Effect of backbone binders on rheological performance of ceramic injection molding feedstocks

Abstract

In a novel binder system, carnauba wax (CW), and acrawax (AW) (N,N′-Ethylene Bis-stearamide) were considered to replace the synthetic backbone polymers (polyolefins) in aluminum oxide (Al2O3) Ceramic Injection Molding feedstocks. For both proposed substitutes there is a significant reduction in viscosity in comparison to polyolefin based binder and also commercially available one, and in case of CW based feedstock also in processing temperature, which is essential for injection molding of reactive powders. For all ceramic feedstocks studied, there is a nonmonotonous dependence of viscosity on shear rate/stress, whose fitting requires eight-parameter model. At the processing-relevant shear conditions, polyolefin based feedstocks show dilatant cause, whereas both CW and AW compounds have a pseudoplastic manner. Thermal characterization was used to evaluate i(miscibility) of the neat binder components, their mixtures and mixtures with Al2O3. The presence of powder lowered melting temperatures of all tested binders except of polyolefin. Further depression in melting point of poly(ethylene glycol) is observed in combination with polyolefin in the presence of powder, and it is related to changes in size of the crystalline domains. POLYM. ENG. SCI., 57:739–745, 2017. © 2017 Society of Plastics Engineers. © 2017 Society of Plastics Engineers