The Importance of Composites in the World

**3**

**Chapter 1**

World

Introductory Chapter: The

*António B. Pereira and Fábio A.O. Fernandes*

and/or use of composites produced by **sustainable materials**.

Importance of Composites in the

The title of this book is composed by three well-known keywords. The first, **composites**, refer to something that is made up of several parts or elements, an overarching thematic. In fact, almost everything in the world is a composite, from the grain of sand to buildings or even the living beings. **Renewable** is a word that contains a fantastic concept, which we all aspire to: Anything renewable can be replaced or has an infinite source. When renewal is made in a timely manner, we can say that it is sustainable. This book provides ways and solutions for the creation

Composites are currently used in a wide range of activity sectors, ranging from consumer electronics to the aeronautics and space industries. The excellent mechanical properties and low specific weight form the basis of the increasing volume of structural applications. An important milestone in the large-scale use of composite materials was the Airbus A380, the largest commercial aircraft in the world. Despite

Natural fibers are increasingly associated with attempts to replace other fibres and also with improvements in reinforcing structures [1]. For example, the incorporation of coconut fibres into a composite material of polyethylene and cork dust has already been studied, and an increase in tensile strength compared to unreinforced material has been found [2]. In another study, different laminates of fibreglass, hemp, flax and basalt were compared in flexural tests. The best performance was achieved by hybrid laminates in comparison with those made of only one type of fibers [3].

Today there are many studies in the field of composite materials with the goal to make the world greener. For instance, in the building sector, Dweib et al. [4] developed an all-natural composite structure for housing roof application. The materials used were resin based on soybean oil and natural fibers such as flax, cellulose, recycled paper and chicken feathers. These composite structures were compared with the wood structures currently used in construction and were completely able to effectively meet the requirements. These examples demonstrate the capability of sustainable composite materials as well as the breadth of exploitable applications. Research teams across the globe are focusing on biocomposites, e.g. fiber-reinforced composites with both reinforcement and matrix from natural and renewable resources and also on hybrid solutions, consisting of natural fibers and oil-derived matrix or vice versa. Currently, hybrid solutions are more successful than fully green ones, usually due to cost, durability, performance and/or restrictions specific to the application. Nevertheless, fully green composites are gaining momentum in

the progress achieved, there are significant obstacles to the generalization of structural applications of composites, not only in terms of high material costs but also due to the complexity of the mechanical behaviour. In fact, there is currently no sufficiently deep knowledge of the mechanisms of damage and ruin, especially with

regard to composites made from renewable and sustainable materials.
