Effect of Peel Angle Upon Peel Force

Measurements of peel force P per unit width are reported for samples of three adhesive tapes, adhering to two different substrates. In all cases, the work of detachment per unit area of bonded interface was found to depend upon the angle θ of detachment, increasing as θ increases. This effect is attributed to dissipation of energy in bending the tape away from the substrate at the line of detachment, to a greater degree as θ increases. Extrapolation to θ = 0 is suggested as a simple way of minimizing contributions to the observed work of detachment that arise from bending an imperfectly-elastic adhering layer as it is peeled away from a flat rigid substrate. But at small peel angles the tape tends to stretch appreciably. Peeling at 45° is recommended to minimize both effects.     

A new method to measure the high-shear bulk properties of pressure sensitive adhesives used in LCD devices

The wide application of pressure sensitive adhesives (PSAs) in thin film transistor liquid crystal display (TFT-LCD) devices is based on their advantages that PSAs provide sufficient bond strength and also are cleanly removable upon debonding. These two essential requirements are not obtainable without a proper understanding of the substrate as well as the rheological properties of the PSA. Unlike other substrates, the polarizer, the core unit of an LCD device, may exhibit a considerable dimension change with temperature and humidity. This imposes a large residual stress on the PSA layer, which often generates serious defects such as partial delamination. To overcome this problem, an accurate control of the rheological properties is required in the design of the PSA. In this study a new method is devised to measure the rheological behavior of thin film PSAs under high shear deformation. This method provided us with important information regarding the effects of molar mass and the level of crosslinking on the rheological behavior of the PSA. These findings along with the new method should be applicable not only to the LCD industry but also to other fields where an accurate control of PSA rheology is required.     

Degradation of Methyl β-D-Ribopyranoside and Methyl β-D-Xylopyranoside by Oxygen in Aqueous Sodium Hydroxide Solution

Methyl β-D-ribopyranoside (1) and methyl β-D-xylopyranoside (2) were degraded by oxygen (0.682 MPa partial pressure) in 1.25 M sodium hydroxide at 120°C. The degradations of 1 and 2 were similar to the previously reported degradations of 1,5-anhydroribitol (3) and 1,5-anhydroxylitol (4), respectively.⁴ Both hydrogen peroxide and stable organic peroxides were detected in the reactions of 1 and 2. The riboside 1 degraded faster than the xyloside 2. This difference in reactivity is proposed to be a function of the relative acidity of the glycosides. Ionization of hydroxyl groups is postulated to be favored in 1, thus facilitating the initiation of the free radical degradation. The degradations of both 1 and 2 exhibited complex kinetics indicating autoinhibited reactions. In spite of the differences in reactivity, glycosidic bond cleavage occurred in approximately 60% of the degradations for both 1 and 2. C-1 radicals, resulting from abstraction of the anomeric hydrogen atom, are proposed to cause the observed autoinhibition via termination reactions with α-hydroxyhydroperoxyl radicals. However, decomposition of the glycosides via C-1 radicals is not believed to constitute a major degradation pathway since the reactivities of 1 and 2 were essentially the same as the analogous 1,5-anhydroalditols, i.e. 3 and 4, respectively. The major acidic degradation products of 1 and 2 were identical, but were formed in different relative ratios. The major acidic products were methoxyacetic acid, lactic acid, glycolic acid, glyceric acid, a methyl 3-C-carboxyfuranoside, and two isomeric 2-C-carboxyfuranosides.     

NOTE: EXTRACTIVE SEPARATIONS WITH HYDROTROPES

Hydrotropic substances, such as, sodium P-toluene sulfonate, potassium P -toluene sulfonate, sodium P -xylene sulfonate, potassium P-xylene sulfonate, sodium benzoate, potassium benzoate, etc., in aqueous solutions, at relatively high concentrations, have been used successfully to separate mixtures of close boiling point substances like 2,6-xylenol/P-cresol, pheno1/o-chlorophenol, P -chlorophenol/2,4-dichlorophenol, and o-cresol76-chloro-o-cresol, dissolved in a suitable solvent. Very high values of separation factor in the range of 10 to 66 have been realised and this novel method appears to be promising for industrial utilization.     

NEW STRATEGIES IN SEPARATION OF CLOSE BOILING(SOLID)MIXTURES : EXTRACTION INTO MICELLAR AND MICROEMULSION MEDIA

Aqueous solutions of various surfactants, such as, sodium lauryl sulphate, lauryl alcohol-7-ethoxylate, cetyl pyridinium chloride, cetyl trimethylammonium bromide, etc., at concentrations above their critical micelle concentration values, known as micellar solutions, and microemulsion solutions consisting of these surfactants and a co-surfactant, n-butanol, have been used successfully to separate mixtures of isomeric/non-isomeric close boiling substances like o-nitrochlorobenzene/ p-nitrochlorobenzene, o-nitrotochlorbenzene, p-nitrotoluene, 2,6-xylenol/ p-cresol, -2,4-dichloro-phenol/2,4,6-trichlorophenol, o-isopropylphenol/ p-isopropylphenol, from their solid mixtures. Exceptionally high values for the separation factor have been realized and these novel methods appear to be promising for industrial utilization.     

Effects of Cα -Oxidation in the Fungal Metabolism of Lignin

C_α-Oxidation (benzyl alcohol oxidation) is a prominent reaction in the degradation of lignin by white-rot fungi. This study showed that such oxidation markedly retards metabolism of a nonphenolic β-O-4 model compound, 1-(3-methoxy-4-ethoxyphenyl)-2-(o-methoxyphenoxy)propane-1,3-diol, by cultures of Phanerochaete chrysosporium Burds. Surprisingly, however, selective chemical C_α -oxidation of spruce lignins enhanced their depolymerization by the cultures. Thus the decrease in intrinsic degradability of substructures is more than compensated by another effect of C_α-oxidation in lignin. One possibility is that the oxidation increases the accessibility of the lignin to enzymes by decreasing its steric complexity. This study also revealed that the β-O-4 model, like lignin in wood, is degraded in part via C_α-oxidation by P. chrysosporium. Reduction of the α-carbonyl groups thus formed does not occur. Addition of L-glutamate to ligninolytic cultures completely suppresses their competence to degrade the model compound, as it does their ability to oxidize lignin to CO₂. This result strengthens past evidence indicating that substructure models are metabolized by the same enzyme system as lignin.     

Laboratory-Scale Counter-Current Centrifugal Contactor Demonstration of an Innovative-SANEX Process Using a Water Soluble BTP

In this paper the development and laboratory-scale demonstration of a novel “innovative-SANEX” (Selective Actinide Extraction) process using annular centrifugal contactors is presented. In this strategy, a solvent comprising the N,N,N’,N’-tetraoctyldiglycolamide (TODGA) extractant with addition of 5 vol.-% 1-octanol showed very good extraction efficiency of Am(III) and Cm(III) together with the trivalent lanthanides (Ln(III)) from simulated Plutonium Uranium Refining by Extraction (PUREX) raffinate solution without 3^rd phase formation. Cyclohexanediaminetetraacetic acid (CDTA) was used as masking agent to prevent the co-extraction of Zr and Pd. An(III) and Ln(III) were co-extracted from simulated PUREX raffinate, and the loaded solvent was subjected to several stripping steps. The An(III) were selectively stripped using the hydrophilic complexing agent SO₃-Ph-BTP (2,6-bis(5,6-di(sulfophenyl)-1,2,4-triazin-3-yl)pyridine). For the subsequent stripping of the Ln(III), a citric acid based solution was used. A 32-stage process flow-sheet was designed using computer-code calculations and tested in annular miniature centrifugal contactors in counter-current mode. The innovative SANEX process showed excellent performance for the recovery of An(III) from simulated High Active Raffinate (HAR) solution and separation from the fission and activation products. ≥ 99.8% An(III) were recovered with only low impurities (0.4% Ru, 0.3% Sr, 0.1% Ln(III)). The separation from the Ln(III) was excellent and the Ln(III) were efficiently stripped by the citrate-based stripping solution. The only major contaminant in the spent solvent was Ru, with 14.7% of the initial amount being found in the spent solvent. Solvent cleaning and recycling therefore has to be further investigated. This successful spiked test demonstrated the possibility of separating An(III) directly from HAR solution in a single cycle which is a great improvement over the former multi-cycle strategy. The results of this test are presented and discussed.     

Variation of Specific Gravity,Fibre Length and Cell Wall Thickness in Young Salix Clones

Specific gravity, fibre length and cell wall thickness of various hybrid Salix clones were compared. The densest clone was 1.47 times denser than the least dense clone. The highest specific gravity was 0.5, found in Salix viminalis L. whereas the lowest was 0.372, found in Salix dasyclados L. The clone with longest fibre was 1.34 times that of the clone with shortest fibre. Clones with long fibre also showed high specific gravity such as Salix viminalis L. The cell wall thickness in Salix clones varies from 0.0025 mm to 0.0037 mm or 1.48 times from minimum to maximum cell wall thickness. Since the above fibre properties indicate various paper strength characteristics such as flexibility coefficient and felting index, it is possible to select clones with superior characteristics for propagation as suitable source for pulp and paper industry.     

Synthesis,characterization, and antimicrobial activity of chitosan hydrazide derivative

A series of modified chitosan derivatives 1–4 has been synthesized. Modification process of chitosan was achieved through a sequence of four reactions starting by protection of its amino group with benzaldehyde (derivative 1), followed by reaction with epichlorohydrine (derivative 2), then reaction with benzhydrazide (derivative 3), and finally restoring the free amino groups on the chitosan by removing of benzaldehyde molecules (derivative 4). These four derivatives were characterized by elemental analyses, FTIR, and X-ray. The four chitosan derivatives showed better antibacterial and antifungal activities than that of chitosan. Derivative 4 exhibited the highest antimicrobial activity relative to the other derivatives.     

Hydrogen Isotope Separation by Catalyzed Exchange Between Hydrogen and Liquid Water

Abstract

The discovery, at Chalk River Nuclear Laboratories, of a simple method of wetproofing platinum catalysts so that they retain their activity in liquid water stimulated a concentrated research program for the development of catalysts for the hydrogen-water isotopic exchange reaction. This paper reviews 10 years of study which have resulted in the development of highly active platinum catalysts which remain effective in water for periods greater than a year.

The most efficient way to use these catalysts for the separation of hydrogen isotopes is in a trickle bed reactor which effects a continuous separation. The catalyst is packed in a column with hydrogen and water flowing countercurrently through the bed. The overall isotope transfer rate measured for the exchange reaction is influenced by various parameters, such as hydrogen and water flow rates, temperature, hydrogen pressure, and platinum metal loading. The effect of these parameters as well as the improved performance obtained by diluting the hydrophobic catalyst with inert hydrophilic packing are discussed.

The hydrophobic catalysts can be effectively used in a variety of applications of particular interest in the nuclear industry. A Combined Electrolysis Catalytic Exchange - Heavy Water Process (CECE-HWP) is being developed at Chalk River with the ultimate aim of producing parasitic heavy water from electrolytic hydrogen streams. Other more immediate applications include the final enrichment of heavy water and the extraction of tritium from light and heavy water. Pilot plant studies on these latter processes are currently in progress.     

Summative Analysis of Nine Common North American Woods

The summative analysis of lignocellulosic materials has heretofore been a complicated process or the analysis has been incomplete. The Bomb/HPLC summative analysis method presented in this report results in a complete analysis of woody materials using a sample preparation scheme that is easily adopted into a normal laboratory routine. The method relies on HPLC for the majority of the component analyses. To demonstrate the applicability and reproducibility of the Bomb/HPLC method, ten wood samples, from nine different wood species, were analyzed in triplicate and the summative analysis of each sample was effected. The ten woods analyzed were: American beech ( Fagus grandifolia ), Quaking aspen ( Populus tremuloides ), Black cherry ( Prunus serotina ), Sugar (Hard) maple ( Acer saccharum ), Red (Soft) maple ( Acer rubrum ). White ash ( Fraxinus americana ), Yellow birch ( Betula verrucosa ), Douglas fir heartwood and Douglas fir sapwood ( Pseudotsuga menziesii ), and White fir sapwood ( Abies concolor ). The average summative analysis for the group of thirty samples was 99.13 ± 0.51% on an unextracted basis, 99.07 ± 0.45% on an extractive-free basis. There were no significant unidentified peaks in any of the HPLC chromatograms. The range of mass balance determinations for the group of ten wood specimens on unextracted and extractive-free bases was 98.43 to 99.63% and 98.31 to 99.60%, respectively.     

Peel mechanics of adhesive joints

A review is given of the mechanics of peeling rupture of an adhesive joint, consisting of a flexible adhering strip peled away from a layer of adhesive. Attention is drawn to a number of anomalous results that cannot be accounted for solely, in terms of the thermodynamic work of formation of two new surfaces. The work of detachment is found to be generally much larger than the theoretically-predicted amount. Moreover, the value obtained is greater for thicker layers of adhesive, and for detachment at a peel angle of 180° rather than at 90°. Also, it is found to increase with increasing thickness of the adhering strip, passing through a maximum value in some cases and then decreasing as the strip thickness is increased still further. All of these effects are attributed to dissipative processes, for example, plastic yielding, in one or both of the adhering layers as they are peeled apart. Some quantitative relationships are given for the additional peel forces arising from plastic yielding of the adherend or the adhesive.     

COMPARISON OF CATION EXCHANGE RESINS FOR RECOVERING AMERICIUM AND PLUTONIUM FROM CHLORIDE SALTS

ABSTRACT

Macroreticular and microreticular cation exchange resins were compared for their capability of recovering americium and plutonium from solutions of calcium, magnesium, potassium, and sodium chlorides. Americium and plutonium breakthrough capacity and elution behavior of the resins were determined. Of the resins tested, Dowex MSC-1 was selected as the most efficient because of its favorable capacity and excellent elution behavior. Actinide eluting agents were also studied. More concentrated (9.0M) nitric acid was found to elute plutonium faster than 7.0MHNO₃used previously while 7.0MHNO₃-0.1MNaNO₂eluted americium fastest.     

The Truex Process and the Management of Liquid Tru Uwaste

Abstract

The TRUEX (TRansUranium Extraction) process is a new generic actinide extraction/recovery process for the removal of all actinides from acidic nitrate and chloride nuclear waste solutions. A brief review of the relevant chemistry of the TRUEX process and a summary of the current status of development and deployment of TRUEX process flowsheets to treat specific acidic waste solutions at several U.S. DOE sites is presented.     

HYDRODYNAMICS AND MASS TRANSFER IN DOWNFLOW BUBBLE COLUMN

Gas holdup, effective interfacial area and volumetric mass transfer coefficient were measured in two and three phase downflow bubble columns. The mass transfer data were obtained using the chemical method of sulfite oxidation, and the gas holdup was measured using the hydrostatic technique. Glass beads and Triton 114 were used to study the effects of solids and liquid surface tension on the gas holdup and the mass transfer parameters a and k_L a . The gas holdup in three phase systems was measured for non-wettable (glass bead) and wettable (coal and shale particles) solids.

The mass transfer data obtained in the downflow bubble column were compared with the values published for upflow bubble columns. The results indicate that in the range of superficial gas velocities (0.002-0.025) m/s investigated, the values of the mass transfer coefficient were of the same order of magnitude as those observed in upflow systems, but the values of interfacial area were at least two fold greater. Also, the results showed that the operating variables and the physical properties had different influences on a and k_L a in the downflow bubble column. Correlations for a and k_L a for the downflow bubble column are proposed which predict the data with adequate accuracy in the range of operating conditions investigated.     

Relationship Between the B-Ring Hydroxylation Pattern of Condensed Tannins and their Protein-Precipitating Capacity

A series of condensed tannin derivatives with non-, mono-, di- and tri-hydroxylated B-rings were synthesized starting from phloroglucinol and benzaldehyde derivatives. The protein-precipitating capacity of these condensed tannin derivatives showed 1) A condensed tannin with only a 4′-hydroxylated B-ring has almost the same protein-precipitating capacity as that of a condensed tannin with 3′,4′-dihydroxylated or 3′,4′,5′-trihydroxylated B-rings. 2) The complexing ability of phenolic hydroxyl groups in the B-ring are effective in the order of p- > m- > o-positions.     

Anthraquinone Losses During Alkaline Pulping

Extensive loss of anthraquinone (AQ) or the active catalyst anthrahydroquinone (AHQ) from the AQ –- AHQ catalytic cycle has been explained in part by side reactions leading to the reaction product anthrone (anthracen-9-one), followed by subsequent formation of adducts with lignin quinone methides. Degradation of an adduct between anthrone and the quinone methide of guaiacylglycerol-β-guaiacyl ether, under soda pulping conditions, resulted in a complex mixture of products. The mixture included 3-guaiacylbenzanthrone, bianthronyl, bianthrone, guaiacol, AQ, trans-coniferyl alcohol, trans-coniferylaldehyde, cis- and trans-1-(3-methoxy-4-hydroxyphenyl)-2-(2-methoxyphenoxy)ethene, vanillin, and 2-methoxy-4-vinylphenol. C-13 NMR studies of lignins isolated from soda/AQ spent liquors indicated the presence of residual anthrone adducts and a significant content of chemically attached AQ.     

Amides as Phase Modifiers for N,N′-Tetraalkylmalonamide Extraction of Actinides and Lanthanides from Nitric Acid Solutions

Abstract

The N,N′-tetraalkylmalonamides are a class of compounds under development for transuranic (TRU) separations under high nitric acid conditions. There are several issues that challenge the further development of these ligands. One is the development of improved synthetic procedures that lend themselves to commercial scale-up. Another major issue is the third-phase formation that occurs when the N,N′-tetraalkylmalonamides are contacted with medium-to-high nitric acid concentrations in hydrocarbon solvents. To address the synthesis issue we have developed a new synthetic approach for preparing these materials. Third-phase formation can be eliminated by addition of diluent modifiers such as tributylphosphate (TBP). TBP is inappropriate if a nonphosphate-containing process stream is required. Amides have been proposed as alternatives for TBP in a variety of applications because of their ease of synthesis and the variety of substituents that can be generated. We have been able to develop an amide phase-modified system that extends the working process range of alkylmalonamides (0.5 M) in dodecane (unbranched hydrocarbon) from 3.5 M to 7.5 M nitric acid and in Isopar H (branched hydrocarbon) from 4.0 M to 10.0 M nitric acid using 1.0 M di-2-ethylhexylacetamide/0.5 M alkylmalonamide. The K_d values were comparable to extraction with alkylmalonamide in Isopar H or hydrogenated tetrapropylene (TPH) solvents. The overall extraction system was more robust than the phase-unmodified system allowing for greater temperature and acid concentration fluctuations without third-phase formation.     

Supported Extractant Membranes for Americium and Plutonium Recovery

Abstract

Solid supported liquid membranes(SLM) are useful in transferring and concentrating americium and plutonium from nitrate solutions. Specifically, DHDECMP (d ihexyl-N, N-diethylcarbamoyImethylphosphonate) supported on Accurel or Celgard polypropylene hollow fibers assembled in modular form transfers >95% of the americium and >70% of the plutonium from high nitrate (6.9 M), low acid (0.1 M) feeds into 0.25 M oxalic acid stripping solution. Membranes supporting TBP (tri-n-butylphosphate) also transfer these metal ions. Maximum permeabilities were observed to be 1 × 10^?3 cm sec^?1, similar to the values for other systems. The feed:strip volume ratio shows an inverse relationship to the fraction of metal ion transferred. Cation exchangers may be used to concentrate americium from the strip solution.     

Substituent Effects on 13C Chemical Shifts of Aromatic Carbons in β-O-4 and β-5 type Lignin Model Compounds

Abstract

Substituent effects on the chemical shifts of aromatic carbons in lignin model compounds have been elucidated from ¹³C NMR spectra of guaiacyl and syringyl type monomerio and β-O-4 model compounds and guaiacyl type β-5 model compounds. Evaluation of the observed values of substituent chemical shift (SCS) for the aromatic carbons leads to elucidation of a generalized SCS additivity rule, for estimation of the chemical shifts of aromatic carbons in ring A of β-O-4 and β-5 type substructures in model compounds and in ring B of β-O-4 substructures in lignin preparations, with errors of less than 1 ppm. The rule is applicable to substructures of both guaiacyl and syringyl types, using an appropriate parent compound as reference instead of benzene. Signals in the aromatic region of the ¹³C NMR spectra of β-O-4 and β-5 type model compounds are reassigned on the basis of the observed SCS's as well as APT spectra of the compounds.