Abstract

The concept of lightening has been essential for the use of composites in different industrial sectors, especially in transport applications. Composites are strategic for the objectives of sustainable mobility, being the behaviour against fire, one of the aspects to improve in these materials.

For this reason, the flame retardancy of thermoplastic prepregs and thermosetting prepregs, applicable to the transport sector, has been studied by incorporating superficial flame-retardant layers based on expandable graphite. In the case of thermoplastic composites, work has been done with polypropylene laminates reinforced with fiberglass fabrics, addressing flame retardancy by incorporating a functional layer of expandable graphite.

In the case of thermosetting composites, furanic basalt fibre and recycled carbon fibre prepregs have been studied. The flame retardancy of basalt prepregs has been addressed incorporating halogen-free flame retardants in thermosetting matrix, and the flame retardancy of recycled carbon fibre prepregs has been addressed by a combined strategy incorporating halogen-free flame retardants in thermosetting matrix and superficial fire-retardant layers on the composite, based on expandable graphite.

Abstract

Carbon fibre polymer composites (CFRP) are widely used in the aeronautical industry thanks of their excellent properties. However, they also have some limitations mainly due to the polymeric nature of their matrix. One of the most significant is their poor resistance to high temperatures

Abstract

Carbon fibre polymer composites (CFRP) are widely used in the aeronautical industry thanks of their excellent properties. However, they also have some limitations mainly due to the polymeric nature of their matrix. One of the most significant is their poor resistance to high temperatures (>130ºC), which restricts their use to structural applications away from heat sources, thus avoiding areas close to engines or turbines. To date, this problem has been solved in two ways.

The first one is the use of metals for the manufacture of these components, mainly titanium. Performance at high temperatures is suitable, but this generates in an increase in the weight and, with it, an increase in fuel consumption and emissions. 

The other possibility explored is the covering of structures with thermal blankets. This protects and insulates the structural composite, but the manufacturing process is inefficient due to the high cost of the raw material and the numerous operations required for installation and assembly/taping.

The present work is committed to the development of a multifunctional CFRP designed from a commercial thermosetting resin prepreg widely used in aeronautics which, together with a combination of certain materials, will make it possible to obtain a CFRP that can act as a thermal barrier and, at the same time, meet its mechanical, fire and lightning protection requirements.

In addition to the selection of the appropriate material, the processing of the material has been studied and it has been determined that both the lamination and curing processes can be carried out together, in the same way that conventional CFRP is manufactured. This will allow rapid industrialisation, the execution of a reduced number of operations and, consequently, a reduction in costs.

Los composites poliméricos de fibra de carbono (CFRP) son ampliamente utilizados en la industria aeronáutica ya que poseen excelentes propiedades. Sin embargo, también presentan algunas limitaciones derivadas, principalmente, de la naturaleza polimérica de su matriz. Una de las más significativas es su pobre resistencia a altas temperaturas (>130ºC) ya que restringe su uso a aplicaciones estructurales alejadas de focos de calor, evitando así, las zonas próximas a los motores o turbinas. Esta problemática, hasta la fecha, es solventada por dos vías.

La primera es el uso de metales para la fabricación de estos componentes, principalmente titanio. Las prestaciones a altas temperaturas son buenas, pero da lugar un amento en el peso del avión y, con ello, un aumento en el consumo de combustible y las emisiones derivadas.  

La otra vía explorada es el recubrimiento de las estructuras con mantas térmicas. Con ello se consigue proteger y aislar al composite estructural pero el proceso de fabricación resulta ineficiente debido al alto coste de la materia prima y a las numerosas operaciones necesarias para llevar a cabo su instalación y montaje/encolados.

El presente trabajo apuesta por el desarrollo de un CFRP multifuncional diseñado a partir de un prepreg de resina termoestable comercial y ampliamente utilizado en aeronáutica que, junto con una la combinación de ciertos materiales, permitirán la obtención de un CFRP que pueda actuar de barrera térmica y, a la vez, cumplir con sus requerimientos mecánicos y de protección al fuego y a los rayos.

Además de la selección del material adecuado, se ha estudiado el procesado del material determinando que tanto el proceso de laminado como el curado se puede realizar en conjunto, de igual forma que se lleva a cabo la fabricación de CFRP convencionales. Esto permitirá una rápida industrialización, la ejecución un reducido número de operaciones y, por consiguiente, una reducción en los costes.