Journal of the Korea Academia-Industrial cooperation Society (한국산학기술학회논문지)

The Korea Academia-Industrial cooperation Society (한국산학기술학회)
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Toughening of PLA stereocomplex by Impact modifiers

충격보강제에 의한 PLA stereocomplex의 강인화 연구

  • Nam, Byeong-Uk (Department of Applied Chemical Engineering, Korea University of Technology and Education) ;
  • Lee, Bum-Suk (Department of Applied Chemical Engineering, Korea University of Technology and Education)
  • 남병욱 (한국기술교육대학교 응용화학공학과) ;
  • 이범석 (한국기술교육대학교 응용화학공학과)
  • Received : 2011.12.02
  • Accepted : 2012.02.10
  • Published : 2012.02.29
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Abstract

We tried to blend PLLA and PDLA at overall compositions to form PLA stereocomplexes (SC). The presence of the SC crystalline phase in the PLLA matrix was verified by differential scanning calorimetry (DSC). As a result, a various PDLA composition of the PLA SC blends can influence PLA SC formation. And the largest amount of PLA SC crystallites was formed when PLLA/PDLA ratio is 50/50. In addition, we have tried to do PLA SC toughening with two impact modifiers in 92/8, 85/15 ratio of PLLA/PDLA to enhance the mechanical properties such as impact strength. Thermal and mechanical properties of PLA SC were investigated by DSC, HDT, Izod impact tester and UTM. PLA SC formation decreased when 10-20 wt% of Strong120 (impact modifier) was added. On the other hand, there is no effect on PLA SC formation when 10-20% of Elvaloy (impact modifier) was added. HDT values dramatically increased over $100^{\circ}C$ with the addition of PDLA. However, HDT decreased as Strong120 and Elvaloy content increased. Finally, we could find well balanced composition of toughened PLA SC with 10wt% of impact modifier in flexural modulus and impact strength.

광학 이성질체인 PLLA와 PDLA를 전 조성에서 블렌드하여 PLA stereocomplex(SC)를 제조하였고 DSC를 통해 PLLA matrix안의 SC결정 형성 정도를 파악하였다. 결과적으로 PLA SC blend의 PDLA 함량이 SC 결정 생성 정도에 영향을 주며 PLLA/PDLA=50/50의 조성일 때 가장 많은 SC 결정이 생성되었다. 더 나아가 고유의 낮은 충격강도를 보강하기 위하여 PLLA/PDLA=92/8, 85/15 조성에서 충격보강제(Impact modifiers)를 도입하였다. 제조된 PLA SC/Impact modifiers의 열적기계적 성질은 DSC, HDT, Izod Impact tester, UTM을 통해 측정하였다. DSC 측정 결과 PLA SC 결정은 Strong120(Impact modifier)가 10-20wt% 도입되면 감소하는 경향을 보이나 반면에 Elvaloy가 도입될 때에는 아무런 영향을 주지 않는 것으로 관찰되었다. HDT의 값은 PDLA의 도입에 따라 급격하게 $100^{\circ}C$이상으로 증가하였다. 하지만 Strong120과 Elvaloy가 도입됨에 따라 감소하는 경향을 보였다. 결국 Toughening된 PLA SC에서 10wt%의 Impact modifier를 blend하여 가장 최적의 충격강도와 굴곡탄성율을 갖는 물성을 발견할 수 있었다.

Keywords

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