# Integrating Cork Biochar as a Green Filler via Photopolymerization
## 3 Results and Discussion
### Mechanical Properties of Cork Biochar Polymer Composites (CBPCs)  
To complete the material characterization, mechanical testing was conducted to evaluate the Young's modulus (E), tensile strength (\(\sigma_{\tau}\)), and elongation at break (\(\varepsilon_{\tau}\) %) of the printed CBPC parts. These tests provide valuable insights into the structural performance  
Figure 6: Electrical conductivities of cork biochar photopolymer composites and neat photocurable resin. and suitability of 3D-printed CBPCs for specific applications. In simple terms, Young's modulus reflects the stiffness of a material under stress. A high Young's modulus indicates greater stiffness and reduced deformation under load, whereas a low Young's modulus indicates greater flexibility and easier deformation. In general, the tensile strength of polymer composites reflects their ability to withstand the forces applied without breaking or undergoing permanent. Fracture elongation indicates the extent to which a material can be stretched before experiencing tensile failure. This is a crucial measure of the ductility or plastic deformation of CBCPs. Materials with greater elongation at break can stretch further before breaking, indicating increased energy absorption capacity and enhanced resistance to tensile fractures. The overall mechanical properties of CBPCs with different cork biochar loading levels are presented in Table 2, with the standard deviation (SD). The mechanical properties of the photocurable resin, which acts as the polymer matrix of the composites, were markedly modified by the addition of cork biochar to form CBPCs. Young's modulus, tensile strength, and elongation at break were significantly different between the pristine matrix and the biochar, highlighting the effect of biochar within the polymeric matrix. Using the statistical methods of analysis of variance (ANOVA) and multiple comparisons, the influence of different percentages of cork biochar on the mechanical properties of CBPCs was analyzed. To further investigate these differences, post hoc comparisons such as [PERSON]'s HSD test were conducted to determine which specific pairs of reinforcement materials exhibited significant differences in mechanical properties. The ANOVA revealed significant differences in the mechanical properties of CBPCs based on the percentage of cork biochar used. Specifically, Young's modulus, tensile strength, and percentage elongation at break showed statistically significant variations (\(p<0.05\)) among the composite formulations. Young's modulus values differ significantly among various CBPCs with different percentages of cork biochar. There was a significant difference in modulus between neat resin and CBPCs with cork biochar at percentages ranging from 0.5% to 1.5%\(w\)/\(w\). Lower percentages do not yield such significance, indicating that [PERSON]'s modulus is not significantly affected by levels below 0.5%\(w\)/\(w\) in cork biochar. The CBPCs 0.15%\(w\)/\(w\), CBPCs 0.25%\(w\)/\(w\), and CBPCs 0.35%\(w\)/\(w\) did not display notable differences compared with each other. In the ANOVA analysis for tensile strength, there was a significant difference when comparing the resin with the entire range of CBPC series, indicating a significant modification of the tensile strength by the cork biochar at any percentage level of the cork biochar. In contrast with the findings for [PERSON]'s modulus, the comparisons between CBPCs-0.35%\(w\)/\(w\), CBPCs-0.5%\(w\)/\(w\), CBPCs-1%\(w\)/\(w\) and CBPCs-1.5%\(w\)/\(w\) did not reveal significant differences, possibly due to close values and comparable dispersion achieved in this range within the polymer matrix. Finally, it was noted that CBPCs-0.15%\(w\)/\(w\)