Lower plastic limit

The minimum water content for which a small sample of soil or similar material will barely deform or crumble in a standardized test method. Also termed the lower plastic limit . See also Atterberg Limits, Liquid Limit, Plasticity Number. 

P= (Upper plastic limit)—(Lower plastic limit). 

The sensitivity of the plastic properties upon concentration have even induced Atterberg to introduce certain specified concentrations as a measure of the plasticity of clays. A clay is characterized by its plastic number, which is the diflFerence between the "dipper and " lower plastic limits . The upper plastic limit is the moisture content at which the yield stress just becomes measurable. At the moisture content corresponding to the lower plastic limit, the yield stress is so high that the day has lost its plastic deformability. 

A cavity s maximum storage capacity is almost proportional to its Maximum Allowable Operating Pressure (MAOP). MAOP is fixed by tightness considerations, which in theory at least, are based on the impermeability (and plasticity limit) of the salt rock to hydrocarbons when pressure remains lower than stresses equal to the weight of the overburden (approximately 0.023 MPa per meter depth). 

Murray [91] has described a gas chromatographic method for the determination in water of triarylphosphate esters (lmol S-140, tricresyl phosphate, cresol phosphate). These substances are used commercially as lubricant oil and plastic additives, hydraulic fluids and plasticisers. The method involves extraction from the samples, hydrolysis and measurement of the individual phenols by gas chromatography as the trimethylsilyl derivatives. The lower detection limit was about 3ppm. 

Examinations of the same and of other lead-bearing samples for spontaneous fission events with large proportional counters in Dubna seemed to confirm these findings, but further measurements [37] of thin samples sandwiched between two plastic fission-track detectors showed that the events were background caused by cosmic-ray induced reactions of lead. Other groups [38] found no evidence for spontaneous fission activities in lead and other samples at a lower detection limit of 10" 3 g/g achieved with the sandwich technique. Even lower limits down to 10"17 g/g can be reached by etching... 

Various means of particle identification are possible with optical microscopy. These include dispersion staining for identification of asbestos particles [44] and the use of various mounting media [45], Proctor et. al. [46,47] dispersed particles in a solidifying medium of Perspex monomer and hardener. This was poured into a plastic mold that was slowly rotated to ensure good mixing. Microscope analyses were carried out on thick sections a lower size limit of 5 p,m was due to contamination. 

Two-site immunometric or sandwich assays that made use of two or more antibodies directed at different parts of the PRL molecule were next to be developed. As with other two-site IRMA assays, the capture antibody is attached to a solid phase separation system and the second or signal antibody is labeled with a detection molecule (e.g., radio-isotope, enzyme,fluorophor, or chemiluminescence tag ). In some assays, the capture antibody is attached to the wall of test tubes, plastic beads, microtiter plates, ferromagnetic particles, or glass-fiber paper. Other assays have used the strep-avidin approach that couples biotin to the signal antibody with avidin linked to a solid phase. Most of the current immunometric assays for PRL have been adapted to fully automated immunoassay systems. Compared with the older traditional RIA methods, these automated immunometric assays for PRL generally achieve lower detection limits (0.2 to 1.0 ig/L) and improved precision (interlaboratory coefficients of variation of <8% at all concentrations), and have superior specificity (<0.05% crossreactivity with GH). 

If an organosol is used, lower plasticizer loadings are possible, but they will limit the thickness of the applied coating. At the same time the volatile solvents force one to select a lower initial preheat temperature of the object to be coated. 

PLASTIC MOLD HEAT (1) LOWER PROCESSING LIMIT (2) NORMAL FORMING HEAT (3) UPPER LIMIT (4) SET HEAT (5)... 

In the cable industry, plasticization of CPVC by phthalates and phosphates improves the flexibility and processability of CPVC. However, the addition of plasticizer lowers the limiting oxygen index and increases smoke production. The schematic diagram below illnstrates the mechanism of degradation in the absence (A) and the presence (B) of the smoke-suppressing componnd - basic iron oxide, FeOOH. " ... 

Typical values of plastic limit for silts and clays are between 5% and 30%, with the silty soils having lower values. Materials that cannot be rolled to a 3.2 mm thread are characterised as non-plastic materials. 

Lower explosive limit—The lowest concentration of a substance that will produce a fire or fiash when an ignition source is present, expressed as a percent of vapor or gas in the air by volume. Low-level waste—Radioactively contaminated industrial or research waste such as paper, rags, plastic bags, medical waste, and water-treatment residues. 

The plasticity index is a measure of the plasticity of a soil. The plasticity index is the size of the range of water contents where the soil exhibits plastic properties. The PI is the difference between the liquid limit and the plastic limit (PI = LL - PL). Soils with a high PI tend to be clay, those with a lower PI tend to be silt. 

Another environmental trend with a bearing on plastics usage is the use of water-based paints. This movement is very strong, because of the desire to reduce solvent emission. Its effect on plastics is likely to be adverse, because topcoat oven temperatures are tending to become higher rather than lower, thus limiting the choice of plastics for car panels to certain more expensive materials. 

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