Tadaaki Inomata

Improvement in adhesive strength of fluorinated polymer films by atmospheric pressure glow plasma

Abstract We tried to treat poly (vinyl fluoride) (PVF), poly(tetrafluoroethylene- co -hexafluoropropylene) (FEP) and poly(tetrafluoroethylene- co -perfluoro [alkyl vinyl ether]) (PFA) films by atmospheric pressure glow plasma to increase their adhesive strength with an epoxy resin. Their adhesive strength could be improved; the maximum peel force values obtained from a 180° peel test were over 2.00, 0.90 and 0.62kgf 20 mm −1 , respectively. These values were near or higher than those of the control sample films treated by a surfactant: 1.06, 0.47 and 0.70kgf 20 mm −1 , respectively. In this study, we found that the O 2 /He plasma-treated films had the highest peel forces although their contact angles were highest and their amounts of incorporated oxygen or nitrogen atoms were least; He plasma treatment also showed better effects on the overall results.

Development of silica coating methods for powdered pigments with atmospheric pressure glow plasma

Abstract We examined silica coating methods on Fe 3 O 4 (black), FeOOH (yellow) and Lithol Rubine BCA (RED) powders by means of atmospheric pressure glow plasma CVD with tetraethoxysilane. These pigments were deteriorated easily by heating or oxidation. However, cooling the discharge tube and depositing protective films on the pigments before plasma oxidation could prevent the deterioration. We developed three ways to make protective films, which suited each pigments characteristics.

Development of powder antifoamer by atmospheric pressure glow plasma

Abstract Atmospheric pressure glow (APG) plasma treatment does not require a vacuum pump that is equipped with a low pressure plasma device. With treatment for organic powder, APG plasma can modify the surface roughness and wettability. In this study, we treated polystyrene films and powder by APG plasma, surveyed the changes of surface morphology, and examined the antifoaming effects of powders. A high exposure time (for this study, 20 min) in He+CF4 plasma, polystyrene powders were introduced onto approximately 55% of fluorine atoms. This powder gave a better result for antifoaming properties.

Effect of bromomethane on the ignition in methane-oxygen-Argon mixtures behind reflected shock waves

Abstract The ignition delay times of methane-bromomethane-oxygen mixtures with argon were studied in the temperature range of 1400–2000K behind reflected shock waves. Ignition delay times, identified by the increase of pressure and OH emission, could be fit by the following expression: τ = 2.87 x 10 −11 exp (50,7OO/RT) X [ CH 4 l 0.33 [ O 2] −1.05 [ CH 3 Br ] 0.66 s The analytical investigation of the reaction mechanism gave calculated induction times in good agreement with experimental results. This system has 13 important reactions which control the induction time. Ignition was most sensitive to the following reactions: the decompositions of bromomethane and of formyl radical and the consumption of methyl radical.

Direct measurements of the rate coefficients for the reactions of some hydrocarbons with chlorine atoms at high temperatures

The reactions of methane, ethylene, ethane, and propane with chlorine atoms have been studied at hightemperatures by using a laser photolysis-shock tube apparatus coupled with atomic resonance absorption spectroscopy. Chlorine atoms were produced by the laser photolysis of silicon tetrachloride. The overall rate coefficients were experimentally determined from the decay of chlorine atoms as: k (CH 4 +Cl)=10 −9.26±0.26 exp[−(35.7±6.6) kJ mol −1 / RT ] cm 3 molecule −1 s −1 (1100–1550 K) k (C 2 H 4 +Cl)=10 −9.67±0.16 exp[−(35.8±3.9) kJ mol −1 / RT ] cm 3 molecule −1 s −1 (1100–1550 K) k (C 2 H 6 +Cl)=10 −9.96±0.05 cm 3 molecule −1 s −1 (1100–1400 K) k (C 3 H 8 +Cl)=10 −9.77±0.06 cm 3 molecule −1 s −1 (1100–1400 K) where the error limits are given at the two standard deviation level. With systematic errors also considered, the reliabilities, Δ[log k (RH+Cl)], were evaluated to be ±0.2 for reactions CH 4 +Cl and C 2 H 4 +Cl and to be ±0.15 for reactions C 2 H 6 +Cl and C 3 H 8 +Cl. These results are in good agreement with the extrapolations of the kinetic data measured up to 800 K by Pilgrim et al. To examine the product channels of these reactions, an ab initio molecular orbital calculation was performed at the QCISD(T)/6-311G ( d,p )//MP2(full)/6–31G( d ) level. The calculation shows that the energetically favorable channels of CH 4 _Cl, C 2 H 6 +Cl, and C 3 H 8 +Cl are H abstraction by Cl atoms. In the C 2 H 4 +Cl system, the measured rate coefficient has no total density dependence so that the Cl addition to ethylene is negligible in this experimental temperature range, although the addition channel has no energy barrier. Based on transition state theory, the rate coefficients were also calculated and discussed. The reactions of hydrocarbons with Cl atoms are suggested to follow the Evans-Polanyi law.

Zirconia coating on amorphous magnetic powder by atmospheric pressure glow plasma

Abstract We examined a method for coating zirconia on flat amorphous Co 70.3 Fe 4.7 Si 10 B 15 powder (fa-Co) by atmospheric pressure glow plasma with Zr(OC 4 H 9 ) 4 . XPS analysis was performed to determine the existence of ZrO 2 on the surface of the treated powder. The fa-Co obtained strong resistance to oxidization by this zirconia coating method. Resistivity measurements revealed that fa-Co coated with ZrO 2 was insulating. We also improved the permeability as a function of frequency of composite cores made from fa-Co by this zirconia-coating method.

Infrared absorption spectra and normal coordinate analysis of metal-dl-β-phenylalanine chelates

Abstract The infrared absorption spectra of dl -β-phenylalanine and its metal chelates have been investigated from 3700 to 270 cm−1. Detailed assignments of the observed absorption bands have been made based on a comparison of the spectra with the spectra of N-deuterated ligand and metal chelates, and with the spectra of some thoroughly studied, similar compounds. A normal coordinate analysis has been accomplished for the metal chelates as a 25-body problem utilizing a modified Urey-Bradley force field. The force constants obtained for metal-nitrogen bonds vary in the order Pt(II) > Cu(II) > Ni(II) = Co(II) = Zn(II). The nature of the carboxylate-metal bonding has been discussed, using the separation of the carboxylate antisymmetric and symmetric stretching vibrations as a basis for comparison. The separation increases in the order Ni(II) = Co(II)

Ozone, ammonia and NOx destruction in corona discharge tubes coated with ozone catalyst

The NH 3 , O 3 and NO x reduction from NH 3 /air and NO x /air systems were studied in a corona discharge tube. In the negative corona discharge, the NH 3 was decomposed and NO x , NO, O 3 production was suppressed even in air. The NO x reduction reaction in corona discharge was explained by an enhancing of electron impact dissociation in a low field strength discharge.

Ashing of Organic Compounds with Spray-Type Plasma Reactor at Atmospheric Pressure

We examined the ashing treatment at atmospheric pressure by means of three spray-type reactors fed with O2/He or O2/Ar mixture gases. These differed in the size or the shape of their nozzles. Such reactors were able to ash an organic compound (OFPR-800; a photoresist) even at atmospheric pressure. The results showed that the following procedures are important for increasing the ashing rate: to make the gas speed after blowing out fast; to decrease the O2 content while increasing the gas speed; and to use a gas mixture which has a slow decay rate of the active species, such as the oxygen radicals. Especially, when we used O2/Ar mixture gas for the ashing treatment, the ashing rate became quite fast and was as fast as that of a general low pressure glow plasma.

THERMAL DECOMPOSITONS OF 1,1,1-TRIFLUOROETHANE AND PENTAFLUOROETHANE IN A TURBULENT FLOW REACTOR

Abstract The thermal decompositions of 1,1,1-trifluoroethane (CH3CF3) and pentafluoroethane (CHF2CF3) were studied by using a turbulent flow reactor at atmospheric pressure over the temperature ranges of 1213–1333 K and 1273–1373 K. The rate coefficients for these thermal decompositions were determined from the first-order decays of the reactants to be k(CH3CF3) = 1012.9±1.2 exp[−(276 ± 29) kJ ⋅ mol−1/RT] and k(CHF2CF3) = 1013.9±1.4 exp [−(324 ± 36) kJ ⋅ mol−1/RT]s−1. To examine the reaction paths, we identified the decomposition products using gas chromatography-mass spectrometry (GC-MS) and performed ab initio MO calculations. These results showed that the sequential HF elimination reactions, CH3CF3 → CH2CF2 + HFand CH2CF2 → CHCF + HF, were favorable for the CH3CF3 pyrolysis. On the other hand, four initial steps: CHF2CF3 → CF3CF + HF, CHF2CF3 → CF2CF2 + HF, CHF2CF3 → CHF3 + CF2 and CHF2CF3 → CHF2 + CF3, were possible for the CHF2CF3 pyrolysis. Such a difference in the reaction paths between the CH3CF3, and CHF2CF3 pyrolyses can be explained by fluorine hyperconjugation and by repulsion between the fluorine atoms on the 1- and 2-carbons of each hydrofluoroethane.