Monomer volatile

Dibasic acid monomers, 59 Dibasic acid poly esterifications, 17 Dibromo derivatives, 82 Dibutyltin dilaurate (DBTDL), 232 Dicarboxylic acid monomers, volatilization of, 72... 

As previously discussed, K IDS does not always provide accurate quantitative data. Therefore, SFC was performed on the macromer. The monomer volatility is not a problem in these studies. Figure 5 is chromatogram of the MMA macromer. The first large broad peak is due to monomer. Identification was based upon retention time comparison to a standard. Each of the corresponding peaks are due to the oligomers up to the 15-mer. We attribute the minor distribution to (VIII). 

The compounds which gave the heaviest coatings after heating (taking into account the amount of monomer volatilized), included triallyl-amine, acrylonitrile, toluene, and styrene. As the list in Table I shows it is not necessary for the monomer to be a vinyl compound in the strict sense of the word for a non-volatile polymer product to form in corona discharge. Toluene, benzene, benzotrifluoride, and even acetone gave measurable yields. There seemed to be no pattern of relationship between the structure of a monomer and its yield in corona polymerization. 

Many chemical reactions, such as polymer formation reactions, arc exothermic and readily monitored by DSC methods. Here, the determination of the rate of heat release, d/lldi, is used to determine the extent of reaction as a function of lime. Polymerization kinetics can be studied in both a temperature scanning and an isothermal mode. With some polymer systems, factors such as monomer volatility and viscosity can affect the measured kinetics. 

Emission of monomers. Volatile organic compounds (VOC), formaldehyde during production of the wood-based panels and during their use... 

In a typical commercial process for the manufacture of butyl rubber, isobutene and a small amount of isoprene (l-5-4-5%) are diluted with methyl chloride in a volume/volume ratio monomer/diluent of 30/70. This feed together with a dilute (0-2%) solution of aluminium chloride in methyl chloride are added simultaneously at the base of the reaction vessel which is cooled with liquid ethylene to about -100°C and which contains a powerful stirrer. A violent exothermic reaction occurs and the rubber is formed almost instantaneously. The process operates continuously and the resulting mixture of rubber, solvent and unreacted monomers are fed to a flash tank containing steam or hot water. The solvent and monomer volatilize whilst the rubber forms a slurry in the water. This slurry is treated with a stabilizer and the rubber is then Altered, dried, compacted in an extruder, sheeted on a mill, banded and cut to a size suitable for packing. 

The widely used Parylene C owes its popularity ptincipaHy to the room temperature volatiUty of its monomer. The Parylene C monomer, chloro-A-xylylene, has become the de facto performance standard. By comparison, the Parylene N monomer, A"xylylene itself, is too volatile and would perform better ia a sub-ambient temperature deposition system. The Parylene D monomer, dichloro-A-xyljlene [85586-88-5] is too heavy, and causes distribution problems ia larger deposition systems. 

A schematic of a continuous bulk SAN polymerization process is shown in Figure 4 (90). The monomers are continuously fed into a screw reactor where copolymerization is carried out at 150°C to 73% conversion in 55 min. Heat of polymerization is removed through cooling of both the screw and the barrel walls. The polymeric melt is removed and fed to the devolatilizer to remove unreacted monomers under reduced pressure (4 kPa or 30 mm Hg) and high temperature (220°C). The final product is claimed to contain less than 0.7% volatiles. Two devolatilizers in series are found to yield a better quaUty product as well as better operational control (91,92). 

The Ts of methacryhc polymers may be regulated by the copolymerization of two or more monomers as illustrated in Figure 1. The approximate T value for the copolymer can be calculated from the weight fraction of each monomer type and the T (in K) of each homopolymer (15). Acrylates with low transition temperatures are frequently used as permanent plasticizers (qv) for methacrylates. Unlike plasticizer additives, once polymerized into the polymer chain, the acrylate cannot migrate, volatilize, or be extracted from the polymer. 

Gas chromatography (gc) has been used extensively to analyze phenoHc resins for unreacted phenol monomer as weU as certain two- and three-ring constituents in both novolak and resole resins (61). It is also used in monitoring the production processes of the monomers, eg, when phenol is alkylated with isobutylene to produce butylphenol. Usually, the phenoHc hydroxyl must be derivatized before analysis to provide a more volatile compound. The gc analysis of complex systems, such as resoles, provides distinct resolution of over 20 one- and two-ring compounds having various degrees of methylolation. In some cases, hemiformals may be detected if they have been properly capped (53). 

Liquid-Injection Molding. In Hquid-injection mol ding (LIM), monomers and oligomers are injected into a mold cavity where a rapid polymerization takes place to produce a thermoset article. Advantages of these processes are low cost, low pressure requirement, and flexibiHty in mold configuration. Conventional systems, such as isocyanate with polyol, release Htfle or no volatiles. The generation of substantial volatiles in the mold is obviously undesirable and has represented a significant obstacle to the development of a phenoHc-based LIM system. A phenoHc LIM system based on an... 

For aqueous inks, the resins are water- or alkali-soluble or dispersible and the solvent is mosdy water containing sufficient alcohol (as much as 25%) to help solubilize the resin. To keep the alkah-soluble resin in solution, pH must be maintained at the correct level. Advances include the development of uv inks. These are high viscosity inks that require no drying but are photocurable by uv radiation. In these formulations, the solvent is replaced by monomers and photoinitiators that can be cross-linked by exposure to uv radiation. The advantage of this system is the complete elimination of volatile organic compounds (VOC) as components of the system and better halftone print quaUty. Aqueous and uv inks are becoming more popular as environmental pressure to reduce VOC increases. 

Most general-purpose release agents have been developed for this market in part because of their low toxicity and chemical inertness and do not usually present health and safety problems. Some of the solvent dispersions require appropriate care in handling volatile solvents, and many supphers are offering water-based alternatives. Some of the sohds, particularly finely divided hydrophobic sohds, can also present inhalation problems. Some of the metallic soaps are toxic, although there is a trend away from the heavier, more toxic metals such as lead. The reactive type of release coating with monomers, prepolymers, and catalysts often presents specific handling difficulties. The potential user with health and safety questions is advised to consult the manufacturer directly. 

Commercial polystyrenes are normally rather pure polymers. The amount of styrene, ethylbenzene, styrene dimers and trimers, and other hydrocarbons is minimized by effective devolatilization or by the use of chemical initiators (33). Polystyrenes with low overall volatiles content have relatively high heat-deformation temperatures. The very low content of monomer and other solvents, eg, ethylbenzene, in PS is desirable in the packaging of food. The negligible level of extraction of organic materials from PS is of cmcial importance in this appHcation. 

The batch-suspension process does not compensate for composition drift, whereas constant-composition processes have been designed for emulsion or suspension reactions. It is more difficult to design controUed-composition processes by suspension methods. In one approach (155), the less reactive component is removed continuously from the reaction to keep the unreacted monomer composition constant. This method has been used effectively in VT)C-VC copolymerization, where the slower reacting component is a volatile and can be released during the reaction to maintain constant pressure. In many other cases, no practical way is known for removing the slower reacting component. 

Dichloroethane [107-06-2] ethylene chloride, ethylene dichloride, CH2CICH2CI, is a colorless, volatile Hquid with a pleasant odor, stable at ordinary temperatures. It is miscible with other chlorinated solvents and soluble in common organic solvents as well as having high solvency for fats, greases, and waxes. It is most commonly used in the production of vinyl chloride monomer. 

A polymer is joined to itself by cementing with a solution of the same polymer in a volatile solvent. The solvent softens the surfaces, and the dissolved polymer molecules bond them together. Components can be joined by monomer-cementing the surfaces are coated with monomer which polymerises onto the pre-existing polymer chains, creating a bond. 

Emission of volatile noxious chemicals from wood-based panels during their production can be caused by chemicals inherent to wood itself, like terpenes or free acids, as well as by volatile compounds and residual monomers of the adhesive. The emission of formaldehyde as well as free phenol effluents is a matter of concern. 

The alkoxides and aryloxides, particularly of yttrium have excited recent interest. This is because of their potential use in the production of electronic and ceramic materials,in particular high temperature superconductors, by the deposition of pure oxides (metallo-organic chemical vapour deposition, MOCVD). They are moisture sensitive but mostly polymeric and involatile and so attempts have been made to inhibit polymerization and produce the required volatility by using bulky alkoxide ligands. M(OR)3, R = 2,6-di-terr-butyl-4-methylphenoxide, are indeed 3-coordinate (pyramidal) monomers but still not sufficiently volatile. More success has been achieved with fluorinated alkoxides, prepared by reacting the parent alcohols with the metal tris-(bis-trimethylsilylamides) ... 

Dimeric nitroso compounds with tertiary alkyl groups show more tendency toward dissociation into the monomers. For example, 2-methyl-2-nitrosopropane is so volatile in the form of the monomer that it can hardly be isolated from organic solvents. For the prepara-... 

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