Release Of Acetic Acid Research Articles

The Deterioration Characteristics of Archival Cellulose Triacetate Base Cinematograph Film

AbstractMany cellulose triacetate base cinematograph films, originally introduced in the 1950s,- are now exhibiting signs of irreversible deterioration. This degradation is characterized by the release of acetic acid from the film base and plasticizer deposits on the film surface. Such degradative processes subsequently result in loss of image. Copying of film is both costly and results in loss of image resolution. We have therefore undertaken studies to establish the physical and chemical degradation characteristics of such films. Here the role of factors such as emulsion layer, plasticizer and film container have been considered along with the influence of external environmental factors such as temperature and relative humidity. The relationship between both naturally and artificially-aged filmstocks has been considered, since this is necessary not only for a reliable assessment of film performance but for a realistic interpretation of the mechanistic processes involved. An understanding of the latter i...

Degradation of historic cellulose triacetate cinematographic film: The vinegar syndrome

The degradation of cellulose triacetate based cinematographic film has been studied by moisture regain, viscometry, uv absorption, pH and degree of insolubilisation. Analysis of naturally aged films indicates a correlation between moisture regain, acidity and degree of degradation. Artificial ageing studies at various temperatures and at different humidities show that temperature, moisture regain and pH are important related factors in the degradation mechanism. The results show conclusively that the degradation of acetate based film, which is often accompanied by the release of acetic acid, is associated with an acid catalysed hydrolysis of the ester groups resulting in a consequent reduction in the molecular weight of the polymer.

Measurement of erythrocyte acetylcholinesterase and plasma cholinesterase activity by a differential pH technique.

We describe a new electrochemical method for the determination of erythrocyte acetylcholinesterase activity (EC 3.1.1.7) and plasma cholinesterase (EC 3.1.1.8) activity, based on the measurements of pH variation due to release of acetic acid from acetylcholine. The major advantages of the differential pH procedure are simplicity, high reproducibility, no need for pre-treatment of samples, automatic correction of sample blanks, and speed and direct measurement of enzymatic reaction. The proposed methods are linear up to 7400 U/L at 30 degrees C and correlate well with the manual spectrophotometric method of Ellman for plasma cholinesterase and for washed erythrocytes. We adapted the same technique for the determination of erythrocyte cholinesterase using whole blood as sample and quinidine sulphate as inhibitor of pseudocholinesterase.

Behaviour of α-functional organotransition metals. Synthesis, characterisation and some reactions of 1-acetoxyalkyl derivatives of iron(II) and molybdenum(II)

Acetoxyalkyl metal derivatives M(C 5H 5)(CO) n [CHROC(O)Me] [M = Fe, n = 2; M = Mo, n = 3; R = H, Me] are readily prepared by reaction of bromoalkylacetates with the appropriate cyclopentadienylcarbonylmetallate anion. The complexes are characterised by their NMR ( 1H and 13C) and IR parameters and by mass spectrometry. The acetoxyethyl species are thermally labile via β-hydrogen transfer. Treatment of acetoxymethyl complexes with protic acids leads to carbon-oxygen cleavage and release of acetic acid; HCl affords chloromethyl complexes, carboxylic acids yield new carboxylatomethyl derivatives, HBF 4 leads to decomposition. The metalloesters are resistant to hydrolysis, transesterification and carboxylate displacement by nucleophiles (HO −, MeO −, H 2N − Et 2N −). Migratory insertion of CO could not be induced.

Total heat balance study of anaerobiosis inTubifex tubifex (M�ller)

1. Simultaneous measurement of rates of heat production, oxygen uptake and release of volatile fatty acids (VFA), acetic and propionic acid, byTubifex tubifex (Muller) showed that the steady-state anaerobic heat production as calculated from the release of anaerobic end-products, acetic and propionic acid, is similar to the direct measured anaerobic heat production under oxic as well as anoxic conditions. 2. The anaerobic heat production of lowPO2 acclimated animals amounts to 20–30% of the steady-state total aerobic plus anaerobic heat production measured on highPO2 acclimated animals under air saturated conditions. 3. The agreement between the observed and calculated rates of anaerobic heat production suggest that no anaerobic endproducts are accumulated in the animals under steady-state conditions and further that acetic and propionic acid are the only anaerobic end-products of quantitative importance. 4. The production and subsequent release of all anaerobic end-products is interpreted as representing a mechanism by whichTubifex and other facultative anaerobes maintain steady-state anaerobiosis and a simultaneous high calorific efficiency in milieus where extended periods of environmental anoxia are frequently experienced.

Laboratory ensilage of three tropcal pasture legumes - Phaseolus atropurpureus, Desmodium intortum and Lotononis bainesii

Phaseolus atropurpureus, Desmodium intortm, and Lotononis bainesii were ensiled in laboratory silos. Molasses was added to the first two legumes at 0, 2, 4, and 8 per cent of their wet weight. Changes in pH and water activity (Aw) and in contents of lactic acid, volatile acids, and volatile bases were followed during storage. When no molasses was added, P. atropurpureus made poorly preserved silage, D. intortum had some of the features of well preserved silage, and L. bainesii made excellent silage. Only 15 per cent of the nitrogen in the D. intortm silage was present as volatile bases, even though the pH remained above 5.0. No explanation was found for this, but the effects of a rapid release of acetic acid during the initial stages of ensilage deserve further study. The preservation of L. bainesii was probably not due solely to the development of acid conditions (pH <.4.2) as the pH at five days was as high as 4.9. P. atropurpureus and D. intortum with 8.0 per cent of molasses made well preserved lactic-acid silage but the smaller additions usually gave rise to butyric-acid silage. Measurements of water activity (Aw) suggested that low values during the initial stages of ensilage were a prerequisite for the production of stable lactic-acid silage.

Cyclization of Diene Polymers

Abstract 1. During the cyclization of natural rubber (unmasticized pale crepe) in phenol solution containing P2O5 as a catalyst, there is a drop in viscosity of the solutions—sharply at the beginning of the process and insignificantly after 5 hours cyclization time. 2. The speed of solution of rubber in phenol containing P2O5 is considerably greater than in pure phenol. This indicates that cyclization is started in the gel state and proceeds to full solution, and accelerates the breakdown of the gel fraction of the rubber. 3. Release of acetic acid, during oxidation of rubber for various periods of cyclization with chromic acid, diminishes in the course of the first four hours of the process, and then remains constant, whereas the viscosity continues to lessen. This serves to show that the process of breakdown goes forward even after the cyclization process is completed. 4. Unsaturation of cyclorubber, determined by the reaction with perbenzoic acid, amounts to approximately 25% of the original known unsaturation of rubber. 5. The presence in the ultraviolet spectrograph of cyclorubber of absorption bands at 275–280 mµ and in the infrared spectrograph of a series of absorption bands at 690 and 740−1, and again at 1500 to 1600 cm−1, indicates bound phenol in cyclorubber.