Layer-by-Layer nanostructured interphase produces mechanically strong and flame retardant bio-composites

In this manuscript, the Layer-by-Layer technique is used to modify the surface of flax fabrics using a quad-layer architecture (QL) prior to their assembly in polylactic acid biocomposites. The aim is to produce nanostructured interphases capable of conferring flame retardancy while maintaining mechanical properties. Only 2.5 QL significantly improve the flame retardancy and fire safety of the prepared composites as demonstrated by LOI values of 25.3%, considerably reduced flame spread rates and the substantial reduction in peak of heat release rate (−33%) and maximum average rate of heat emission (−30%) during cone calorimetry. Mechanical testing showed improved modulus and limited reductions in flexural strength. These results make the approach developed in this manuscript very attractive in the design of advanced biocomposites with optimized fire retardancy and mechanical properties.