Synergistic Effect of Talc and Titanium Dioxide on Poly(lactic acid) Crystallization: An Investigation on the Injection Molding Cycle Time Reduction
- 77 Downloads
Injection molding cycle time is one of very important parameters relating to the plastic production rate. In neat poly(lactic acid) (PLA), it requires more than 25 min to obtain its half crystallinity (t1/2). This indicates that the injection molding of neat PLA with high degree of crystallinity (Xc) and high production rate is impossible. This research aims to increase the crystallization rate of PLA by combining two inorganic fillers namely; titanium dioxide (TiO2) and talc. Differential scanning calorimetry (DSC) study indicated that the t1/2 of PLA decreased from 27 min to < 81 s, while the Xc increased by around 16% with the adition of TiO2. Modifying PLA with talc was found to reduce t1/2 down to 36 s and the Xc increased from 0.92 to 20% only at a heating rate of 1 °C/min. The combination of talc and TiO2 was significantly increased the Xc for all cooling rates applied. Synergistic crystallization behavior was clearly observed when TiO2 was added to PLA/talc for all TiO2 concentrations. Minimum t1/2 of 18 s was observed together with the increased Xc by around 26% when TiO2 was added to PLA/talc at 3 wt%. This reduced the injection cycle time from around 28 min, in neat PLA, down to 68 s at this TiO2 content. With the presence of talc and TiO2, the flexural modulus of the composites was improved significantly.
KeywordsPolymer-matrix composites Biodegradable polymers Crystallization Nucleating agents Injection molding cycle time
The authors would like to acknowledge the research grant supported by Srinakharinwirot University (Contract No. 045/2560). Thanks are extended to Mr. Kittisak Phromsuk, Miss Wipada Kijmaneekul and Miss Weraphattra Kodwongsa for their valuable comments.
- 23.Thamaphat K, Limsuwan P, Ngotawornchai B (2008) Phase characterization of TiO2 powder by XRD and TEM. Kasetsart J (Nat Sci) 42:357–361Google Scholar