bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of solvent on radical polymerization of vinyl benzoate
Authors: Kamachi Mikiharu , Satoh Jiro , Nozakura Shun‐Ichi 
Published: April 2003

AbstractAbsolute rate constants of the vinyl benzoate polymerization have been measured by use of the intermittent illumination method in various aromatic solvents and ethyl acetate at 30°C. The determination of absolute rate constants showed that effects of solvent on the polymerization rate of vinyl benzoate were mainly ascribed to the variation of kp values with solvents rather than that of kt values. The kp values for solvents used increased in the order: benzonitrile < ethyl benzoate < anisole < chlorobenzene < benzene < fluorobenzene < ethyl acetate. There was an eightfold difference between the largest and the smallest values The large variation among kp values was explained neither by the copolymerization through solvents nor the chain transfer to solvents, but by a reversible complex formation between the propagating radical and aromatic solvents. This explanation was supported by a correlation between kp values and calculated delocalization stabilizations for the complexes.
Surface grafting of polyethylene by mutual irradiation in methyl acrylate vapor. II. High‐energy electrons irradiation
Authors: Yamamoto Fumio , Yamakawa Shinzo , Kato Yoshinori 
Published: April 2003

AbstractVapor‐phase mutual grafting of methyl acrylate (MA) onto polyethylene (PE) at high dose rates from an electron accelerator yields the same surface graft structure as does the grafting at low dose rates from 60Co sources; i.e., a homopolymer layer (consisting of only MA component) is easily formed on the inner graft copolymer layer (consisting of both MA and PE components) as a result of the continuously increasing surface graft composition. To produce the surface layer, 4‐MeV electron irradiation with a linear electron accelerator requires only less than 3 min of irradiation time at dose rates of more than 2 Mrad/min, whereas γ irradiation with a 60Co source requires at least 1 hr at dose rates of less than 2 × 103 rad/min. The rate of monomer consumption (or polymerization) in the surface homopolymer layer shows no dependence of irradiation time and a positive dependence of dose rate. It has been suggested that this kinetic feature at the high dose rates shows some contribution of vapor‐phase homopolymerization and subsequent deposition (onto the grafting surface) followed by recombination with the grafted side chain radicals, although secondary graft copolymerization from the grafted chain radicals is still the principal process for the growth of the surface homopolymer layer.
Modification of poly(vinyl chloride). XXIX. Cross linking of poly(vinyl chloride) with 2‐dibutylamino‐4,6‐dithiol‐s‐triazine and MGO
Authors: Mori Kunio , Nakamura Yoshiro 
Published: April 2003

AbstractThermal crosslinking of poly(vinyl chloride) (PVC) with 2‐dibutylamino‐4,6‐dithiol‐s‐triazine (DB) and MgO has been studied to determine the kinetic parameters such as induction period (t0), rate constant (k), and activation energy (E), and to elucidate the structure of crosslink and the crosslinking mechanism. The thermal crosslinking was treated as a pseudo‐first‐order reaction. In the crosslinking, k and t0 were about 0.075 min−1 and 6.8 min at 180°C, respectively, and E was 16.6 and 14.2 kcal/mole for k and 1/t0, respectively. The structure of crosslink was confirmed to be indicated as the following scheme (I) from the results of model reactions and IR spectra of crosslinked products
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The crosslinking reaction was found to proceed through the following three processes: (1) formation of DB‐Mg from DB and MgO; (2) formation of DB‐Mg pendants by the reaction of PVC with DB‐Mg; and (3) formation of crosslink by the reaction of PVC with DB‐Mg pendants.
High‐transition‐temperature polyamides based on 2(2‐aminophenyl)1,1‐dimethylethylamine
Authors: Lee Lester T. C. 
Published: April 2003

AbstractNovel polyamides have been prepared from the 2(4‐aminophenyl) 1,1‐dimethylethylamine (APDEA) and various diacyl compounds. Unique properties have been found in these polyamides in that they possess a high glass‐transition temperature (Tg), yet have an exceptionally high Tg/Tm ratio. Structure—property relationships in these interesting polyamide and copolyamide systems are investigated. Unsubstituted polyamides and those with saturated rings were synthesized to demonstrate the important role played by the methyl substitution and the rigid ring in affecting the Tg and Tm. It seems reasonable to conclude that the gem‐dimethyl substituents and the stiff phenyl group or the interaction of these two groups with each other and with other adjacent segments in this particular molecular architecture contribute to this desirable transition‐temperature performance.
Degradation of polymer mixtures. IX. Blends of polystyrene with polybutadiene
Authors: McNeill I. C. , Ackerman L. , Gupta S. N. 
Published: April 2003

AbstractThe degradation of cis‐1,4‐polybutadiene, polystyrene, and blends of PB and PS has been studied by thermogravimetry, thermal volatilization analysis, and differential scanning calorimetry. Volatile products have been investigated and separated by subambient TVA and characterized spectroscopically. In the degradation of the blends, there is no change in the nature of the volatile products of degradation, but the rate of degradation of the PS component is markedly reduced. The PB component is the first to break down, and during the initial period of degradation of the PB, the PS degradation is apparently inhibited. It is suggested that some of the volatile products of decomposition of PB, most notably 4‐vinylcyclohexene, may diffuse into the PS phase in the blend and act as radical inhibitors.
Collapsed conformation of poly(methacrylic acid) chain containing nonionic hydrophilic units
Authors: Ponrathnam S. , Rao S. P. , Kapur S. L. 
Published: April 2003

AbstractCopolymers of methacrylic acid (MAA) and a nonionic hydrophilic monomer N‐vinylpyrrolidone (NVP) were synthesized by polymerization in aqueous solution in the absence of metal ions. The NVP content of the copolymers ranged from 2 to 36 mole % with sequences of MAA interrupted at random by a single unit of NVP at all compositions. The pH‐induced conformational transition of these copolymers was followed by potentiometric titration and viscosity studies and the results were compared with those of pure poly(methacrylic acid) (PMAA). The negative free energy of transition from the un‐ionized compact from to expanded structure showed a gradual decrease with increasing NVP content, and the collapsed conformation observable for PMAA at low degrees of ionization (0 < α < 0.3) disappeared at NVP contents greater than 15 mole%. These findings are supported by viscosity data. The results suggest that long‐range methyl–methyl hydrophobic contacts still possible in higher NVP content copolymers are not sufficient to bring about the collapse of the molecule and a minimum average sequence length of about 20 MAA units is required to compact the molecule. Hydrophilic “shielding” of MAA chains by NVP segments could also partly destabilize the collapsed structure.
13C‐NMR sequence analysis. 11. Anionic copolymerization of lactams
Authors: Kricheldorf Hans R. , Hull William E. 
Published: April 2003

AbstractUsing sodium as the catalyst and benzoylchloride as cocatalyst, copolymerizations of γ‐butyrolactam with ε‐caprolactam and ω‐capryllactam were carried out at 100°C. In a similar manner copolymerizations of ε‐cparolactam, ω‐capryllactam, and ε‐laurinlactam were achieved at 150 and 250°C without a cocatalyst. The 90.5‐MHz 13C‐NMR spectra of all random copolyamides in fluorosulfonic acid show three or more CO signals that allow the ratio of homogeneous (AA and BB) to heterogeneous (AB and BA) amide groups to be determined. These results cleárly demonstrate that despite the reaction temperature or reactivity of the lactams the copolyamides do not contain long homogeneous blocks (An and Bn). The CO signals of the random copolyamides were assigned by comparison with the corresponding homopolyamides and alternating copolyamides. Solutions of the alternating copolyamide (‐β‐Ala‐ε‐Aca‐)n, in fluorosulfonic acid were measured to determine whether the 13C chemical shifts and line widths are dependent on concentration.
Microstructure determination of poly‐(1,3‐pentadiene) by a combination of infrared, 60‐MHz NMR, 300‐MHz NMR, and X‐ray diffraction spectroscopy
Authors: Beebe D. H. , Gordon C. E. , Thudium R. N. , Throckmorton M. C. , Hanlon T. L. 
Published: April 2003

AbstractA quantitative procedure has been developed for characterizing the complete microstructure of polymers of 1,3‐pentadiene, including the tacticity of any crystalline component. This can be accomplished by a combination of infrared spectroscopy, X‐ray crystallinity, and 300‐MHz NMR spectroscopy. A series of high structural purity polymers were synthesized with a series of previously unreported mixed microstructures. These samples were characterized by using the three techniques mentioned, including the previously unreported 300‐MHz NMR data. With those results a 60‐MHz NMR/IR method of spectroscopy was developed to determine the composition of poly(1,3‐pentadiene)s in terms of percent cis‐1,2‐, cis‐1,4‐, trans‐1,4‐, and 3,4‐pentadiene units.
Synthesis and polymerization of novel formamidinium salts: A new pathway to polyamides derived from aromatic diamines
Authors: Spiewak J. W. 
Published: April 2003

AbstractA new polycondensation pathway has been developed for the preparation of polyamides at high temperatures. p‐Phenylenediamine was converted to N,N‐p‐phenylene bis(N′,N′‐dimethylformamidine) (I), which formed 1–1 and 2–1 salts with terephthalic and adipic acids, respectively:
magnified imageDicarboxylate salts were polymerizable by heating in bulk or suspension. Low‐molecular‐weight poly(p‐phenyleneterephthalamide) was obtained from N,N‐p‐phenylene bis(N',N'‐dimethylformamidinium) terephthalate above 225°C. The low degree of polymerization was due to terephthalic acid sublimation as well as to the well‐known intractability of poly(p‐phenyleneterephthalamide). High‐viscosity poly(p‐phenyleneadipamide) was obtained from N,N‐p‐phenylene bis(N′,N′‐dimethylformamidinum hydrogen adipate) above 200°C. Both salts liberated dimethylformamide (DMF) during polymerization. The adipate salt also released 1 mole of adipic acid during the high‐temperature vacuum stage of polymerization. A polycondensation mechanism was proposed for each salt, based on thermal gravimetric analysis (TGA‐MS) and infrared (IR) analyses.The hydrolysis of N,N‐p‐phenylene bis(N',N'‐dimethylformamidine), N,N‐p‐phenylene bis(N',N'‐dimethylformamidinium chloride), and the two dicarboxylate salts of (I) was monitored by nuclear magnetic resonance (NMR) at room temperature. The dihydrochloride salt was most resistant to hydrolysis (kH 6.9 × 10−9 sec−1; relative rate 1.0) followed by (I) 7.1, terephthalate salt, 14.9, and adipate salt, 27.2. Both dicarboxylate salts possessed sufficient hydrolytic stability for use as polycondensation monomers
Effect of hydrogen bonding on the acid character of some synthetic copolymers
Authors: Chatterjee S. K. , Pachauri L. S. 
Published: April 2003

AbstractA copolymer of p‐hydroxybenzoic acid, formaldehyde, and p‐bromoaniline was prepared in the presence of acid catalyst, and five fractions have been separated from it. Br content of each of the fractions was determined by chemical analysis, and on the basis of mole ratio of repeating units present in the copolymer chain, the total amounts of acidic and basic groups in a given weight of the copolymer were calculated. Nonaqueous titrations of all the fractions have been carried out in acidic and basic medium with suitable titrants. An excellent correlation was observed between the calculated and observed values of functional groups. The features of the titration curves were interpreted in terms of intramolecular hydrogen bonding and homoconjugation.
Alternating copolymerization of propylene oxide and carbon dioxide with an alumina supported diethylzinc catalyst
Authors: Soga Kazuo , Hyakkoku Kyoko , Izumi Katsuyuki , Ikeda Sakuji 
Published: April 2003

AbstractDiethylzinc was allowed to react with γ‐alumina in n‐heptane at 50°C, and the copolymerization of propylene oxide and carbon dioxide was investigated in some detail at 30–90°C by using the reaction product as a catalyst. From an analysis of the catalyst it was found that diethylzinc reacted with the surface hydroxyl groups of γ‐alumina mainly to give the following A‐type species by evolving ethane:
magnified imageThe catalyst showed considerably high activity for the copolymerization. The polymer obtained was a white solid with a high molecular weight soluble in benzene, acetone, dioxane, and methylene chloride and insoluble in diethyl ether and water. It was confirmed as an alternate copolymer of propylene oxide and carbon dioxide.The copolymerization was also conducted with a reaction mixture of the catalyst and catechol in which the molar ratio of catechol to the A‐type species was varied. The copolymerization activity decreased linearly with an increase in the molar ratio and disappeared completely at the molar ratio of unity.On the basis of these results it has been concluded that the A‐type is the true active species for the copolymerization.
Thermal degradation of ammonium polymethacrylate and polymethacrylamide
Authors: McNeill I. C. , Zulfiqar M. 
Published: April 2003

AbstractThe degradation of ammonium polymethacrylate and polymethacrylamide has been studied by a combination of thermal analysis methods (TVA and TG) and examination of volatile and involatile products by infrared analysis. It is shown that total reaction comprises an initial cyclization and further fragmentation of the modified chain at higher temperatures to yield gaseous volatiles. The partially degraded NH4PMA contains anhydride ring and cyclic imide structures in the chain. Quantitative comparison of yields of isocyanic acid and carbon dioxide has shown that imidization is the major reaction and anhydride formation is of less importance. The mechanisms of the various reactions are discussed.
Structure of chlorinated poly(vinyl chloride). V. Molecular parameters of chlorinated poly(vinyl chloride)
Authors: Lukáš R. , Janča J. , Mrkvičková L. , Pokorný S. , Kolínský M. 
Published: April 2003

AbstractThe molecular parameters of samples of chlorinated poly(vinyl chloride) (CPVC) and chlorinated β,β‐dideuterated poly(vinyl chloride) (β,β‐d2‐CPVC) were determined by gel permeation chromatography (GPC), light scattering, osmometry, and viscometry. Comparison of GPC, light scattering, osmometric, and viscometric data resulted in a discussion of the possibility of degradation and the causes of changes in the solution properties in chlorination of PVC and ββ‐dideuterated poly(vinyl chloride) (ββ‐d2‐PVC). The results obtained are discussed in relation to the mechanism of chlorination of PVC.
Cation‐exchanging macroreticular composites
Authors: Vasudevan Padma , Singh Maninder , Nanda Satish , Sarma N. L. N. 
Published: April 2003

AbstractSulfonated phenol formaldehyde resins were prepared under different conditions. Composites of these resins with sulfonated coals were also prepared and their physical properties and structure were studied. It was found that the resins are macroreticular and possess high surface areas.
Thermooxidative degradation of polyethylene. I and II. Structural changes occurring in low‐density polyethylene, high‐density polyethylene, and tetratetracontane heated in air
Authors: Holmström Arne , Sörvik Erling M. 
Published: April 2003

AbstractSamples of low‐density polyethylene (LDPE), high‐density polyethylene (HDPE), and tetratetracontane (n‐C44H90) free from additives were heated in air at temperatures between 120 and 180°C. As a comparison, “as received” HDPE containing unspecified additives has also been included.The structural changes have been studied with gel chromatography, viscometry, infrared spectroscopy, differential scanning calorimetry, and gravimetric measurements.LDPE, HDPE, and n‐C44H90 follow the same course of thermooxidative degradation when they are free from additives and present in the molten state. Both molecular‐diminishing and enlargement reactions occur. At temperatures below 150°C molecular enlargement is not observed until after rather long exposure times, whereas at higher temperatures enlargement occurs immediately. The difference is because “peroxide curing” becomes increasingly important above 150°C, whereas ester formation is operating at all temperature levels. Degradation below Tm is restricted to the amorphous phase that results in a different degradation pattern.In accelerated testing work extrapolations of the Arrhenius type in the prediction of structural change are thus not justified, even within the actual narrow temperature range. Neither are changes in commonly used standards like carbonyl content justified as a measure of the changes; for example, in mechanical properties.The stabilizer in the unpurified HDPE not only influences the induction period but also the course of the thermooxidative degradation.
Some perfluorocarbocyclic ethers and polyethers from hexafluorobenzene
Authors: Toy Madeline S. , Stringham Roger S. 
Published: April 2003

AbstractHigh‐resolution nuclear magnetic resonance (NMR) spectroscopy was used to determine the microstructures of some perfluorocarbocyclic ethers and polymers from reactions of bis(fluoroxy)‐difluoromethane and hexafluorobenzene. The thermal and photochemical reactions of CF2(OF)2 and excess hexafluorobenzene are described. The structures of several new perfluoro‐1,3‐dioxolanes in which the rings constituted part of a bicyclic system were elucidated by 19F‐NMR, gas chromatograph, gas chromatograph‐infrared, and gas chromatograph‐mass spectra.The copolymers of molecular weight about 2500 are, with 40% of the difluoromethylenedioxy groups, estimated by 19F‐NMR to be in the polymer chain and the rest as pendant groups to the perfluorocyclohexylene and perfluorocyclohexenylene moieties. The suggested polymer structures are described and the mechanisms discussed.
Alternating copolymers of propylene and alkyl acrylates
Authors: Logothetis A. L. , McKenna J. M. 
Published: April 2003

AbstractHigh‐molecular‐weight alternating and acrylate‐rich copolymers of propylene and ethyl acrylate were prepared by using boron trifluoride to complex the acrylate ester. The polymerizations were run at room temperature and autogeneous pressures with free‐radical initiation. The polymers were characterized by their nuclear magnetic resonance (NMR) and infrared (IR) spectra, differential scanning calorimetry, and gel permeation chromatography. The proton and 13C NMR spectra show that the equimolar copolymers are alternating to a high degree.
Low glass transition temperature fluorocarbon ether bibenzoxazole polymers
Authors: Evers Robert C. 
Published: April 2003

AbstractFluorocarbon ether bis(o‐aminophenol) monomers were prepared by a multistep synthetic route based on the copper‐promoted coupling of 4‐iodophenyl acetate with 1,8‐diiodoperfluoro‐3,6‐dioxaoctane, 1,11‐diiodoperfluoro‐3,9‐dioxaundecane, 1,14‐diiodoperfluoro‐5,10‐dimethyl‐3,‐6,9,12‐tetraoxatetradecane, and 1,17‐diiodoperfluoro‐3,6,9,15‐tetraoxaheptadecane. Acetic acidpromoted polycyclocondensations of the monomers with long‐chain fluorocarbon ether‐diimidate esters and ‐dithioimidate esters led to linear fluorocarbon ether‐bibenzoxazole polymers soluble in 1,1,1,3,3,3‐hexafluoroisopropanol and 1,1,2‐trichloro‐1,2,2‐trifluoroethane. Polymer structures were verified by elemental and infrared spectral analysis. The polymers were rubbery gums and could be obtained in the inherent viscosity range of 0.20–0.79 dlg−1. Selection of monomers governed the glass transition temperatures of the resultant polymers. As expected, the polymers exhibited lower glass transition temperatures with increased fluorocarbon ether content, a minimum value of −58°C being achieved. None of the polymers exhibited crystalline melt temperatures. Based on thermogravimetric analysis data, the thermooxidative stability of the polymers tended to decrease with increased fluorocarbon ether content. Onset of breakdown during thermogravimetric analysis in air occurred in the 350–400°C range. Isothermal aging of the polymers in air indicated good thermooxidative stability at 260°C; only 5% weight loss was recorded after 200 hr.
Kinetic studies of the radiation‐induced graft polymerization of butadiene onto poly(vinyl chloride) powder
Authors: Omichi Hideki , Yoshida Kenzo , Suzuki Kazuya , Araki Kunio 
Published: April 2003

AbstractThe radiation‐induced graft polymerization of butadiene onto poly(vinyl chloride) powder was studied. By the kinetic treatment of elementary reactions the values of kp and kt[Z] of the graft polymerization were obtained. The activation energy of the propagation was calculated as 16.0 kcal mole−1. The value of kp was proportional of the 0.42 power of the dose rate and that of kt[Z] was proportional to the 0.84 power of the dose rate.
Improved methods of estimating monomer reactivity ratios in copolymerization by considering experimental errors in both variables
Authors: Van Der Meer R. , Linssen H. N. , German A. L. 
Published: April 2003

AbstractExisting methods of calculating monomer reactivity ratios in copolymerization are reviewed briefly, evaluated, and classified according to their mathematical and computational similarities. More attention is paid to procedures based on the integrated copolymer equation with which calculation of r values is performed most often by electronic computer. Unfortunately, until now all procedures have shown shortcomings because the real‐error structure of the observations has not been taken into account. A new algorithm that does account correctly for measurement errors in both variables is described. A computational method is illustrated for copolymerization data obtained from quantitative gas chromatographic analysis of the monomer feed throughout the reaction. It is shown that the actual error structure of the variables corresponds to the assumed error structure. Reliability of the estimates is substantially increased, compared with the existing methods. Standard deviations of the monomer reactivity ratios are given and appear to be in good agreement with reality.
Alternating copolymerization of benzofuran and acrylic monomers in the presence of organoaluminum compounds
Authors: Furukawa Junji , Kobayashi Eiichi , Nagata Shiro 
Published: April 2003

AbstractThe copolymerization of benzofuran and acrylic monomers, such as acrylonitrile, methacrylonitrile, methyl acrylate, and methyl methacrylate, was investigated in the presence of aluminum compounds as complexing agents for acrylic monomers. Among the various kinds of aluminum compound, ethylaluminum sesquichloride is the most suitable for alternating copolymerization, whereas ethoxyaluminum compounds of low acidity allow the incorporation of excess acrylic monomer and dichloride of strong acidity is likely to induce cationic homopolymerization of benzofuran as a side reaction. The equimolar amount of sesquichloride with respect to acrylic monomer is necessary for alternating copolymerization. Azobisisobutylonitrile (AIBN) is an effective initiator but benzoyl peroxide is not. Nuclear magnetic resonance (NMR) of the copolymer indicates that the copolymer is essentially alternating, although some block sequences of acrylic monomer sometimes exist. As a mechanism the copolymerization via a ternary complex of acrylic monomer, aluminum compound, and benzofuran is considered.Free acrylic monomer participates in copolymerization when the amount or acidity of the complexing agent is insufficient. A quantitative relation between monomer and copolymer composition is derived from a scheme based on the copolymerization of the donor monomer‐acceptor monomer complex with free acrylic monomer.