Showing papers on "Bulk polymerization published in 1978"
TL;DR: In this paper, the authors used the triplet excited state of the diacetylene monomer as the chain initiation species to obtain the activation energy of 2,4hexadiyne-1,6-diol bis-(p-toluene sulfonate) (PTS).
Abstract: Results are presented for the thermal, ultraviolet, and γ-ray polymerization of 2,4-hexadiyne-1,6-diol bis-(p-toluene sulfonate) (PTS). Monomer extraction is used to obtain polymer conversion-vs.-time curves at 30, 50, and 80°C. In agreement with previous work over a narrower temperature range, the curves all display a dramatic autocatalytic effect with an onset at about 10% conversion to polymer. Although the polymerization rate undergoes a 200-fold change over this temperature range, the shape of the conversion curves does not change. These data yield an activation energy (E) of 22.2 ± 0.4 kcal/mole when interpreted in terms of the time required to reach 50% polymer. An annealing technique is used to provide a closer look at the autocatalytic region. In that case, E = 22.5 ± 0.8 kcal/mole is determined from measurements of the time required to go from 10 to 50% polymer at temperatures ranging from 23 to 80°C (a 500-fold change in rate). Thermal polymerization rates measured in the low-conversion limit using a spectroscopic method based on diffuse reflectance yield E = 22.8 ± 0.6 kcal/mole. Thus E is independent of polymer conversion and the autocatalytic effect can be best understood as arising from a large increase in the propagation length of the polymer chains. The autocatalytic effect is shown to be present in both UV and γ-ray polymerization. In the case of γ-ray polymerization, conversion-vs.-time and spectroscopic measurements are consistent with inhomogeneities in the polymer concentration caused by particle tracks. Activation energies for UV and γ-ray polymerization are quite low (2-3 kcal/mole) and confirm that the chain initiation event makes the major energetic contribution to E. The polymerization mechanism is discussed in detail. The photopolymerization experiments can be consistently interpreted with a model based on the triplet excited state of the diacetylene monomer as the chain initiation species.
127 citations
TL;DR: In this article, the kinetics of the dibutyltin dilaurate catalyzed bulk polymerization of 4,4′-diphenylmethane diisocyanate (MDI) with poly-ϵ-caprolactone were studied by infared spectroscopy and adiabatic temperature rise.
Abstract: The kinetics of the dibutyltin dilaurate catalyzed bulk polymerization of 4,4′-diphenylmethane diisocyanate (MDI) with poly-ϵ-caprolactone were studied by infared spectroscopy and adiabatic temperature rise. The overall reaction order was found to change from 3/2 to 2 with increasing temperature. At temperatures above 80°C, the order with respect to catalyst was found to decrease with concentration from 1 to 1/2. The results were consistent with a Michaelis Menten type kinetic scheme.
98 citations
Abstract: An experimental investigation of the kinetics of bulk thermal polymerization of styrene in the temperature range of 200°–230°C is reported. Conversions and molecular weight averages were measured by gel permeation chromatography. At elevated temperatures, oxygen in the polymerization mixture appears to have negligible effect on the rate of polymerization and the molecular weights of the polymer. Experimental evidence suggests that the molecular weight development of the polymer is strongly influenced by transfer reactions.
98 citations
TL;DR: In this paper, the extent of fluorine-abstraction and the rearrangement of atoms which occur during the plasma polymerization of tetrafluoroethylene were investigated using an inductive rf discharge of the monomer.
80 citations
TL;DR: In this paper, the reactivity of free radicals generated by the thermal decomposition of 2,2′-azobisisobutyronitrile (AIBN) is compared with that of the free radicals from 2, 2′-zobis-2,4-dimethyl valeronitrile in nitrogen atmosphere at 60°C.
47 citations
Patent•
25 May 1978TL;DR: In this paper, a photo-initiator initiates polymerization in the surface layer thereby generating sufficient heat to activate the thermal initiator and cause the polymerization to proceed throughout the bulk of the monomer.
Abstract: A composition is prepared of a liquid vinyl monomer, a UV-activated photo-initiator, a thermal initiator, and an accelerator. The composition also preferably contains a free-radical scavenger and a vinyl oligomer. Upon exposure to ultraviolet light the photo-initiator initiates polymerization in the surface layer thereby generating sufficient heat to activate the thermal initiator and cause the polymerization to proceed throughout the bulk of the monomer.
40 citations
TL;DR: A detailed study of the kinetics of initiated homopolymerization of acrylonitrile in dimethylformamide and dimethylsulphoxide at 40-60° was made in this paper.
37 citations
TL;DR: In this article, the free-radical polymerization of phenylacetylene initiated by azobisisobutyronitrile at 50°C was studied in bulk and in the presence of benzene and toluene.
Abstract: The free-radical polymerization of phenylacetylene initiated by azobisisobutyronitrile at 50°C was studied in bulk and in the presence of benzene and toluene. The polymerization rate is approximately first-order with respect to the initiator concentration. The number-average molecular weight of the polymer is independent of the initiator concentration in bulk and is approximately proportional to the monomer concentration in the presence of the two diluents, but independent of their nature. The data are consistent with a mechanism based on first-order decay of active to inactive radicals. This step appears to exert the major control over kinetic and molecular chain lengths. Chain transfer to the monomer is concluded to be absent or to make only a small contribution to molecular termination.
34 citations
TL;DR: In this paper, it was shown that the degree of polymerization of poly(methyl methacrylate)(PMMA) obtained at 30°C or below increases with an increase in monomer conversion and the single peak of a molecular weight distribution curve shifts with monomer conversions.
Abstract: Monomer is added to chromium(II) acetate (Cr2+) and benzoyl peroxide (BPO) previously treated at 10°C in dimethylformamide (DMF)(the ageing process), and polymerizations are performed. It is found that the degree of polymerization of poly(methyl methacrylate)(PMMA) obtained at 30°C or below increases with an increase in monomer conversion and the single peak of a molecular weight distribution curve shifts with monomer conversion. These results suggest that a “living” polymerization occurs in the homogeneous polymerization of MMA initiated by the aged “Cr2++ BPO” system.The polymerizations of various vinyl monomers with this initiator system are carried out at 25°C. The polymerization activity is relatively high for MMA, acrylonitrile, methyl acrylate and acrylamide but low for styrene, vinyl acetate and vinyl chloride. The molecular weights of polyacrylonitrile and poly(methyl acrylate) also increase with the monomer conversion.By copolymerizing MMA with acrylonitrile, it is found that polymerizations with aged “Cr2++ BPO” proceed via a free radical intermediate. The polymerization rates (Rp) of MMA at 25 and 30°C are expressed by the following relation, Rp= const.[aged “Cr2++BPO”]0.7–1.0[MMA].The mechanism of a “living” radical polymerization is discussed in terms of a transition metal complex with free radicals.
34 citations
Patent•
13 Jan 1978
TL;DR: In this article, a continuous mass polymerization of olefinically unsaturated monomers in the presence of a polymerization initiator is carried out in one or more tubular reactors provided with internal static mixing elements.
Abstract: A process for the continuous mass polymerization of olefinically unsaturated monomers in the presence of a polymerization initiator. The polymerization is carried out in one or more tubular reactors provided with internal static mixing elements. A portion of the reaction mass produced in the reactor is recirculated back to the reactor as feed.
32 citations
TL;DR: In this paper, the emulsion polymerization of styrene has been carried out in a continuous stirred reactor at 50°C, and the average number of radicals per particle was usually, but not always, > 0.5.
TL;DR: In this article, it was suggested that photolysis of di-η5-cyclopentadienyldimethyltitanium(IV) leads to the initiation of free-radical polymerization.
Patent•
18 Aug 1978TL;DR: In this article, an ionized gas plasma is established in an electrical field in contact with a non-vapor volume of monomer (liquid and/or solid) to initiate propagation of polymerization therein.
Abstract: An ionized gas plasma is established in an electrical field in contact with a non-vapor volume of monomer (liquid and/or solid). The plasma creates active polymerization sites in the monomer volume to initiate propagation of polymerization therein. After initiation, the partially-polymerized monomer volume is postpolymerized in the absence of the ionized gas plasma to yield a very high molecular weight polymer which may be essentially free of cross-linking in desirable forms including commercial quantities of bulk self-supporting polymer or a coating. Suitable monomers include liquid vinyl monomers (e.g., methyl, methacrylate) and solid crystalline monomers (e.g., 1,3,5-trioxane).
TL;DR: The mechanism of the water-soluble persulfate-initiated emulsion polymerization of styrene has been investigated by the conventional dilatometric and gravimetric methods at low concentration of the monomer (5% v/v) as mentioned in this paper.
Abstract: The mechanism of the water-soluble persulfate-initiated emulsion polymerization of styrene in the aqueous media at 50°C has been investigated kinetically by the conventional dilatometric and gravimetric methods at low concentration of the monomer (5% v/v). It has been found that the initial rate of polymerization Vp is approximately proportional to initiator concentration [I] to the 0.50 power, i.e., Vp ∝ [I]0.50, and the viscosity-average molecular weight Mv is approximately inversely proportional to the 0.50 power of the initiator concentration, i.e., Mv ∝ [I]−0.50. With the progress of the reaction, the initiator exponent of the reaction rate equation decreases gradually from 0.50 to 0.25, but that of the molecular weight (1) equation remains constant up to 20% conversion and thereafter begins to decrease. Since the kinetic data at zero conversion satisfy the steady-state kinetics of the free-radical-initiated homogeneous vinyl polymerization, it is suggested that the initiation of emulsion polymerization of styrene is a two-step process. It starts in the aqueous phase by the primary free radicals from the water-soluble initiator or secondary free radicals derived from the soap molecules. The second step occurs in the monomer-leaded micelles by the water-soluble or water-insoluble macroradicals or by radicals derived from the soap molecules. The latter are likely to be produced in the aqueous phase by the oxidation of soap with S2O82−ions or SO4− radicals. It has been noted that the rate of thermal decomposition of persulfate increases by a factor of 6–8 times under different experimental conditions in the presence of soap.
TL;DR: In this paper, the aqueous polymerization of acrylonitrile initiated by an acidified bromate-thiourea redox system has been studied under nitrogen atmosphere.
Abstract: The aqueous polymerization of acrylonitrile initiated by an acidified bromate–thiourea redox system has been studied under nitrogen atmosphere The rate of polymerization is independent of thiourea concentration over the range 2–9 × 10−3M and reaches maximum at 9 × 10−3M The rate varies linearly with [monomer] The initial rate of polymerization as well as the maximum conversion increases within the range of 4–225 × 10−3M KBrO3, but beyond 225 × 10−3M the rate of polymerization decreases The initial rate and the limiting conversion increases with increasing polymerization temperature in the range 30–45°C; and beyond 45°C they decrease The effect of certain neutral salts, water-soluble solvents, and micelles of cationic, anionic, and nonionic surfactants on the rate of polymerization has been investigated
Patent•
30 Nov 1978TL;DR: In this article, a continuous low pressure gas phase process for the production of solid particulate polymers during an exothermic polymerization reaction in a uniform diameter vertical fluidized bed reactor system is described.
Abstract: A continuous low pressure gas phase process for the production of solid particulate polymers during an exothermic polymerization reaction in a uniform diameter vertical fluidized bed reactor system which comprises feeding a polymerization catalyst and a gaseous stream containing at least one polymerizable monomer to a fluidized bed of polymer particles and removing the exothermic heat of reaction by indirect cooling means in the reactor and removing dry particulate polymer. Also, apparatus for the polymerization process is described.
TL;DR: In this article, the non-activated polymerization of 2-pyrrolidone initiated with potassium tert-butoxide (conc. range 0,24-4,97 mole-%) was studied at 40°C.
Abstract: The non-activated polymerization of 2-pyrrolidone initiated with potassium tert-butoxide (conc. range 0,24–4,97 mole-%) was studied at 40°C. In accordance with theory, the conversion increases linearly with polymerization time and with initiator concentration. The linear dependence on conversion of the content of basic groups in the polymer and, above all, of the number of polymer molecules, and its independence on the initiator concentration up to 30% conversion indicate that a stationary state between formation and destruction of growth centres is very rapidly reached.
TL;DR: In this paper, a water-soluble initiator was used in various concentrations to determine the molecular weight distribution and degree of long-chain branching of a polyvinyl chloride (PVC) seed.
Abstract: Vinyl chloride was polymerized at 59–92% of saturation pressure in a water-suspended system at 45–65°C with an emulsion poly(vinyl chloride) (PVC) latex as a seed. A water-soluble initiator was used in various concentrations. The monomer was continuously charged as vapor from a storage vessel kept at lower temperature. Characterization included determination of molecular-weight distribution and degree of long-chain branching by gel permeation chromatography (GPC) and viscometry, thermal dehydrochlorination, and microscopy. The polymerization rate decreases with decreasing pressure but is reasonable even at the lowest pressure. The molecular weight decreases with decreasing pressure and increasing initiator concentration and also with increasing polymerization temperature, if the initiator concentrations are chosen to give a constant initiator radical concentration. The degree of long-chain branching increases with increasing initiator concentration and decreasing monomer pressure but is unaffected by the polymerization temperature, if the initiator radical concentration is kept constant. The thermal stability decreases with decreasing Mn, while the degree of long-chain branching has only a minor influence. The most important factor in the system influencing the molecular parameter is the monomer accessibility.
Patent•
3 Aug 1978TL;DR: In this article, a two-layer coating on the internal surfaces of the polymerization reactor was proposed to reduce the polymer buildup on the inner surfaces of a polyaromatic amine, or like material.
Abstract: This invention relates to a process of producing vinyl polymers by an inversion polymerization technique in the presence of a two layer coating on the internal surfaces of the polymerization reactor. By inversion polymerization is meant conducting the initial stage of the polymerization reaction wherein the monomer or monomers being polymerized constitute the continuous phase and in the latter stage of polymerization, water constitutes the continuous phase. The coatings comprise an undercoating of a polyaromatic amine, or like material, and the top coating is comprised of a water-soluble suspending agent, such as an alkyl or alkyl hydroxyalkyl cellulose ether. By means of the present inventive process, polymer buildup on the internal surfaces of the reactor are substantially reduced.
TL;DR: In this paper, the authors showed that the initiator exponent is a function of initiator concentration ranging from 0.35 at high concentration to about 0.65 at low concentration.
TL;DR: In this paper, the rate constants of the unimolecular cyclization reaction to those of the bimolecular propagation reaction of the uncyclized allyl and vinyl radicals, KA and KV, are estimated to be 9.7 and 1.35 mole/liter by fitting the kinetic equations obtained here to the dependence of the degree of cyclization on monomer concentration.
Abstract: Radical polymerization of methyl allyl maleate is kinetically discussed in terms of cyclopolymerization using 2,2′-azobisisobutyronitrile (AIBN) as an initiator and benzene as a solvent at 60°C. The ratios of the rate constants of the unimolecular cyclization reaction to those of the bimolecular propagation reaction of the uncyclized allyl and vinyl radicals, KA and KV, are estimated to be 9.7 and 1.35 mole/liter by fitting the kinetic equations obtained here to the dependence of the degree of cyclization on monomer concentration, respectively; the large difference between KA and KV is also discussed in detail. On the basis of these results the formation mode and the sequence distribution of the structural units of the polymer produced are discussed in detail; thus, for the polymer obtained in the bulk polymerization, about 90% of the cyclic structures can be formed via the intramolecular attack of uncyclized allyl radical on maleic double bond and the probability of succession of the cyclic structural units in diad sequence is exemplified as 0.27.
Patent•
26 Jul 1978
TL;DR: In this article, a low molecular weight polymer for controlling polymerization temperature whose composition and properties are similar to those of the objective polymer, is added to part of the mixture of 100 parts by wt.
Abstract: PURPOSE: To prepare an acrylic low molecular weight polymer in the absence of any solvent or dispersing medium, by polymerizing a (meth)acrylic ester under control of reaction temperature in the presence of a chain transfer agent and an initiator. CONSTITUTION: A low molecular weight polymer for controlling polymerization temperature whose composition and properties are similar to those of the objective polymer, is added to part of the mixture of 100 parts by wt. of a (meth)acrylic ester and 0.1W20 parts by wt. of a chain transfer agent, in such an amount as to be 30W90 wt.% of the total charge, followed by initial polymerization in the presence of an initiator or heating and agitation and subsequently adding solwly further initiator and the rest of the mixture of the system to complete the polymerization. COPYRIGHT: (C)1980,JPO&Japio
TL;DR: In this paper, the polymerization of acrylamide has been studied in ethanol at 80°C with 2,2′-azobisisobutyronitrile (AIBN) as the initiator.
Abstract: The polymerization of acrylamide has been studied in ethanol at 80°C with 2,2′-azobisisobutyronitrile (AIBN) as the initiator, and also in water at 60°C with 4,4′-azobis-4-cyanopentanoic acid (ACV) as the initiator. For the first system, it was found, approximately, that the well defined in duction period showed an inverse dependence on both the initial monomer and initiator concentrations, but was directly proportional to the square root of the initial oxygen concentration. For the second system, the rate of oxygen uptake was approximately directly proportional to the monomer and initiator concentration but independent of the oxygen concentration. The results obtained for these two systems are compared.
TL;DR: In this article, the initiator exponent and monomer exponent values were found to be 0.5 and 2, respectively, at low initiator concentrations, while the corresponding values at high initiator concentration conditions were zero and 3.0.
Abstract: Iodine monobromide easily induces photopolymerization of methyl methacrylate (MMA) at 40°C under visible light. Initiator exponent and monomer exponent values were found to be 0.5 and 2, respectively, at low initiator concentrations, while the corresponding values at high initiator concentration conditions were zero and 3. The chain transfer constant of IBr at 40°C was found to be 13.0. Kinetic and other data indicate a radical polymerization mechanism involving complexation of monomer molecules with iodine monobromide prior to radical generation, and termination is believed to take place biomolecularly at low IBr concentrations and unimolecularly, involving reaction with the initiator, at high IBr concentrations (initiator termination).
TL;DR: In this paper, the authors examined the reaction between biscyclopentadienyl titanium dichloride and aluminium alkyls and alkyl chlorides and concluded that the active initiating species is a Ti(IV) complex, and not the paramagnetic Ti(III) complexes.
Patent•
19 May 1978TL;DR: In this paper, a Bingham fluid is used to feed the fine-divided solid polymerization catalyst to the polymerization zone, where the mixture of a wax and a hydrocarbon is a liquid at ambient temperature.
Abstract: A process is provided for the polymerization of an olefin such as ethylene in the vapor phase in a moving bed of particles of the polymerized olefin in which novel means are employed to feed the finely-divided solid polymerization catalyst to the polymerization zone. The process is carried out by pumping into the polymerization zone a Bingham fluid which has the finely-divided solid polymerization catalyst uniformly dispersed throughout a solid continuous phase, which is a mixture of a wax and a hydrocarbon which is a liquid at ambient temperature.
TL;DR: In this paper, the polymerization of vinyl monomer initiated by an aqueous solution of sodium polystyrenesulfonate (PSS-Na) was carried out at 85°C.
Abstract: The polymerization of vinyl monomer initiated by an aqueous solution of sodium polystyrenesulfonate (PSS-Na) was carried out at 85°C. Methyl methacrylate (MMA) and styrene were polymerized, while acrylonitrile was not. The rate of polymerization of MMA decreased with the increase of the degree of polymerization of PSS-Na. However, the polymerization was not initiated by sodium ethyl benzenesulfonate which was a unit molecule of PSS-Na. The polymerization proved to be a radical reaction. The polymerization was considered to commence with the formation of hydrophobic areas with PSS-Na in the aqueous phase. MMA is incorporated into these areas, and there the polymerization is initiated and proceeds. The hydrophobic areas were assumed to be similar to the micelles formed by anionic detergents such as sodium alkylbenzene sulfonate. An initiation mechanism is proposed.
TL;DR: In this paper, triconstructured block copolymers containing the sequence styrene, p-tert-butylstyrene, styrene were prepared in an emulsion system by using isotactic polypropylene hydroperoxide as the initiator together with triethylenetetetramine as an activator.
Abstract: Triblock copolymers containing the sequence styrene, p-tert-butylstyrene, styrene were prepared in an emulsion system by using isotactic polypropylene hydroperoxide as the initiator together with triethylenetetramine as an activator, according to the method of Mikulasova and co-workers. Polymerization of styrene continued after removal of the initiator from the emulsion by filtration and eventually reached 100% conversion after 4 hr at 35°C. tert-Butylstyrene at 80°C and styrene at 35°C were added successively to the system, with each polymerization reaction carried to 100% conversion before the next monomer was added. Thin-layer chromatography was used to separate the homopolymers and block copolymers in order to determine the purity of the product. Monomer compositions of the block copolymers was verified by infrared analysis. The existence of two separate phases in the extracted block copolymer was indicated by the observation of two distinct glass transition temperatures.
Patent•
14 Sep 1978TL;DR: In this article, a mixture of calcium and zinc acrylate is used to reduce the amount of polymer scale formation during polymerization, and a further improvement in thermal stability is achieved by conducting the polymerization with the added presence of an epoxy compound containing a reactive vinyl or allyl group.
Abstract: Polymerization of vinyl chloride monomer, by either suspension or emulsion polymerization, optionally in the presence of a monoethylenically unsaturated comonomer, is carried out in the presence of a mixture of calcium and zinc acrylate. The presence of the calcium and zinc acrylate yields a more thermally stable product and reduces the amount of polymer scale formation during polymerization. A further improvement in thermal stability is achieved by conducting the polymerization with the added presence of an epoxy compound containing a reactive vinyl or allyl group.