EFFECTS OF DIELECTRIC BARRIER DISCHARGE PLASMA MODIFICATION ON SURFACE PROPERTIES OF TROPICAL HARDWOODS AT LOW PRESSURE

The study investigated the use of dielectric barrier discharge (DBD) for surface modification of Shorea contorta (white lauan), Gmelina arborea (yemane) and Acacia mangium. Wood specimens were exposed to oxygen plasma at various intensities ranging from 5.8 to 46.5 kW-min m-2. Surface free energy was calculated based on contact angle measurements to determine thermodynamic changes on plasma modified wood. Surface characteristics were evaluated using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and atomic force microscopy (AFM). Results of the study showed that plasma modification resulted in significant increase in surface free energy of the three wood species investigated. ATR-FTIR indicated that plasma-treated wood had higher surface polarity compared with untreated controls. AFM 3D image showed that oxygen plasma was capable of cleaning and etching wood surface resulting in the degradation of primary and secondary cell walls. Eksperimen ini mengkaji penggunaan peluahan sawar dielektrik (DBD) untuk mengubah suai permukaan Shorea contorta, Gmelina arborea dan Acacia mangium. Spesimen kayu didedahkan kepada plasma oksigen pada keamatan berbeza daripada 5.8 kW-min m-2 hingga 46.5 kW-min m-2. Tenaga permukaan bebas dikira berdasarkan ukuran sudut sentuh untuk menentukan perubahan termodinamik kayu yang diubah suai oleh plasma. Ciri permukaan dinilai menggunakan spektroskopi pantulan keseluruhan dikecilkan jelmaan Fourier inframerah (ATR-FTIR) dan mikroskopi daya atom (AFM). Keputusan menunjukkan pengubahsuaian plasma menghasilkan peningkatan signifikan dalam tenaga permukaan bebas bagi ketiga-tiga spesies kayu yang dikaji. ATR-FTIR menunjukkan bahawa kayu yang dirawat dengan plasma mempunyai kekutuban permukaan yang tinggi berbanding dengan kawalan yang tidak dirawat. Imej 3D menunjukkan plasma oksigen berupaya membersihkan serta memunar permukaan kayu lalu menyebabkan penguraian dinding sel primer dan sekunder.