# Additive Manufacturing and Chemical Engineering: Looking for Synergies from a Bibliometric Study
## 3 Results and Discussion
### Bibliometric Network Analysis  
This section presents the primary findings of the bibliometric network analysis of the scientific literature related to chemical engineering and additive manufacturing. First, the strategic diagrams of each defined subperiod were depicted: 2002-2017 (Figure 5), 2018-2019 (Figure 6), 2020 (Figure 7), 2021 (Figure 8), and 2022 (Figure 9). The strategic diagrams presented 30 clusters in total, of which 12 were identified as motor themes, 5 were classified as basic and transversal, 8 were designated as emerging or declining themes, and 5 were categorized as highly developed and isolated themes. The structure of each cluster can be observed in Figures S1-S30 in the Supplementary Materials. The size of each cluster is an indication of the number of documents included therein. Furthermore, the total number of citations, h-index, absolute centrality, and density values are presented for each cluster in Table 10. Thematic evolution is illustrated in Figure 10, which depicts the progression of the research field across the various subperiods addressed in this study. The dynamic conceptual evolution of scientific research related to additive manufacturing and chemical engineering was investigated through the analysis of the thematic evolution. Paying attention to Figure 10, three main families of clusters can be highlighted. These families of clusters were clearly identified because they showed continuous evolution from the initial to the last subperiods throughout the complete time interval selected to be studied, meaning there were no lapses in their evolution. This fact revealed that they were attractive thematic areas for researchers throughout all the subperiods considered. The first cluster family found began with the cluster \"_Chemistry_\" in the first subperiod and its structure can be observed in Figure S1. A large number of connections between keywords were observed in this cluster, indicating a high level of cohesion and relevance among them. Keywords with strong connections include _Scaffolds, Tissue Scaffold, Tissue Engineering_, and _Chemistry_. In the second subperiod, the cluster was renamed \"_Tissue Scaffold_\" (Figure S8). New keywords emerged there such as _Bioprinting, Bone Regeneration_, and _Tissue Regeneration_. During the third period, the cluster reverted to the original name \"_Chemistry_\"(Figure S15). The connections remained quite similar and the keyword _Procedures_ appeared, which in subsequent subperiods was maintained and presented significant connections. In the fourth period, the cluster changed its name to _\"Tissue Scaffold\"_ (Figure S19). The keyword _Hydrogels_ was incorporated and it presented a strong connection with _Tissue Scaffold_. Finally, in the fifth subperiod, the cluster retained its name (Figure S24), and the appearance of the keyword _Polyesters_ must be mentioned. As can be observed in Figures 5-9, the five clusters that formed this first family were all of motor themes. Moreover, they presented the highest density values and some of them also exhibited the highest centrality values (specifically during the first, third, and fourth subperiods). Consequently, the relevance of this cluster family within the research scenario was beyond any doubt. This cluster family showed a consistent and coherent evolution across subperiods, maintaining connections among the most relevant keywords. The thematic topic represented by this cluster family could be directly correlated to the keyword category Biofabrication identified in the previous section during the keyword analysis. It reflected the growing interest in bioprinting and biomedical applications, especially in relation to the manufacturing of implants, prosthetics, scaffolds, and artificial organs. These applications of additive manufacturing have the potential to improve the quality of life for people suffering from diseases or injuries affecting their tissues or organs.