Plexiglass, 763 table

Although the production of polymers has contributed to pollution— many of them are not biodegradable—they have varied uses as synthetic fibers, films, pipes, coatings, and molded articles. Polymers are also being used increasingly as coalings for medical implants. Names such as polyethylene, poly(vinyl chloride) (PVC), Teflon, polystyrene, Orion, and Plexiglas (Table 12-3) have become household words. 

More recently, the circular array was proposed to assess the reflectivity of cylindrical specimens [3]. First, a circular C-scan image was obtained. The total scan time was about 25 min., which does not include a relatively time consuming alignment of the specimen. From the circular C-scan image, circular B-scan profiles were chosen in specific planes. The transducer was a focused high frequency transducer with a center frequency of 25 MHz of the transducer bandwidth. This frequency corresponds to a wavelength of 0.11 mm and 0.25 mm in the Plexiglas specimen and the AlSi-alloy, respectively. Additional experimental parameters are presented in Table 1. 

The three pairs of reflection tomograms are listed in Table 2, showing the artificial and real discontinuities in the Plexiglas and A/5i-alloy cylinder, respectively. 

Table 2. Discontinuities in Plexiglas specimen and AZ5i-alloy.

These variables are illustrated in Figure 6.10. Zilliox and Muntzer (1975) also evaluated the effects of falling and rising water tables on Ah in their Plexiglas laboratory model. When the water table fell, the capillary pressures Pc vo and PcOA were nearly equal, whereas Ah was positive at equilibrium. When the water table rose, they observed that P°A varied little and Pcwo decreased considerably. As a result, Ah decreased and could become negative. Hence, the actual thickness could be greater than the apparent thickness. 

By using the method described on p 193T, Coleburn and Liddiard, Jr obtained particle velocities, Up, and pressures for typical shock-producing systems. Their data are given in Table II, p 1931, using brass and Plexiglas as specimen-plates of various thicknesses... 

Measurements of the transit times of weak shock waves ( 10Q bar) were used to obtain sound wave velocities in larger specimens than listed in Table II. In the arrangement of Fig 3 a cylinder (or slab) of the expl was immersed in a Plexiglas container filled with water. Initiation of the detonator produced a shock wave which arrived nearly plane thru the water at the surface of the expl specimen. The motion of wave was recorded by a smear camera using a shadowgraph technique. Plots of Us up relationships showed that the resulting curves were nearly straight lines and that for particle velocities, up, from 0.3 to 1.2 mm/ftsec, shock wave velocities are ... 

D. Kite, Jr, Safety Hazard Classification of Water-Wet Explosives , PATR 3223 (1965) (AD-460363/5ST) [Table 7 lists deton data for 18 granular w-filled expls loosely packed in Plexiglas tubes of 1.75" ID with wall thicknesses of from 1/8" to 1/4". Expl column lengths were from 10" to 20". Deton was achieved using either 33g Tetryl pellets or 40-grain RDX wafers, electric cap initiated. 

Enclosed 50 x 30 cm wood, plastic, or Plexiglas arena, marked into 10-cm squares (Table 18.1). Gray or black arenas are typically used. If an arena is not available, a large animal cage marked into squares with indelible ink may be used (10, 12). 

Extraction units. The extraction chromatography columns are built of plexiglas, the solid stationary phase being immobilized in the column between two sintered glass discs. The caracteristics of the columns employed are given in Table IV. 

Most bottom samples were obtained by Scuba divers using specially constructed plexiglas box cores (Fig. 13 of Part I). The method of obtaining cores is described in Part I, Gravity cores were also taken at each station on one or more occasions as previously described. Box cores were taken in summer, fall, and winter-spring periods from 1974 to 1976 sampling was carried out over 2-year periods at FOAM and NWC and for 1 year at DEEP (Table III of Part I, this volume, p. 253). 

Confine your work with radioisotopes to a small area in the laboratory. A convenient plan is to use a stainless steel tray lined with absorbent blotter paper coated on the bottom side with polyethylene. The paper must be replaced every day. If the radioactive matenals are volatile, the work should be done in a fume hood. If spills occur, a small work area such as a tray is much easier to clean than a large lab bench. If or other strong j8 emitter is used, it is necessary to work at all times with shielding between yourself and the radioactive samples. The most cost-effective and convenient shielding material is Plexiglas. The thicknesses of shielding required for various materials are given in Table 6.3. 

Commercial impact-modified acrylic resins (Table 19.15) exhibit five- to tenfold improvement in the notched Izod impact strength and the ultimate tensile elongation compared to the neat PMMA resin. These impact-modified acrylics are usually blended captively by the manufacturers of the acrylic resins. The base resin in a typical weatherable grade (Plexiglas DR, Rohm and Haas) could be a methyl methacrylate copolymer with ethylacrylate and styrene, while the rubber additive (ca. 10 %) could be an emulsion-polymerized, PMMA-grafted, cross-linked poly (n-butylacrylate) rubber of controlled particle size (<200 nm). The nonweatherable impact-modified acrylic (XT, CYRO) typically consists of a MMA/S/AN copolymer with MBS (ca. 10 %) rubber particle dispersions. 

The critical assemblies, in the form of rectangular prisms, were assembled by a remote split-table device. Plutonium dioxide-potystyrene compacts (1.12 g Pu/cm, Pu-240 = 2.2%, and H/Pu atomic ratio 15) in 2-in. cubes were the basic fuel material. These were alternated with 2-ln. cubes of Plexiglas (CsH, ) to form a three-dimensional checkerboard array of fuel and Plexiglas. The fuel core had cross-sectional dimensions of 12.16 x 12.06 in. While the length of one section cf the fuel core remained fixed at 2.03 in., the other sectioi located on the opposite side of the test interface was varied to achieve criticality. 

Experimentally determined critical sizes and masses obtained from Plexiglas-reflected parallelepipeds, constructed from 2- X 2- x 2-in. PuOi-UOa-polystyrene fuel compacts, are shown in Table n. Calculated values of k ff have been obtained for these critical systems utilizing ENDF/B-n cross-section data with diffusion theory, transport ttieory, and Monte Carlo-type calculations. Typical resiHts obtained were 1.027 a 0.007, with the Monte Carlo code KENO-I, for the reflected 40.72-X 40.64- X 36.42-cm assembly of 7.89 wt% Pu fuel and 0.991 with the diffusion theory code HFN, for a reflected infinite slab of this same material. 

The critical experiments were performed with 2- x 2-in. fuel compacts, 2 in. and - in. thick, assembled on a remotely operated split-table machine. Nuclide compositions and densities are given in Table I for the fuel and the Plexiglas reflector used In the experiments. 

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