Monomer solvent mixture

Monomer-solvent mixture Film thickness mm. Dose rate R/hr. Total dose MRad, Increase in weight Composition of craft Efficiency of grafting M M.Wt. of PS side chains M.Wt. of PS produced in solution... 

The broad single peak distribution found with the mutual sample is not unexpected. It is known that with the film thickness and monomer-solvent mixture used the graft polymerization is diffusion controlled. The average chain length reached will be dependent on the distance of the growth site from the film surfaces resulting in the broad spectrum of chain lengths actually found. 

Polymers that are insoluble in their own monomers or in the monomer— —solvent mixture separate as a solid phase from the homogeneous solution in the course of the reaction. Such polymerizations are designated as precipitating. Their course is complicated by sorption of the initiator, growth centres, monomer and solvent on the solid surface. A detailed investigation of the consequences of the whole complex of factors is very difficult. 

The structure of the copolymer between ethene and COF j depends upon the polymerisation temperature and the concentration of the components in the monomer/solvent mixture. In addition, the rate of copolymerization of CHj=CHj and COFj, at 0 or 25 "C, decreases as the COFj concentration in the monomer mixture increases [1997]. 

Radiation initiation for solution vinyl polymerization is more complex. A special feature of radiation is that it attacks all components of the system including the solvent. With a monomer-solvent mixture, therefore, the rate of initiation can be represented by a linear equation as follows ... 

It may be that the polymer is insoluble in the monomer-solvent mixture from which it is formed. Polypropylene and PVC are two examples where the polymer has very limited solubility in the monomer. As polymerization proceeds, the polymer will precipitate from the reacting mass to form a dispersed phase of polymer swollen with the monomer-solvent mixture. This is called a slurry polymerization. (Phase inversion can occur at high conversions to give a bulk polymerization.) A typical slurry polymerization is autorefrigerated. The heat of polymerization causes the reacting mass to boil it is condensed and returned to the reactor. The gas-phase processes for polyethylene and polypropylene are conceptually similar to slurry polymerizations. The continuous phase is now a gas and the dispersed phase is a fluidized solid, but the heat of polymerization is still removed through the low-viscosity, continuous phase. 

Di self-diffiisivity of monomer-solvent mixture Doi constant pre-exponential factor, and E activation energy for a jump per mole... 

Monomer/solvent mixture 38/62 (w/w), initiator perfluorobenzoyl peroxide, polymerization temperature 60°C, polymerization time 24 h, yield of polymers 50-80%. 

Current inventions show improvements in solvent utilization, as follows. PVC-based adhesive for PVC pipes, typically containing solution of PVC in tetrahydrofuran, was replaced by solution of chlorinated PVC in 1,3-dioxolane and/or its derivatives whieh are far less toxic than THF. Ethanol is used in polyimide adhesive and dental adhesive. Monomer solvent mixture is used in crosslinkable acrylate adhesive, which permits formulation of VOC-free composition. Polyurethane hot-melt adhesive produced from polyacrylates and polyesters does not need solvents for its production and cure which occurs under the effect of moisture. Similar observations can be made for sealants. For example, sealing agent for semiconductor light emitting elements have been made from acrylic monomers without application of solvent. Material for production of printed wiring board was produced and cured without solvent from polymethacrylate. It is clear from these examples that new processes are consciously directed towards less toxic solutions. 

Monomer-soluble initiators are used in this polymerization technique. The monomer phase containing an initiator is dissolved in an inert solvent or solvent mixture including a steric stabilizer. The polymers or oligomer... 

Competition between the various species present in the reaction mixture such as monomer, solvent, and backbone for the growing polymer radical, which means that there is competition between chain growth and various chain transferring steps. 

A stream of monomer (or mixture of monomers) is made to flow rapidly over the surface of an alkali metal. If the reaction with the metal is sufficiently slow, a low concentration of monomer" ions will result. In view of the high concentration of the monomer, the monomeric" ions would add further monomer to form the dimeric and polymeric radical ions. Of course, the final product is not a radical, but it would result from a polymerization which took place to some extent on the radical ends. The mixture of monomers may be recirculated many times to increase the conversion and a solvent may be added to the system when necessary. 

The industrial process for which this methodology was developed comprised polymerizing a monomer in the presence of a mixed solvent, the catalyst and other Ingredients. Once the batch polymerization is complete, the product requires removal of the solvents to a specified level. The solvents, an aromatic Cy and aliphatic Cy compounds, are removed by a two-step process schematically shown in Figure 1. As shown, the polymer slurry is initially flashed to a lower pressure (Pj ) in the presence of steam and water. The freely available solvent in the polymer-solvent mixture is removed by the shift in thermodynamic equilibrium. Solvent attached to the surface of the polymer particle is removed by the steam. In this first step, 90% of the total solvents are recovered. The remaining solvents are recovered in the second flash, where the effluent is almost all water with very low concentrations of the solvents. 

Fig. 1. Preparation of configurational biomimetic imprinted networks for molecular recognition of biological substrates. A Solution mixture of template, functional monomer(s) (triangles and circles), crosslinking monomer, solvent, and initiator (I). B The prepolymerization complex is formed via covalent or noncovalent chemistry. C The formation of the network. D Wash step where original template is removed. E Rebinding of template. F In less crosslinked systems, movement of the macromolecular chains will produce areas of differing affinity and specificity (filled molecule is isomer of template).

The solvent used in the anionic polymerization of 1,4-DVB by n-BuLi also has an important effect on the polymer structure. If polymerization reactions are carried out in benzene/THF mixtures, the onset of macrogelation can be retarded by increasing the THF fraction in the solvent mixture [230]. Hexane, that is a solvent for the monomer but a precipitant for the resulting polymer, was not suitable because an insoluble aggregate was formed within a few minutes [230]. For hexane /THF mixtures with equal volumes, the conditions for the synthesis of a soluble polymer depends on the concentrations of 1,4-DVB and n-BuLi (Fig. 50). The course of the curve in the transition region from a soluble polymer to a macrogel is similar to that shown in Fig. 48 for n-BuLi/THF. 

In a typical polymerising experiment, a mixture of monomer, solvent and initiator is allowed to feed into a chain of three polymerising reactors. The first reactor is having three heating zones. 

The monomer/oligomer mixtures were used In the third step of the reaction sequence, the replacement of bromine with 2-methyl-3-butyn-2-ol by use of the bls(trlphenylphosphlne) palladium chloride catalyst system. This reaction used a trlethylamine/pyridine solvent system to replace the bromines on the ether sulfone with ethynyl groups protected by acetone adducts. The acetone protecting groups were then removed In a toluene/methanol/potasslum hydroxide solvent system. 

In one approach, polymethacrylate-type monoliths have been fabricated by copolymerization of the chiral monomer 0-9-[2-(methacryloyloxy)ethylcarbamoyl]-10,11-dihydroquinidine 1 or 0-9-(tert-butylcarbamoyl)-ll-[2-(methacryloyloxy) ethylthio]-10,ll-dihydroquinine 2 (see Figure 1.34a), the comonomer 2-hydroxyethylmethacrylate (HEMA), the crosslinker ethylenedimethacrylate (EDMA) in presence of the binary porogenic solvent mixture cyclohexanol and 1-dodecanol, directly in a single step within fused-silica capillaries. Initiation of the polymerization by either thermal treatment or UV irradiation yielded microglobular polymer morphologies, such as those well known from their corresponding nonchiral... 

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