## 1 Introduction  
Metal injection molding (MIM) enables the manufacture of economic metallic complex geometries of small size (below 200 g) at high production volume (around 20,000 parts/year), covering a niche that is still unrivalled by other technologies including additive manufacturing. Today, it is a mature technology in the market in the midst of a steady growth stage. This near net-shape processing method uses high solid loading polymers (such mixtures are named feedstocks and contain the desired metallic powder with an organic binder in the adequate ratio, composed of polymers and additives) that are injected into the needed shape. The injected part then undergoes thermal or catalytic processes (binder removal) and is sintered under thermal cycles below the melting point of the metal (consolidation of metallic particles). This post-processing involves time-consuming steps, and the success of the entire chain primarily depends on the quality and rheology of the feedstock. In Europe, the MIM demand is growing, and this market is present in strategic sectors such as automotive, tools, medicine, aeronautics, defense and even electronics, having launched since 2020, probably due to the pandemic situation [1]. Interestingly, MIM and indirect additive manufacturing (AM) based on printable filaments or feedstocks (MEX, materials extrusion) show advantageous similarities, and advances in the development of such hybrid feedstocks has been reported elsewhere [2; 3]. Thus, these technologies entered the scene to potentially cover the short series production or even MIM parts prototyping and gained tremendous momentum, having a significant impact across various industriesin the past decade. In fact, filament-based MEX was considered the indirect technology holding the lowest time until industrial use and one of the highest maturity indexes [4]. However, metallic components consumers are becoming more and more ambitious regarding the size and complexity of the component, pushing the limits of both technologies, which sometimes can lead to inefficient binder release, loss of dimensional control, internal porosity or bubbles and crack defects. To face the current challenges this fact brings to MIM and AM shaping, exhaustive control over the feedstock robustness, rheology and reliability should be addressed to accomplish an injectable material that can be subsequently debound and sintered. Moreover, in the case of the catalytic debinding reaction, the polyacetal (POM) component of the binder is chemically degraded under an acidic atmosphere, releasing formaldehyde, which should be environmentally managed due to its toxicity and explosive character. Previous efforts to improve the catalytic reaction and the debinding rate in this stage were made in terms of the set-up conditions. For example, variations in the catalyst concentration and the flow rate of the gas carrier within the oven debinding zone allow optimization of the process [5]. Regarding the feedstock composition, the tendency is to move towards lowering viscosity by using lower molecular weight polymers, lowering the processing temperature or formulating water-soluble based binders that could contribute to a greener solution avoiding organic solvents [6; 7]. Nevertheless, there is a scarcity of literature exploring chemical modifications within the binder, specifically targeting the enhancement of the debinding rate in a more environmentally conscious metallic manufacturing process. This study highlights that crafting injectable feedstocks with a high powder content transcends the mere adjustment of binder composition (backbones, flow adjusters and surfactants) to ensure pseudoplastic behavior and suitable viscosity under injection conditions. Moreover, it explores the intricacies of interactions between polymer components and metal powder, underlining the necessity of a detailed examination of both rheological and thermal parameters.