Volume 61 Issue 2 (2011) - Годишник на ТУ - София - Технически ...

Table 2. Carbon peak C s1 components or proportions of oxygen and carbon functional groups ofDouglas fir and pine heart wood surfaces before (K) and after plasma pre-treatment (SO, SN, SHF)determined from high-resolution XPS-spectra.Carbon peak C s1 components, %Kind of Wood:Density, kg/m 3SamplesC1 (C-Cor C-H)C2 (C-O,C-OH)C3 (C=O,O-C-O)C4(O-C=O)nC1/nC2 32C i(285.00.4 eV)(286.00.4 eV)(288.70.4 eV)(289.50.4 eV)- -Heart Douglas К (Non-Treated) 64.1 31.0 4.9 0.0 2.068 35.9Fir woodSO(Pseudotsuga DBD55.4 38.9 5.7 0.0 1.424 44.6menziesii, PretreatedSN 58.1 23.5 12.8 5.6 2.472 41.9Canada):678 kg/m 3 SHF 57.5 35.0 6.2 1.3 1.643 42.5Heart Pine К (Non-Treated) 54.1 34.8 8.8 2.3 1.554 45.9WoodSO(Pinus Sylvestris,Bul-Pre-SN 45.2 40.4 11.9 2.6 1.119 54.8DBD50.9 37.2 9.8 2.1 1.368 49.1garia: treated371 kg/m 3 SHF 45.4 40.1 12.0 2.5 1.132 54.6The high-resolution spectrum of the oxygen peak O 1s includes the following mainfour different chemical states of oxygen atom on the wood surfaces: O1 (531.50.4eV) – O=C; O2 (532.50.4 eV) – O-H; O3 (533.00.4 eV) – O-C or H-O-H; andO4 (534.50.4 eV) – not defined [13]. The carbon states and oxygen states are relevant– C3 to O1 and C2 to O3, but the amounts of C2 and C3 and O1 and O3 aren’tcorresponding. The found difference is due to the water (H-O-H) absorbed in thesurface layer, Table 3.XPS findings revealed that DBD pre-treatment increases the nO/nC ratio byoxidation of the Douglas fir surfaces and decreases the nC1/nC2 ratio, Table 2.ACKNOWLEDGMENTSThe financial support of the National Science Fund, Ministry of Education and Scienceof Bulgaria, for the Bulgarian-Romanian Bilateral Research Project „Developmentof New Properties by Surface Modification of Polymers Based Materials” isgratefully acknowledged.83