Article
  • Physical Properties of Very Low Density Polyethylene/Low Density Polyethylene Blends
  • Lee JY, Kim BS
  • 초 저밀도 폴리에틸렌과 저밀도 폴리에틸렌 블렌드의 물성
  • 이재연, 김봉식
Abstract
Very low density polyethylene (VLDPE) and low density polyethylene (LDPE) were melt blended in a mixer equipped at torque rheometer. Thermal and mechanical properties of the blends were investigated with LDPE content. To investigate compatibilization effect on the blends with VLDPE with different short chain branch (SCB) content, VLDPE-1 and VLDPE-2 with SCB contents, 20 and 15 mole% , respectively were used. VLDPE homo-polymer showed two melting peaks, i.e. low temperature endotherm (LTE) and high temperature endotherm (HTE). However, a melting temperature and a heat of fusion at LTE of LDPE blends with VLDPE-1 were higher than them of LDPE blends with VLDPE-2 but they showed the same result at HTE. Thermal properties of blends mainly depended on SCB content of VLDPE. Crystallinity of LDPE blend with VLDPE-1 increased slowly with LDPE content. But it increased abruptly with LDPE content in the blends with VLDPE-2. Maximum crystallinity of 40.4% was obtained in VLDPE-2/LDPE 20/80. Maximum tensile modulus of 135 MPa was also obtained in VLDPE-2/LDPE 20/80 and thls is higher than that of LDPE. Maximum tensile strength of 23.2 MPa was obtained in VLDPE-2/LDPE 40/60 and this is higher than that of pure VLDPE and LLDPE/LDPE blends. These results were explained by cocrystallization at the interface between VLDPE and LDPE.

Torque rheometer를 이용하여 초 저밀도 폴리에틸렌 (VLDPE)과 저밀도 폴리에틸렌 (LDPE)을 용융 블렌드하고, LDPE 함량에 따른 열적, 기계적 특성을 조사하였다. VLDPE의 short chain branch (SCB)의 함량에 따른 블렌드의 상용화 특성을 조사하기 위하여 SCB의 조성비가 서로 다른 VLDPE-1 (SCB 함량 20mo1e%)과 VLDPE-2(SCB 함량 15mo1e%)를 사용하였다. VLDPE의 용융거동은 LLDPE와 다르게 두개의 용융피이크인 low temperature endotherm (LTE)과 high temperature endotherm (HTE)을 나타내었으며, 블렌드의 열적 특성은 VLDPE의 SCB 함량에 의존하는 경향을 나타내었다. VLDPE-1/LDPE 블렌드의 LTE 거동에서 VLDPE-2/LDPE 블렌드에 비하여 융점과 융해열은 증가하였지만 HTE 거동은 거의 유사하였다. VLDPE-1과 LDPE 블렌드의 결정화도는 LDPE의 함량에 따라 매우 완만하게 증가하였다. 그러나 VLDPE-2와 LDPE 블렌드의 결정화도는 LDPE의 함량에 따라 급격하게 증가하였으며, VLDPE-2/LDPE가 20/80일때 결정화도는 40.4%로서 가장 우수하였다. 또한 VLDPE-2/LDPE 20/80의 인장 탄성률은 135MPa로서 LDPE 단독 중합체보다 약 35MPa 증가하였다. 또한 VLDPE-2/LDPE 40/60의 인장강도는 23.2MPa로서, VLDPE 단독 중합체 또는 기존의 LLDPE/LDPE 블렌드보다 큰 인장강도를 얻었다. 이것은 VLDPE와 LDPE의 계면에서 발생한 cocrystallization에 의한 것으로 해석된다.

Keywords: VLDPE; LDPE; blends; thermal properties; mechanical properties

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  • Polymer(Korea) 폴리머
  • Frequency : Bimonthly(odd)
    ISSN 0379-153X(Print)
    ISSN 2234-8077(Online)
    Abbr. Polym. Korea
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This Article

  • 1996; 20(4): 593-600

    Published online Jul 25, 1996