Abstract: A bulk polymerization process for free radical polymerization of vinyl monomers in a wiped surface reactor is disclosed. Referring to FIG. 1; monomer streams 5 (after purification and silica gel column 2) and 7 are combined with free radical initiator 9 to form a premix 16. Pump 18 transfers the premix stream 22 through static mixer 24 into a wiped surface reactor 27. The reactor can be a counter rotating twin screw extruder which produces polymer stream 36 without the need of solvent and using residence times much shorter than prior art solution or emulsion processes. Some unique pressure sensitive adhesive acrylate polymers have been produced. They are believed to have a relatively high degree of branching. The bulk polymerization process permits the manufacture of pressure sensitive adhesive articles by extruding directly from the twin screw extruder onto a substrate.

Abstract: Considerable interest has been generated recently by the preparation of large monodisperse polymer latices by a multistage swelling process. Dispersion polymerization in organic media has been shown to be an alternative route to the preparation of large monodisperse polymer colloids. The size of the resulting particles is known to be dependent on the polarity of the reaction medium. Several other factors are also extremely important in determining both the size and size distribution of the resulting particles. These include the temperature of the reaction and the level of initiator. The temperature affects both the rate of free radical formation and the thermodynamic properties of the polymerization system. It is shown that monodispersity can be achieved over a considerable range of temperatures provided that a particular level of initiator is used at a given temperature. It is also shown that higher levels of initiator at a particular temperature actually produced larger particles. Interestingly, the level of initiator was not found to significantly change the overall rate of polymerization.

Abstract: Fragmentation of support/catalyst particles during propylene polymerization in the gas phase is analyzed via a mathematical model including energy and mass transfer with chemical reaction processes. The rupture phenomenon is considered specifically by the model, and evaluated as it proceeds in time, Two different regions are recognized in the polymerizing particle at fragmentation time: an inner core resembling the original solid support/catalyst structure, and an external set of layers where most of the polymerization occurs. Model predictions concerning the effects of fragmentation on polymerization are discussed. The influence of different degrees of fragmentation on thermal runaways and monomer availability at active sites located inside the support/catalyst/polymer complex is shown. Monomer concentration profiles inside the growing particles are explained in terms of the combined fragmentation-polymerization interaction. Results show a strong influence of catalyst structure on critical phenomena during early polymerization stages, and suggest the possibility of controlling critical parameters via the definition of fragment structure at catalyst preparation time.

Abstract: The molecular weight of polyalkylene oxides produced by the polymerization of a cyclic oxide in contact with a catalyst comprising the reaction product of a dihydrocarbyl zinc compound and a linear alkanediol in contact with a silica dispersion aid and nonionic surfactant in an inert diluent is controlled by the continuous addition of a very dilute solution of chain transfer agent having a pKa value of from 9 to 22 to the polymerizing mixture during the polymerization reaction at a carefully controlled rate so as not to terminate the polymerization reaction.

Abstract: The bulk polymerization of methyl methacrylate (MMA) with 1,2-disubstituted tetraphenylethanes, tetraphenylsuccinodinitrile (TPSN), tetra(p-methoxyphenyl)succinodinitrile (TMPSN), and pentaphenylethane (PPE), was investigated. These compounds were found to serve as thermal iniferters to induce living radical polymerization via a mechanism close to the model proposed previously (see Eq. 2). However, the living nature was not so high, because undesirable side reactions occurred. The oligomer with molecular weight of 2500 was isolated from the reaction mixture of MMA with TPSN, which was found to cause further polymerization of MMA. From the polymerization of styrene (St) with the polymers obtained by these iniferters, the block copolymers were produced.

Abstract: Influence des conditions de polymerisation (radicalaire, anionique, en masse ou en solution)

Abstract: The possibility of multiple steady states for a polymer particle is examined for propylene and ethylene, liquid and gas phase polymerizations. It is shown that multiple steady states should not occur in conventional diluent slurry polymerizations, but are always a possibility for gas phase and bulk propylene slurry reactions. Simulations to determine particle temperatures as a function of particle diameter show that polymer melting is predicted immediately upon catalyst injection for many cases in a gas phase reactor and for some cases in bulk polymerization. The practical implications of this result are discussed.

Abstract: A detailed kinetic model for the bulk styrene polymerization initiated by symmetrical diperoxyester bifunctional initiators is presented. When chain termination occurs via a combination termination mechanism, six distinct polymeric species are identified in accordance with the nature of the polymer end units. It is shown that the unequal thermal decomposition characteristics of the peroxides of the bifunctional initiator system lead to the formation of polymers having considerably higher molecular weight than those obtained by the monofunctional intiator systems. It has also been found that high monomer conversion, high molecular weight, and narrow molecular weight distribution can be obtained simultaneously by using the bifunctional initiators at high reaction temperatures. This is due to the reinitiation and propagation of inactive polymers carrying undecomposed peroxides. The molecular-weight-increasing effect of the bifunctional initiator is more pronounced at high reaction temperatures. The new possibilities of increasing the monomer conversion and controlling the polymer molecular weight properties more effectively through the use of bifunctional initiators are discussed.

Abstract: The kinetics of the polymerization of hexamethylcyclotrisiloxane D3 initiated by lithium 2,4,4-trimethyl-1-pentanolate (CH3)3CCH2CH(CH3)CH2OLi in THF solution in the range 0–60°C has been investigated. Polymerization was essentially first order in respect to monomer. Independent of the temperature in the range from 0 to 60°C, the external order of the rate with respect to initiator changed from 0.25 to 0.33 by changing the initiator concentration from 10−1 M to 10−3 M. This change indicates a change in the degree of aggregation from 4 to 3 of the propagation-active siloxanolate groups. The presence of aggregates and the change in their degree of aggregation from 4 to 3 has been independently and quantitatively confirmed by viscometry carried out before and after quenching the living D3 polymerization by Men−4SiCln (n=1–4) and Cl2SiMeCH2CH2MeSiCl2. Evidently most of the siloxanolate end groups are organized into aggregates whose size is controlled by the concentrations of the siloxanolate groups in the range from 10−3 to 10−1 M but insignificantly by the temperature from 0 to 60°C. Propagation is due to a relatively small proportion of active unaggregated ion pairs.

Abstract: Transport of liquid cyclohexane through well characterized, initially glassy, crosslinked polystyrene slabs was investigated. The samples were produced by bulk polymerization of styrene and divinyl benzene using benzoyl peroxide as an initiator at 90°C for 48 h; they had initial crosslinking ratios, X, between 0.005 and 0.025 mol DVB/mol styrene, initial thickness of 0.25 mm to 1.80 mm, and the aspect ratio was maintained above 10 to achieve one-dimensional transport. The results of cyclohexane uptake as a function of time were used to elucidate the effects of degree of crosslinking and sample geometry on the mechanisms of penetrant transport. These results were interpreted in terms of relaxational and diffusional mechanisms.

Abstract: An equilibrium model relating temperature, pressure, monomer conversion and monomer phase distribution for vinyl chloride polymerization has been developed. This model can be used to determine the monomer conversion beyond the pressure drop by measurement of reactor temperature and pressure. It can also be used to estimate monomer conversion at the pressure drop point and the distribution of monomer in all the phases over the entire extent of polymerization. A series of experiments to measure the solubility of VCM in water and PVC were carried out in the temperature range 40–70°C. Correlations of the solubility of VCM in water and the VCM–PVC interaction parameter with temperature, respectively, were obtained from the experimental data.

Abstract: A process for production of a vinyl polymer by suspension polymerization or emulsion polymerization of at least one kind of vinyl monomer in an aqueous medium is disclosed. In this process, the polymerization is carried out in a polymerizer, the inner wall surface and portions of the auxiliary equipment thereof which may come into contact with the monomer during polymerization having a surface roughness of not greater than 5 μm and being previously coated with a scaling preventive comprising at least one selected from dyes, pigments and aromatic or heterocyclic compounds having at least 5 conjugated π bonds. According to this process, scaling on the inner wall surface of a polymerizer, etc. during polymerization can be prevented effectively and surely.

Abstract: Poly(methyl methacrylate) and poly(methyl methacrylate–co‐maleic anhydride) were prepared by free‐radical, bulk polymerization using 0.005 mole % benzoyl peroxide as an initiator at 50 °C for 24 h. The resulting transparent cylinders were cut in a lathe into disks of 14‐mm diameter and 2.2‐mm thickness. Samples were also prepared in the form of thin slabs of 14×2×1 mm3. Subsequently, they were irradiated by γ rays at the level of 2–12 Mrad and their molecular weight distribution was determined by gel permeation chromatography. Changes in their structure before and after irradiation were determined by infrared spectroscopy. Their sensitivity values Gs and solubility characteristics in various solvents were determined. Planar and radial dissolution studies were performed in pure methyl ethyl ketone or ethanol at 26 °C. The positions of the solvent/gel and gel/glassy fronts were followed as functions of time. The results were correlated with the pseudosteady‐state solutions of a new mathematical model incorp...

Abstract: The effect of 2,2′-azoisobutyronitrile (AIBN) on the kinetics and mechanism of emulsion polymerization of butyl methacrylate was studied in the presence of anionic emulsifier disodium dodecylphenoxybenzene disulfonate (Dowfax® 2A1) at 60°C. The ratio between the proportion of the polymerization in monomer droplets and that of the polymerization in the aqueous phase was determined for the overall initial rate of butyl methacrylate polymerization in the region of the increasing polymerization rate (interval I). Using the model of polymerization in discrete particles, the portion of the polymerization in monomer droplets with a diameter of 100 nm in the overall polymerization rate is 24,4%; the portion of the polymerization in the water phase is only 0,022% for a concentration of Dowfax® 2A1 of 5 · 10−2 mol · dm−3, and 60,4% and 0,054% for a Dowfax® 2A1 concentration of 1 · 10−2 mol · dm−3. The exponent of the emulsifier concentration in the equation for the polymerization rate is 0,56 for interval I and 0,36 for interval II; the exponent for the concentration of AIBN over the conversion range between 0 and 30% is 0,34. For the proposed reaction mechanism it is assumed that 2-cyanoisopropyl radicals, generated from AIBN in the water phase, are responsible for the initiation of polymerization in micelles swollen by monomer and in polymer/monomer particles. Polymer/monomer particles are formed also by co-precipitation of oligomer radicals, which in turn are formed by polymerization of monomer molecules present in the water phase. Polymerization within monomer droplets has no significant influence on the course of emulsion polymerization.

Abstract: The applicability of the modified Smith-Ewart model to the butyl methacrylate emulsion polymerization in interval II, initiated by both 2,2′-azoisobutyronitrile (AIBN) and ammonium persulfate at 60°C, was tested. The equilibrium monomer concentration in the latex particles in interval II was found to be constant and independent of the emulsifier concentration and the initiator type used. The rate of initiation increases with increasing emulsifier concentration for the polymerizations initiated with a water-soluble initiator. In the systems with the oil-soluble initiator, the rate of initiation is independent of the emulsifier concentration. The rate of polymerization increase with increasing emulsifier concentration for both initiator systems. In the system with the oil-soluble initiator lower values of the polymerization rate and higher values of the viscosity-average molecular masses of the polymer were observed. The number of particles, the radical concentration within polymer particles and the calculated rate of polymerization increase, while the mean particle radius decreases with increasing concentration of the emulsifier for both systems. The average-number of radicals per particle and the ratio of the rate constants for propagation and termination was found to be independent of the emulsifier concentration and the initiator type. A good agreement was observed between the estimated and observed particle radii for both initiator systems. The Smith-Ewart model was found to be applicable for the emulsion polymerization of butyl methacrylate initiated by both ammonium persulfate and AIBN.

Abstract: In a process for producing a high impact styrene resin by continuously polymerizing a styrene monomer in bulk in the presence of a rubbery polymer, the improvement wherein a polymerization line is used which is comprised of an initial-stage polymerization line (II) following a material feed line (I) and consisting of one or more tubular reactors having fixedly set therein a plurality of mixing elements having no moving parts, a main polymerization line (III) following the initial-stage polymerization line (II) and consisting of one or more tubular reactors having fixedly set therein a plurality of mixing elements having no moving parts, and a recycle line (IV) which branches between the initial-stage polymerization line (II) and the main polymerization line (III) and returns to the initial-stage polymerization line (II), and a minor part or a major part of a flow of the initial-stage polymer solution leaving the initial-stage polymerization line (II) is recycled through the recycle line (IV) while the remaining non-recycled initial-stage polymer flow is polymerized in the main polymerization line (II).

Abstract: Self‐thermal initiated gas phase polymerization in styrene vapor is investigated employing the nucleation and growth of liquid monomer droplets (in supersaturated styrene vapor) for detection. The results show rather definitively that styrene does polymerize thermally, in the vapor phase, at temperatures as low as 250 K. The same is true for α‐methylstyrene which is also studied (but not so thoroughly). Phenylacetylene retards the gas phase polymerization of styrene. Polymers with degree of polymerization in the range 9 to 24 are involved in this study. The degree of polymerization increases with temperature and bimolecular termination appears to be absent. The total concentration of growing radicals is of the order of 6×103 cm−3. Thermal initiation appears to have second order kinetics. The rate constant for propagation is the same in the gas as in the liquid. At 0 °C (where we easily observe the formation of polymers), 23 million years would be required to observe the disappearance of monomer by standar...

Abstract: A propylene-ethylene block copolymer is produced by continuous bulk polymerization in which propylene alone is polymerized or propylene and ethylene are copolymerized at the ethylene/propylene reaction ratio of 6/94 using propylene as a liquid medium, and subsequently by batch-wise copolymerization in which propylene and ethylene are copolymerized at the ethylene/propylene reaction ratio from 85/15 to 5/95.

Abstract: Water-in-oil emulsions of monomers which form water-soluble polymers are polymerized in the presence of a biphase initiator system containing both an oil-soluble initiator and a water-soluble initiator or activator or alternatively a water-soluble initiator and an oil-soluble activator which results in polymers having improved performance characteristics. In addition, the system permits the satisfactory polymerization of monomers which could not have been reproducibly polymerized.

Abstract: The specification discloses a monovinylidene aromatic polymer having a molecular weight of at least 50,000 and an extremely narrow molecular weight distribution of less than 1.5, preferably with at least 80% by weight of the polymer having a molecular weight within plus or minus 30% of the weight average molecular weight. This polymer is produced through anionic polymerization of a pure feed stock which is first cooled to a temperature at which an anionic initiator preferentially reacts with impurities present in the feed stock and initiates the polymerization reaction but does not substantially propagate styrene polymerization. The initiator is uniformly dispersed into the feed stock while maintaining it at the lower temperature and the feed stock temperature is subsequently increased to a temperature at which polymerization of the sytrene proceeds normally. The resulting polymer is especially well adapted to injection molding in that exceptional strength properties are achieved in combination with good processability, e.g., melt flow rate.

Abstract: A process for preparing a toner obtained by a suspension polymerization method comprises stirring a mixture containing at least a polymerizable monomer containing 5 to 500 ppm of a polymerization inhibitor dissolved in the polymerizable monomer and a colorant; preparing a polymerizable monomer composition by adding a polymerization initiator to said mixture; stirring the prepared polymerizable monomer composition; and carrying out suspension polymerization of the polymerizable monomer composition dispersed in an aqueous medium.

Abstract: The determination of the structure of the end groups in poly(δ-valerolactone) (poly(δVL)) by using 1H, 31P NMR, and IR spectroscopy showed that in the cationic polymerization of δVL, propagation proceeds via cyclic dialkoxycarbenium ions as active species and the monomer molecules are incorporated into the polyester chains by an alkyl-oxygen bond scission. In the anionic polymerization of δVL, propagation proceeds via alcoholate anions and monomer molecules are added with breaking the acyl-oxygen bond. A similar cationic mechanism operates with alkylating ((CH3)2I⊕SbF6⊖) and acylating (CH3CO⊕SbF6⊖) initiators. However, with the latter, the cyclic dialkoxycarbenium active centers coexist with the acylium cations during the initial period of polymerization. Finally, however, the cyclic dialkoxycarbenium ions become the only active species. The mechanisms of ionic propagation in the polymerization of β-propiolactone, δ-valerolactone, and e-caprolactone are compared.