Clariant, a world leader in specialty chemicals, is providing the all-important fire protection element in the development of commercially viable, flame retarded thermoplastic composites based on renewable oyster shell fillers.

Research led by the Unité Matériaux et Transformations (UMET) at the University of Lille in France has shown that it is possible to achieve effective flame retardancy for oyster shell reinforced polypropylene (PP) composites using Clariant’s Exolit AP non-halogenated flame retardants. Results indicated a significant increase in the thermal stability of the PP compound with phosphate-based Exolit AP760 added to the high performance compound.

Eurostar Engineering Plastics, developer of the “green” PP compound, is at the forefront of the development and commercialization of halogen-free flame retardant compounds. The company has chosen oyster shells as a unique source of mineral filler that avoids the environmental disadvantages and high energy consumption of standard mining processes, and contributes to landfill reduction through recycling.

Exolit AP adds to the improved environmental profile of the composite; it does not show toxic effects, and does not accumulate in the environment, since it is (bio-) degradable by breaking down to naturally occurring phosphate. The flame retardant can also be added at low dosage with a low impact on mechanical properties.

“The project results herald a breakthrough in the feasibility of using bio-based materials in high-end application areas, such as the automotive and building and construction industries, where effective flame retardancy is required,” comments Professor Sophie Duquesne, who is leading the research group from Unité Matériaux et Transformations (UMET).

“In addition to oyster shells we are also actively researching the viability of achieving flame retardancy when vegetal fillers such as flax are used, to further extend possibilities for more environmentally-friendly materials in demanding environments.”