The effect of ozone surface treatment of montmorillonite (MMT) was investigated in thermal stabilities of polypropylene (PP) nanocomposites. Sodium montmorillonite (Na+-MMT) was organically modified with dodecylammonium chloride. The surface properties of MMT, including the specific surface area (SBET), equilibrium spreading pressure (πe), and London dispersive component (γSL), were studied by the BET method with N2 adsorption. Also, the thermal stabilities of the nanocomposites were investigated in DSC and TGA. As experimental results, πe and γSL of the ozonized dodecylammonium chloride (DA-MK(O3)) were increased in about 1.7 and 3.5 mJ/m2, resulting from the increasing of the micropores. From the DSC results, it was found that the melting temperature and crystallization temperature of PP/DA-MK and PP/DA-MK(O3) were higher that those of pure PP. These results were explained that dodecylammonium chloride of nano-scale led to a nucleation effect for PP crystallization. Also, it was found that Et of the PP/DA-MK (O3) nanocomposies was increased within about 64 kJ/mol. These results were probably explained by the improvement of dispersivity of DA-MK (O3) in a PP matrix.
표면처리된 몬모릴로나이트 (montmorillonite, MMT)가 PP 나노복합재료의 열안정성에 미치는 영향을 조사하였다. Na+-MMT는 dodecylammonium chloride를 이용하여 유기적으로 개질하였다. 비표면적 (SBET), 평형확산압력(πe), 그리고 비극성 요소(γSL)를 포함하는 표면 특성은 N2 흡착을 이용하는 BET 방법을 이용하여 고찰하였다. 또한, 나노복합재료의 열안정성은 시차주사열량계 (DSC)와 열중량 분석기 (TGA)를 통해 알아보았다. 실험 결과, 오존처리된 dodecylammonium chloride (DA-MK (O3))의 πe과 γSL는 1.7과 3.5 mJ/m2로 증가하였는데, 이는 미세기공이 증가하기 때문으로 판단된다. DSC 결과로부터, PP/DA-MK와 PP/DA-MK (O3)의 용융 온도와 결정화 온도는 순수한 PP보다 더 높았는데, 이러한 결과는 나노크기의 DA-MK가 PP 결정화를 위한 핵생성 효과를 유도하기 때문으로 판단된다. 또한, PP/DA-MK (O3) 나노복합재료의 열안정성은 64 kJ/mol 향상되었는데, 이는 PP 매트릭스 내 DA-MK (O3)의 분산성 향상에 기인하는 것으로 판단된다.
Keywords: montmorillonite; polypropylene; nanocomposites; ozone treatment; thermal stabilities