(4g) Fundamental Study on Processing-Structure-Properties Relationships of Acrylonitrile-Butadiene-Styrene (ABS) for Material Extrusion Additive Manufacturing (MatEx AM)

Today, Acrylonitrile-Butadiene-Styrene (ABS) is known as the most common material for material extrusion additive manufacturing (MatEx AM) due to its well-balanced properties and easy availability. Although a wide range of ABS sources have already been available on the market and there have been many studies using them, very little work has been done on understanding relationship between processing (i.e., polymerization and post processing) – structure (i.e., microstructural multiphase) – properties (i.e., toughness) of ABS for MatEx AM. In this work, these relationships are evaluated using as-printed and annealed Izod impact strength with three or more ABS grades with different characteristics, such as mass or emulsion polymerization, uni- or bimodal distribution of Butadiene (BD) rubber particles in Styrene-co-Acrylonitrile (SAN) Matrix. For as-printed, the order of Izod impact strengths is almost the same as that of bulk (i.e., injection molded part) value. Among them, the interesting thing is that even though bulk values are almost same, ABS grade(s) with bimodal distribution of BD rubber particles has a higher impact strength than the unimodal distribution. On the other hand, it revealed completely different results after post-processing (i.e., annealing). ABS grade(s) made by mass polymerization, which is less as-printed Izod impact strength, has a significant annealing effect on improving toughness and its value had even become almost the same as the bulk value. In addition, ABS grade(s) with bimodal distribution of BD rubber particles has a better annealing effect on its toughness than that with unimodal distribution. Fractographic and rheological characterizations elucidate the processing-structure-properties relationships of ABS for MatEx AM.