EV systems

Eig. 8. Sulfiir-based cure system designs where conventional systems are polysulfidic, EV systems are mono-/disulfidic, and semi-EV systems are clean polysulfidic. A shows pendent sulfide groups terminated by accelerator B, monosulftde cross-links C, disulfide cross-links D, polysulftde cross-links... 

If natural mbber compounds are subjected to thermal aging plus fatigue, the conventional systems perform no better than EV systems. The compromise obtained by usiag semi-EV systems iavolves the balance between heat aging and flex life. 

Fig. 9. Distribution of sulfur cross-links ia a carbon black-filled NR, where A is the conventional, B the semi-EV, and C the EV system.

Clearly, the EV system exhibits the greatest number of thermally stable and S2 cross-links. As expected, the conventional and semi-EV look similar ia cross-link distribution, but again, the semi-EV system has fewer extraneous moieties. Physical properties of these compounds are summarized ia Figure 10. 

AH three systems give similar tensile strength, elongation, and hardness properties. Hysteresis (heat buildup) measured by tan 5 shows an advantage for conventional and semi-EV systems and unaged fatigue follows the expected pattern. 

Further variation of the structure of nitroso compound and diisocyanate yielded NOVOR 924. An NR vulcanizate containing NOVOR 924 is more reversion-resistant than any EV system [63]. 

A term apphed to vulcanisation systems in which sulphur or a sulphur donor is used very efficiently for crosslinking the rubber. EV systems produce vulcanisates with crosslinks that are mainly monosulphidic, which are thermally and mechanically stable. 

Diatomic Radical Slate (eV) System (Region of Absorption) Lifetime Kef-... 

Figure 3. Specific peak-power, averaged over the last 10 s of a 20-s pulse, as a function of the depth of discharge for Lucas-Chloride, 535 kg, 192-V ISDA tubular Pb-A batteries. EV power-train constraints imposed. (Courtesy of Lucas Chloride EV Systems, 1984.)...

ANL/OEPM-82-5 Report for DOE, Contract No. W-31-109-Eng-38 (1982) Lucas Chloride EV Systems, Battery Specifications (1984). 

Other studies with this system have shown a sensitivity comparable to ABC techniquesSubsequently, EnVision+ (EV+) was introduced. This was a modified EV system that showed increased sensitivity by using a mixture of dextran polymers. The EnVision system has been shown to offer many advantages over prior methods such as ABC and B-SA. It offered high sensitivity and allowed increased dilutions of the primary antibody. It has also been used for signal amplification in combination with in situ hybridization (ISH), where it has also been shown to increase sensitivity and shorten assay times. ... 

Thermo-oxidative stability is primarily a function of the vulcanization system. Peroxide vulcanization or cure systems tend to perform best for reversion resistance as a result of the absence of sulfur and use of carbon-carbon crosslinks. Efficient vulcanization (EV) systems that feature a low sulfur level (0.0-0.3 phr), a high acceleration level, and a sulfur donor similarly show good heat stability and oxidation resistance. Such systems do, however, have poor resistance to fatigue because of the presence of predominantly monosulfidic crosslinks. Conventional cure systems that feature a high sulfur level and low accelerator concentration show poor heat and oxidation resistance because the polysulfidic crosslinks are thermally unstable and readily oxidized. Such vulcanization systems do, however, have better fatigue resistance. Semi-EV cure systems, which are intermediate between EV and conventional systems, are a compromise between resistance to oxidation and required product fatigue performance. 

Reviewed earlier, a semi-EV system is a compromise designed to produce, in structural terms, a vulcanizate containing a balance of monosulfldic and polysulfidic crosslinks at a defined optimum cure state. If polysulfidic crosslinks are to persist over extended periods, new ones must be created to replace those lost through reversion. With use of normal acceleration systems, there is limited opportunity for such events. Maintenance of a polysulfidic network through the curing process thus dictates utilization of... 

LASERS - Labeling of lasers should follow 21 CFR 1040, the Federal Laser Product Performance Standard. The spaces in which lasers are located should also have a similar warning at the entrance. The label will depend upon the class of laser involved. All of the labels will include a stylized sunburst symbol, with a tail extending to the left (see Chapter 5). The signal word CAUTION is to be used with Class II and IIIA laser systems while the signal word DANGER is to be used for aU Class IIIB and Class EV systems. 

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