A trouble‐free first layer adhesion for polypropylene‐based materials in material extrusion‐based additive manufacturing

Striking just the right balance between high toughness, moderate strength, and excellent chemical resistance, polypropylene (PP) is a particularly interesting material for the use in material extrusion-based additive manufacturing, also known as fused filament fabrication (FFF). However, this promising material suffers from a high susceptibility to part distortion, especially warpage and build-platform detachment, due to the material’s high degree of crystallinity and its fast crystallisation rate. Consequently, the production of dimensionally stable and accurate parts is a real challenge. The present study attempts to facilitate the production of warpage-free PP components processed by FFF by optimising the adhesion between the first deposited layer and the build-platform. In this regard, the challenges are twofold. Firstly, PP filaments do not adhere on standard build platform materials, which results in the need to develop novel tailored platform materials. Secondly, PP filaments reveal a highrisk of welding when deposited onto PP-based build platforms. This study reports the material selection of a platform material tailored to PP-based filaments based on contact angle measurements that shows optimal adhesion during printing and minimal adhesion during removing the finalized parts, while still counteracting welding. After a rigorous parametric optimization of the processing parameters by an in-situ characterization of the adhesion forces, distortion- and warpage-free technical components could be produced of different types of PP-based materials by FFF. A particularly important factor that doubles the adhesion forces was found to be the roughness of the build platform.