柠檬酸醚酯增塑剂的合成及增塑聚乳酸

Synthesis of Tri-(Triethylene Glycol-monobutyrate)Citrate and Its Plasticizing Effect for Poly(Lactic Acid)

利用两步酯化法合成新型醚酯增塑剂——柠檬酸三(三甘醇单丁酯)酯(TTBC),通过红外光谱(FT-IR)和核磁共振氢谱(1 H-NMR)对其进行表征,将聚乳酸(PLA)和TTBC按一定质量比进行熔融共混。采用差示扫描量热仪(DSC)、偏光显微镜(POM)、电子拉力机以及平行平板流变仪研究了不同含量的TTBC对PLA/TTBC性能的影响。结果表明:随着TTBC含量增加,PLA的玻璃化转变温度(Tg)、熔点(Tm)和冷结晶温度(Tcc)均逐渐向低温移动,邵氏D硬度逐渐降低。PLA/TTBC的断裂伸长率均在300%以上,拉伸强度保持在10MPa以上。PLA/TTBC的复数黏度(η*)和黏流活化能(ΔEη)显著下降。通过与增塑剂含量为25%(质量分数)的PLA/TBC对比发现,TTBC的增塑效率与耐迁移性均高于TBC。

Tri-（triethylene glycol-monobutyrate）citrate （TTBC） as a new ether-ester plasticizer was synthesized by two-step esterification. The chemical structure of TTBC was characterized by 1H-nu- clear magnetic resonance and infrared spectroscopy. TTBC was used for plasticizing poly（lactic acid） （PLA） via a melt-compounding process. The effect of TTBC content on the properties of PLA/TTBC blends was studied by differential scanning calorimetry, polarizing optical microscopy, electronic tes- ting machine and parallel plate rheometer. The results show that with the increase of TTBC content, the glass transition temperature （Tg）, melting point （Tm）, and cold crystallization temperature （Tcc） of PLA gradually shift to a lower temperature and their Shore D hardness decreases. The breaking elongation of PLA/TTBC blends is above 300%, while the corresponding tensile strength of PLA/ TTBC blends maintains at above 10MPa. The rheology of PLA/TTBC shows that the complex viscos- ity （ η ） and viscous flow activation energy （△Eη） reduce significantly. Compared with PLA/TBC- 25, TTBC has a higher plasticizing efficiency and migration resistance than TBC.