Fiber reinforced structural material from the waste of a multilayer food packaging film: Interactions, structure, properties

• fibers with different sizing resulted in considerably differing properties. • fibers sized for commodity polymers are encapsulated into the polyethylene phase. • interfacial interactions determine structure, deformation processes and properties. • fiber sized for PA adheres strongly to the matrix and provides stress transfer. • different interactions result in dissimilar deformation processes and mechanisms. A multilayered packaging film consisting of three polyamides (PA), a polyethylene (PE) and a maleated polyethylene (MAPE) component acting as adhesive layer was reprocessed into glass fiber reinforced composites by chopping the waste, compounding and injection molding. The polyamides are miscible or at least develop strong interactions with each other, and PE and MAPE also form a homogeneous phase. The mediocre properties of the blend could be upgraded by the addition of glass fibers. The fiber covered with a sizing optimized for commodity polymers is embedded in polyethylene, thus it develops weak interactions with the PA matrix. The fiber having a sizing optimized for PA adheres strongly to the PA matrix resulting in efficient stress transfer and large strength. The property profile of the reprocessed material is in the range of commercial fiber reinforced PA composites and its price is very competitive.