Wallace plasticity

Wagner equation Wagner number Wakamatsu reaction Waldhof fermentor Walkman Wallace plasticity Wallach procedure Wall baffles Wallboard Wall geometries Wallpaper paste Wallpaper pastes Wallpapers Wall plaster Walnut oil... 

Plasticity Retention Index. The oxidation behavior of natural mbber may affect both the processing characteristics and final vulcanizate performance, and the plasticity retention index (PRI) test can be used to give an indication of both. Natural antioxidants present in natural mbber give some protection and a measure of the efficacy of protection is given by PRI. PRI% = P q j Pq x 100, where Pq is the initial Wallace plasticity and P q is the... 

There are obvious advantages in a technique whereby the behaviour of a rubber in a vulcanisate could be assessed by a test carried out on the raw rubber. The PRI test consists in measuring the Wallace Plasticity of the raw rubber before and after ageing for 30 minutes at 140 °C, the aged plasticity being expressed as a percentage of the unaged (BS 903-A59.2). Plasti-Corder... 

Size exclusion chromatography was used to determine the inherent molar mass distribution of latex samples taken directly from the tree. This was shown, subject to the influence of harvesting and processing, to govern both initial Wallace plasticity and Mooney viscosity of natural... 

Retention Index (PRI), a measure of resistance to heat oxidation, and Wallace Plasticity (Pq), a measure of plasticity under controlled conditions. 

Results are presented of high strain testing for the characterisation and quality assurance of NR using the RPA 2000 rubber process analyser. Such testing was found to be more effective in detecting processability ditferences than traditional processing tests such as Mooney viscosity or Wallace plasticity. 24 refs. 

Table 3 shows the Wallace plasticities of these compounds and the tensile properties of the vulcanizates cured at the optimum conditions. From this table, the sample IS-ML showed the best tensile... 

The entropy production terms in (7.4) and (7.5) come from plastic deforma-tional heating. Following Wallace [15]... 

Wallace [15], [16] gives details on effects of nonlinear material behavior and compression-induced anisotropy in initially isotropic materials for weak shocks, and Johnson et ai. [17] give results for infinitesimal compression of initially anisotropic single crystals, but the forms of the equations are the same as for (7.10)-(7.11). From these results it is easy to see where the micromechanical effects of rate-dependent plastic flow are included in the analysis the micromechanics (through the mesoscale variables and n) is contained in the term y, as given by (7.1). 

D.C. Wallace, Thermoelastic-Plastic Flow in Solids, Los Alamos Report LA-10119, 1985. 

Wallace, D.C., Thermoelastic-Plastic Flow in Solids, Los Alamos National Laboratory, University of California Report No. X-4 84-114U, Los Alamos, NM, 82 pp., February 1984. 

An instrument for measuring the plasticity of an elastomer, e.g., Wallace Rapid Plastimeter Plastisol... 

What was the first synthetic plastic Although some nineteenth-century experiments should be mentioned, such as the 1869 molding process for cellulose nitrate discovered by John and Isaiah Hyatt, probably the first major breakthrough came in 1910 with Leo Baekeland s discovery of phenol formaldehyde resins (Bakelite ). These are still the leading thermoset plastics made today. The pioneering work of Wallace Carothers at Du Pont in 1929 produced the nylons now used primarily as fibers but known as the beginning of thermoplastic resin technology. 

Table 14. Plasticity of natural rubber containing 0.66 ml/g of different monomers in Wallace...

ISO 200722 specifies a rapid plastimeter procedure using an instrument with one platen either 7.3, 10 or 14 mm diameter and the other platen of larger diameter than the first (i.e. disc type method). The size of the first platen is chosen such that the measured plasticity is between 20 and 85. The test piece is cut with a punch which will give a constant volume of 0.40 0.04 cm, the thickness being approximately 3 mm and the diameter approximately 13 mm. The test piece is pre-compressed to a thickness of 1 0.01 mm within 2 sec and heated for 15 sec. The test load of 100N is then applied for 15 sec when the test piece thickness is measured. The usual temperature of test is 100°C and the result is expressed as the thickness of the test piece at the end of the test in units of 0.01 mm and called the rapid plasticity number. The Wallace rapid plastimeter, and presumably other commercial instruments, conform to this specification but it would be sensible to check with the manufacturers. A technically identical method is given in BS 903 Part A5923. 

Wallace. J.F. "Casting." Advanced Materials A Ptrnesscs, 53 (January 1990). W eeks. R.A. Casting of Film, Modem Plastics Encyclopedia. Price Siem Sloan Publishing. Los Angeles. CA. 1997... 

In Chapter 14 (p. 226) you studied the different addition polymers produced from alkenes. Not all polymers are formed by addition reactions, though. Some are produced as a result of a different type of reaction. In 1935 Wallace Carothers discovered a different sort of plastic when he developed the thermoplastic, nylon. Nylon is made by reacting two different chemicals together, unlike poly(ethene) which is made only from monomer units of ethene. Poly(ethene), formed by addition polymerisation, can be represented by ... 

Synthetic fibres may be made from cellulose or plastics. Hilaire Chardonnet made the first synthetic fibre from cellulose in 1889. Wallace Carothers made the first plastic-based synthetic fibre nylon in 1935. Ladies stockings were the first articles to be made of nylon. Second World War gave a boost to the production of nylon. 

Wallace et al. (20) correlated GC retention volumes of several poly(vinyl chloride) powders with their uptake of plasticizer. Since the diffusion of plasticizers into polymer powders is controlled by the external surface area, the diffusion coefficient of the plasticizer and some shape factor, a correlation with GC measurements could be expected. It was found that plasticizer absorption ( drying ) took place only when the polymer was heated to a temperature immediately above the glass transition temperature as defined by the minimum of the experimental retention diagram. 

The discovery of nylon is one example. In 1928, E.l. DuPont de Nemours and Company appointed a young, 32-year-old chemist from Harvard, Wallace Carothers, as the director of its new research center. The goal was to create artificial fibers similar to cellulose and silk. In 1930, Julian Hill, a member of Carothers team, dipped a hot glass rod in a mixture of solutions and unexpectedly pulled out long fibers such as the one shown in Figure 1-14. Carothers pursued the development of these fibers as a synthetic silk that could withstand high temperatures and eventually developed nylon in 1934. Nylon s first use was in a toothbrush with nylon bristles. During World War 11, nylon was used as a replacement for silk in parachutes. Nylon is used extensively today in textiles and some kinds of plastics. 

The Scintistrip plates developed by Wallac/Perkin Elmer are made by incorporating the scintillant into the entire plastic [46, 47]. The target of interest is immobilized on the surface. 

Let us consider the timeline of a class of industrial products - synthetic polymers or pldstics. The first completely synthetic plastic wasBaKeiite invented in 2907 by Leo H- BaeKeland (2863- 29 ). It was a rigid, lightweight material and used to maKe everything from hairbrushes to handles of frying pans. Wallace Hume Carothers (2896 -2937) developed a new polyamide fibre which was marKeted as Nylon in 2938. 

Nylon, the first commercial thermoplastic engineering polymer, is the prototype for the whole family of polyamides. Nylon 6,6 began at Du Pont with the polymer experiments of Wallace Carothers in 1928, and made its commercial debut as a fiber in 1938 and as a molding compound in 19A1. By 1953, 10 million lbs of nylon 6,6 molding compound represented the entire annual engineering plastic sales. 

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