• analytical model
• automotive
• basalt
• bio
• composite
• extrusion
• Ludovic
• natural fiber
• polyamide
• simulations
• sustainable

The aim of this work was the optimization of processing conditions to produce a bio polyamide 11 based composite with short basalt fibers for automotive applications. The industrial method to produce this composite involves using a twin-screw extruder to properly mix the polymer and the fibers. Fiber length determines properties of the composite, including density, strength, stiffness, elastic and flexural modulus, therefore it is a crucial factor to minimize the fiber breakage during the extrusion and suitable mixing within the polymeric matrix. Consequently, the objective of this thesis is to investigate this phenomenon. Using LUDOVIC® software the final length distribution and the fiber breakage was predicted. A Design of Experiment (DOE) was carried out to find the proper speed of the screws, combined to the flow rate, to maximize the global mixing index reducing the energy consumption. Once the extrusion parameters were selected the predicted results were verified by the real extrusion process. Three different basalt fibers content (10, 15 and 20 wt.%) were produced. Subsequently, injection molding was performed to obtain specimens for the evaluation of the main mechanical and thermal properties. Finally, the adhesion between fibers and matrix was evaluated by analytical models and validated by SEM micrographs.