Monomer stabilization acrylic

Polymers in Schemes 12 and 13 were the first examples of the preparation of pyridinium and iminopyridinium ylide polymers. One of the more recent contributions of Kondo and his colleagues [16] deals with the sensitization effect of l-ethoxycarbonyliminopyridinium ylide (IPYY) (Scheme 14) on the photopolymerization of vinyl monomers. Only acrylic monomers such as MMA and methyl acrylate (MA) were photoinitiated by IPYY, while vinylacetate (VA), acrylonitrile (AN), and styrene were unaffected by the initiator used. A free radical mechanism was confirmed by a kinetic study. The complex of IPYY and MMA was defined as an exciplex that served as a precursor of the initiating radical. This ylide is unique in being stabilized by the participation of a... 

L. B. Levy, "The Effect of Oxygen on Vinyl Acetate and Acrylic Monomer Stabilization," Process Safety Progress, 12, No. 1,47 (January 1993). 

Uses. Inhibitor for acrylic monomers stabilizer for chlorinated hydrocarbons and ethyl cellulose UV inhibitor... 

Since TEMPO is only a regulator, not an initiator, radicals must be generated from another source the required amount of TEMPO depends on the initiator efficiency. Application of alkoxyamines (i.e., unimolecular initiators) allows for stoichiometric amounts of the initiating and mediating species to be incorporated and enables the use of multifunctional initiators, growing chains in several directions [61]. Numerous advances have been made in both the synthesis of different types of unimolecular initiators (alkoxyamines) that can be used not only for the polymerization of St-based monomers, but other monomers as well [62-69]. Most recently, the use of more reactive alkoxyamines and less reactive nitroxides has expanded the range of polymerizable monomers to acrylates, dienes, and acrylamides [70-73]. An important issue is the stability of nitroxides and other stable radicals. Apparently, slow self-destruction of the PRE helps control the polymerization [39]. Specific details about use of stable free radicals for the synthesis of copolymers can be found in later sections. 

Uses Antioxidant for lubricants, rubber, waxes monomer stabilizer insecticide mfg. of dyes polymerization inhibitor for acrylic ester monomers chain transfer agent in rubber prod. polymerization control agent in food-pkg. adhesives food and feed additive treatment of food-producing animals mfg. of chlorpromazine and related antipsychotic drugs anthelmintic drug antioxidant in dry rosin size in mfg. of paper/paper-board in contact with aq./fatty foods in food-contact rubber articles for repeated use... 

Inhibition of spontaneous polymerization of (meth) acrylates is necessary not only at their storage but also in the conditions of their synthesis proceeding in the presence of sulfuric acid. In this case, monomer stabilization is more urgent, since sulfuric acid not only deactivates mat r inhibitors but also is capable of intensifying polymer formation. The concentration dependence of induction periods in these conditions has a brightly expressed nonlinear character. And, unlike polymerization in bulk, decomposition of polymeric peroxides is observed at relatively low temperatures in the presence of sulfuric acid, and the values [X] of the amines studied are by ca. 10 times lower than [HQ]. ... 

Inhibition of spontaneous polymerization of (meth) acrylates is necessary not only at their storage but also in the conditions of their synthesis proceeding in the presence of suffirric acid. In this case, monomer stabilization is more urgent, since sulfuric... 

Conditions Synthesis period, h Viscosity, Pa s Solid residual, % Average size of polymer particle, pm Gravitational stability of dispersion, 24 h(T = 45 °C) Monomer odour (acryl- nitrile)... 

X-Tone, Stone colorants, FM Group Xantar, Polycarbonate, DSM Engineering Plastics Xenoxyl Stabilizer, Antioxidant and monomer stabilizer for acrylics, Zeneca Specialties... 

Chain transfer in acrylic polymerizations was measured by the amount of gel in the latex products (Table II) (77). Reaction temperature, monomer feed time, and percent CAM have all been found to influence gel content. No gel was observed in surfactant stabilized acrylic latexes with CAM concentrations at or less than 1 phm, regardless of feed time or polymerization temperature. With CAM concentrations between 5 and 10 phm, the acrylic polymerizations had more than 60% gel when the reaction temperatures were above 65°C, and a monomer feed time of two hours. Gel was also observed to increase in 5 phm CAM latexes when the feed time was increased to greater than three hours. Latexes containing higher gel contents produce marginal particle coalescence resulting in poor scrub resistance. Conversely, low polymerization temperatures (such as 45T) with moderate amounts of CAM (5-10 phm) and short monomer feed times (less than three hours), resulted in latexes that had complete coalescence and exhibited good scrub resistance. 

Hydrolytic stability and pH have to be considered when selecting a cationic monomer. Cationic acrylate esters are susceptible to base hydrolysis above pH 6, resulting in the loss of cationic charge on the polymer. The rate of hydrolysis is concentration and temperature dependent. In contrasL cationic acrylamide copolymers containing amide monomers such as APTAC and MAPTAC are reasonably stable up to a pH of 9-10. Acrylamide/MAPTAC copolymers and... 

Uses Emulsifier for o/w or w/o emulsions, ester waxes and fatty acids, emulsion polymerization (acrylic esters, styrene and vinyl monomers) stabilizer for emulsions, suspensions, and latexes... 

The principal monomers butadiene, styrene, vinyl acetate, (meth)acrylates and acrylonitrile essenhally determine the material properties of films made from the corresponding dispersions the glass transition temperature, the water absorption capacity, the elasticity, etc. Auxiliary monomers, which are only used in a small proportion, usually <5 %, control important properties such as colloid-chemical stabilization (acrylic acid, methacrylic acid, acrylamide, methacrylamide), crosslinking within the particles (difunctional acrylates, divinylbenzene, etc.) or hydrophilic properties (OH-containing monomers, such as hydroxyacrylates). Reactive monomers which still contain a latently reactive group even after incorporation into the polymer, for example glycidylmethacrylate or N-methylol(meth)acrylamide, can form a network between various particles and polymer molecules after film formation. 

Latex paint Obtained by emulsion polymerizing. A suitable monomer in water. The final material is a stable emulsion of polymer particles coalesce, giving a strong film with a gloss. To give abrasion resistance to the film, sometimes inorganic fillers such as CaCOa are added. Because of their chemical stability, acrylic emulsions are preferred. 

Acryhc acid and esters are stabilized with minimum amounts of inhibitors consistent with stabihty and safety. The acryhc monomers must be stable and there should be no polymer formation for prolonged periods with normal storage and shipping (4,106). The monomethyl ether of hydroquinone (MEHQ) is frequentiy used as inhibitor and low inhibitor grades of the acrylate monomers are available for bulk handling. MEHQ at 10—15 ppm is generally... 

In normal practice, inhibitors such as hydroquinone (HQ) [123-31 -9] or the monomethyl ether of hydroquinone (MEHQ) [150-76-5] are added to acrylic monomers to stabilize them during shipment and storage. Uninhibited acrylic monomers should be used prompdy or stored at 10°C or below for no longer than a few weeks. Improperly iahibited monomers have the potential for violent polymerizations. HQ and MEHQ require the presence of oxygen to be effective inhibitors therefore, these monomers should be stored in contact with air and not under inert atmosphere. Because of the low concentration of inhibitors present in most commercial grades of acrylic monomers (generally less than 100 ppm), removal before use is not normally required. However, procedures for removal of inhibitors are available (67). 

Minimize stocks and segregate from other chemicals and work areas. Where appropriate, keep samples dilute or damp and avoid formation of large crystals when practicable. Add stabilizers if possible, e.g. to vinyl monomers. Store in specially-designed, well-labelled containers in No Smoking areas, preferably in several small containers rather than one large container. Where relevant, store in dark and under chilled conditions, except where this causes pure material to separate from stabilizer (e.g. acrylic acid). 

Outdoors Well-spaced tanks, possibly with water cooling, refrigeration, buried Some monomers (e.g. acrylic acid) may require provisions to avoid freezing Provision for inhibitor/stabilizer addition Provision for atmosphere inerting may be required ... 

Alkyl cyanoacrylate monomers have been copolymerized with a variety of monomers, both by radical and anionic initiation. The radical-initiated copolymerization with acrylic monomers was performed with a sufficient amount of an acid stabilizer present to suppress polymerization by anionic means [19]. This investigation has been covered extensively elsewhere. 

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