determined by the properties of the fibre, the fraction of fibre in the composite and the structure, or fibre architecture. Processing technologies have been developed which maximise fibre content and precisely control the fibre architecture allowing for the manufacture of components with mechanical properties tailored to service requirements. Many composites offer significant advantages in specific stiffness and/or specific strength over metals. This makes them attractive for applications where high mechanical performance and minimum weight are important. However, the wider acceptance of composites is based on their ability to offer a more cost-effective alternative. In particular, composites also allow a dramatic reduction in the parts count in many applications, which leads to significant manufacturing advantages and greater economy.