## 4 Discussions  
This study successfully demonstrated the tunability of injection molding parameters for manufacturing miniplate implants, assessing their mechanical and biodegradation performances with varied compositions of PLA, sago starch and PEG at different injection  
Figure 9: The crystalline phase and molecular interaction of the miniplate specimens with pure PLA compared to various sample compositions of SPLA0P10, SPLA20P0, SPLA20P10 and SPLA20P20 with injection molding temperature of 180 \({}^{\circ}\)C.  
temperatures (150 \({}^{\circ}\)C, 160 \({}^{\circ}\)C, 170 \({}^{\circ}\)C and 180 \({}^{\circ}\)C). Optimal conditions for miniplate fabrication were identified at 170 \({}^{\circ}\)C for PLA/sago starch with 10% PEG, yielding favorable mechanical properties and a degradation rate of 7.97% over 28 days. For PLA/starch with 20% PEG, optimal conditions were at 150 \({}^{\circ}\)C, resulting in specific mechanical properties and a degradation rate of 10.22%. Mechanical assessments revealed that incorporating PEG into pure PLA (SPLA0P10) resulted in relatively high mechanical performance, showing a linear correlation with increasing injection temperature. The optimal composition and injection temperature for mechanical properties were identified as SPLA0P10 at 170 \({}^{\circ}\)C and 180 \({}^{\circ}\)C, achieving high ultimate stress, elastic modulus and break elongation. These findings were corroborated by bending tests, emphasizing the favorable mechanical aspects of SPLA0P10 at 170 \({}^{\circ}\)C. On the other hand, the addition of sago starch to pure PLA material (SPLA20P0) significantly increased ultimate stress, surpassing that of PLA/PEG with no sago (SPLA0P10). However, it also led to a notable decrease in elongation at break across different temperature settings, as observed in both tensile and bending tests. It was suggested that achieving higher mechanical properties for SPLA0P10 required injection molding at higher temperatures (180 \({}^{\circ}\)C in this study), while lower temperatures (150 \({}^{\circ}\)C in the current study) seemed more effective for SPLA20P0 to achieve high ultimate stress and elastic modulus. Interestingly, the addition of sago starch and PEG together to the PLA, as observed in SPLA20P10 and SPLA20P20, resulted in a general decrease in mechanical performance across the tested temperatures, indicating an antagonistic interaction between sago starch and PEG plasticizer when blended into the PLA-based implant, affecting its mechanical resistance. Nevertheless, the inclusion of sago starch proved effective in optimizing the biodegradation rate of the PLA miniplate implant, necessitating comprehensive characterization to determine the most optimal compositions and manufacturing parameters when combining the three materials: PLA, sago and PEG plasticizer. A higher biodegradation rate was observed with a larger weight composition of the hydrophilic component, primarily due to the presence of sago starch. In general, the PEG interphase layer enhanced the interface between PLA and sago starch, as confirmed in SEM imaging of the miniplate with a PEG content of 10% by weight (SPLA20P10) in a previous study [27]. An increase in the sago starch content in the PLA blend significantly improved the mass loss rate of the miniplate samples. A comprehensive review on the biodegradation of PLA in medical implants and systems has been conducted by [PERSON] et al. indicating that the degradation rate of PLA material inside the human body primarily occurs through the hydrolysis of its ester-bond polymeric backbone. This process is commonly dependent on lattice shapes, porosity structure, pH and temperature of the surrounding environments [44; 45; 46]. However, PLA's inherent hydrophobic properties and resistance to hydrolysis result in a slow degradation rate in crystalline phase hydrolysis, posing a challenge in tissues and rendering it unsuitable for use as medical appliances due to its extended degradation period [5; 18]. [PERSON] et al.