본 연구에서는 폴리락틱산(PLA)의 용융강도를 향상시키기 위하여 몬모릴로나이트(MMT), 기능성 단량체인 글리시딜 메타크릴레이트(GMA)와 반응개시제를 함유한 PLA를 이축압출기로 개질한 후 열적 특성과 및 유변학적 특성을 조사하였으며, X선 회절장치(XRD) 및 투과전자현미경(TEM) 사진을 이용하여 MMT의 분산도를 측정하였다. 이 나노복합체의 $T_g$는 GMA 함량이 증가하면 감소하는 경향을 보였으나, MMT의 양에는 크게 영향을 받지 않았다. 또한 표면분석에 의해 MMT의 양이 증가할수록 박리형(exfoliation) 보다는 삽입형(intercalation)에 가까운 나노복합체가 형성된 것을 확인하였다. 복합점도 및 저장탄성률은 MMT의 첨가에 의해 크게 증가되었다.
In this study, poly(lactic acid) (PLA) was modified by reactive extrusion with a functional monomer GMA(glycidyl methacrylate), MMT(montmorillonite), and initiator to enhance the melt strength. Each modified PLA was prepared with different amounts of GMA and MMT and was characterized by measuring thennal- and melt-viscoelastic properties. The degree of dispersion of MMT was measured by X-ray diffraction(XRD) and transmission electron microscopy(TEM). The glass transition temperature($T_g$) of modified PLA-GMA-MMT nanocomposite decreased with increasing GMA content, but was a little affected by the amount of MMT. Surface analysis showed that the nanocomposite became more intercalated than exfoliated as the amount of MMT increases. The complex viscosity and storage modulus of the nano-composite were greatly increased by addition of MMT.
