• SIMULTANEOUS THERMAL ANALYSIS ON PLASMA-AIDED CAPILLARY IMPREGNATION FOR EUROPEAN WHITE PINE FLAME RETARDATION IMPROVEMENT

    Machines. Technologies. Materials., Vol. 10 (2016), Issue 2, pg(s) 5-8

    Simultaneous Thermal Analysis (STA, TGA and DSC) unifies the simultaneous application of thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) to one and the same wood sample in a single instrument, under perfectly identical conditions – same atmosphere, gas flow rate, pressure, heating rate, thermal contact, etc. New thermal analysis approaches for integral distinguishing between the flaming and glowing combustion of wood were discussed. The results obtained by STA were used in a new way in order to reveal the influence of plasma-aided capillary impregnation on thermal decomposition and glowing of wood controlled by oxygen and nitrogen containing flame re- tardant. New integral criterion of thermal behavior and decomposition such as specific enthalpy change has been developed by investigating samples of European White Pine (Pinus Sylvestris, Bulgaria) wood. This study has been developed also as part of a large investigation on plas- ma-chemically activated (polarized, functionalized) wood surface and its capillary impregnation with nitrogen- and phosphor flame retardant containing water solution.

  • CAPILLARY PENETRATION (SPREADING AND WICKING) MECHANISMS IN PLASMA-AIDED SURFACE FINISHING PROCESSES

    Machines. Technologies. Materials., Vol. 10 (2016), Issue 1, pg(s) 53-56

    The plasma-aided flame retardation of wood, wooden products and cellulosic fibrous materials has been conceived and developed as a surface finishing process of capillary impregnation with nitrogen- and phosphorous flame retardant containing water solution. The surface pre-treatment in atmospheric pressure dielectric barrier discharge plasma substantially alters its capillary activity – the spreading on the wood surface and the wicking in the depth of wood, thus improving some basic characteristics of the impregnation process. This study has been developed as part of a large investigation on plasma-chemically activated (polarized, functionalized) wood surface and surfactants enhanced plasma aided capillary impregnation with nitrogen- and phosphor flame retardant containing water solution. The experimental studies of capillary activity changes on European white pine (Pinus Sylvestris, Bulgaria) wood surfaces using selected surfactants and spreaders show that they have substantial contribution to the effective plasma-aided capillary activity and impregnation processes.

  • PLASMA SURFACE TECHNOLOGY PROMOTING CAPILLARY IMPREGNATION OF WOOD: XPS ANALYSIS OF DIFFERENT PLASMA PRE-TREATED WOOD SURFACES

    Machines. Technologies. Materials., Vol. 8 (2014), Issue 11, pg(s) 2-11

    X-ray Photoelectron Spectroscopy (XPS) also referred to as Electron Spectroscopy for chemical analysis (ESCA) was used to characterize the surfaces of plasma-chemical treated wood in air by dielectric barrier discharge (DBD). The plasma-surface pre-treatment of wood, wooden products and cellulosic fibrous materials has been developed for promoting capillary impregnation and plasma-aided flame retardency. In this study, XPS has been used since it has proved to be suitable investigation method to characterize the composition of a plasma pre-treated material surface. This method is a powerful analytical and non-destructive technique which has already been used for the analysis of plasma modified wood surfaces and in the characterization of wood’s reactions. Changes due to the plasma-chemical process were identified from the survey large spectra as well as from the detailed C and O spectra. The oxidative changes were quantified with the 1s 1s atomic ratio of oxygen to carbon and with a detailed analysis of the contributions to the C and O peaks.
    1s 1s

  • WOOD SURFACE ENERGY DETERMINED BY SESSILE DROP TECHNIQUE AS QUALITY PARAMETER OF PLASMA-CHEMICAL MODIFYED WOOD SURFACES

    Machines. Technologies. Materials., Vol. 8 (2014), Issue 10, pg(s) 50-2

    The analysis of pre-treated wood surfaces, which have been plasma modified is also very informative for wood quality. Our measuring instruments determine the wettability based on the contact angle. The optical shape analysis of drops which are dispensed onto the surface is a reliable method for carrying out this measurement. The aim of this study was to verify possibility of determining the contact angle values of the plasma activated wood and calculate the surface free energy and its components of wood from the obtained contact angle values using Zisman, Equation of state (EOS), Fowkes and Wu theory and calculation method. Based on the contact angle data, the surface energy was obtained from the polar-dispersive(non-polar) approach. This study has been created as part of a large investigation on plasma- chemically activated wood surface and flame retardant treated wood.

  • SIMULTANEOUS THERMAL ANALYSIS INVESTIGATION ON PLASMA-AIDED FLAME RETARDANCY OF WOOD

    Machines. Technologies. Materials., Vol. 8 (2014), Issue 10, pg(s) 9-12

    Simultaneous Thermal Analysis (STA) unifies the simultaneous application of thermogravimetry and differential scanning cal- orimetry to one and the same wood sample in a single instrument, under perfectly identical conditions – same atmosphere, gas flow rate, pressure, heating rate, thermal contact, etc. A new thermal analysis approach to distinguish between the flaming and glowing combustion of wood was discussed. The results obtained by STA were used in a new way, to reveal the influence of plasma-aided capillary impregnation on thermal decomposition and glowing of wood controlled by oxygen and nitrogen containing flame retardant. New integral criteria of thermal behavior and decomposition such as specific enthalpy change, and specific heat flux or heat release rate, have been developed by investigat- ing three species rain-forest wood (Mérida, Yucatán) – Mexican white cedar (Cupressus Lusitanica); Caoba mahogany (Swietenia macro- phylla); and Tzalam (Lysiloma bahamensis).