## 4 Conclusions  
To address the challenges that MIM and MEX technologies are facing today, a comprehensive overview with a complete thermal and rheological characterization of a unique feedstock oriented to catalytic debinding that contains special additives (melamine) is reported. The following conclusions can be extracted:  
* Chemical interactions between melamine and the conventional binder components demonstrated a detrimental acid-base reaction to keep the melamine functional groups  
Figure 6: Viscosity (\(\eta\)) comprising complex viscosity (\(\eta^{*}\)) at low shear rates 1 \(\times\) 10\({}^{-7}\)–1 \(\times\) 10\({}^{-1}\) s\({}^{-1}\) and apparent viscosity (\(\eta_{\text{app}}\)) at high shear rates 1 \(\times\) 10\({}^{-1}\)–1 \(\times\) 10\({}^{4}\) s\({}^{-1}\) for the neat feedstocks FA and FE and the feedstocks with melamine, FA-MM and FE-MM. The injection zone between 1000 and 7000 s\({}^{-1}\) shear rate is highlighted, while the printing zone is considered in the range of 100–500 s\({}^{-1}\).  
active. Therefore, an ester-based surfactant (E) was successfully employed, confirming by torque and microstructural studies that the role of E in the binder is preserved upon melamine addition.
* Melamine additive moves the POM thermal decomposition towards higher temperature and notably drops the yield stress and the activation energy rheological parameters, probably due to supramolecular interactions found between the binder, MM and surfactant that enhance the binder-powder compatibility. At low shear rates, it is reckoned that the melamine is not significantly affecting the complex viscosity, and the solid particles embedded in the polymer matrix with surfactant E are causing less of an effect in the rheological properties than with A, since the difference between G\({}^{\prime}\) and G\({}^{\prime\prime}\) is lowered. Unexpectedly, melamine is critical at high shear rates, enhancing the polymer chain alignment under the shear direction, which improves the flow properties, with a lubrication accomplished by this additive in the mixtures.
* Moreover, feedstock FE-MM has been proven to keep the melamine functionality unaltered, to later react with formaldehyde.  
Thus, a securer handling of formaldehyde is suggested for this strategy once it is transferred to the postprocessing of the shaped green parts in subsequent work.  
Conceptualization, C.B., J.H. and G.H.; investigation, C.B.; resources, G.H.; writing--original draft preparation, C.B.; writing--review and editing, J.H. and G.H.; visualization. C.B., J.H. and G.H.; supervision, G.H.; project administration, C.B.; funding acquisition, C.B. All authors have read and agreed to the published version of the manuscript.  
[PERSON] acknowledges the funding for this work received by the Spanish R&D Program oriented to the Challenges of the Society through the research project PID2019-104986 RJ-I00/AEI/10.13039/501100011033 and an associated postdoctoral research contract. [PERSON] acknowledges his postdoctoral researcher contract under the University of Castilla-La Mancha's own R&D&I Plan, jointly financed by the European Social Fund (ESF) and the European Social Fund Plus (ESF+) via project 2022-UNIVERS-11006 and contract 2022-POST-20884. This work was also made possible through the support of the University of Castilla-La Mancha's own R&D&I Plan via project 2022-GRIN-34467.  
The raw data supporting the conclusions of this article will be made available by the authors on request.  
The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.