Effects of POE-g-MAH on properties of PP-based binder in metal injection molding

The objective of this study is to explore the effects of maleic anhydride-grafted polyolefin elastomer (POE-g-MAH) on properties of polypropylene (PP)-based binder. The viscosity of feedstocks as well as properties of green parts, brown parts and sintered parts were investigated. Through the analysis of viscosity, the feedstock containing 8 vol% POE-g-MAH in binder was supposed to be more suitable for the injection molding. The impact absorbed energy at break increased with increasing POE-g-MAH content in binder while the bending strength decreased first and then increased. The introduction of POE-g-MAH improve the density distribution and increased the density of green parts. After debinding, most binder components were removed regardless of the POE-g-MAH content in binder. As for the parts after sintering, the carbon content decreased with an increase in POE-g-MAH content. The results suggest that POE-g-MAH act as a toughening agent as well as compatibilizer for PP-based binder/metal powder system. The mechanical properties of the green parts could be enhanced even after multiple injection and in addition the powder-binder separation trend could be decreased. (paper)