Poly decomposition

Molybdenum trioxide is a condensed-phase flame retardant (26). Its decomposition products ate nonvolatile and tend to increase chat yields. Two parts of molybdic oxide added to flexible poly(vinyl chloride) that contains 30 parts of plasticizer have been shown to increase the chat yield from 9.9 to 23.5%. Ninety percent of the molybdenum was recovered from the chat after the sample was burned. A reaction between the flame retardant and the chlorine to form M0O2 012 H20, a nonvolatile compound, was assumed. This compound was assumed to promote chat formation (26,27). 

Molybdenum is also a smoke suppressant for poly(vinyl chloride). It promotes the formation of cis- rather than the trans-polymeric decomposition products which ate the precursors for smoke. The sources for molybdates ate Climax Performance Material Cotp. and Sherwin WiUiams. 

SolubiHty parameters of 19.3, 16.2, and 16.2 (f /cm ) (7.9 (cal/cm ) ) have been determined for polyoxetane, po1y(3,3-dimethyl oxetane), and poly(3,3-diethyloxetane), respectively, by measuring solution viscosities (302). Heat capacities have been determined for POX and compared to those of other polyethers and polyethylene (303,304). The thermal decomposition behavior of poly[3,3-bis(ethoxymethyl)oxetane] has been examined (305). 

Pyrotechnic mixtures may also contain additional components that are added to modify the bum rate, enhance the pyrotechnic effect, or serve as a binder to maintain the homogeneity of the blended mixture and provide mechanical strength when the composition is pressed or consoHdated into a tube or other container. These additional components may also function as oxidizers or fuels in the composition, and it can be anticipated that the heat output, bum rate, and ignition sensitivity may all be affected by the addition of another component to a pyrotechnic composition. An example of an additional component is the use of a catalyst, such as iron oxide, to enhance the decomposition rate of ammonium perchlorate. Diatomaceous earth or coarse sawdust may be used to slow up the bum rate of a composition, or magnesium carbonate (an acid neutralizer) may be added to help stabilize mixtures that contain an acid-sensitive component such as potassium chlorate. Binders include such materials as dextrin (partially hydrolyzed starch), various gums, and assorted polymers such as poly(vinyl alcohol), epoxies, and polyesters. Polybutadiene mbber binders are widely used as fuels and binders in the soHd propellant industry. The production of colored flames is enhanced by the presence of chlorine atoms in the pyrotechnic flame, so chlorine donors such as poly(vinyl chloride) or chlorinated mbber are often added to color-producing compositions, where they also serve as fuels. 

In practice, 1—10 mol % of catalyst are used most of the time. Regeneration of the catalyst is often possible if deemed necessary. Some authors have advocated systems in which the catalyst is bound to a polymer matrix (triphase-catalysis). Here separation and generation of the catalyst is easy, but swelling, mixing, and diffusion problems are not always easy to solve. Furthermore, triphase-catalyst decomposition is a serious problem unless the active groups are crowns or poly(ethylene glycol)s. Commercial anion exchange resins are not useful as PT catalysts in many cases. 

Commercial interest in poly(vinyl chloride) was revealed in a number of patents independently filed in 1928 by the Carbide and Carbon Chemical Corporaration, Du Pont and IG Farben. In each case the patents dealt with vinyl chloride-vinyl acetate copolymers. This was because the homopolymer could only be processed in the melt state at temperatures where high decomposition rates occurred. In comparison the copolymers, which could be processed at much lower temperatures, were less affected by processing operations. 

Poly(acrylonitrile) has found little use as a plastics material because it softens only slightly below its decomposition temperature of about 300°C. In addition it does not dissolve in its monomer so it cannot be shaped by bulk casting. It will,... 

Poly-p-phenylene has been prepared in the laboratory by a variety of methods, including the condensation of p-dichlorobenzene using the Wurtz-Fittig reaction. Although the polymer has a good heat resistance, with decomposition... 

Several substituted linear polyphenylenes have also been prepared but none appear to have the resistance to thermal decomposition shown by the simple poly-p-phenylene. 

The simplest aromatic polysulphone, poly-(p-phenylene sulphone) (formula I of Table 21.3) does not show thermoplastic behaviour, melting with decomposition above 500°C. Hence in order to obtain a material capable of being processed on conventional equipment the polymer chain is made more flexible by incorporating ether links into the backbone. 

Water-soluble polymers obtained through a radical polymerization [e.g., poly(acrylic acid) PAA] often contain sodium sulfate Na2S04 as a decomposition product of the initiator. The peak of Na2S04 is eluted before the dimer. In the interpretation of the chromatogram, a typical GPC program has to be truncated before the Na2S04 peak, or at a Mpaa value of about 200. The calibration curve in this region can be flattened by an additive small pore column as well, but the principle problem remains unsolved. 

The residual frae.lton contained iosquitorpones together with poly-meridea and decomposition products of myTceue. 

MAIs may also be formed free radically when all azo sites are identical and have, therefore, the same reactivity. In this case the reaction with monomer A will be interrupted prior to the complete decomposition of all azo groups. So, Dicke and Heitz [49] partially decomposed poly(azoester)s in the presence of acrylamide. The reaction time was adjusted to a 37% decomposition of the azo groups. Surface active MAIs (M, > 10 ) consisting of hydrophobic poly(azoester) and hydrophilic poly(acrylamide) blocks were obtained (see Scheme 22) These were used for emulsion polymerization of vinyl acetate—in the polymerization they act simultaneously as emulsifiers (surface activity) and initiators (azo groups). Thus, a ternary block copolymer was synthesized fairly elegantly. 

Yagci and Deniziigil [44] applied the method of partial decomposition of MAIs introducing styrene and methyl methacrylate blocks into poly(amide)s. The poly-(amide)-based MAI had been prepared by a reaction of AIBN with formaldehyde (see Scheme 10). Evidently, since each unit of the preformed MAI carries one azo group, there are enough azo sites in every MAI molecule for a controlled and adjustable partial decomposition. 

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