New fiber reinforced composites for flame retardancy

© Fraunhofer IFAM
Limiting Oxygen Index (LOI)-Test.
© Fraunhofer IFAM
Overview of a GRP sample series after LOI test has been performed.

In order to ensure operational safety, the investigation of flame retardancy is of utmost importance in a wide range of industries, like in railway, civil engineering, ship-building, aerospace, or even in the automotive industry. The experts at Fraunhofer IFAM have extensive capabilities both for the synthesis of polymers and the production of fiber-reinforced polymers (FRP) with flame retardant properties, and for carrying out fire tests.


Polybenzoaxine systems show promising properties regarding the manufacturing of flame retardant FRP

Fraunhofer IFAM offers in-depth knowledge of the current standards in these areas (e.g. DIN 45545; SOLAS guidelines - International Convention for the Safety of Life on Sea - of the International Maritime Organization, IMO) and is able to formulate and synthesize polymers with high flame retardant properties.

For ideal flame retardancy, the staff therefore develop and synthesize benzoxazines as well as reactive flame retardant additives for benzoxazines and other systems. A particular focus is on biobased starting materials. These polymers are later used to manufacture fiber-reinforced polymers, such as FRPs made from benzoxazines and carbon, glass, basalt or natural fibers and flame-retardant layers as paint coatings or laminate layers. Polybenzoxazine-based composites show great potential for meeting fire safety requirements in various applications, even without the use of halogenated flame retardants. They show promising properties regarding the flame retardancy and are characterized by lower heat release rates, lower smoke density and toxicity in case of fire in comparison to epoxy based systems.

In addition, we offer various characterization methods, e.g.:

  • UL94 test - for determining the flammability of polymers and fiber-reinforced polymers in response to small flames).
  • Limiting Oxygen Index (LOI) test - for determining the minimum required oxygen concentration of a mixture that will upheld the combustion.

In addition, by using PCFC (Pyrolysis Combustion Flow Calorimetry), samples can be screened in the mg range to obtain information on, for example, heat release rate, energy generated during combustion and ignition temperature.

© Fraunhofer IFAM
UL94 Test.
© Fraunhofer IFAM
Benzoxazine sample after UL94 test has been performed.

Flame retardant and bio-based fiber-reinforced composites for structural lightweight construction in ships in the "GreenLight" project

In the "GreenLight" project, bio-based fiber-reinforced composites are to be developed for load-bearing components in the construction of passenger ships, which at the same time meet the high fire safety standards. Under the leadership of Fraunhofer IFAM, the project partners MEYER WERFT GmbH & Co.KG and INVENT GmbH are contributing their expertise in materials development, manufacturing processes, and shipbuilding. The project is supported by four other associated partners with their experience in materials and semi-finished products as well as their sustainability, approval, and operational safety. Due to the longevity of the materials, further aspects such as dismantling as well as component and material cycles are already taken into account in the design and material development phase.

The institute is developing bio-based benzoxazines for the manufacturing of composite materials. In addition, bio-based flame retardant additives are being developed in order to be used in benzoxazine formulations.


The "Mat4Rail" project group developed innovative materials for the competitiveness of railway construction

The European railway industry needs a change in technology and design for the next generation of railway vehicles in order to remain globally competitive. However, currently available FRP materials do not meet the fire, smoke, and toxicity requirements of the railway sector and therefore cannot be used for the production of car body shells.

Innovative materials and modular design are seen as key to success in the European railway vehicle transport sector. Composite materials with their unique properties have shown great potential for lighter, more energy and cost efficient structural components in relevant sectors such as the aerospace or automotive industry.

In the "Mat4Rail" project, Fraunhofer IFAM collaborated with a total of 15 partners. In the process, the institute developed new formulations and manufacturing conditions for benzoxazine-based composite materials. To meet fire safety standards, pure resin systems as well as formulations with different flame retardants were presented and investigated.