## 3 Results and Discussion
### Structural Comparison of P3 HBHrk with Different Nucleating Agents
#### 3.2.4 Mechanical Testing  
Mechanical tests were conducted to assess the effects of the nucleating agents on the mechanical properties of P3 HBHfx. As shown in Table 5 and Figure 9, most nucleated samples maintained mechanical performance comparable to that of the neat polymer, with variations in Young's modulus, tensile strength, and elongation at break, generally within 10%. All specimens were injected into a mold set at 50 \({}^{\circ}\)C, allowing consistent crystallization across the samples. However, as discussed later, the heterogeneous nucleation introduced by the additives and homogeneous nucleation in the neat polymer result in different spherulite sizes due to their distinct induction times.  
Specifically, samples with enhanced crystallization and higher nucleation efficiency, such as PHH_05 PHB, PHH_05 BN, and PHH_05 Talc or PHH_2 Talc, exhibited a more pronounced decrease in modulus, from 2264 MPa in the neat sample to values between 1866 and 2060 MPa, representing a reduction of up to 17%. These samples also exhibited a slight increase in the elongation at break. This behavior is attributed to changes in crystalline morphology, particularly the formation of larger spherulites through heterogeneous nucleation, which results in reduced stiffness.  
Although an inverse relationship between the modulus and elongation is often expected in polymer systems, such a trend was not clearly observed here. This is primarily because the absolute differences in the elongation at break across the samples are relatively  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Sample**} & **Young’s Modulus** & **Tensile Strength** & **Elongation at** \\  & **(MPa)** & **(MPa)** & **Break (\%)** \\ \hline P3 HBHfx & 2264 \(\pm\) 138 & 33.7 \(\pm\) 0.4 & 4.0 \(\pm\) 0.2 \\ PHH\_05 LAK & 2260 \(\pm\) 213 & 30.8 \(\pm\) 0.2 & 3.8 \(\pm\) 0.1 \\ PHH\_05 UFC & 2309 \(\pm\) 42 & 34.1 \(\pm\) 0.4 & 3.9 \(\pm\) 0.1 \\ PHH\_05 PHB & 1866 \(\pm\) 119 & 32.4 \(\pm\) 0.3 & 4.8 \(\pm\) 0.2 \\ PHH\_05 BN & 2060 \(\pm\) 19 & 34.5 \(\pm\) 0.4 & 4.5 \(\pm\) 0.2 \\ PHH\_05 Talc & 1906 \(\pm\) 43 & 30.0 \(\pm\) 0.4 & 3.6 \(\pm\) 0.1 \\ PHH\_2 Talc & 1943 \(\pm\) 46 & 31.2 \(\pm\) 0.6 & 3.9 \(\pm\) 0.2 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Mechanical properties of P3 HBHfx and the corresponding nucleating agents.  
Figure 9: Mechanical properties of P3 HBHfx with different nucleating agents. (**a**) Young’s modulus; (**b**) tensile strength; (**c**) elongation at break.  
small, typically within \(\pm\)0.5%, as indicated in Table 5. Given this narrow range, it is difficult to establish a correlation between stiffness and ductility.  
To further explore the influence of processing conditions, additional tests were conducted on PHH_05 BN at different mold temperatures (50 \({}^{\circ}\)C, 60 \({}^{\circ}\)C, 70 \({}^{\circ}\)C, and 80 \({}^{\circ}\)C). As shown in Figure 10, increasing the mold temperature led to a further decrease in stiffness, as evidenced by the lower modulus and higher elongation at break. This trend is consistent with the expected formation of larger spherulites in heterogeneously nucleated samples under slow cooling conditions.  
These findings highlight the importance of considering the interplay between nucleating agents and processing parameters when optimizing the mechanical properties of P3 HBHHx. While efficient nucleators improve crystallization kinetics and potentially reduce cycle time, their influence on crystalline morphology can affect stiffness. Therefore, achieving a balance between enhanced processability and acceptable mechanical performance is essential for industrial applications.