Distribution of rubber particles in the weld zone of fused filament fabricated acrylonitrile butadiene styrene and the impact on weld strength

Abstract

Fused filament fabrication (FFF) is a common additive manufacturing method for polymers that has been widely adopted due to its low cost and ease of use. However, FFF remains limited in high performance applications due to the weak mechanical properties of the welds between printed fibers, including for parts manufactured from acrylonitrile butadiene styrene (ABS). This study uses atomic force microscopy (AFM) to obtain high resolution nanomechanical maps of the distribution of butadiene particles around weld interfaces in FFF-ABS specimens. From quantitative image analysis, a decrease in the average size and density of the polybutadiene particles is observed within a 5–10 µm region across multiple welds. We find that the lack of craze-inducing polybutadiene particles within the weld zone promotes brittle fracture between printed fibers and results in a reduced weld strength as measured by trouser tear experiments. To improve the fracture toughness of FFF-ABS, methods to promote particle migration into the weld region during or after printing could be considered. • Fused filament fabrication of ABS leads to welds with brittle fracture behavior. • Nanomechanical atomic force microscopy is used to map the weld microstructure. • An altered distribution of toughening rubber particles within the weld is observed. • Trouser tear testing suggests the altered particle distribution causes the weak and brittle welds.