bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymerization of methylmethacrylate initiated by hydrogenation catalysts
Authors: Iwatsuki Shouji , Kasahara Hideo , Yamashita Yuya 
Published: April 2003

AbstractRANEY metals (Ni, Fe, Co), URUSHIBARA metals (Ni, Co) and ULIMANN cu initiate the polymerization of methylmethacrylate. Diamines, diols or organic halides enhance their reactivity.In the presence of CCl4, the polymerization rate (Rp) is proportional to the square root of the amount of both metals and CCl4, and to the first power of the monomer concentration, but Rp becomes constant and independent of the concentration of CCl4 when there is a great excess of CCl4.We concluded that this polymerization follows the free radical mechanism and the participation of a zero‐valent metal atom in the initiation reaction including complex formation between metal and CCL4 is suggested.
Kinetic studies in ethylene polymerization with ZIEGLER type catalysts. IV. Effect of electron donors on the ratio of trivalent to tetravalent titanium sites
Authors: Schindler A. 
Published: April 2003

AbstractThe incorporation of D in the form of CHD groups, exclusively occuring with polymer chains attached to Ti(IV) sites, was used for the determination of electron donor effects on the ratio of Ti(III) to Ti(IV) sites. Combined measurements of polymer yields and CHD group contents supplied the data for the calculation of the ratio of the corresponding complexing constants. These ratios indicated that for a considerable fraction of the Ti(III) sites the electrophilicity was as high as for most of the Ti(IV) sites. The spread in the degree of electrophilicity was found to be greater for Ti(III) sites than for Ti(IV) sites. The latter result might indicate a more uniform structure for Ti(IV) sites.
The cyclo‐copolymerization of diallyl compounds and sulfur dioxide. III. Some diallylamine derivatives and sulfur dioxide
Authors: Harada Susumo , Arai Kunio 
Published: April 2003

AbstractCopolymers of sulfur dioxide with a series of diallyl compounds of the general formula A or B were prepared. – These copolymerizations were carried out in dimethylsulfoxide, methanol or acetone using radical initiators. The properties of the copolymers were investigated.
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Studies on the polymerization of 3.3‐bis‐(chloromethyl)‐oxacyclobutane with anhydrous aluminium chloride
Authors: Prakash Ajai , Patra S. K. , Krishnan M. , Thampy R. T. 
Published: April 2003

AbstractThe cationic polymerization of 3.3‐bis‐(chloromethyl)‐oxacyclobutane with anhydrous aluminium chloride was studied varying the temperature, initiator concentration, and reaction time in order to get a polymer of high molecular weight. The viscosity‐molecular weight relationship of this polymer was determined in cyclohexanone. A mechanism similar to that proposed for BF3 as initiator has been put forwarded in the light of experimental results obtained.
Condensation polymerization of N‐dithiocarbonyl alkoxycarbonyl‐amino acids. Part 4. Effect of optical isomer on condensation polymerization of N‐dithiocarbonyl ethoxycarbonyl‐alanine
Authors: Higashimura T. , Suzuoki K. , Kato H. , Okamura S. 
Published: April 2003

AbstractCondensation polymerization of N‐dithiocarbonyl ethoxycarbonyl‐L‐alanine (DTE‐L‐alanine) was carried out in various solvents and the effect of an optical isomer was examined. The rate of polymerization of the L‐ as well as the racemic monomer increased with increasing monomer concentration, polarity of solvent, and polymerization temperature. However, the molecular weight of the polymer was independent of the polarity of solvent. High polymers were obtained in 1.4‐dioxane, ethylene glycol diacetate, and n‐butyl acetate. Poly‐alanine having a high molecular weight (ηsp/c > 1.5) in dichloroacetic acid at 30°C was prepared under profitable conditions.The rate of polymerization of the L‐monomer and the molecular weight of the polymer obtained were much larger than that of the DL‐monomer. Addition of a small amount of DL‐monomer to the L‐monomer remarkably decreased both the rate of polymerization and the molecular weight of the polymer. In the polymerization of DTE‐L‐alanine without catalyst no racemization was observed. L‐Monomer was preferentially incorporated into the growing polymer produced from L‐monomer, i.e. asymmetric selection was observed as was the case with N‐carboxy‐alanine anhydride.
Zum mechanismus der thermischen Chlorwasserstoff‐abspaltung aus Polyvinylchlorid. 4. Mitt. Über die Länge der Polyensequenzen in partiell dehydrochloriertem Polyvinylchlorid
Authors: Thallmaier Von M. , Braun D. 
Published: April 2003

AbstractBeim theremischen Abbau von Polyvinylchlorid in Stickstoffatmosphäre entstehen durch Chlorwasserstoffabspaltung verschieden lange Polyensequenzen. Durch Analyse der Elektronenspektren kann die Sequenzlängenverteilung im Polymeren näherungsweise ermittelt wowie die abgespaltene Chlorwasserstoffmenge mit dem spektroskopisch bestimmten Polyengehalt verglichen werden.Die Polyensequenzlängenverteilung verschiebt sich nach kürzeren Sequenzen bei steigender Abbautemperatur sowie bie zunehmender Abbaudauer. Beim Abbau von Polyvinylchlorid in Folien ist im Vergleich zu abgebautem Polymerpulver eine merkliche Verschiebung zu längeren Sequenzen zu beobachten. Vinylisobutyläther als Comonomerbaustein bewirkt eine beträchtliche Verschiebung der Sequenzlängenverteilung nach kürzeren Polyensequenzen.Die spektroskopisch gefundene Polyenmenge stimmt mit der abgespaltenen Chlorwasserstoffmenge nur bie sehr niedrigen Abbauumsätzen überein, während mit zunehmendem Abbauumsatz ein immer größers Polyendefizit gefunden wird. Es muß daher auf den Verbranch von Polyensequenzen in Folgereaktionen geschlossen werden, an denen in erster Linie längere Polyensequenzen beteiligt sind. Die Versuche lassen ferner den Schluß zu, daß die Bildung längerer Polyensequenzen sehr rasch erfolgt, nachdem sich der Startschritt der Chlorwasserstoffabspaltung an einer labilen Stelle vollzogen hat. Mit zunehmender Abbaudauer ändert sich, abgesehen von den oben erwähnten Folgereaktionen, nur die Zahl, nicht aber die mittlere Länge der gebildeten Polyensequenzen wesentlich.
Vinylpolymerisation 175. Mitt.. Polymerisation von methylencyclobutanen
Authors: Takemoto Von Kiichi , Izubayashi Masuji 
Published: April 2003

AbstractDie Polymerisation sowie die Copolymerisation einer Reihe von Methylencyclobutanen wurden unter verschiedenen Bedingungen untersucht. Es ergab sich, daß Methylencyclobutane nicht homopolymerisieren, aber radikalisch mit einigen Vinylmonomeren ziemlich leicht copolymerisit werden können. Die Copolymerisationsparameter wurden ermittelt und die gewonnenen Werte zu den entsprechenden σ‐Werten in Beziehung gesetzt. Aus den Versuchsergebnissen wurde geschlossen, daß die Copolymerisation durch die exo‐Methylengruppe in Methylencyclobutanen ausgelöst wird.
Thermodynamics of addition polymerisation. Part 2. The heat capacity, entropy and enthalpy of isotatic poly (4‐methyl‐1‐pentene)
Authors: Melia T. P. , Tyson A. 
Published: April 2003

AbstractAn adiabatic vacuum calorimeter has been used to measure the heat capacity of isotactic poly(4‐methyl‐l‐pentene) from 80 to 310°K. An approximate extrapolation procedure has been used to estimate heat capacities below 80°K. Entropy and enthalpy values have been derived and are listed at ten degree intervals. The entropy of polymerisation of gaseous 4‐methyl‐l‐pentene at 1 atm pressure and 298.16°K to crystalline polymer, ΔS0, has been calculated as −51.7 ± 0.6 cal deg−1 mole−1. The glass transition temperature of the polymer was found to be 290°K. An approximation is made of the number of vibrating units per repeating unit at 298.16°K.
Zum copolymerisationsverhalten extrem sperriger α‐substituierter styrole
Authors: Lüssi Von H. 
Published: April 2003

AbstractDie Copolymerisation von Methacrylnitril mit Atropasäuremethylester, α‐Methoxystyrol und Diphenyläthylen wurde untersucht. Unter der Annahme, daß der vorletzte Grundbaustein die Reaktivität der wachsenden Polymerkette beeinflussen kann und daß nie mehr als zwei α‐substituierte Styrolgrundbausteine unmittelbar aufeinander folgen können, wurde eine allgemeingültige Gleichung für Copolymerisationen mit solchen extrem sperrigen Monomeren abgeleitet. Die drei in dieser Gleichung auftretenden Copolymerisationsparameter lassen sich durch die Q‐ und ϵ‐Werte der Monomeren und zusätzliche „sterische Parameter”︁ ausdrücken. Diese sterischen Parameter stellen anschauliche Kennzahlen für die auftretenden sterischen Hinderungen dar.
Kinetics of polymerization of benzyl acrylate in bulk
Authors: Patra S. K. , Mangaraj D. 
Published: April 2003

AbstractThe kinetics of polymerization of benzyl acrylate has been studied at 55, 60, and 65°C with azobisisobutyronitrile as initiator. The overall rate of polymerization, degree of polymerization, chain transfer due to monomer, and the ratio of propagation and termination constant were calculated. The overall activation energy, the difference between the activation energy of propagation and termination, and the frequency factor are also reported.
The thermal degradation of poly(methyl acrylate). III. The mechanism of volatile formation
Authors: Cameron G. G. , Kane D. R. 
Published: April 2003

AbstractThe effects of the free radical inhibitor 1.4‐diaminoanthraquinone on the evolution of carbon dioxide and methanol during the pyrolysis of poly(methyl acrylate) have been studied. The experiments lead to the conclusion that these volatiles are formed in competing side processes of the free radical chain reaction which causes back bone fragmentation. In the light of IR and UV spectroscopic measurentents possible reaction routes are considered.
Polyoxymethylene single crystals. III. Deformation behavior
Authors: Garber C. A. , Geil P. H. 
Published: April 2003

AbstractSolution grown single crystals of polyoxymethylene have been drawn uniaxially on Mylar to elongations of 90 %. Dark field electron micrographs suggest that these crystals are composed of a mosaic block structure with lateral dimensions of about 300 Å. Deformation occurs by a combination of mechanisms: plastic draw, “brittle” fracture (and formation of fibers), shear along distinct slip lines above 30 % draw, and wrinkling of the lamellae parallel to the draw direction. Striated structures observed along wrinkles and fibers may be an unexplainable artefact of the replicating process rather than a representation of true structure. However, the direct observation of coalescing fibers from an interface region (along crack edges), strongly suggests local melting and subsequent recrystallization.A method was also developed for studying the formation of these crystals under uniaxial compression. Wrinkles developed normal to the compression direction. When the sample is reextended to its original elongation, no trace of the compressive deformation can be found.
Gleichgewichtspolymerisation von laurinlactam
Authors: Elias Von Hans‐Georg , Fritz Andrea 
Published: April 2003

AbstractDie Gleichgewichtspolymerisation von Laurinlactam wurde zwischen 260 und 320°C mit organischen Säuren und Aminen als Initiatoren (Molverhältnis 0,01‐1,00) untersucht. Laurinlactam wurde durch Vorpolymerisation mit Natrium gereinigt. Die Reaktionsenthalpien und ‐entropien ergaben sich für die Polymerisation zu ΔH3 = −3,1 kcal/mol und ΔS3 = −3,75 Clausius/mol, für die Bildung der N‐Lauroylaminolaurinsäure aus Laurinsäure und Laurinlactam zu ΔH = −3,35 kcal/mol und ΔS = −4,5 Clausius/mol. Die obere thermodynamische Grenztemperatur der Polymerisation beträgt ca. 550°C. Bei 260 und 280°C gehorcht die Polymerisationsgeschwindigkeit bei der Polymerisation mit 1 Molproz. Laurinsäure einer Gleichung 1. Ordnung in bezug auf das Monomere mit einer Aktivierungsenergie von 28,5 kcal/mol und einer Aktionskonstante von 1,5·107 kg·mol−1·s−1. Bei 300 und 320°C ist die Anfangsgeschwindigkeit (Umsatz kleiner als ca. 50%) größer als erwartet, nicht aber die Polymerisationsgeschwindigkeit zwischen ca. 70 und 96% Umsatz.
Effects of radiation on styrene and α‐methyl styrene in aqueous solution. A study by pulse radiolysis
Authors: Schneider Christel , Swallow A. J. 
Published: April 2003

AbstractDiluted aqueous solutions of styrene and α‐methyl styrene were irradiated with 2 μsec pulses of 4 Mev electrons. The absorption spectra of transient species formed under irradiation were taken and kinetic studies on the decay of the absorptions were carried out. From the influence of various additives on the absorption spectra and from the kinetic data obtained we conclude that the absorption at 345 mμ for styrene and at 350 mμ for α‐methyl styrene is due to radicals formed by addition of OH• to the aromatic ring. The decay of the substituted hydroxycyclohexadienyl follows a second order kinetics with a rate constant of k ≈ 1091.·mole−1 sec−1.The long‐lived UV‐absorption with maxima at 305 mμ and 320 mμ we attribute to the polymerizing styrene radical with the structure of a substituted benzyl. Such radicals can be formed by electron attachment to the styrene followed by rapid protonation, and by addition of H• and OH• to the vinyl double bond.
Vinyl polymerization. 201. Polymerization of methyl methacrylate initiated by diphenyldiazomethane or by methyl 1‐methyl‐2‐(9′‐anthryl)‐cyclopropylcarboxylate
Authors: Nakaya Tadao , Ohashi Koichi , Tmoto Minoru 
Published: April 2003

AbstractA study on the polymerization of methyl methacrylate (MMA) initiated by methyl 1‐methyl‐2‐(9′‐anthryl)‐cyclopropylcarboxylate (ACP) and by diphenyldiazomethane (DDM) was made. It was found that ACP could polymerize MMA with almost the same rate as 9‐anthryldiazomethane. The rate of the polymerization initiated by DDM was found to be expressed by the equation:

Contrary to ACP, methyl 1‐methyl‐2.2‐diphenyl‐cyclopropylcarboxylate was found to be unable to initiate the polymerization of MMA at 80°C.
Determination of transfer to monomer in the vinyl chloride polymerization
Authors: Vidotto G. , Crosato‐Arnaldi A. , Talamini G. 
Published: April 2003

AbstractThe monomer (CM) and solvent (CS) transfer constants were determined by a study of the vinyl chloride polymerization in 1.2‐dichloroethane solution at 50°C.It was found the value of 1.1·10−3 for CM and the value of 4.5·10−4 for CS.The value of CM, here determined, is compared with those reported by other authors and obtained from polymerization experiments carried out in bulk under heterogeneous conditions.
Formation of poly(acrylhydroxamic acid)‐copper chelates
Authors: Hatano Masahiro , Nozawa Tsunenori , Yamamoto Takakazu , Kambara Shu 
Published: April 2003

AbstractIn order to clarify the mechanism of the catalytic reactions of poly(acrylhydroxamic acid)‐copper chelates on the decomposition reaction of hydrogen peroxide, the stability constants of these chelates were measured by using a modified BJERRUM'S method, and each fraction of chemical species was estimated on the basis of chelate chemical theory. The chelate formation proceeds through the following two steps:
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where HL means the ligand group, b1 and b2 mean the stability constants of CuL+ and CuL2, respectively. The value of b1 decreased with the increase of the ratio of the total concentration of cupric ion to the total concentration of the ligand, TCu/THL and with the increase of the molecular weight of the ligand polymer. The variation of the value of b2 was more significant than the variation of the value of b1. Therefore, it was confirmed that the increase of TCu/THL and the increase of the molecular weight of the ligand polymer resulted in the increase of the fraction of CuL+ species in the chelate‐polymer.
Effect of oxygen on acrylonitrile polymerization in water solutions
Authors: Ozols Gunars , Parts Adolf Gustav 
Published: April 2003

AbstractThe kinetics of polymerization of acrylonitrile initiated by iron(III) salts and hydrogen peroxide in water solution in an atmosphere of nitrogen containing varying amounts of oxygen was investigated at 26.0 ± 0.1°C. Increased amounts of oxygen decrease the rate of polymerization as well as the average molecular weight of the formed polymer. The rate of polymerization falls to zero with the increasing content of oxygen. There is, however, no difference in the rate of polymerization or the molecular weight of the formed polymer if the oxygen content of the nitrogen was decreased by careful deoxygenation from 13.5 ppm to less than 1 ppm.The length of the induction period is in agreement with the inhibition scheme as proposed by SCHULZ and HENRICI.
Aqueous solutions of polyvinylpyrrolidone
Authors: Goldfarb Jorge , Rodriguez Silvio 
Published: April 2003

AbstractThe properties of polyvinylpyrrolidone, in water and salt solutions, are examined by measuring the heat capacities, specific volumes and reduced viscosities. The heats of solution in water are of the order of −4 kcal per mole of monomer unit, they are decreased in the presence of salts. The results are discussed in terms of the mechanism of the stabilizing effect of hydrophylic colloids on hydrophobic ones. No evidence is found in terms of the existence of more “structural water” in the vicinities of the polymer molecules; this is taken to imply that stabilization is not effected through hydration multilayers of “ice‐like water”. A mechanism of stabilization based on the signs and magnitudes of the heats of solution of colloids in water is proposed.
Über die Polykondensation von N‐Oxymethylbrenzschleimsäureamid in Ameisensäure mit Bortrifluoridätherat
Authors: Mihajlov Von Marin , Peeva Nadezhda 
Published: April 2003

AbstractEs wurde festgestellt, daß die Polykondensation des N‐Oxymethylbrenzschleimsäureamids in Ameisensäure mit Bortrifluoridätherat als Katalysator schnell und glatt verläuft. Die Polykondensationsgeschwindigkeit nimmt beträchtlich mit Erhöhung der Säurekonzentration und der Temperatur zu. Polymere mit Erweichungspunkten über 260°C werden bei Temperaturen von 30 his 75°C in 83‐ bis 94‐proz. Ameisensäure innerhalb 1 bis 16 Stdn. erhalten. IR‐spektroskopisch wurde gezeigt, daß sie identisch sind mit den Polymeren, die von MOLDENHAUER durch Polykondensation des N‐Oxymethylbrenzschleimsäureamids im Gemisch von Schwefel‐ und Essigsäure unter 0°C oder aus 5‐Aminomethylbrenzschleimsäureäthylester hergestellt wurden.
Schmelztemperaturen in strikt regulären eutektischen Systemen aus linearen, taktisch aufgebauten Ketten
Authors: Kilian Von Hanns‐Georg 
Published: April 2003

AbstractAufbauend auf binären Systemen aus verschieden langen linearen Ketten werden die allgemeinen thermodynamischen Beziehungen für ideal athermische und strikt reguläre Mischungen molekulardisperser Homopolymerer hergeleitet. Für kristallisierende Systeme aus linearen, taktisch aufgebauten Ketten werden die Beziehungen für die „maximalen Schmelztemperaturen”︁ von Kettenkristallen (extended chain crystals) unter der Bedingung der eutektischen Fraktionierung berechnet. Diese Beziehungen werden für unterschiedliche Grenzfälle in leichter handbare Ausdrücke übergeführt.Messungen der Lösungstemperaturen von Kettenkristallen erlauben eine Bestimmung der Wechselwirkungsparameter in der flüssigen Mischung von Vielteilchensystemen. Bei unzureichenden Kenntnissen über die Kolloidstruktur der partiell kristallisierten Systeme bringt die Diskussion der „Liquiduskurven”︁ schon qualitative Information über die Eigenschaften der Mischsysteme.
Polymerisation of acrylonitrile by V5+/cyclohexanol‐redox system
Authors: Saccubai S. , Santappa M. 
Published: April 2003

AbstractThe effects of the concentrations of monomer, cyclohexanol, V5+, H2SO4, HSO, SO, Cl− and ionic strength at 40 to 60°C on the rate of V5+ disappearance and the rate of polymerisation of acrylonitrile were studied. From the experimental results, it was concluded that the organic free radicals formed during the decomposition of the V5+‐cyclohexanol complex, initiated polymerisation and that the polymer radicals were terminated by V5+ ion. An appropriate kinetic scheme was proposed and the various rate and energy parameters were evaluated.
Polymerization of acenaphthylene by iodine in a D. C. field
Authors: Cerrai P. , Andruzzi F. , Giusti P. 
Published: April 2003

AbstractThe polymerization of acenaphthylene initiated by iodine at 30°C in ethylene dichloride solution has been investigated in a D.C. Field. The experiments were carried out in special polymerization devices which allowed us to work with electric field strengths ranging from 0.33 to 1.5 Kv/cm and to follow at the same time the reaction kinetics by dilatometry. The general features of this polymerization are analogous to those of the polymerization of styrene initiated by iodine (S‐shaped time‐conversion curves, cocatalysis by hydrogen iodide).For the lower values (0.33 to 0.5 Kv/cm) of field strength no effect was found either on the rate of polymerization or on the molecular weight of the polymers obtained; for higher field strengths only a slight decrease in the rate of polymerization was observed.At the end of the polymerizations electrolysis of the hydrogen iodide formed by a termination process takes place.The results obtained seem to confirm that the polymerization of acenaphthylene by iodine, as that of styrene, is pseudocationic. The reaction mechanism is discussed in details.
Initiierte autoxydation von isotaktischem und ataktischem polybuten‐1 in lösung
Authors: Dulog Von Lothar , Weise Jürgen K. , Kern Werner 
Published: April 2003

AbstractIsotaktisches und ataktisches Polybuten‐1 (PB) wurden bei 70,6°C in brombenzolischer Lösung mit Azoisobuttersäuredinitril als Initiator mit Sauerstoff oxydiert. Die oxydierten Proben wurden isoliert, und der Gehalt an Hydroperoxidgruppen wurde mit Hilfe von Triphenylphosphin bestimint. Cyclische Peroxide, die bei oxydiertem isotaktischem Polybuten 1 möglich sind, können nicht mit Triphenylphosphin bestimmt werden, da sie zerfallen, bevor sie mit dem Phosphin reagieren. Dies wurde an niedermolekularen Modellverbindungen überprüft. Unter den Reaktionsbedingungen war die kinetische Kettenlänge so klein (1 bis 2), daß deutliche Unterschiede der Oxydation von isotaktischem und ataktischem Polybuten‐1 nicht beobachtet werden konnten.
Abbau von aus der schmelze kristallisiertem polyäthylen durch salpetersäure
Authors: Illers Von K.‐H. 
Published: April 2003

AbstractAn Proben aus linearem und verzweigtem Polyäthylen, die aus der Schmelze kristallisiert worden waren und Kristallinitäten zwischen α = 0,44 und α = 0,94 hatten, wurde ein Abbau der amorphen Bereiche durch konzentrierte Salpetersäure vorgenommen. Die durch HNO3 hervorgerufenen Veränderungen werden als Funktion der Säurekonzentration, der Reaktionstemperatur und der Reaktionszeit untersucht. Es werden Untersuchungen von Schmelzverhalten, Dichte, Gewichtsverlust, RÖNTGEN‐Kristallinität, Langperiode, Molekulargewicht und Molekulargewichts Verteilung sowie elektronenmikroskopische Beobachtungen in Abhängigkeit von den verschiedenen Struktur‐ und Reaktionsparametern besprochen.
Preparation and properties of ionic oxymethylene copolymers
Authors: Wissbrun Kurt F. 
Published: April 2003

AbstractOxymethylene copolymers containing pendant ionic groups have been prepared and some of their properties examined. The ionic copolymers differ from non‐ionic copolymers in that the crystalline order is poorer, which results in increased transparency and ductility and in decreased stiffness and strength. The reduction of crystalline order is dependent upon the rate of cooling from the melt. Melt viscosity and temperature dependence of melt viscosity of ionic copolymers are higher than those of non‐ionic copolymers. Introduction of ionic groups also increases water sensitivity. Ionic oxymethylene copolymers neutralized with divalent cations were examined briefly, and these show some unusual aging effects.