Material extrusion based additive manufacturing with blends of polypropylene and hydrocarbon resins

Filament based material extrusion additive manufacturing (MEAM) is one of the most commonly used techniques in additive manufacturing. In spite of recent notable development in the MEAM process, there is still a need to develop more materials that can be printed consistently using this technique. Isotactic polypropylene (PP), a popular thermoplastic material, undergoes rapid crystallization and subsequent volume contraction. This can lead to residual stress buildup in PP parts when processed using MEAM, resulting in poor adhesion to the printing platform, poor geometric tolerance, and mechanical performance. In this work, the effects of varying composition of low molecular weight hydrocarbon resins added to PP are investigated. Specifically, the thermal behavior, crystallization, morphology, and printability of the blends are studied. The rapid crystallization of PP has been delayed by the incorporation of hydrocarbon resins that provided a larger time window for the residual stresses to relax. The additi...