Physical strength improvement

To expand the usefulness of wood products, it is often desirable to increase the physical strength, improve chemical resistance, and slow degradation. One method of effecting these changes is to impregnate the porous wood... 

Another significant end-use for polyamines is in preparation of paper wet-strength resins. These are polyamide, modified formaldehyde, and polyamine resins used to improve the physical strength of tissue, toweling, and packaging paper products. The cationic formaldehyde resins include both urea—formaldehyde and melamine—formaldehyde types (248,249). Cationic functionaHty is imparted by incorporation of DETA, TETA, and/or TEPA in... 

Stationary phase materials are synthesized from different raw materials. Those stationary phase materials synthesized from inorganic materials, such as silica and alumina, are physically strong but chemically unstable. Conversely, stationary phase materials synthesized from organic materials, such as polystyrene or poly(vinyl alcohol), are chemically stable but physically weaker. Improvements in the chemical stability of inorganic stationary phase materials and in the physical strength of organic stationary phase materials are required the marketed products do not have both and have to be used under restricted conditions in liquid chromatography. 

Established indications for somatropin (growth hormone) include growth hormone deficiency in children, Turner s syndrome, Noonan s syndrome, and renal insufficiency in children. Other well-studied indications include idiopathic short stature, adult growth hormone deficiency, osteoporosis, and catabolic states associated with acute and chronic illness and injury. Body composition, respiratory muscle function, physical strength, and height improved in a 12-month trial of somatropin in 54 children with Prader-Willi syndrome (1). 

Carrel AL, Myers SE, Whitman BY, Allen DB. Growth hormone improves body composition, fat utilization, physical strength and agility, and growth in Prader-Willi syndrome a controlled study. J Pediatr 1999 134(2) 215-21. 

AASs are used nonmedically to improve athletic performance, physical appearance, and fighting ability. AAS-using bodybuilders believe that AASs enhance their physical strength, boost their confidence and... 

It is interesting to note that these characteristics also are necessary to impart physical reinforcement and resulting cohesive strength improvement to the adhesive or sealant. 

Non-reactive diluents. These diluents are low-viscosity materials which do not have any reactive sites and thus do not react with the epoxy systems. These diluents generally impart flexibility and improve the impact resistance, giving better thermal mechanical shock resistance. However, there is a sacrifice in physical strength, chemical resistance and high-temperature performance. Addition of 30 parts non-reactive diluent to 100 parts epoxy resin usually does not affect the physical properties of the system. Commonly used non-reactive diluents are nonyl phenol, furfuryl alcohol and dibutyl phthalate. 

In 1944, Socony-Vacuum Oil Company started manufacture of synthetic silica-alumina catalyst in the form of beads (262). This catalyst was reported to contain about 10% alumina. The bead catalyst gives about the same product distribution as the pelleted synthetic catalyst and was developed primarily to achieve greater physical strength for use in the TCC process. The bead catalyst has also been used in Houdry fixed-bed units (51,171). Subsequently, a harder bead catalyst was developed for use in the air-lift units. The improved bead catalyst consists of approximately 15% alumina and 85% silica and contains 0.003% chromium to minimize afterburning by suppressing formation of carbon monoxide during regeneration (333). 

It has been pointed out that surface treatment of fibers significantly improves the physical strength of the composite (14). The reinforcing fibers should be surface-treated before use. Examples of the treatment include chemical treatment, such as silane compounds and titanates (20), and (fiysical treatment such as corona and ultraviolet pl na (14). 

Thus all successful chlor-alkali membranes currently employ a perfluorocarboxylate polymer to lower the rate of hydroxide ion transport. The sulfonate portion of some of these membranes is present mainly to add strength to the thinner carboxylate barrier layer. Fabric backing is also used in some cases to improve physical strength. 

Talc also positively improves retention of flexural properties of WPC after long underwater exposure. For example, after 210 days of underwater exposure of an HDPE-based WPC with 60% filler content (wood flour and talc combined), drop in physical strength was 26% (6% talc), 20% (20% talc), 17% (27% talc), and 16% (30% talc). The corresponding figures for drop in flexural modulus were as follows 51% (6% talc), 45% (20% talc), 40% (27% talc), and 37% (30% talc) [6-8]. 

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