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 (S_BET), equilibrium spreading pressure (π_e), and London dispersive component (γ_S^L), 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, π_e and γ_S^L 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 E_t 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 (S_BET), 평형확산압력(π_e), 그리고 비극성 요소(γ_S^L)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 π_e과 γ_S^L는 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