# Heat-Resistant Behavior of PLA/PMMA Transparent Blends Induced by Nucleating Agents
## 3 Results and Discussion
### Morphology Analysis  
Figure 6 presents the internal morphology of the pure PLA and blends after brittle fracture, as well as their corresponding post-treatment. The surface of the pure PLA appeared smooth in the SEM group (a). The different types of added nucleating agents were uniformly dispersed in the PLA matrix. Specifically, TMC-300 appeared granular, while TMB-5 exhibited a different morphology. No significant morphological changes were evident in the PLA and PMMA blends, displaying homogeneous structures with no  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Samples** & **80 \({}^{\circ}\)C (96 min)** & **90 \({}^{\circ}\)C (29 min)** & **100 \({}^{\circ}\)C (5 min)** \\ \hline PLA & 343 & 274 & 268 \\ PLA/TMC-300 & 344 & 270 & 246 \\ PLA/TMB-5 & 319 & 264 & 264 \\ PLA/TMC-328 & 350 & 260 & 272 \\ PLA/PMMA & 223 & 242 & 206 \\ PLA/PMMA/TMC-300 & 216 & 242 & 231 \\ PLA/PMMA/TMB-5 & 186 & 245 & 217 \\ PLA/PMMA/TMC-328 & 227 & 233 & 190 \\ \hline \hline \end{tabular}
\end{table}
Table 4: The grain sizes of blends after isothermal crystallization at different temperatures (unit: Å).  
Figure 5: The WAXD curves of each sample component after isothermal crystallization at (**a**) 80 \({}^{\circ}\)C, (**b**) 90 \({}^{\circ}\)C, and (**c**) 100 \({}^{\circ}\)C for 96 min, 29 min, and 5 min.  
visible macroscopic phase separation. This homogeneity stayed constant after adding the nucleating agent to the PLA/PMMA blends, while the morphology of the nucleating agent remained unchanged.  
Figure 6: The SEM images of the PLA blends after (**a**) no isothermal crystallization treatment and (**b**) isothermal crystallization and etching at 80 \({}^{\circ}\)C, (**c**) 90 \({}^{\circ}\)C, and (**d**) 100 \({}^{\circ}\)C, respectively (the scale in the figure is 2 \(\upmu\)m).  
The annealed PLA blends were etched to remove the amorphous regions, obtaining different morphologies in the SEM groups (b), (c), and (d). As shown in Figure 6b, it was evident that the addition of the nucleating agent did not cause obvious changes, and no significant changes were evident in the crystal morphology after nucleating agent addition. However, when PMMA was added to the PLA matrix, the size of the original dense holes decreased, and occasional larger holes appeared. After adding the nucleating agent, the dense holes became smaller, while the number of larger holes decreased to varying degrees, which was attributed to the uniform dispersion of PMMA within the PLA matrix. During amorphous region etching, the interaction between the PLA and PMMA was relatively weak, leading to PMMA etching and larger hole formation. Moreover, adding a nucleating agent to the PLA/PMMA blend system improved the interaction force between the PLA and PMMA interfaces, reducing PMMA etching. Furthermore, nucleating agent addition increased the system crystallinity, causing the amorphous molecular chains of the PMMA to intertwine with the PLA crystalline region, making them less susceptible to etching. Therefore, the pores in the PLA/PMMA blend system containing the nucleating agent were smaller under the combined influence of increased nucleation sites and a slower crystallization rate. Although this was similar to the trend shown in Figure 6c,d, it varied in different conditions.