Strength chemistry

The TAPPI monograph (64) is an excellent source of additional information on technical and economic aspects of wet strength. An informative overview of the chemistry and mechanisms involved in wet strength chemistry can be found in reference 65. 

Dunlop-Jones, N., Wet-strength chemistry, in Paper Chemistry, 2nd Edn, Roberts, J. C. (Ed.), Blackie Academic Press, London, 1996, pp. 98-119. 

C. Gao, S. Leporatti, S. Moya, E. Donath and H. Moehwald, Swelling and shrinking of polyelectrolyte microcapsules in response to changes in temperature and ionic strength. Chemistry — A European Journal, 9(4), 915-920 (2003). 

This step encompasses procedures that are usually performed within the scope of an optimization. In doing so, mostly the interactions between the sample and the stationary phase are changed. The intention is a change of the retention factor k (mostly enhancement), but ideally also of the separation factor Ct. Otherwise, at constant interaction strength ( chemistry constant and therefore k and a as well), one attempts to enhance the plate number or in the case of a miniaturization to prevent dilution or to enhance the relative mass sensitivity. Using a trial-and-error procedure, one needs 1-2 weeks. Using a systematic procedure, aided perhaps by an optimization program, the time can be reduced measurably see Part 4 for chapters on computer-aided optimization. 

Yajima, S., Hayashi, J. (1975). Continuous silicon carbide fiber of high tensile strength. Chemistry Letters, 9, 1. 

The chemistry of cement slurries is complex. Additives will be used to ensure the slurry remains pumpable long enough at the prevailing downhole pressures and temperatures but sets (hardens) quickly enough to avoid unnecessary delays in the drilling of the next hole section. The cement also has to attain sufficient compressive strength to withstand the forces exerted by the formation over time. A spacer fluid is often pumped ahead of the slurry to clean the borehole of mudcake and thereby achieve a better cement bond between formation and cement. 

Technetium is a silvery-gray metal that tarnishes slowly in moist air. The common oxidation states of technetium are +7, +5, and +4. Under oxidizing conditions technetium (Vll) will exist as the pertechnetate ion, TcOr-. The chemistry of technetium is said to be similar to that of rhenium. Technetium dissolves in nitric acid, aqua regia, and cone, sulfuric acid, but is not soluble in hydrochloric acid of any strength. The element is a remarkable corrosion inhibitor for steel. The metal is an excellent superconductor at IIK and below. 

An area of great interest in the polymer chemistry field is structure-activity relationships. In the simplest form, these can be qualitative descriptions, such as the observation that branched polymers are more biodegradable than straight-chain polymers. Computational simulations are more often directed toward the quantitative prediction of properties, such as the tensile strength of the bulk material. 

Thus far the importance of carbon cluster chemistry has been in the discovery of new knowl edge Many scientists feel that the earliest industrial applications of the fullerenes will be based on their novel electrical properties Buckminsterfullerene is an insulator but has a high electron affinity and is a superconductor in its reduced form Nanotubes have aroused a great deal of interest for their electrical properties and as potential sources of carbon fibers of great strength... 

Eactors that could potentiaHy affect microbial retention include filter type, eg, stmcture, base polymer, surface modification chemistry, pore size distribution, and thickness fluid components, eg, formulation, surfactants, and additives sterilization conditions, eg, temperature, pressure, and time fluid properties, eg, pH, viscosity, osmolarity, and ionic strength and process conditions, eg, temperature, pressure differential, flow rate, and time. 

The boron atom in boron trifluoride is hybridized to the sp planar configuration and consequently is coordinatively unsaturated, ie, a Lewis acid. Its chemistry centers around satisfying this unsaturation by the formation with Lewis bases of adducts that are nearly tetrahedral sp [ The electrophilic properties (acid strengths) of the trihaloboranes have been found to increase in the order BF < BCl < BBr < BI (3,4). 

Because of constitutional complexity, the exact chemistries of nickel-base superalloys must be controlled carehiUy in order to avoid the precipitation of deleterious topologically close-packed (TCP) phases and extraneous carbides after long-term high temperature exposure. Heat-treatment schedules and thermomechanical treatments in the case of wrought alloys also are important to provide optimum strength and performance. 

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