Ketone peroxides peroxide value

Butanone peroxide [Methyl ethyl ketone peroxide] Ceiling value C.HijOg 1338-23-4 0.2 ppm... 

The 2003 ACGIH ceiling-threshold limit value (C-TLV) for methyl ethyl ketone peroxide is 0.2 ppm (1.5mg/m ). 

Two resins were used to do the first study on laminate construction. The first was a brominated epoxy vinyl ester resin with antimony pentoxide and the second was a brominated unsaturated polyester resin. They were both promoted to cure at room temperature with methyl ethyl ketone peroxide catalyst. The panels were then postcured at 250°F (121°C) for 8 h. Panels were prepared that varied in glass content from 25% to 70% and panel thickness varying from 0.05 in. to 0.25 in. and were tested at the same testing facility. A summary of the FSI test data for the first set of panels tested are shown in Figures 23.1 and 23.2. This graph in Figure 23.1 plots the FSI value versus the panel thickness. This data would indicate that the thickness of the test panel has no effect on the measured... 

Peroxide value. The oxidation of oils and fats leads to the formation of hydroperoxides. The hydroperoxides readily decompose to produce aldehydes, ketones, and other volatile products, which are characteristic of oxidation rancidity. The method for determination of peroxide concentration is based on the reduction of the hydroperoxide group with HI (or KI) to liberate free iodine, which may be titrated. The... 

A large proportion of the volatiles identified in vegetable oils are derived from the cleavage reactions of the hydroperoxides of oleate, linoleate, and linolenate (Section D). A wide range of hydrocarbons (ethane, propane, pentane and hexane) appears to be formed in soybean oil oxidized to low peroxide values. A number of volatiles identified in vegetable oils that are not expected as primary cleavage products of monohydroperoxides include dialdehydes, ketones, ethyl esters, nonane, decane, undecane, 2-pentylfuran, lactone, benzene, benzaldehyde and acetophenone. Some of these volatiles may be derived from secondary oxidation products, but the origin of many volatiles still remains obscure. However, studies of volatile decomposition products should be interpreted with caution, because the conditions used for isolation and identification may cause artifacts, especially when fats are subjected to elevated temperatures. 

The high-strength Basalt fiber (Plain weave, 150 g/m2) which is supplied by ASA. TEC, Austria are used in the present study. The isopthalic polyester resin used for matrix system is ISO-4503 procured from Vasavibala resins (P) Ltd., Chennai (viscosity 500-600 cps, acid value 15-19, gel time 15-25 min, heat deflection temperature 95 °C). One weight percent of accelerator (cobalt Napthanate) and 1 wt% of methyl ethyl ketone peroxide (MEKP) catalyst were mixed with the polyester resin. The type of epoxy resin used here is LY 556 and the hardener HT 951 both supplied by M/s Hindustan Ciba Geigy Limited, Mumbai, India. 

In this study, computer aided group contribution method was used to obtain values of the enthalpy and Gibbs free energy of methyl ethyl ketone peroxide (MEKPO) decomposition processes. Feasibilities of each decomposition reaction set were studied, and then ATad for feasible decomposition processes was obtained with A H and Cp from group contribution method. 

The preparation of a new class of processable heavily fluorinated aciylic resins with veiy low dielectric constants is described. The title compounds 2 and 5 were prepared through the condensation of the respective aicohols 1 and 4 with aciyloyl chloride. Unlike tetrafluoroethylene, monomers 2 and 5 are ea to process into polymers under normal conditions due to their liquid or semisolid nature. Radical polymerization of the title compounds with a trace amount of azobisisobutyronitrile or methyl ethyl ketone peroxide at 85-100 leads to homopolymers 3 and 6 and copolymer 7. All polymers exhibit dielectric constants around 2.10-2.24 over a frequency region of 500 MHz to 18.5 GHz the variation of dielectric constant values over the measured frequency region is within 0.03 for each polymer. These values are very close to the minimum known dielectric constants of 2.0-2.08 for poly(tetrafluoroeth-ylene) and 1.89-1.93 for a terpolymer of 2,2-bis-(trifluoromethyl)-4,5-difluoro-1,3-dioxole 8, perfluoropropylene and tetrafluoroethylene 9. The dielectric constants for poly(tetraf1uoroethylene) measured with the same method are observed to be around 1.96-1.99 in order to validate the accuracy of our measurement. 

The radicals are then involved in oxidations such as formation of ketones (qv) from alcohols. Similar reactions are finding value in treatment of waste streams to reduce total oxidizable carbon and thus its chemical oxygen demand. These reactions normally are conducted in aqueous acid medium at pH 1—4 to minimize the catalytic decomposition of the hydrogen peroxide. More information on metal and metal oxide-catalyzed oxidation reactions (Milas oxidations) is available (4-7) (see also Photochemical technology, photocatalysis). 

A related procedure, which may be of value from the preparative standpoint, involves the preparation of /rans-nitrosomethane dimer by adding a solution of diacetyl peroxide in sec-butyl nitrite to warm sec-butyl nitrite [50]. From the product of the reaction it has been assumed that this preparation involves the generation of free methyl radicals which react with the nitrite to give nitrosomethane and alkoxy radicals. The latter disproportionate to ketones and alcohols, while the nitroso compound dimerizes. 

Figure 6 shows the variation of peroxide concentration in methyl ethyl ketone slow combustion, and similar results, but with no peracid formed, have been found for acetone and diethyl ketone. The concentrations of the organic peroxy compounds run parallel to the rate of reaction, but the hydrogen peroxide concentration increases to a steady value. There thus seems little doubt that the degenerate branching intermediates at low temperatures are the alkyl hydroperoxides, and with methyl ethyl ketone, peracetic acid also. The tvfo types of cool flames given by methyl ethyl ketone may arise from the twin branching intermediates (1) observed in its combustion. 

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