Strengthening the interfacial bonding between the hydrophobic plastic matrix and the hydrophilic wood flour is important to secure good physical properties of the composite. Therefore, wood flour was hydrophobized with soybean oil and the effects of the hydrophobization on the physical properties of the polypropylene (PP)/wood flour composites were investigated. Hydrophobized wood flours with attached soybean oil contents of 1.02-11.63 g to 20 g of neat wood flour were prepared by changing soybean oil/ethanol solution concentration, and their hydrophobicity was analyzed by compatibility test, Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analyzer (TGA). PP/wood flour (80/20 by weight) composites were prepared by melt-mixing and compression molding, and their impact strengths, tensile properties and water-resistance were measured. With increasing the soybean oil content attached to the wood flour the impact strength, elongation at break and water-resistance of the composites increased, and tensile strength was the highest when the attached soybean oil content was 3.00 g. Scanning electron microscope (SEM) images confirmed that the interfacial bonding between the PP matrix and the wood flour was strengthened by the hydrophobization of the wood flour with soybean oil.

소수성인 플라스틱 매트릭스와 친수성인 목분 사이의 계면결합력을 높이는 것이 복합재료의 좋은 물성 확보에 중요하다. 따라서 콩기름을 이용하여 목분을 소수화 처리하고, 목분의 소수화가 폴리프로필렌(PP)/목분 복합재료의 물성에 미치는 영향을 조사하였다. 콩기름/에탄올 용액의 농도를 달리하여 20 g의 순수한 목분에 콩기름이 1.02-11.63 g 결합된 소수화 목분을 각각 제조하였고, 상용성 시험, 적외선분광기(Fourier transform infrared spectroscopy, FTIR) 및 열중량분석기(thermogravimetric analyzer, TGA)로 소수성을 분석하였다. PP/목분(80/20 중량비) 복합재료는 용융혼합 및 압축성형에 의해 제작하였고 충격강도, 인장특성 및 내수성을 측정하였다. 목분에 결합된 콩기름의 함량이 증가할수록 복합재료의 충격강도, 파단신율 및 내수성이 증가하였고 인장강도는 3.00 g의 콩기름이 결합되었을 때 가장 높았다. 목분을 콩기름으로 소수화 처리하여 PP/목분 사이의 계면결합력이 높아졌음을 주사전자현미경(scanning electron microscope, SEM) 사진으로 확인하였다.

Keywords: polypropylene, composites, wood flour, soybean oil, modification.