Abstract: PURPOSE: To obtain a copolymer having improved color tone, impact and heat resistance, by adding a vinyl cyanide monomer at a specific rate to an emulsion polymerization system of an aromatic vinyl monomer and another vinyl monomer from the initial stage to polymerize the monomers. CONSTITUTION: (A) An aromatic vinyl monomer, e.g. α-methylstyrene, and (B) a vinyl monomer, e.g. acenaphthylene, are dissolved in water to give an aqueous solution thereof containing 65W80wt% the component (A) and 0W20wt% the component (B) based on the monomers. A water-soluble free radical generator, e.g. potassium persulfate, and an emulsifier, e.g. sodium dodecylbenzenesulfonate, are added thereto to carry out the aqueous emulsion polymerization. (C) 15W30wt% cyanide monomer, e.g. acrylonitrile, is added at a lower rate than the polymerization rate to the emulsion polymerization system from the initial polymerization stage to carry out the polymerization while keeping the total number of moles of the components (A) and (B) at 1.5W3 times that of the component (C) during the rate of polymerization in the range of 0W90% to give the aimed copolymer. COPYRIGHT: (C)1981,JPO&Japio

Abstract: Possibilities for long-lived propagating species in cationic polymerization of vinyl compounds were investigated. p-Methoxystyrene (p-MOS) was polymerized with iodine as an initiator at 0°C. In carbon tetrachloride the molecular weight of the polymers increased with increasing conversion. After the completion of the polymerization, p-MOS was added to cause a further increase of the molecular weight of the polymer. These features were not observed in the polymerization in polar solvents such as methylene chloride. On the basis of these findings, the nondissociated propagating species is considered to be long-lived, whereas the dissociated propagating species is considered to be short-lived. It is also pointed out that a long-lived growing chain is possibly involved in the polymerization of styrene with perchlorate anion as a counterion at low temperatures.

Abstract: The anionic polymerization of tert-butyl acrylate was studied to determine the experimental conditions for preparing poly(acrylic acid) having narrow molecular weight distributions. If the monomer is carefully purified, the monomer can be anionically polymerized with n-butyllithium in tetrahydrofuran at −78°C. The propagation proceeds by living mechanism, though side reactions seem to occur at the initiation stage. The polymer obtained can be hydrolyzed with hydrobromic acid without degradation.

Abstract: The solution polymerization of styrene in methylene dichloride catalysed by trifluoromethanesulfonic acid takes place at a high rate even at low catalyst concentration. The S-shaped course of the conversion curves is explained by a reaction mechanism, in which the catalyst rapidly forms an inactive complex with one monomer molecule, and this monomer-acid complex is in equilibrium with the free catalyst molecule from which the propagating species are formed. Therefore, the formation of active initiating species becomes a slow process which depends also on the change of monomer concentration during polymerization. It is assumed that the active initiating species are formed from two or three molecules of acid and this process is supposed to be a determining step in the mechanism of the styrene polymerization. The conductivity of the polymerizing system is caused probably by at least two species: firstly by the 1-aralkyl-3-phenylindanyl cation which was found by means of UV spectroscopy and which is formed during and after the polymerization as product of termination reaction; secondly by another species, which takes part, as we assume, in the propagating process, probably as polystyryl carbcation.

Abstract: The free volume at the onset of the gel effect depends both on chain length and temperature. For high molecular weights, the conversion at which the gel effect appears can be related to the critical entanglement. Balke and Hamielec have proposed that the onset of the gel effect in the bulk polymerization of methyl methacrylate occurs at a characteristic free-volume value [1]. Cardenas and O'Driscoll have introduced the concept of polymer entanglement to describe quantitatively the main factors of the bulk polymerization carried out to high conversion, but retained some elements of the free-volume theory to characterize the onset of the gel effect [2]. Nevertheless, there seems to be some incompatibility between the two theories, since the amount of entanglement, for a given conversion, depends upon the molecular weight of the polymer while the free volume is almost independent of it. If a critical amount of entanglement must be reached to produce the gel effect, the conversion at which the effect...

Abstract: The electrolysis of acrylamide in sodium nitrate/N,N-dimethylformamide solutions leads to polymer formations simultaneously in the anode and cathode compartments. The influences of monomer concentrations, current levels, nature of some electrode metals and supporting electrolytes on polymerization were examined. Anodic polymers of high molecular weights were obtained (ca. 105). The current-voltage curves and other experimental findings strongly suggest that the direct reduction of acrylamide at the cathode leads to the cathodic polymerization which is like the polymerization by anionic initiators in which the monomer gives a polymer of amide structure via a hydrogen transfer process. On the other hand, the anodic polymerization is possibly initiated by the species produced by the anodic reaction of the supporting electrolyte and is analogous to the free-radical polymerization of acrylamide. Infrared spectra of the polymers show that the cathodic polymer is a polyamide whereas the anodic has a CC chain structure .

Abstract: Radical polymerization of 2-methyl-5-ethynylpyridine (MEP) and the structure and some properties of phenylacetylene and pentafluorophenylacetylene polymers were investigated. As the first step in polymerization of MEP in the presence of azo-1-cyclohexylcarboxylic acid dinitrile at 94-115°C the monomer conversion is proportional to the quantity of decomposed initiator: 1 mole of initiator causes transformation of 5-7 mole of monomer. At a high degree of polymerization the yield of polymer is not proportional to the initial initiator concentration. The products generated in MEP polymerization initiated thermally or by azo compounds were investigated by means of gel-permeation chromatography, ozonation, 1H-NMR, IR, and UV spectroscopy. Initiation with azo compounds afforded cyclic trimer (tripicolylbenzene) and a fraction with a number average molecular weight Mn of 1550. Thermal polymerization yielded the dimer (picolyl-substituted quinoline or isoquinoline), tripicolylbenzene, hexaraer, and fracti...

Abstract: The ultraviolet-initiated polymerization of octadecyl methacrylate (ODMA, octadecyl 2-methyl-2-propenoate) as a monomolecular layer at the gas-water interface was studied. The polymerization was carried out at 27°C at the nitrogen-water interface; air inhibits the polymerization. At 27°C the ODMA monolayer exhibits three different states which were characterized by surface pressure-area diagrams and by surface potential measurements. The ODMA monolayer was polymerized under constant surface pressure in the range between 0 and 10 dyne/cm. The polymerization was followed by recording the contraction of the film. The conversion was determined by comparison of the area per monomer unit during polymerization with the area of mixed monolayers formed from ODMA and poly-ODMA as well as by infrared spectroscopy. The polymerization in the condensed state of the monolayer (at high surface pressure) is considerably faster than in the expanded state (at low surface pressure). As the polymer has a condensing effect on the monomer in the mixed monolayer, autocatalysis is suggested at low surface pressures. The resulting polymer was studied by x-ray diffraction. The structure of the freshly collapsed film is determined by the conformation of the polymer at the interface; the data after crystallizing the same sample from the melt point to higher tacticity of the poly-ODMA prepared in monolayers than that of poly-ODMA prepared by normal radical polymerization in solution.

Abstract: When the structure of a primary radical resembles that of the chain end of the polymer radical, the rate of the primary radical termination is approximately the same as the termination rate between the oligomer radical and the polymer radical. The rate constant of termination between polymer radicals of chain length n and s, which involve the primary radicals, is kt,ns = const.(ns)−a. In the polymerization of methacrylonitrile initiated by 2,2′-azobisisobutyronitrile in dimethylformamide at 60.0°C, the value of a is found to be 0.091. From data obtained previously in the bulk polymerization of styrene initiated by 1-azobis-2-phenylethane at 60.0°C, the value of a is found to be 0.167. Because such a values are so large that they are not estimated by the excluded volume, the termination rates are discussed by adding the dependence of the diffusion of the segments to that for chain length.

Abstract: Vinyl chloride was polymerized at 40–96% of saturation pressure in water suspended systems at 55°C with suspension PVC as a seed. The monomer was continuously charged as vapor from a storage vessel kept at lower temperature. Characterization included molecular weight distribution (MWD) and degree of long-chain branching (LCB) by GPC and viscometry, thermal dehydrochlorination, microscopy, and technical standard tests. A granular seed was necessary to obtain granular polymer and reasonable polymerization rate. In properly seeded systems with monomer-soluble initiator, crust formation is very low. With monomer-soluble initiator the polymerization reactions are restricted to the seed polymer, comprise its total structure, reducing its porosity. At pressure near saturation, molecular weight increased with conversion, and autoacceleration occurred. The changes in molecular weight are presumably due to the lack of a liquid monomer phase, which reduces the mobility of the radicals leading to decreased t...

Abstract: The solid-state thermal polymerization of 2,4-hexadiyne-1, 6-diol has been studied by a variety of methods. Pure monomer heated under vacuum or in an inert gas atmosphere is found to polymerize readily, unlike material heated in air. X-ray diffraction reveals that samples anneal during polymerization. Initially, a long chain polymer is formed, but above 20% conversion a less perfect product is obtained. Measurements suggest a complex molecular rearrangement during the nonideal phase of polymerization. Possible models for this process are discussed.

Abstract: Processes for making copolymers comprising treating a reaction mixture of a monomer and a substrate comprising ferromagnetic material located in a polymeric matrix so as to polymerize the monomer in a manner that it forms a polymeric shell grafted on to and surrounding the substrate, the polymerization of the monomer being initiated by adding the components of a redox system sequentially to the reaction mixture.

Abstract: Postirradiation polymerization of 2,3-dimethylbutadiene in deoxycholic acid canal complexes was studied under various reaction conditions. The polymerization was carried out in degassed sealed tubes since the atmosphere had a large effect upon the polymer yield. Addition of 2,3-dimethylbutane led to a sharp drop in polymer yield, while hydroquinone showed little effect on the polymerization. The rate of postirradiation polymerization was found to increase with increase in reaction temperature and irradiation dose. The apparent activation energy was obtained as 13.7 kcal/mole in a temperature range between -14 and 30/sup 0/C. Existence of living free radicals having a long lifetime, the gradual change of the monomer into the polymer within the canals, and the effective spatial control in canals are discussed on the basis of the postirradiation polymerization behavior, nature of the adducts, and the structure of the polymers.

Abstract: Kinetics of living radical polymerization of styrene in emulsion initiated by polypropylene hydroperoxide with triethylenetetramine is proposed on the basis of a two stage mechanism. In the first stage fast initiation and propagation occur on the surface of polypropylene. In the second stage continuous chain propagation without termination proceeds in polymer particles in the emulsion. Dependence of rate and degree of polymerization on reaction time, initiator and activator concentrations predicted by the kinetics are ascertained by experimental results. Each polymer particle in the emulsion is suggested to consist of one polymer molecule with a living chain end. Main requisites for the living nature of this system are probably fast and/or limited decomposition and heterogeneity of the initiator in the emulsion polymerization.

Abstract: A process for producing tetrafluoroethylene/hexafluoropropylene copolymer having a hexafluoropropylene content of 8 to 20% by weight and having an excellent stress-cracking resistance and also excellent heat resistance, molding properties, chemical resistance and electrical characteristics, which comprises polymerizing tetrafluoroethylene monomer and hexafluoropropylene monomer in the presence of a polymerization initiator, wherein the tetrafluoroethylene monomer is used in a large amount at the first stage of the polymerization reaction and thereafter the polymerization reaction is continued in a smaller amount of the tetrafluoroethylene monomer.

Abstract: Investigations of the particle morphology of poly(vinyl chloride) produced under quiescent conditions during radiation-induced bulk polymerization over the temperature range -30 to 70/sup 0/C were carried out. The observations were mainly confined to the early stages of polymerization. For polymerization temperatures below about 20/sup 0/C, the systems remain predominantly homogeneous during the entire polymerization and the polymer particles increase in size linearly with conversion. At higher temperatures the polymer particles rapidly settle and become cemented together. The findings are discussed in the light of the kinetic data on vinyl chloride polymerization, and a process of particle formation and growth, resembling that recently proposed by Fitch for emulsion systems, was formulated. Primary particles are initially formed by the coiling up of single macromolecules or single macroradicals and, subsequently, they increase in size by sweeping up growing free radicals from the liquid monomer phase. The free radicals which escape capture give rise to new primary particles, but their number progressively decreases as the number of the dispersed particles increases. Simultaneously, the polymer particles undergo flocculation which in a short time results in the formation of large agglomerates. As the volume of the resulting agglomerates increases, the flocculation rate decreases and, eventually, becomesmore » so low that the flocculation does not proceed further. At low temperatures the flocculation almost ceases when the agglomerates are still small enough for sedimentation to occur only very slowly. However, this is not the case at higher temperatures. The addition of substances such as alcohols, brings about a reduction in the flocculation rate and, hence, in the size of the agglomerates formed at the end of the flocculation process. In this way, one can also obtain at high temperatures agglomerates of small sizes which remain dispersed for a long time.« less

Abstract: A plasma polymerization process for the deposition of a dielectric polymer coating on a substrate comprising disposing the substrate in a closed reactor between two temperature-controlled electrodes connected to a power supply, maintaining a vacuum within the closed reactor, causing a monomer gas or a gas mixture of a monomer and diluent to flow into the reactor, generating a plasma between the electrodes, and varying and controlling the dielectric constant of the polymer coating being deposited by regulating the gas total and partial pressures, the electric field strength and frequency, and the current density. A monomer, such as a polar saturated or unsaturated nitrogen-containing compound, or a monomer and diluent, such as a saturated or unsaturated aliphatic hydrocarbon and nitrogen, can be polymerized to form a dielectric coating having a varying dielectric constant in accordance with this plasma polymerization process.

Abstract: A process for preparing a latex by efficiently homogenizing an aqueous mixture containing an emulsifier and a water-insoluble solvent for the monomer(s) to be polymerized, adding monomer and if desired further water to the homogenized mixture and also a water-soluble polymerization initiator. Instead of a water-soluble polymerization initiator an oil-soluble polymerization may be used having sufficient solubility to diffuse through the aqueous phase into the drops of water-insoluble solvent and monomer.

Abstract: A process for the free-radical polymerization of a vinyl monomer, including vinyl aromatic monomer, at least two distinct, progressively higher polymerization temperatures, each between the temperatures of from about 50° C and 130° C, in the presence of at least two free-radical initiators, one of which, used in relatively minor proportions, is di-t-butyl diperoxycarbonate and the other, used in relatively major proportions, has a ten hour half-life temperature below 90° C. The distinct temperatures for polymerization may occur as separate parts of a polymerization in which the temperature of the system continually increases.

Abstract: The various models and their rate expressions developed for the bulk polymerization of vinyl chloride are checked against carefully evaluated experimental data. Only Ugelstad's and Olaj's models yield rate expressions consistent with experiment.