สำนักราชบัณฑิตยสภา

227 Suda Kiatkamjornwong et al วารสารราชบัณฑิตยสถาน ปีที่ ๓๗ ฉบับที่ ๑ ม.ค.-มี.ค. ๒๕๕๕ Experimental Plasma treater A diagram of the radio-frequency plasma generation and treatment (RF, CESAR 1310, Dressler HF-Technik GMbH, Germany) is shown in Figure 1. The main compo- nents of system are the reactor chamber, the RF generator, the gas supply system and the impedance matching network. A base pressure at 4×10 -3 Pa was achieved using a turbo molecular pump backed by a rotary vane pump. After the base pressure was reached, a specified gas was allowed to enter the chamber via a mass flow controller. Procedure PLA sheet Polylactide sheet with a thickness of 300 µm (Biogreen World) was used a printing substrate. The sheet size 17.8 × 12.2 cm were cleaned with 2% solution of a dish washing detergent (Teepool) and rinsed with de-ionized water until a clear sheet was obtained. The sheets were air-dried in a clean room. The clean sheets were exposed with the oxygen plasma at 30, 50, 70 and 100 W for 30 s in the chamber. Another set of sheets was irradiated with the oxygen plasma at 30 W for 10, 15, 20, 25, 30 and 40 min. All the untreated sheets and the treated sheets were measured for surface energies by contact angle measurement (FACE contact angle, CA-A, Kyowa Interface Science, Japan) with deionized water and methylene iodide. Surface energies of the plastic sheets are calculated based on the geometric mean theory [10],