# Enhancement of Mechanical Properties of PCL/PLA/DMSO2 Composites for Bone Tissue Engineering
## 3 Results
### Mechanical Properties  
The three-point bending tests for the specimens of the composites were conducted, and the stress-strain curves were plotted to determine 0.2% offset yield strengths and moduli for specimens. As shown in Figure 4 and Table 3, the highest yield strength was observed under the PLA/PCL/30 wt% DMSO\({}_{2}\) composite specimen. The yield strength for the PLA/PCL/30 wt% DMSO\({}_{2}\) composites was 2.81-239.49% higher than that of the other composites. The highest modulus was observed in the pure PLA specimen, and the modulus was 32.90-661.08% higher than that of the other composites. As DMSO\({}_{2}\) concentration was increased, yield strengths and moduli were increased.  
In a previous study, the natural brittleness, poor elongation at break, and high modulus material for PLA and ductileness, high elongation at break, and low modulus material for PCL were verified [32; 54; 55]. The yield strengths and moduli for PLA, PCL, and PLA/PCL composites followed the following order: PLA \(>\) PLA/PCL composites \(>\) PCL. These findings were corroborated by previous research [32].  
Yield strengths for pure PLA, pure PCL, and PLA/PCL composites vary from 21.5 MPa to 39.9 MPa, from 10.3 to 19.2 MPa, and from 16.75 MPa to 47.5 MPa, respectively, according to the literature [31; 56; 57; 58; 59; 60]. The measured yield strengths for PLA, PCL, and PLA/PCL composites in this study were consistent with the yield strength ranges reported in previous studies. The moduli for pure PLA, pure PCL, and PLA/PCL composites were investigated  
Figure 4: Stress–strain curves of specimens of pure PLA, pure PCL, PLA/PCL composites, and PLA/PCL/10, 20, and 30 wt% DMSO\({}_{2}\) composites.  
\begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Process**} & **0.2\% Offset Yield Strength (MPa)** & **Modulus (MPa)** \\  & **(Mean \(\pm\) Standard Deviation)** & **(Mean \(\pm\) Standard Deviation)** \\ \hline Pure PLA & 32.56 \(\pm\) 2.78 & 3227.97 \(\pm\) 147.47 \\ Pure PCL & 13.7 \(\pm\) 0.44 & 424.00 \(\pm\) 2.94 \\ PLA/PCL & 27.57 \(\pm\) 4.22 & 2168.97 \(\pm\) 201.30 \\ PLA/PCL/10 wt\% DMSO\({}_{2}\) & 37.81 \(\pm\) 2.83 & 2278.63 \(\pm\)109.39 \\ PLA/PCL/20 wt\% DMSO\({}_{2}\) & 45.24 \(\pm\) 3.13 & 2330.97 \(\pm\) 81.72 \\ PLA/PCL/30 wt\% DMSO\({}_{2}\) & 46.51 \(\pm\) 1.53 & 2428.81 \(\pm\) 26.15 \\ \hline \hline \end{tabular}
\end{table}
Table 3: The 0.2% offset yield strength of pure PLA, pure PCL, PLA/PCL composites, and PLA/PCL/10, 20, and 30 wt% DMSO\({}_{2}\) composites.  
to be about 3000 MPa, 417 MPa, and 2900 MPa, respectively [31; 59; 61]. The moduli measured in this study exhibited findings comparable to those reported in the literature review.  
The elongation of PCL was 227.74% higher than that of PLA. However, the yield strength and modulus of PCL were 137.70% and 661.08% lower than those of PLA, respectively. The yield strength and modulus of PLA/PCL composites increased by 101.24% and 411.32%, respectively, compared to those of pure PCL. However, the elongation decreased by 220.50% compared to that of pure PCL. As the DMSO\({}_{2}\) content increased, the elongation increased by 12.50-14.96%, accompanied by increases in yield strength and modulus. Moreover, the elongation and yield strength of PLA/PCL/30 wt% DMSO\({}_{2}\) composites increased by 86.75% and 42.84%, respectively, compared to those of PLA.