Shearing commercial specifications

Some U.S. governmental lubricant requirements for nontactical equipment is now acquired as Commercial Item Descriptions (CID), rather than against specific military numbers. A new classification system for shear-stable, high VI hydraulic fluids was balloted by ASTM in 1994. 

Specific Commercial Rotational Viscometers. Information on selected commercial rotational viscometers can be found ia Table 7. The ATS RheoSystems Stresstech rheometer is an iastmment that combines controlled stress as well as controlled strain (shear rate) and oscillatory measurements. It has a torque range of 10 to 50 mN-m, an angular velocity range of 0 to 300 rad/s, and a frequency range of seven decades. Operation and temperature programming (—30 to 150°C higher temperatures optional) are computer controlled. 

Table 1 contains the metal-to-metal engineering property requirements for Boeing Material Specification (BMS) 5-101, a structural film adhesive for metal to metal and honeycomb sandwich use in areas with normal temperature exposure. The requirements are dominated by shear strength tests. Shear strength is the most critical engineering property for structural adhesives, at least for the simplistic joint analysis that is commonly used for metal-to-metal secondary structure on commercial aircraft. Adhesive Joints are purposefully loaded primarily in shear as opposed to tension or peel modes as adhesives are typically stronger in shear than in Mode I (load normal to the plane of the bond) loading. 

A large number of different commercial viscometers, which provide a variety of geometries and a range of viscosity and shear rates, can be used to characterize a fluid. Specialized techniques have been developed to suit specific purposes [125-127],... 

Both adhesive and hydrodynamic forces depend on the size of the particles. The two forces were calculated for CaC03 fillers of various particle sizes homogenized in a PP matrix. The results are presented in Fig. 3. At a certain particle size adhesion exceeds shear forces, aggregation of the particles takes place in the melt. Since commercial fillers have a relatively broad particle size distribution, most fillers show some degree of aggregation and the exact determination of the particle size, or other filler characteristics where aggregation appears, is difficult. Experiments carried out with 11 different CaC03 showed this limit to be around 6 m /g specific surface area [25]. 

Combinations of cationic starch and anionic microparticles are useful commercial systems. Shear-sensitive flocculation occurs, allowing microscale reflocculation in the formed paper sheet, which improves dewatering and retention.63,75,76 The microparticles can be colloidal silica, aluminum silicate, poly(silicic acid) or bentonite of specific size and surface area.77 79 Cationic, anionic or polymeric aluminum-containing compounds can be additional components. A three-part coacervate system uses a high molecular weight anionic polyacrylamide, cationic starch and silica.80 Cooking cationic starch in the presence of an anionic silica hydrosol was reported to improve drainage and retention.81... 

Aqueous pectin dispersions show flow behavior similar to many other polysaccharide solutions. Flow curves of specific viscosity rpp vs. shear rate have a Newtonian plateau (constant r sp) at low shear rates, followed by a shear thinning region at moderate shear rates (Morris et al., 1981). Most pectin solutions have relatively low viscosity compared to some other commercial polysaccharides, such as guar gum, mainly because of the lower MW. Consequently, pectin has limited use as a thickener. 

From R D to quality control, rheology measurements for each phase of the product development life cycle involve raw materials, premixes, solutions, dispersions, emulsions, and full formulations. Well-equipped laboratories with stress- and strain-controlled oscillatory/steady shear rheometers and viscometers can generally satisfy most characterization needs. When necessary, customized systems are designed to simulate specific user or process conditions. Rheology measurements are also coupled with optic, thermal, dielectric, and other analytical methods to further probe the internal microstucture of surfactant systems. New commercial and research developments are briefly discussed in the following sections. 

Id meet to qualify and assure a reliable part. This assignment, undertaken by NASA MSFC in 1974, led to the first document for the procurement of adhesives to be used in hybrid microcircuits. After further coordination and revisions, this initial document was formally released as a specification in 1978 and revised in 1982 as NASA MSFC-SPEC-592, Specification For The Selection and Use of Organic Adhesives in Hybrid Microcircuits." For the first time, the critical requirements for ionic contaminants, electrical resistivity, die-shear strength, corrosivity, and outgassing were specified. Work on the development and evaluation of adhesives continued into the mid-1980s and, as a result, several commercially available adhesives were qualified." ... 

Figure 12 Interfacial shear resistance r versus specific interaction parameter Isp for C fibers and an epoxy matrix (DGEBA-DDS). The C fibers were (1) untreated, (2) oxidized, (3) sized, and (4) commercial sized PAN-based fibers. The epoxy matrix was a diglycidyl ether of bisphenol A with 35 parts by weight of diamino diphenyl sulfone (DGEBA-DDS). (Reprinted from Ref. [95].)...

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