Formic acid, film from

FIGURE 12.2 Variation of open-circuit potential with time for I iOj film electrodes, prepared by anodization of Ti, in contact with BS. Base solution SI and S2 0.1 and 0.5 mM salicylic acid Ml and M2 1 and 10 mM methanol FI and F2 1 and 10 mM formic acid solutions. (From Li and Shen, 2006. J. Solid State Electrochem. 10, 980-986, with permission from Springer.)... 

Phenoxaphosphine ring-containing poly (1,3,4-oxa-diazoles) were synthesized by cyclodehydration of poly-hydrazides obtained from (BCPO) and aliphatic and aromatic dihydrazines [152]. All these polymers are soluble in formic acid, w-cresol and concentrated H2SO4. The polyhydrazides yield transparent and flexible films when cast from DMSO solution under reduced pressure at 80-100°C. The polyhydrazides exhibit reduced viscosities of 0.24-0.40 dl/g in DMAC. Phenoxaphosphine ring-containing oxadiazole polymers showed little degradation below 400°C. 

Chitin films can be manufactured from DMAc solutions or by other approaches, for example, blend films of beta-chitin (derived from squid pens) and poly(vinyl alcohol) (PVA) were prepared by a solution casting technique from corresponding solutions of beta-chitin and PVA in concentrated formic acid. Upon evaporation of the solvent, the film having 50/50 composition was found to be cloudy [224]. 

Figure 13.3 Potentiodynamic electrooxidation of (a) formic acid, (b) formaldehyde, and (c) methanol on a Pt/Vulcan thin-film electrode (7 xgpt cm, geometric area 0.28 cm ) in 0.5 M H2SO4 solution containing 0.1 M HCOOH (a), HCHO (b), or CH3OH (c). The potential scan rate was 10 mV s and the electrolyte flow rate was 5 p-L s at room temperature). The top panels show the faradaic current (solid lines), the partial currents for Ci oxidation to CO2 (dashed lines) and for formic acid formation (dash-dotted line), calculated from the respective ion currents, and the difference between the measured faradaic current and the partial current for CO2 oxidation (formic acid oxidation (a), formaldehyde oxidation (b)), or the difference between faradaic current and the sum of the partial currents for CO2 formation and formic acid oxidation (methanol oxidation, (c)) (dotted line). The solid lines in the lower panels in...

Figure 13.6 Potential-step electro-oxidation of formaldehyde on a Pt/Vulcan thin-film electrode (7 p,gpt cm, geometric area 0.28 cm ) in 0.5 M H2SO4 solution containing 0.1 M HCHO upon stepping the potential from 0.16 to 0.6 V (electrolyte flow rate 5 pL at room temperature). (a) Solid line, faradaic current transients dashed line, partial current for HCHO oxidation to CO2 dotted line, difference between the net faradaic current and that for CO2 formation, (b) Solid line, m/z = 44 ion current transients gray line potential-step oxidation of pre-adsorbed CO derived upon HCHO adsorption at 0.16 V, in HCHO-free sulfuric acid solution, (c) Current efficiency transients for CO2 formation (dashed line) and formic acid formation (dotted line).

The decomposition of formic acid over evaporated Pd-Au alloy films has been studied by Clarke and Rafter (69) the same reaction on Pd-Au alloy wires was studied by Eley and Luetic (128). The alloy films were prepared in a conventional high vacuum system by simultaneous evaporation of the component metals from tungsten hairpins. The alloy films were characterized by X-ray diffraction and electron microscopy. The X-ray diffractometer peaks were analyzed by a method first used by Moss and Thomas (SO). It was found that alloys deposited at a substrate temperature of 450°C followed by annealing for one hour at the same temperature were substantially homogeneous. Electron microscopy revealed that all compositions were subject to preferred orientation (Section III). 

The decomposition of formic acid was studied on clean Cu(l 10) by TPRS (75). Formic acid adsorbed at either 190 K or 300 K with an initial sticking probability of unity. The adsorption roughly followed Langmuirian behavior. Multilayers were not adsorbed down to 190 K condensed HCOOH was reported to desorb from copper films below 190 K (90). Chemisorbed... 

The polymer precipitates immediately and stirring is continued for an additional 5 min. The polymer is filtered, boiled in water for 15 min, filtered, dried under reduced pressure at 70°C to afford a quantitative yield of polymer, inherent viscosity 0.31 (sulfuric acid), polymer melt temperature 306°C. The polymer is soluble in formic acid from which a film can be cast. 

Film from Formic Acid. A solution (1% w/v) of the curdlan in formic acid was spread onto a teflon block and allowed to dry, forming a thin transparent film. 

Film from Formic Acid. Dissolution in formic acid also esterifies curdlan giving the formate bands in the spectrum (Fig. 13). 

Fig. 6 Dynamic mechanical behavior for different film species of a cellulose composite synthesized with a monomer mixture of VP/GMA = 3/7, representing an effect of the chemical treatment of an original sample (CELL/P(VP-co-GMA)[0]) with aqueous formic acid [F] or sodium hydroxide [S] solution. CELL content = 4.5 wt%. (Reproduced from [73])...

Hudson et al. used Ca(NC>3)2—MeOH to dissolve silkworm silk and did not manage to obtain good fibers directly. They also casted film from such a solution and then dissolved the film in formic acid and trifluoroacetate acid... 

There is ample evidence that in strongly protic solvents, proteins generally exist in an unfolded configuration, resembling roughly the random-coil form of polypeptides. Thus, Ambrose and Elliott (1951) showed that insulin treated with formic acid and cast as a film exhibits a shift in the maximum of the C=0 infrared stretching frequency from 1657 cm for... 

Figure 1 shows a plot of pressure increase against time for an experiment at 189.2° with 14.9 mm. of formic acid decomposing on a 31.3-mg. high-vacuum film, and values calculated from Equations (1), (2), and (3) with appropriate constants. The exact dependence of pressure increase on the time is somewhat obscured at the end of the reaction by diffusion of formic acid vapor, partly present as dimer in the cooler portion of the apparatus, into the reaction flask from the dead space of the spoon gauge. 

Poly(methyl methacrylate) (PMMA) and Related Polymers.—The photolysis of PMMA in methyl acetate, chloroform, CH2C12, and benzene solution has been shown to be consistent with scission resulting from random absorption directly by the polymer without participation of the solvent.199 The photolysis of thin films of PMMA in 02 has been shown to produce methanol, formaldehyde, methyl acetate, methyl formate, water, formic acid, carbon dioxide, and methane.200 The reactions caused by light in PMMA in the presence of atomic... 

Dimethylformamide (DMF) has been known since 1893, but since the 1950s, it has evolved as an important solvent. Its main uses are as a solvent for spinning acrylic fibers, polyurethane and polyamide coatings and films, PVC, polyacrylonitrile, extraction of aromatics from petroleum, selective solvent for removal of acid gases from natural gas, solvent for dyes, electrolyses in galvanization processes, and paint remover and cleaner [16]. By 1980, the worldwide production of DMF had grown equal to the production of formic acid at 220,000 metric tons per year [18]. By 1993 the U.S. production of formic acid was 30 to 35 mm pounds and DMF production had grown to 60 to 65 mm pounds. 

Figure 10.8 Tafel plots of the electrocatalytic oxidation of 0.1 M formic acid in 0,1 M HCIO4 at different platinum-based alloy electrodes dispersed in a polyaniline film and containing 0,1 mg cm of platinum (—) Pt (---) Pt-Ru (...) Pt-Sn (—) Pt-Ru-Sn. (Reprinted with permission from ref 69)...

Several experimental results support the adsorption mechanism for stationary conditions of the passive layer. Even the stationary passive current density depends on the composition of the electrolyte. For iron in 0.5 M H2SO4, the passive current density is 7 pA cm , whereas less than lpAcm is detected in 1 M HCIO4. From these observations, a catalysis for the transfer of Fe + from the passive layer to the electrolyte by S04 ions was concluded [55, 56]. Similarly, the dissolution Ni + from passive nickel and nickel base alloys is accelerated by organic acids hke formic acid and leads to a removal of NiO from the passive layer [57]. Additions of citrate to the electrolyte cause the thinning of passive layers on stainless steel and increase its Cr content [58]. Apparently Fe and Ni ions are complexed at the surface of the passive film, which causes an enhancement of their dissolution into the electrolyte. It should be mentioned that the dissolution of Cr " " apparently is not catalyzed by these anions and remains... 

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