Finishing initiator

Initia.tors, The initiators most commonly used in emulsion polymerization are water soluble although partially soluble and oil-soluble initiators have also been used (57). Normally only one initiator type is used for a given polymerization. In some cases a finishing initiator is used (58). At high conversion the concentration of monomer in the aqueous phase is very low, leading to much radical—radical termination. An oil-soluble initiator makes its way more readily into the polymer particles, promoting conversion of monomer to polymer more effectively. 

Nearly all polymerization processes and products require a post-reaction process to remove and reduce to an acceptable level residual monomer(s), solvent or diluent. End use properties can be adversely affected by high levels of residuals through toxicity, odor, or poor physical properties. In the cases of residual solvent or diluent, a separation process involving the evaporation of the volatile components (devolatilization) can be used. Devolatilization can be used for residual monomer removal, but completing the polymerization of monomer is an attractive alternative when applicable. Polymerization finishing is usually accomplished with an increase in temperature to kick-off a finishing initiator or the addition of an initiator. (D For the dispersion... 

TEMPERATURE FOR SEMI-BATCH AND FINISHING MONOMER FEED RATE DURING SEMI-BATCH STEP INITIATOR FEED RATE DURING SEMI-BATCH STEP TOTAL INITIAL LOADING TIME FOR SEMI-BATCH STEP MONOMER WT. % AT START OF FINISHING INITIATOR WT. PERCENT AT START OF FINISHING TIME FROM START OF... 

Oil-soluble initiators have commonly been used in hybrid miniemulsion polymerization to improve monomer conversions. In most cases, the oil-soluble initiator was used as a. finishing initiator to increase final monomer conversion, while a water-soluble initiator was used to carry out the majority of the polymerizations. These types of polymerizations will be discussed later. 

The rational for the use of finishing initiators that have appreciable solubility in the polymer particle follows. At high conversions, the concentration of monomer in the aqueous phase is very low and water-phase termination of hydophilic radicals becomes excessive. The rate of radical entry into polymer particles is thus greatly reduced and the polymerization rate falls to a very low level prematurely. 

When security is considered later, this requirement yields the statement that any subset of the participants that includes the signer can carry out initialization successfully even if all the other participants try to disturb them. This is why initialization sometimes needs identities as output parameters If the structure of an implementation prescribes that more participants than the signer play an active part in initialization, they may always disrupt. Thus the best thing one can do is to detect disturbances and to finish initialization with fewer participants. In these cases, the users will want to know with whom initialization was finally successful. 

Properties Liq. m.w. 208.33 dec. 180 C Uses Crosslinking agent for elastomers, resins initiator for curing polyester resins finishing initiator for styrenics a synergist for some halogen-containing flame retardants polymer modifier... 

Examining another important measure of supply chain performance, cycle time, we realize that there are several different types of cycle time. The most obvious one, the one that most people relate to, is the amount of time it takes to produce a product from start to finish. Initially, it took 141 flow days at Z... 

The lithiation of allene can also be carried out with ethyllithium or butyl-lithium in diethyl ether (prepared from the alkyl bromides), using THF as a cosolvent. The salt suspension which is initially present when the solution of alkyllithium is cooled to -50°C or lower has disappeared almost completely when the reaction between allene and alkyllithium is finished. 

Manufacturing processes have been improved by use of on-line computer control and statistical process control leading to more uniform final products. Production methods now include inverse (water-in-oil) suspension polymerization, inverse emulsion polymerization, and continuous aqueous solution polymerization on moving belts. Conventional azo, peroxy, redox, and gamma-ray initiators are used in batch and continuous processes. Recent patents describe processes for preparing transparent and stable microlatexes by inverse microemulsion polymerization. New methods have also been described for reducing residual acrylamide monomer in finished products. 

There are numerous variations of the wet process, but all involve an initial step in which the ore is solubilized in sulfuric acid, or, in a few special instances, in some other acid. Because of this requirement for sulfuric acid, it is obvious that sulfur is a raw material of considerable importance to the fertilizer industry. The acid—rock reaction results in formation of phosphoric acid and the precipitation of calcium sulfate. The second principal step in the wet processes is filtration to separate the phosphoric acid from the precipitated calcium sulfate. Wet-process phosphoric acid (WPA) is much less pure than electric furnace acid, but for most fertilizer production the impurities, such as iron, aluminum, and magnesium, are not objectionable and actually contribute to improved physical condition of the finished fertilizer (35). Impurities also furnish some micronutrient fertilizer elements. 

Oligomeric Vinylphosphonate. A water-soluble oligomer, Fyrol 76 [41222-33-7] is produced by reaction of bis(2-chloroethyl) vinylphosphonate and dimethyl methylphosphonate with elimination of all the chlorine as methyl chloride (127,128). This Hquid, containing 22.5% P, is curable by free-radical initiation, on cotton or other fabrics. Nitrogen components, such as A/-methylolacrylamide or methylolmelamines, are usually included in the finish, which can be durable to multiple launderings (129,130). 

Initially, fluorescent whitening agents (FWAs) were used exclusively in textile finishing the detergent and paper industries followed thereafter. These products are also used in fiber spinning masses, plastics, and paints. 

The decomposition kinetics of an organic peroxide, as judged by 10-h HLT, largely determines the suitabiUty of a particular peroxide initiator in an end use appHcation (22). Other important factors ate melting point, solubiUty, cost, safety, efficiency, necessity for refrigerated storage and shipment, compatibihty with production systems, effects on the finished product, and potential for activation. 

Shade Stains. These stains are usually applied after the sealer or first topcoat and are typically sprayed on specific areas to compensate for uneven color distribution during the initial finishing process. For instance, perhaps the gla2e was wiped too clean on an edge. Rather than going back to restain or gla2e that small area, the finisher can spray a small amount of this shade stain on the desired area and achieve the same result in a fraction of the time. 

Physical distressing is usually a part of the initial finishing procedure and is done in the white wood stage. Finish distressing is normally part of the latter phases of the finishing operation. Like the pad and shade stains, distressing stains are usually appHed over the sealer or between coats of topcoat. 

Liquids. Some Hquid dyes are made directly from the thionation melt by additions of caustic soda and sodium hydrosulfide. Hydrotropic substances are sometimes added, either at the initial thionation stage or after the polysulfide melt is finished in order to keep the reduced dye in solution. Pardy reduced Hquids are also available. They are usually more concentrated than fully reduced Hquids, thus saving packaging and transportation costs. However, they require a further addition of reducing agent to the dyebath in order to obtain full color value. On the other hand, fully reduced Hquids are... 

In mbber production, the thiol acts as a chain transfer agent, in which it functions as a hydrogen atom donor to one mbber chain, effectively finishing chain growth for that polymer chain. The sulfur-based radical then either terminates with another radical species or initiates another chain. The thiol is used up in this process. The length of the mbber polymer chain is a function of the thiol concentration. The higher the concentration, the shorter the mbber chain and the softer the mbber. An array of thiols have subsequendy been utilized in the production of many different polymers. Some of these apphcations are as foUow ... 

Quarpel is an important combination of fluorochemical finish and resin-based extender developed by the U.S. Army Natick Laboratories for military use. This finish typicaUy contains 4—6 wt % commercial fluorochemical emulsion, 4—6 wt % resin-based repeUent emulsion, 0.1 wt % acetic acid, and 5 wt % isopropyl alcohol. If necessary, the formulation includes a catalyst to cross-link the resin-based component. Quarpel specifications demand exceUent initial water and oU repeUency and exceUent durabUity to washing and dry cleaning. 

Resin-based finishes are appUed to fabrics by padding. A concentration of 1.5% resin soUds on the weight of the fabric is a common appUcation level. The concentration of repeUent soUds required for good initial repeUency and good durabUity is about 0.3—0.5%, based on the weight of the fabric. The compositions of commercial products are proprietary. 

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