bluuebunny/crossref_metadata_2025 huggingface dataset:
Monomer reactivity ratios in graft copolymerization
Authors: Odian George , Kruse Robert L. , Kho Jose H. T.
Published: April 2003

This paper discusses monomer reactivity ratios in various radiation‐ and redox‐initiated graft copolymerizations. The polymers studied were polyethylene, cellulose acetate, poly(vinyl chloride), polytetrafluoroethylene, poly(vinyl alcohol), and poly(methyl methacrylate); the comonomer mixtures were styrene–acrylonitrile, methyl acrylate–styrene, acrylonitrile–methyl acrylate, and vinyl acetate–acrylonitrile. The polymer–comonomer mixture systems were so chosen as to permit study of both homogeneous and heterogeneous systems. The homogeneous systems included systems of low and high viscosity. The heterogeneous systems included both polymers swollen by the comonomer mixture and polymers not swollen by the comonomer mixture. None of the homogeneous grafting systems studied showed deviations from the normal copolymerization behavior under a variety of experimental conditions. Monomer reactivity ratios in graft copolymerization were the same as the values in nongraft copolymerization. The heterogeneous systems in which the polymer was swollen by the comonomer mixture yielded grafted copolymer compositions which were the same as those in nongraft copolymerization. The heterogeneous grafting system polytetrafluoroethylene/styrene–acrylonitrile showed deviations from normal copolymerization behavior at low degrees of grafting when the reaction was only on the polymer surface. The behavior became normal at higher degrees of grafting when the system approaches that in which the polymer is swollen by the comonomers. In all reaction systems, it was found that the use of radiation to initiate the reaction does not in any way affect the copolymerization behavior of the two monomers in a comonomer pair.
Metallation of unsaturated polymers and formation of graft copolymers
Authors: Tate D. P. , Halasa A. F. , Webb F. J. , Koch R. W. , Oberster A. E.
Published: April 2003

The use of N,N,N′,N′‐tetramethylethylenediamine (TMEDA) is known to enhance the metallation of capability of butyllithium. It has been found that this TMEDA–BuLi reagent smoothly metallates olefins in high yields at 50°C in less than 4 hr by replacement of allylic hydrogen. This reaction has been applied to unsaturated polymers such as polybutadiene and polyisoprene. The resulting products have lithium atoms scattered along the chain. The amount of lithium on the chain can be varied over wide limits. Each lithium atom on the chain can act as a site for grafting or adding functional groups to the base polymer. Thus, this method allows the preparation of polymers having controlled amounts of branching as well as the introduction of functional groups into the polymer. Through the use of this metallation technique, polymers containing styrene and butadience grafts are specifically reported. In addition, polymers containing hydroxyl or carboxyl groups along the backbone are prepared by using this technique.
Steady‐state kinetics during initial stages of radical bulk polymerization of acrylonitrile
Authors: Amdur S.
Published: April 2003

The bulk polymerization of acrylonitrile with azobisisobutyronitrile as initiator and FeCl3 as terminator was studied at 60°C. It was found that the reaction proceeds like solution polymerization and does not exhibit the familiar autoacceleration found in bulk polymerizations. It was concluded that a steady‐state condition of growing radical chains exists. Initial rates, to approximately 3% conversion, were measured dilatometrically and were found to be proportional to the ratio of the initiator to terminator concentration, where this ratio is smaller than 3 : 1 and are due to the predominance of the FeCl3 monoradical termination mechanism. On increasing the ratio of initiator to FeCl3, the usual biradical termination mechanism becomes important as well. Assuming that the ratio of propagation constant to termination constant in this work is similar to the knwon ratio in DMF solution, a monomer “effective” concentration in the bulk of about 20% of the nominal concentration of pure acrylonitrile (14.38 mole/l. at 60°C) can be calculated. This result is interpreted by a molecular mechanism for the bulk polymerization of acrylonitrile.
Oligomeric silazanes
Authors: Breed L. W. , Elliot R. L.
Published: April 2003

High conversions of oligomeric silazanes that are not volatile at 200°C/0.1 mm are obtained when hexamethylcyclotrisilazane or octamethylcyclotetrasilazane is heated with a molar deficiency of dichlorodimethylsilane at 175°C. The oligomers, which show moderate solvolytic stability, contain disilazane, trisilylamine, and cyclodisilazane units. They are structurally similar to materials that have been prepared by others from hexamethylcyclotrisilazane and ammonium bromide. When the oligomers are treated with ammonia and heated to 325°C, evidence can be found in their spectra for the presence of oligocyclodisilazane structures.
α–γ transition in nylon 6
Authors: Abu‐Isa Ismat
Published: April 2003

The α to γ transition that occurs in nylon 6 upon iodine treatment was investigated by infrared spectroscopy, differential thermal analysis, and x‐ray diffraction techniques. Thin films of nylon (0.2 mil) were treated in either iodine–potassium iodide aqueous solution or in iodine vapor. Very short treatment times, in the order of 30 sec, were found to effect the transition when a solution 0.5M with respect to iodine was used. The infrared spectra of the iodine nylon complexes formed from either the α‐ or γ‐nylon 6 treated in vapor or dissolved iodine were all similar. This is an indication that molecular iodine is the active species in forming the complex. The temperature of the washing solution used to remove the iodine from the nylon determines whether an α‐nylon 6 or γ‐nylon 6 is obtained from the complex after washing. Nylon 6 plaque surfaces and thin films are similar in their behavior towards the iodine treatment. The γ‐nylon 6 is a stable modification at all temperatures below its melting point. The conversion of the γ form back to the α modification can occur only if the hydrogen bonding is severely affected, e.g., by phenol treatment, iodine treatment, melting, etc. Infrared spectroscopy provided no evidence for an α–γ transition in nylon 6 on heating the sample continuously through its melting point. The shapes of the melting peaks in the above two modifications of nylon 6 were sufficiently different to provide a means of identifying the two crystalline forms.
Irradiation‐grafted polymeric films. I. Preparation and properties of acrylic acid–grafted polyethylene films
Authors: Hamil H. F. , Adams L. M. , Harlowe W. W. , Martin E. C.
Published: April 2003

Graft copolymers of low‐density polyethylene film and acrylic acid have been prepared by the direct grafting technique. The properties of 27.4, 33.9, 41.2, and 46.4 wt‐% poly(acrylic acid) graft copolymer films have been compared. Measurements include degree and uniformity of grafting, gel water content, degree of swelling on wetting, tensile strength, elongation, ion‐exchange capacity, water‐vapor transmission, and water flux and solute rejection under reverse osmosis conditions. These properties were found to vary as the composition of the graft copolymer changed; most properties were found to be a linear function of the degree of grafting.
Hydrogen‐transfer polymerization of cis‐ and trans‐crotonamides
Authors: Kobuke Yoshiaki , Hanji Katsumi , Furukawa Junji , Fueno Takayuki
Published: April 2003

cis‐ and trans‐Crotonamides were polymerized in the presence of sodium tert‐butoxide in pyridine. It was found that both monomers undergo concurrent geometrical isomerization as well as polymerization. Polymers resulting from these isomeric monomers had identical microstructures. The rates of both polymerization and isomerization were evaluated from kinetic measurements. Kinetic investigations have also shown that the specific first‐order rate coefficient was independent of the isomer compositions and was identical for cis and trans monomers. The activation enthalpy was evaluated to be 15.0 kcal/mole.
Thermoplastic elastomers via radical polymerization. II
Authors: Zaganiaris Emmanuel J.
Published: April 2003

Simple models are used to study the formation of thermoplastic elastomers using a method for preparation of block copolymers introduced by Tobolsky and Rembaum. It was found that a small excess of isocyanate groups produce branched block copolymers with significantly reduced fractions of AB and B type molecules.
Polymerization studies on 1‐ferrocenyl‐1,3‐butadiene
Authors: Van Landuyt Dennis C. , Reed Samuel F.
Published: April 2003

The polymerization behavior of 1‐ferrocenyl‐1,3‐butadiene has been investigated by using both free‐radical and anionic initiation techniques. Polymerization occurred readily under the promoting action of butyllithium; however, no polymerization occurred when azobisisobutyronitrile (AIBN) or benzoyl peroxide was employed as initiator. Copolymerizations were carried out with methyl methacrylate and styrene. The behavior of 1‐ferrocenyl‐1,3‐butadiene in the copolymerizations was followed by dilatometric rate measurements, solution viscosity determinations, and elemental analysis. The major effect observed was a severe reduction in the intrinsic viscosities of the copolymers. An explanation for the observed behavior of 1‐ferrocenyl‐1,3‐butadiene in these reactions is advanced.
Application of gel‐permeation chromatography to studies of the functionality distribution of carboxy‐ and hydroxy‐polybutadienes
Authors: Law Ronald D.
Published: April 2003

Separations of carboxy‐polybutadienes and hydroxy‐polybutadienes according to functionality have been effected using stepwise elution from silica gel. Recoveries in the 95–100% range have been achieved. Subjection of the fractions obtained from the silica gel separation to analysis via gel‐permeation chromatography and infrared or near‐infrared spectroscopy yields not only functionality distribution data, but also provides the relationship between molecular weight distribution and functional type. Analytical techniques and interpretation of data are discussed.
Free‐radical homopolymerization and copolymerization of vinylferrocene
Authors: Lai John C. , Rounsfell Thane , Pittman Charles U.
Published: April 2003

The benzene solution homopolymerization of vinylferrocene, initiated by azobisisobutyronitrile, gave a series of benzene‐soluble homopolymers. Thus, free‐radical copolymerization studies were performed with styrene, methyl acrylate, methyl methacrylate, acrylonitrile, vinyl acetate, and isoprene in benzene. With the exception of vinyl acetate and isoprene, which did not give copolymers with vinylferrocene under these conditions, smooth production of copolymers occurred. The relative reactivity ratios, r1 and r2, were obtained for vinylferrocene–styrene copolymerizations by using the curve‐fitting method for the differential form of the copolymer equation, by the Fineman‐Ross technique, and by computer fitting of the integrated form of the copolymer equations applied to higher conversion copolymerizations. In styrene (M2) copolymerizations, the curve‐fitting and Fineman‐Ross methods both gave r1 = 0.08, r2 = 2.50, while the integration method gave r1 = 0.097, r2 = 2.91. Application of the integration method to methyl acrylate and methyl methacrylate (M2) gave values of r1 = 0.82, r2 = 0.63; r1 = 0.52, r2 = 1.22, respectively. The curve‐fitting method gave r1 = 0.15, r2 = 0.16 for acrylonitrile (M2) copolymerizations. From styrene copolymerizations, vinylferrocene exhibited values of Q = 0.145 and e = 0.47.
Elastomers from the copolymerization of conjugated dienes and styrenes containing chlorine
Authors: Halasa A. F. , Adams H. , Hunter C. J.
Published: April 2003

Copolymers of 1,3‐butadiene and o‐ and p‐chlorostyrenes have been made by use of alkyllithium initiators. These copolymers have a uniform distribution of the chlorostyrene along the chain, suggesting that the reactivity ratio of 1,3‐butadiene and chlorostyrene is close to unity.
Polymerization of butadiene and vinyl ether with catalyst prepared from π‐allyl nickel halide and organic peroxide
Authors: Matsumoto Tsuyoshi , Furukawa Junji , Morimura Hirohisa
Published: April 2003

The π‐allyl nickel halide–organic peroxide system has been found to be active as catalyst for the stereospecific polymerization of butadiene and polymerization of vinyl ether. Benzoyl peroxide is most effective. The catalyst from π‐allyl nickel chloride or π‐allyl nickel bromide and benzoyl peroxide yields predominantly cis‐1,4 polymer with high activity, whereas the catalyst from π‐allyl nickel iodide affords predominantly trans‐1,4 polymer. The catalyst system can be divided into two parts, a benzene‐soluble and a sentially insoluble component. It is concluded that the catalyst activity originates esbenzene‐from the insoluble nickel complex which is composed of halogen atom, benzoyloxy group of conjugated structure, allyl group, and nickel. A structure is proposed for the complex.
Thermal degradation of poly(alkyl acrylates). II. Primary esters: Ethyl, n‐propyl, n‐butyl, and 2‐ethylhexyl
Authors: Grassie N. , Speakman J. G. , Davis T. I.
Published: April 2003

Quantitative analyses of the products of thermal degradation of poly(ethyl acrylate), poly(n‐propyl acrylate), poly(n‐butyl acrylate) and poly(2‐ethylhexyl acrylate) have been made, principally by the combined application of GLC and mass and infrared spectroscopy. Data are recorded in mass balance tables. The major gaseous products are carbon dioxide and the olefin corresponding to the ester group. The minor gaseous products include the corresponding alkane, the alkane/olefin ratio being of the order of 10−2–10−3, and traces of carbon monoxide and hydrogen. The alcohol corresponding to the alkyl group is the major liquid product but there are also traces of monomer and the corresponding methacrylate. Alcohol production exhibits autocatalytic properties. The chain fragment fractions of the products are colored yellow and have average chain lengths of 3.2, 3.3, 3.6, and 5.6 for the ethyl, n‐propyl, n‐butyl and 2‐ethylhexyl esters, respectively. The infrared spectra are similar to those of the parent polymers but with well defined differences. Insolubility develops in the ethyl, n‐propyl, and n‐butyl esters, but the residual material from poly(2‐ethylhexyl acrylate) remains soluble even at very advanced stages of degradation. All of these products and reaction characteristics are accounted for in terms of radical reactions with a unique initiation step.
Polyimidazopyrrolones and related polymers. I. Dianhydrides and o‐acetamidodiamines
Authors: Frost L. W. , Bower G. M.
Published: April 2003

Solutions of polyimidazopyrrolone precursors prepared by reaction of tetraamines and dianhydrides in polar solvents tend to crosslink and gel very easily. Substitution of o‐acetamidodiamines for the tetraamines gives stable solutions. A study of cure mechanisms by TGA, infrared, and pyrolysis experiments with polymers and model compounds indicates that the acetylated materials are converted cleanly to imides at 150°C. At temperatures above 350°C, structural changes and further polymerization occur, with little imidazopyrrolone formation. Polymers derived from tetraamines cure by multiple mechanisms but finally yield the imidazopyrrolone structure. The acetylated polymers and copolymers give acceptable laminates but poor films.
Icosahedral carboranes. XVI. Preparation of linear poly‐m‐carboranylenesiloxanes
Authors: Knollmueller Karl O. , Scott Robert N. , Kwasnik Herbert , Sieckhaus John F.
Published: April 2003

The first members of the series of poly‐m‐carboranylenesiloxanes were synthesized by the ferric chloride‐catalyzed condensation of methoxy‐ and chloro‐terminated monomers and generally obtained as insoluble crosslinked gums It has now been discovered that long‐chain, linear polymers can be prepared by simple hydrolytic condensation of m‐B10H10C2(SiMe2OSiMe2Cl)2 and m‐B10H10C2(SiMe2OSiMe2OSiMe2Cl)2 at ice bath temperature, as well as by acid‐catalyzed condensation of the corresponding silanols. In addition, phenyl‐substituted copolymers have been obtained which show outstanding thermo‐oxidative stability at elevated temperature. These linear polymers are soluble waxes and liquids with molecular weights between 16,000 and 30,000; they are potentially useful as high‐temperature liquids and coatings and can be cured at room temperature to form elastomers.
Methyl methacrylate in sulfur dioxide: Solvated radical polymerization
Authors: Kearney J. J. , Clark H. G. , Stannett V. , Campbell D.
Published: April 2003

Methyl methacrylate may be polymerized by free‐radical initiators in liquid sulfur dioxide without incorporating sulfur dioxide in the polymer chain, even though methacrylate radicals and sulfur dioxide readily as indicated by electron spin resonance studies. An explanation for this anomalous result is advanced, and evidence for the participation of sulfur dioxide in the transition state of the addition reaction is presented.
Poly(ethylene sulfide). III. Oxidative degradation
Authors: Gillis Marina N. , Catsiff E. H. , Gobran Riad H.
Published: April 2003

Injection‐molded poly(ethylene sulfide) containing polyamines and zinc salts as thermal stabilizers has excellent physical properties at room temperature, but discolors rapidly on air aging at 150°C, with embrittlement and general deterioration of properties. Degradative breakdown under these conditions is preponderantly thermo‐oxidative in nature. The site of the polymer's thermo‐oxidative instability was sought in oxidation experiments involving the resin as well as model compounds for the polymer's organic structure. Identification studies were carried out on the oxidation products of 3,6‐dithiaoctane (a model compound). Rate of oxygen consumption by the model compound was measured by a pressure‐bomb technique and by a volumetric method. Oxidation of the model compound was found to proceed indefinitely as long as the supply of oxygen was replenished. Rate of oxidation was nonaccelerating and independent of oxygen pressure within the range 1.7–3 atm O2. The gaseous products of the oxidation of unstabilized (no polyamine) resin were found to be identical to the products from the oxidation of the model compound. A mechanism has been proposed taking into account the products isolated and identified, and the nonaccelerating nature of the oxidation. The poly(ethylene sulfide) structure is able to decompose hydroperoxides via formation of sulfoxides, preventing the acceleration of the oxidation reaction. While effecting this radical deactivation, the polymer chains are cleaved, with a resultant loss in molecular weight and physical properties. Some success has been met in the use of inorganic or metallo‐organic additives as antioxidants. Among these are dithiocarbamate salts and selenocyanates. The effectiveness of these compounds has been demonstrated in the polymer, and a suggested rationale for stabilization is given.
Polymerization of aminoalkyl methacrylates in a thin layer in the presence of atmospheric oxygen
Authors: Jelisejeva V. I. , Morozova E. M.
Published: April 2003

Chemically initiated monomer polymerization in a thin layer in air has been studied. Under these conditions the process is intensively inhibited by oxygen. Aminoalkyl methacrylates characterized by low volatility and high reactivity were used as monomers. Conditions ensuring a high degree of conversion, control of the process have been found determined. Monomer structurization by an active filler such as carbon black and redox initiation with peroxides and copper salts were found to be the main factors diminishing the induction period and increasing rate of polymerization of the aminoalkyl methacrylates.
Pyrolysis–gas chromatographic analysis of poly(vinyl chloride). II. In situ absorption of HCl during pyrolysis and combustion of PVC
Authors: O'mara Michael M.
Published: April 2003

A pyrolysis–gas chromatographic technique for measuring the amount of hydrogen chloride released during the high temperature pyrolysis of poly(vinyl chloride) resins, plastisols, copolymers and compounds containing inert fillers has been developed. The technique, which is also applicable to the analysis of chlorinated polyethylene and chlorinated poly(vinyl chloride), is based on the use of a standard precursor of HCl, poly(vinyl chloride) homopolymer. The analysis has been successfully used to measure the degree of in situ absorption of HCl during pyrolysis by certain basic fillers [K2CO3, CaCO3, CaO, MgO, Al(OH)3, Na2CO3, Al2O3 and LiOH] dispersed in a poly(vinyl chloride)–o‐dioctyl phthalate matrix. Combustion of a number of combustion residues (chloride determination) revealed that the amount of HCl absorbed by the basic filler was independent of the method of degradation (pyrolysis or combustion). Flammability measurements of those matrices having the same composition indicate that in situ absorption of HCl during combustion has little effect on the overall flammability of these materials.
Availability and state of order of hydroxyl groups on the surfaces of microstructural units of crystalline cotton cellulose
Authors: Rowland S. P. , Roberts E. J. , Bose J. L.
Published: April 2003

The relative accessibilities of the hydroxyl groups of the D‐glucopyranosyl units of hydrocellulose have been studied by means of the reaction of N,N‐diethylaziridinium chloride, which produces 2‐(diethylamino)ethyl cellulose. The deviation in the distribution of substituents among the 2‐O‐, 3‐O‐, and 6‐O‐positions of the D‐glucopyranosyl residues in a hydrocellulose from that in a disordered cellulose in which the three types of hydroxyl groups are equally accessible is the basis for estimating the selective accessibilities of the hydroxyl groups in the crystalline cellulose. A particular hydrocellulose, lying within the range of leveling‐off degree of polymerization, was studied in detail; this hydrocellulose, designated EHC (“Exemplar Hydrocellulose”), was formed from fibrous cotton by hydrolysis for 0.67 hr in 2.5N hydrochloric acid at reflux. EHC exhibited higher selective accessibility (larger deviation from equal accessibility) of the hydroxyl groups at C‐2, C‐3, and C‐6, than samples of hydrocellulose formed in shorter or longer periods of hydrolysis. This selective accessibility is discussed in terms of intra‐ and intermolecular hydrogen bonding on the surfaces of crystalline microstructural units in EHC.
Fundamental studies on cationic polymerizations: Molecular weights and molecular weight distributions of polyisobutylenes produced by γ‐irradiation (free ions) and chemical catalysis (ion pairs)
Authors: Kennedy Joseph P. , Shinkawa Akihiro , Williams Ffrancon
Published: April 2003

The molecular weights (M̄n, M̄v, and M̄w) and molecular weight distributions of polyisobutylenes synthesized by γ‐irradiation in the range 29 to −78°C have been determined. The plots of log M̄n, log M̄v, and log M̄w versus 1/T are linear and parallel (EM̄ = −6.36 ± 0.5), and M̄w/M̄n ≈ 3.0 ± 0.5 over this temperature range. The viscosity‐average molecular weights of polyisobutylenes obtained by γ‐irradiation were compared with those of polymers prepared by BF3, EtAlCl2, and AlCl3. It is found that, at the same polymerization temperature, the M̄v of radiation‐induced polyisobutylenes, which propagate by free carbonium ions, is significantly higher than those synthesized by the Lewis acids, which probably propagate via ion pairs. The implications of these findings are discussed, and it is concluded that the counterion in the proximity of the growing cation impedes propagation to a greater extent than it does the competing process of chain transfer to monomer.
Cationic polymerization of vinyl compounds in the presence of tetra‐n‐butylammonium salts
Authors: Masuda Toshio , Higashimura Toshinobu
Published: April 2003

The effects of salts were examined in cationic polymerization of vinyl compounds. Cationic polymerization of styrene was carried out at 0°C, with acetyl perchlorate, stannic chloride, stannic chloride–trichloroacetic acid and boron trifluoride etherate as catalysts. Tetra‐n‐butylammonium perchlorate, fluoroborate and iodide were used as salts. The presence of small amounts of the salts changed both the polymerization rate and the molecular weight of polymer considerably. The consideration of various effects led to the conclusion that the results are explicable principally on the basis of counterion exchange. To confirm this, the copolymerization of 2‐chloroethyl vinyl ether with γ‐methylstyrene was investigated at −78°C. The copolymer composition curve when stannic chloride was used as catalyst was changed and coincided with that of polymer obtained with acetyl perchlorate catalysis when the perchlorate salt was added. This supports the concept of counterion exchange.
Criticisms of claims in the field of isomerization polymerization. I. Polymerization of p‐methylstyrene
Authors: Kennedy Joseph P. , Magagnini P. L. , Plesch Peter H.
Published: April 2003

The polymerization of p‐methylstyrene with cationic initiators at low temperatures has been reinvestigated. It was found that, contrary to claims by Krentsel et al., this polymerization produces a conventional 1,2 structure and consequently proceeds by a conventional mechanism.
Structures of reagent residues resulting from reactions of divinyl sulfone with cotton cellulose
Authors: Rowland S. P. , Cirino V. O. , Bullock A. L.
Published: April 2003

Cotton cellulose in fabric form was crosslinked with divinyl sulfone by catalysis with solutions of sodium hydroxide of normalities ranging from 0.1 to 4.0. The molecular chains of cellulose were hydrolyzed with sulfuric acid to yield hydrolyzates from which simple substituted glucoses (i.e., those bonded to a single unit of DVS), the simple crosslinked glucoses (i.e., those joined together by a single unit of DVS), and complex structures (i.e., those substituted or crosslinked with more than one unit of DVS in the chain) were isolated and measured. The fractions of the reagent residues in the forms of the structures noted above were found to change substantially with the concentration of base employed to catalyze the reaction. The constitution of the reagent residues resulting from reaction in 0.1N base was remarkably simple: 82% of the DVS residues in the form of simple crosslinks and 18% in the form of simple substituents. Complex structures accounted for as much as 70% of the DVS residues under other conditions of reaction.
Side‐chain crystallinity. I. Heats of fusion and melting transitions on selected homopolymers having long side chains
Authors: Jordan Edmund F. , Feldeisen Donald W. , Wrigley A. N.
Published: April 2003

Heats of fusion, melting transitions, and the derived entropies of fusion were obtained by differential scanning calorimetry for examples from three homologous series of homopolymers having long side chains. Homopolymers having side‐chain lengths between 12 and 22 carbon atoms were chosen from the poly(n‐alkyl acrylates), the poly(N‐n‐alkyl‐acrylamides) and the poly(vinyl esters). The data demonstrated that only the outer paraffinic methylene groups were present in the crystal lattice. This was concluded because phase diagrams obtained for mixtures of structurally different monomers and homopolymers, as well as for selected copolymers, showed only isomorphism in the polymeric examples. In addition, scanning curves, reflecting the distribution of crystallite sizes, became narrower as the side chains became longer. The critical chain length required to maintain a stable nucleus in the bulk homopolymers was a constant value for each homologous series. It varied between 9 to 12 carbon atoms. When heats of fusion were determined in the presence of methanol, main‐chain restraints were freed, thus permitting more methylene groups to enter the crystal lattice. Hence, the heats of fusion, the crystallinity, and melting points increased above that of the bulk state. The magnitude of the contribution to the heats of fusion by each methylene group indicated that the hexagonal paraffin crystal modification prevailed in these homopolymers, in agreement with x‐ray data from the literature.
Thermal bulk polymerization of cholesteryl acrylate
Authors: De Visser A. C. , De Groot K. , Feyen J. , Bantjes A.
Published: April 2003

The thermal bulk polymerization of cholesteryl acrylate was carried out in the solid phase, the mesomorphic phase, and the liquid phase to study the effect of monomer ordering on polymerization rate and polymer properties. The rate increased with decreasing ordering (or enhanced mobility) of the monomer. Formation of inhibitive by‐products during the polymerization limited conversions to 35%. The sedimentation constant S0 = 6.2 S was the same for the polymers obtained in the three phases. The weight‐average molecular weight (M̄w) was 480,000 as determined by ultracentrifugation. Poly‐(cholesteryl acrylate) formed in bulk is randomly coiled when dissolved in tetrahydrofuran. The thermal properties of the monomer are given.
Polyesters. I. Rate of polyesterification of γ‐arylitaconic acids with ethylene glycol
Authors: Baddar F. G. , Nosseir M. H. , Gabra G. G. , Ikladious N. E.
Published: April 2003

A kinetic study of the polyesterification reaction of γ‐phenyl‐ γ‐p‐methoxyphenyl‐, and γ‐p‐chlorophenylitaconic acids (1 mole) with ethylene glycol in the presence or in absence of p‐toluenesulfonic acid as a catalyst has been carried out in order to show the effect of substituents on the rate and degree of polymerization. The reaction of 1 mole of the acid and an excess of ethylene glycol has also been studied. In all cases the reaction is found to follow the second‐order rate equation. The mechanism of polyesterification has been discussed. In catalyzed polyesterification electron‐withdrawing groups (CI) decrease the velocity of the reaction. The low values of ρ in both the auto‐catalyzed and catalyzed reaction indicate that this polyesterification is slightly sensitive to the polar nature of the substituent.
Constitutive equations for elastomers
Authors: Tschoegl Nicholas W.
Published: April 2003

General relations were derived by expanding the strain‐energy density function in terms of the invariants of the deformation tensor. Some constitutive equations obtained by keeping a third term in the expansion in addition to the two terms retained in the Mooney‐Rivlin equation were tested in the light of currently available experimental data. It is shown that by the retention of the third term the upswing in the Mooney stress at low values of λ−1 is successfully predicted, and the stress–strain behavior can be described with excellent accuracy up to break, even in carbon black‐filled rubber which is notoriously difficult to describe by the Mooney‐Rivlin equation.
π‐Allyl nickel halide–oxygen system as a catalyst for polymerization of butadiene
Authors: Matsumoto Tsuyoshi , Furukawa Junji , Morimura Hirohisa
Published: April 2003

The π‐allyl nickel halide‐oxygen system was found to be active as catalyst for stereospecific polymerization of butadiene. The catalyst from π‐allyl nickel chloride or π‐allyl nickel bromide yields the polymer of 90% cis‐1,4 content with high activity, whereas the catalyst from π‐allyl nickel iodide affords a polymer of 70% or less cis‐1,4 content. The catalyst systems can be fractionated into two parts on the basis of solubility in benzene. It is concluded that the catalyst activity originates essentially from the benzene‐insoluble nickel complex which is composed of oxygen, halogen, σ‐allyl group, and nickel. The structure of growing polymer terminal is discussed in relation to the mechanism of the stereospecific polymerization.
Radiation‐induced polymerization at high pressure of 2,3,3,3‐tetrafluoropropene in bulk and with tetrafluoroethylene
Authors: Brown Daniel W. , Lowry Robert E. , Wall Leo A.
Published: April 2003

The radiation‐induced polymerization of 2,3,3,3‐tetrafluoropropene was studied as a function of temperature (22–100°C) and pressure (autogenous to 104 atm). Rates have varied 100‐fold for the same reaction conditions probably because of trace impurities. The most rapidly polymerizing material has a rate of 4.5%/hr at 6000 atm, 22°C, and 1500 rad/hr. The activation enthalpy and volume are 4 kcal/mole and −13 cc/mole, respectively. Rates are proportional to the square root of the radiation intensity. Degrees of polymerization varied between 2 × 103 and 2 × 106. In copolymerization with tetrafluoroethylene the reactivity ratios at 22°C and 5000 atm are 0.37 (the ratio for addition to the tetrafluoroethylene‐ended radical) and 5.4 (the ratio for addition to the tetrafluoropropene‐ended radical). Comparison of ratios for the copolymerization of other fluorinej‐containing monomers with tetrafluoroethylene shows that they generally disfavor incorporation of the latter.
Electrochemical preparation of polymers with multinodal molecular weight distributions
Authors: Funt B. L. , Hornof V.
Published: April 2003

A direct electrochemical preparation of polybutadiene to a predetermined molecular weight distribution has been achieved. Butadiene is a good model compound, inasmuch as the rate of electrochemical initiation is high relative to the rate of propagation. Rate constants for the temperature interval of interest and for systems of comparable composition were reported and permitted a priori prediction of the weight fractions and the number average molecular weight of each fraction. Polymer was formed by a series of pulses which successively initiated polymerization, permitted growth in the absence of current, and electrochemically terminated polymerization. The polymers produced showed excellent agreement with calculated composition and distribution in the range of molecular weights 10,000 to 50,000.
Copolymerization of ethylene and vinyl acetate at low pressure: Determination of the kinetics by sequential sampling
Authors: German A. L. , Heikens D.
Published: April 2003

In behalf of a detailed study on the course of copolymerization reactions, this paper describes an improved and generally applicable experimental method and an efficient computational procedure to match. The experimental method is based on quantitative gas chromatography, and permits frequent measurement of the monomer feed composition throughout (co)polymerization processes at pressures up to 40 kgf/cm2 ( = 38.7 atm). The given method is applied to the study of the radical copolymerization of ethylene with vinyl acetate in a series of kinetic experiments, at 62°C and 35 kgf/cm2 ( = 33.9 atm) in tert‐butyl alcohol, in which 20–40% conversion is reached. Monomer feed composition and degree of conversion are entered into a computational procedure based on nonlinear least‐squares methods applied to the integrated version of the copolymer equation. The experimental data, covering a region of ethylene molar feed fractions between 0.24 and 0.74 and copolymer concentrations up to 8 wt‐%, are precisely consistent with the usual model. The respective reactivity ratios are r̂e = 0.743 ± 0.005 and r̂v = 1.515 ± 0.007.
Problems in low‐temperature polymerization of lactams with MAlEt4–n (Lac)n as catalyst
Authors: Konomi Tuyoshi , Tani Hisaya
Published: April 2003

The NaAl(Lac)4‐catalyzed polymerization of ε‐caprolactam at the medium temperature range (70–150°C) was investigated. The initiation temperature was observed to decrease to about 100°C in the case of a high concentration (such as 2.0 mole‐%) of catalyst. Moreover, in the prolonged polymerization of lactams with KAl(Lac)2Et2 catalyst, in the absence of initiator, the low activity of aluminum lactamate as initiator was observed. In connection with the polymerization of lactams with MAl(Lac)nEt4–n catalyst, the reactivity of MAlEt4 (where M is Na or K) with N‐acetyllactams was investigated. The results imply that no consumption of N‐acyllactams by the reaction with MAl(Lac)nEt4–n occurs in the course of the low‐temperature polymerization of lactams.
Curing mechanism for phenol—formaldehyde resins
Authors: Kurachenkov Vladimir Ivanovich , Igonin Leonid Andreevich
Published: April 2003

A pressure DTA method was used to study the curing of resins. The hardening of novolacs by hexamine was studied at pressures up to 5000 kg/cm2. The application of the pressure DTA method to the thermal curing of some dioxymethylated para‐substituted phenols indicates that the endothermic peak observed at about 75°C at ambient pressure is due to the superposition of two peaks due to melting of the substance and formation of ester bonds.
Polyquinazolotriazoles
Authors: Hergenrother P. M.
Published: April 2003

A novel high molecular weight (ηinh = 1.4 dl/g) polyquinazolotriazole (PQT) was prepared from the reaction of 3,3′‐(2″,6″‐pyridinediyl)bis[5‐(o‐aminophenyl)‐1,2,4‐triazole] with isophthalic acid by solution cyclopolycondensation in polyphosphoric acid, with diphenyl isophthalate by melt polycondensation, and with isophthaloyl chloride to form a precursor polyamide which subsequently underway cyclodehydration. Thermal characterization of the PQT by thermogravimetric analysis showed initial weight loss in air commencing at ∼490°C. The PQT exhibited a weight loss of only 4% after aging in static air for 200 hr at 316°C and a Tg of 342°C as measured by differential scanning calorimetry. Prior to polymer synthesis, a series of model compounds was prepared as a guide to polymer synthesis and identification.
Polymerization of propadiene. II. Catalyst systems based on 3d transition metals and various stabilizing ligands
Authors: Van Den Enk J. E. , Van Der Ploeg H. J.
Published: April 2003

A variety of catalyst systems based on 3d transition metals, i.e., V(III), Cr(III), Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and various stabilizing ligands, i.e., propadiene, methylacetylene, phenylacetylene, and 1,4‐butadiene, were prepared. The activity of these catalytic systems towards the polymerization of a series of monomers (propadiene, methylacetylene, phenylacetylene, 1,4‐butadiene, ethene, and propene) is investigated. Optimum conditions for the preparation of 1,2‐polyallene, polymethylacetylene and polyphenylacetylene are given.
Determination of kinetic rate constants in electrochemically initiated anionic polymerization of 1,3‐butadiene
Authors: Funt B. L. , Hornof V.
Published: April 2003

The rate constants for electrochemically initiated polymerization were determined by employing a pulsing technique. An electrochemical titration was conducted in which polymer chains were initiated electrochemically, propagated in the absence of current, and terminated electrochemically. The concentrations of supporting electrolyte and monomer were chosen to correspond to those employed in electropolymerization syntheses. The temperature range −10°C to −72°C gave kp = 1.45 × 102 exp {2600/RT}. The Arrhenius parameters are compared to those from previous studies and are interpreted in terms of ion‐pair propagation. Precise control of molecular weight distributions is implicit from an accurate knowledge of the kinetic parameters and is reported separately.
Polymerization of methyl methacrylate induced with the peracid‐type ion exchange resin
Authors: Koyama Kiyoshi , Nishimura Masato , Hashida Isao
Published: April 2003

The polymerization of methyl methacrylate initiated with a peracid‐type resin was studied. The peracid‐type resin was prepared by the oxidation of cation‐exchange resin (Amberlite IRC‐50) with 60 wt‐% aqueous hydrogen peroxide in the presence of p‐toluenesulfonic acid. It was found that the peracid‐type resin was effective as an initiator for polymerization of methyl methacrylate. The kinetic investigation indicated that this polymerization proceeded by a radical mechanism, and the overall activation energy of polymerization was 15.8 kcal/mole. No effect of macromolecular catalyst on steric structure of the resulting polymer was observed. Some graft polymer was formed in bulk polymerization. On the other hand, only a homopolymer was obtained in solution polymerization. From the results obtained, a possible mechanism of initiation with the peracid‐type resin is proposed and discussed.
Ring‐opening polymerization of ethylene organophosphorothioates: Stereoregular polymerization involving asymmetry at phosphorus
Authors: Vandenberg E. J.
Published: April 2003

Stereoregular polymerization involving asymmetry at phosphorus has been obtained from ethylene methyl or phenyl phosphorothioate with R2MgNH3 catalysts, or, in some cases, with R2Mg alone. The methyl ester gave two types of polymer: an amorphous rubber and a low‐melting (75°C) crystalline polymer. The phenyl ester gave mainly a low‐melting (68°C) crystalline polymer of 2.2 inherent viscosity. Proton and 31P NMR and infrared spectra of these polymers are in accord with the expected chain unit, CH2CH2OP(S)(OR)O. The polymerization mechanism probably involves an anionic ring‐opening step with PO cleavage. Ring opening with CO cleavage appears to be largely excluded. This conclusion is based on the expectation that anionic ring opening with CO cleavage should lead to a rearranged chain unit, CH2CH2OP(O)(OR)S, because of the high nucleophilicity of sulfur as compared with oxygen. Proton and 31P NMR spectra give no evidence for the rearranged unit within the limit of detection (ca. 3%). However, on aging, the methyl ester polymer changes drastically to form up to 40% CH2SP groups. Presumably, the polymer undergoes the well‐known thiono‐thiolo rearrangement characteristic of simple phosphorothioate esters to form CH2CH2OP(O)(SCH3)O chain units. The phenyl ester polymer is stable under the same aging conditions.
Structural changes in polymers of diethyl succinylsuccinate(1,4‐diethoxycarbonyl‐2,5‐dihydroxy‐1,4‐cyclohexadiene) with diamines at high temperatures
Authors: Tai Akira , Higashi Fukuji , Yokomizo Soichiro
Published: April 2003

The structural changes of the polymers having the following structures:
magnified image
at high temperatures were studied by the spectroscopic and thermal analysis. When the polymers were heated in air, they were oxidized predominantly to polymers having the structure:
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The rate of oxidation was fast and the reaction was almost completed within 2 hr at 180°C. In the case of polymer 3, an intramolecular cyclization to form acridone was detected as a minor reaction.
Studies on adsorption of natural and synthetic hymatomelanic acids at air–water and at oil–water interfaces
Authors: Ghosh Kunal , Chatterjee B. C. , Mukherjee S. K.
Published: April 2003

By utilizing a static method, based on slight modification of the Wilhelmy plate method, the interfacial properties of one natural and two synthetic hymatomelanic acids were studied at both the air–water and oil–water interfaces. On this basis their number‐average molecular weights, flexibility and shape of the macromolecular chains at the interface, and the related thermodynamic parameters were evaluated.
Solid‐state polymerization of vinylpyridine coordination compounds
Authors: Agnew N. H. , Brown M. E.
Published: April 2003

A survey of the solid‐state polymerizability of 2‐ and 4‐vinylpyridine (Vpy) complexes of divalent cobalt, nickel, copper, and zinc chlorides has been carried out. The influence of metal ion, ligand, coordination stereochemistry, and crystal structure is discussed. The tetrahedral modification of the complex Co(4‐Vpy)2Cl2 has been found to undergo a particularly facile thermal polymerization below its melting point to yield high molecular weight poly‐4‐vinylpyridine. The polymer is shown to be conventional atactic head‐to‐tail poly‐4‐vinylpyridine. Thermogravimetric methods and optical microscopy have been used to study the thermal polymerization of single crystals of the complex. Results indicate a diffusion‐controlled mechanism in which defective regions in the crystal act as nuclei for the polymerization.
Concentration effects in gel‐permeation chromatography
Authors: Rudin Alfred
Published: April 2003

Peak elution volume in gel‐permeation analysis of polymers depends on sample concentration as well as molecular weight. Elution volume is related to the logarithm of the hydrodynamic volume of the solvated polymer species. The hydrodynamic volume of a given species is, in turn, inversely related to the concentration. Since molecular weight and concentration are interacting variables, the elution volume–molecular weight relation is not uniquely determined. A model is presented which accounts quantitatively for concentration effects, using parameters which are available a priori. The data required are polymer molecular weight, concentration, and density and the Mark‐Houwink relation for the particular polymer‐solvent combination.
Study of the γ‐alumina polymerization of furfuryl alcohol
Authors: Wewerka E. M.
Published: April 2003

The γ‐alumina polymerization of furfuryl alcohol produces a polymer differing in structure from that obtained by polymerization with acid catalysts. In order to gain a better understanding of the basic chemistry of this method of polymerization furfuryl alcohol, studies were done, both with γ‐alumina‐polymerized and acid‐polymerized furfuryl alcohol resins, concerning both the chemical nature of the resin constituents, and the manner in which these constituents affect resin molecular size distribution as measured by gel permeation chromatography. Because of numerous side reactions, the γ‐alumina polymerization of furfuryl alcohol was found to result in the early elimination of many of the molecules containing functional groups necessary to the sustenance of polymerization. As a consequence even at advanced degrees of polymerization there remain relatively large amounts of low molecular weight components that have not further polymerized. At the higher degrees of polymerization, the high molecular weight end of the resin molecular size distribution was observed to be significantly enhanced over that of the acid‐polymerized resins. The latter behavior is attributed to the occurrence of crosslinking reactions made possible by the higher temperature required for polymerization with γ‐alumina. It is further concluded that the curing processes of γ‐alumina‐polymerized furfuryl alcohol resins proceed by a mechanism unlike that of the acid‐polymerized resins.
Studies on substituted lactams (I)
Authors: Klein K. P. , Reimschuessel H. K.
Published: April 2003

Syntheses and reactions of 4‐carboxy‐2‐pyrrolidone, 6,6‐dimethyl‐4‐carboxy‐2‐piperidone, and 5,5‐dimethyl‐4‐carboxy‐2‐pyrrolidone are described. Whereas 4‐carboxy‐2‐pyrrolidone polymerizes upon heating to form a polyimide, the two lactams containing geminal dimethyl groups undergo isomerization. The 6,6‐dimethyl‐4‐carboxy‐2‐piperidone isomerizes to 5,5‐dimethyl‐3‐carboxymethyl‐2‐pyrrolidone, and 5,5‐dimethyl‐4‐carboxy‐2‐pyrrolidone affords isopropylidene succinimide. Possible mechanisms for these reactions are discussed.
Friedel‐crafts copolymerization of thiophene and p‐di(chloromethyl)benzene. II. Products of the later stages of the reaction
Authors: Grassie N. , Colford J. B.
Published: April 2003

Products of the copolymerization of thiophene and p‐di(coloromethyl)benzene in presence of stannic chloride have been separated by using gel‐permeation chromatography (GPC) and identified by using principally mass, infrared, and nuclear magnetic resonance spectroscopy. The GPC separation is not nearly as efficient as the separation of the products of the corresponding benzene–DCMB and diphenylmethane–DCMB reactions which have previously been described. A further complication which makes a kinetic analysis of this reaction more difficult is the occurrence of intramolecular condensation of certain of the earlier products leading to cyclic structures incorporating four aromatic rings. These investigations have made it possible to deduce some of the principal structural differences between the thiophene–DCMB and benzene–DCMB polymers which may have some bearing on the differences which have been found in their thermal stabilities.