Vinyl liquid

Novel vinyl liquid crystalline (l.c.) polymers were synthesized with the UV-sensitive p-methoxycinnamate chromophore incorporated into the side chain of the polymers. The objective of this synthesis was to determine if a molecularly organized environment could influence the yield of a chemical reaction in the solid state. The investigation into the photochemical and physical processes of these thin films revealed that the photodimerization of the p-methoxycinnamate moieties was very sensitive to their geometrical arrangement in the polymer matrix. The relative quantum yield of cyclobutane formation increased by a factor of approximately 8 for the l.c. p-methoxycinnamate film compared to its amorphous analog. This quantum yield approaches the theoretical limit for this system. 

Dinitrosoterephthalamide n (DNTA) A chemical blowing agent for vinyls, liquid polyamide resins, and silicone rubbers. It is especially noted for its low decomposition exotherm. 

A fiowsheet for this part of the vinyl chloride process is shown in Fig. 10.5. The reactants, ethylene and chlorine, dissolve in circulating liquid dichloroethane and react in solution to form more dichloroethane. Temperature is maintained between 45 and 65°C, and a small amount of ferric chloride is present to catalyze the reaction. The reaction generates considerable heat. 

Figure 10.5 The direct chlorination step of the vinyl chloride process using a liquid phase reactor. (From McNaughton, Chem. Engg., December 12, 1983, pp. 54-58 reproduced by permission.)...

C4H8O, CH3COCH2CH3. Colourless liquid with a pleasant odour, b.p. 80°C. It occurs with propanone in the products of the destructive distillation of wood. Manufactured by the liquid or vapour phase dehydrogenation of 2-butanol over a catalyst. Used as a solvent, particularly for vinyl and acrylic resins, and for nitrocellulose and cellulose acetate, also for the dewaxing of lubricating oils. U.S. production 1978 300 000 tonnes. 

BrCHi CHjBr. A colourless liquid with a sweet odour, m.p. 10°C, b.p. 132°C. Manufactured by passing ethene through bromine or bromine and water at about 20 C. Chemical properties similar to those of 1,2-dichloroethane when heated with alkali hydroxides, vinyl bromide is formed. Used extensively in petrols to combine with the lead formed by the decomposition of lead tetraethyl, as a fumigant for stored products and as a nematocide. 

They are colourless liquids with characteristic odours, and are prepared by the condensation of ketones with alkyl orthoformates in the presence of alcohols, or by the reaction of acetylenes with alcohols in presence of HgO and BF3. In some cases trichloroethanoic acid is used as the catalyst. They lose alcohol when heated and form vinyl ethers. Exchange of alcohol groups occurs when the ketals of the lower alcohols are boiled with alcohols of greater molecular weight. See acetals. 

Photopolymerization reactions of monolayers have become of interest (note Chapter XV). Lando and co-workers have studied the UV polymerization of 16-heptadecenoic acid [311] and vinyl stearate [312] monolayers. Particularly interesting is the UV polymerization of long-chain diacetylenes. As illustrated in Fig. IV-30, a zipperlike process can occur if the molecular orientation in the film is just right (e.g., polymerization does not occur readily in the neat liquid) (see Refs. 313-315). 

Liquid- and vapor-phase processes have been described the latter appear to be advantageous. Supported cadmium, zinc, or mercury salts are used as catalysts. In 1963 it was estimated that 85% of U.S. vinyl acetate capacity was based on acetylene, but it has been completely replaced since about 1982 by newer technology using oxidative addition of acetic acid to ethylene (2) (see Vinyl polymers). In western Europe production of vinyl acetate from acetylene stiU remains a significant commercial route. 

Cblorina.ted Pa.ra.ffins, The term chlotinated paraffins covers a variety of compositions. The prime variables are molecular weight of the starting paraffin and the chlorine content of the final product. Typical products contain from 12—24 carbons and from 40—70 wt % chlorine. Liquid chlotinated paraffins are used as plasticizers (qv) and flame retardants ia paint (qv) and PVC formulations. The soHd materials are used as additive flame retardants ia a variety of thermoplastics. In this use, they are combiaed with antimony oxide which acts as a synergist. Thermal stabilizers, such as those used ia PVC (see vinyl polymers), must be used to overcome the inherent thermal iastabiUty. 

Liquid polyalurninum chloride is acidic and corrosive to common metals. Suitable materials for constmction of storage and handling facilities include synthetic mbber-lined steel, corrosion resistant fiber glass reinforced plastics (FRP), ceramics, tetrafluoroethylene polymer (PTFE), poly(vinyhdene fluoride) (PVDF), polyethylene, polypropylene, and poly(vinyl chloride) (PVG). Suitable shipping containers include mbber-lined tank tmcks and rail cars for bulk shipment and plastic-lined or aH-plastic dmms and tote bins for smaller quantities. Except for aluminum chlorohydrates, PAG products are shipped as hazardous substances because of their acidity. 

Liquid trichloroethylene has been polymerized by irradiation with Co y-rays or 20-keV x-rays (9). Trichloroethylene has a chain-transfer constant of <1 when copolymerized with vinyl chloride (10) and is used extensively to control the molecular weight of poly(vinyl chloride) polymer. 

Requirements for heat- and cold-curing denture-base resins prepared from powder—liquids, gels, preopolymerized blanks, and fluid resins composed of acryflc, vinyl, and polystyrene polymers are given in ANSI/ADA specification no. 12 for denture-base polymers. 

Runaway reaction or polymerization—e.g., vinyl chloride monomer (Kim-E and Reid, The Rapid Depressurization of Hot, High Pressure Liquids or Supercritic Fluids, chap. 3, in M. E. Paulaitis et al., eds.. Chemical engineering at Supercritical Fluid Conditions, Ann Arbor Science, 1983, pp. 81-100)... 

The neopentanedlol and triethyl orthoformate were purchased from Aldrich Chemical Co., Inc. and used as received. Failure to distil the methyl vinyl ketone, also obtained from Aldrich Chemical Co., to a clear, colorless liquid before use resulted in difficulty in determining the endpoint of the reaction with HBr. Therefore, the methyl vinyl ketone was distilled prior to use at reduced pressure. 

Low molecular weight liquid nitrile rubbers with vinyl, carboxyl or mercaptan reactive end groups have been used with acrylic adhesives, epoxide resins and polyesters. Japanese workers have produced interesting butadiene-acrylonitrile alternating copolymers using Ziegler-Natta-type catalysts that are capable of some degree of ciystallisation. 

Poly(vinyl chloride) is commercially available in the form of aqueous colloidal dispersions (latices). They are the uncoagulated products of emulsion polymerisation process and are used to coat or impregnate textiles and paper. The individual particles are somewhat less than 1 p,m in diameter. The latex may be coagulated by concentrated acids, polyvalent cations and by dehydration with water-miscible liquids. 

Acrylonitrile (Vinyl cyanide) CH,CHCN Closely resembles HCN in toxic action Poisonous by inhalation, ingestion or skin absorption Emits cyanides when heated or contacted by acids or acid fumes Symptoms flushed face, irritation of eyes and nose, nausea etc. Colourless flammable liquid with mild, faintly pungent odour Elash point 0°C. Dilute water solutions also have low flash points... 

Styrene 32 (Vinyl benzene) C6H5CH CH2 490 1.1-6.1 0.9 3.6 145 Colourless/oily yellow liquid Penetrating odour Polymerizes slowly in air or light, accelerated by heat or catalysts Ignition/explosion possible Usually inhibited Store <21 °C... 

Vinyl acetate -8 CH3C00CH CH2 427 2.6-13.4 1.1 3.0 72 Colourless, partially water soluble liquid Faint odour Polymerizes with heat or organic peroxides... 

VV -values for bromoform and pyrrole, acidic liquids, against poly(vinyl chloride), an acidic polymer, and dimethyl sulfoxide, a predominantly basic liquid, against polyfmethyl methacrylate), a basic polymer, but large values for the acidic liquids against PMMA and the basic liquid against PVC. 2-Iodoethanol, a bifunctional liquid, showed appreciable -values with both polymers. Despite these results in line with expectations, other results based on wettability measurements are not so clear-cut. For example, Vrbanac [94] found significant apparent acid-base interactions of various aromatic liquids against poly(ethylene), presumably a neutral substrate. 

Polyisoprene can be UV or e-beam cured [43,44]. The 3,4 units are particularly prone to crosslinking at low dose [45]. SIS and SBS are also crosslinkable, even conventional linear materials with low vinyl content however, small amounts of liquid trithiol or triacrylate compounds speed cure dramatically [44]. Like UV, e-beam cure is strongly affected by tackifier choice. Hydrogenated, non-aromatic resins provide much less interference with cure [36,37]. 

These adhesives differ from normal hot-melt adhesives, such as the standard ethylene vinyl acetate hot melts. Standard hot-melt adhesives like EVA have no curing mechanism. They are heated above the crystalline melting point and applied as a low-viscosity liquid in the same manner as is the curing hot melt. The bond is closed in the same manner and strength is developed upon crystallization. 

Liquid organic rubbers with reactive functionality can be prepared by several methods. End-functional oligomers are preferred. Chains attached to the network at only one end do not contribute as much strength to the network as those attached at both ends [34], Urethane chemistry is a handy route to such molecules. A hydroxy-terminated oligomer (commonly a polyester or a polyether) can be reacted with excess diisocyanate, and then with a hydroxy methacrylate to form a reactive toughener [35]. The methacrylate ends undergo copolymerization with the rest of the acrylic monomers. The resulting adhesive is especially effective on poIy(vinyl chloride) shown in Scheme 2. 

Another important ether is vinyl ether, a colorless liquid with the characteristic ether odor. Its molecular formula is CjHjOCjHj. Vinyl ether has a flash point of -22°F and an ignition temperature of b80°F. It is highly toxic by inhalation and is used in medicine and in the polymerization of certain plastics. 

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