bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recycling of poly(ethylene terephthalate) (PET)
Authors: De Winter W. , Mariën A. , Heirbaut W. , Verheijen J. 
Published: March 2011

AbstractAfter a survey of the mostly utilized recycling methods for fibres and bottles, the possibilities of recovering films are discussed in more detail. This presentation describes primarily the melt‐recovery method, which is used by us and by other manufacturers. During this process the greatest difficulties arise from the presence of impurities and contaminations. The influence of these determining parameters on the recycling process and on the re‐usability of the recovered PET are elucidated, with special emphasis on the role of the oligomers.
Compatibilization and impact modification of mixed recycled plastics
Authors: Scobbo James J. 
Published: March 2011

AbstractIn order to solve the problems related to the reuse and recycling of polymer materials, approaches must be developed to address the incompatibility of most plastics. In many cases, the complete separation of dissimilar plastics may not be economically feasible or technologically possible, so commingled plastics recycling may be the only option. Our work has concentrated on upgrading the performance of a blend of two incompatible polymers. For this, we have used a model composition of two plastics commonly found in business machine housings. Our approach concentrates on compatibilization of the blend with a tailored copolymer, in addition to impact modification of the different phases. Improvements in mechanical performance of the blends are elucidated through the use of transmission electron microscopy.
Use of compatibilizers in polymer blends
Authors: Boutevin Bernard , Pietrasanta Yves , Robin Jean‐Jacques , Pabiot José , Leseur Benoit 
Published: March 2011

AbstractAmong the different ways of recycling plastic wastes, one of the techniques used consists in processing these products without any preliminary separation of the different plastic families. The bad performances of the obtained materials lead to the use of emulsifiers. The work described in this study concerns the synthesis of emulsifiers prepared by chemical modification of polymers with ozone. This reaction produces the formation of peroxides which are then used to initiate the grafting of comonomers. According to this method, we obtain graft copolymers usable as emulsifiers in the elaboration of polymer blends. Those graft copolymers prepared according to this method improve mechanical performances of polymer blends.
Block copolymer micelles in aqueous media
Authors: Munk P. , Ramireddy C. , Tian M. , Webber S. E. , Procházka K. , Tuzar Z. 
Published: March 2011

AbstractPolystyrene‐block‐poly(methacrylic acid) and poly(methacrylic acid)‐block‐polystyrene‐block‐poly(methacrylic acid) di‐ and triblock copolymers form micelles with polystyrene cores and poly(methacrylic acid) shells when dissolved in water/1, 4‐dioxane mixtures, rich in dioxane. These micelles can be transferred into water rich mixtures, into water, and into aqueous buffers by stepwise dialysis. Quasielastic light scattering and sedimentation velocity experiments show that in dioxane rich mixtures exists a dynamic micellization equilibrium, while in dioxane poor solutions and in aqueous buffers the equilibrium is frozen. The process of mixed micelles formation was observed in dioxane rich solutions.
New synthesis of polyaromatics through oxidative polymerization by using metal complexes with air
Authors: Tsuchida Eishun , Yamamoto Kimihisa , Nishide Hiroyuki 
Published: March 2011

AbstractThe oxidative polymerization provides a new synthetic route to polyaromatics. Poly(p‐phenylene sulfide) (PPS) is produced by oxidative polymerization of thiophenol with a vanadyl complex catalyst. The metal complexes act as an efficient catalyst of oxygen oxidative polymerization. The polymerization to yield PPS is discussed especially focusing on the catalytic mechanism of the complexes.
Hydroformylation of vinyl acetate to α‐acetoxypropanal catalyzed by a silica‐supported polyalumazane‐rhodium complex
Authors: Guan Shi‐You , Huang Mei‐Yu , Jiang Ying‐Yan 
Published: March 2011

AbstractHydroformylation of vinyl acetate was catalyzed by silica‐supported polyalumazane‐rhodium complex to give α‐acetoxypropanal in higher than 90% yield. The product was only α‐acetoxypropanal, isoaldehyde, and no β‐acetoxypropanal, normal aldehyde, or any other by‐product was observed. The catalyst was very stable in the hydroformylation, and it could be reused several times without any remarkable change of catalytic activity.
Activation and copolymerization of CO2 by macromolecule‐metal complexes
Authors: Chen Li‐Ban 
Published: March 2011

AbstractThe activation of CO2 and relevant comonomers can be promoted by using catalysts consisting of appropriate chelating polymers, suitable bimetallic combinations, and prepared by appropriate procedures. In this way, aliphatic polycarbonates, polycarbonate‐polyurethanes, saturated and unsaturated polycarbonate‐polyesters, as well as some other copolymers were synthesized in high yields.
Effects of chemical modification of supports on properties of tertiary amino resin dispersed palladium catalysts for the hydrogenation of methyl acrylate
Authors: Chen Chunfu , Sun Juntan , Li Hong , He Binglin 
Published: March 2011

AbstractTertiary amino resins (TAR) were chemically modified by quaternization with methyl iodide. By this route six partly quaternized tertiary amino resins (PQTAR) with different I/N mole ratio were synthesized. Four different reducing agents, i.e., NaH, LiAlH4, CH3OH‐NaOH and NaBH4, were tested for the preparation of palladium catalysts dispersed on TAR or PQTAR. The rate of hydrogenation of methyl acrylate and the amount of Pd leached from the catalysts during the hydrogenation reaction were found to be dependent not only on the type of reducing agent but also on the structure of polymer support. Both the rate of hydrogenation and the amount of Pd eluted closely relate to the I/N mole ratio of the polymer supports.
Novel synthesis of electroconducting polymers from simple monomers with transition metal complex catalysts
Authors: Toshima Naoki 
Published: March 2011

AbstractElectroconductive polyaromatics or polyarylenes have been successfully prepared by the oxidative polymerization of the corresponding simple monomers over the transition metal complex catalyst. For example, poly(1,4‐phenylene) was prepared from benzene by using oxygen as an oxidant and a copper(I) chloride‐aluminum chloride double complex as the catalyst. The same catalytic system was applied to the preparation of poly(2,5‐pyrrolylene) and poly(2,5‐thienylene) from pyrrole and 2,2′‐bithiophen, respectively. The electrochemical oxidative polymerization was also carried out for the preparation of the poly(1,4‐phenylene) and poly(1,4‐naphthylene) films in the presence of copper(I) chloride and aluminum chloride.
Kinetics of metal exchange reaction of Cu(II)‐poly(vinyl alcohol) complex with Ca(II)‐ethylenediamine‐N,N,N′,N′‐tetraacetic acid in aqueous solution
Authors: Suzuki Tuneo , Shirai Hirofusa , Hojo Nobumasa 
Published: March 2011

AbstractThe kinetics of the metal exchange reaction between the Cu(II)‐poly(vinyl alcohol) complex (Cu(II)‐PVA) and Ca(II)‐ethylenediamine‐N,N,N′,N′‐tetraacetic acid (Ca(II)‐EDTA) were studied by mixing both solutions in a spectrophotometer at pH 9.7–11.0, at μ = 0.10(KNO3) and at 25°C. The reaction is initiated by the formation of unstable Cu(II)‐H‐PVA by the attack of H+ to Cu(II)‐PVA, and while both ligand exchange and metal exchange steps occur, the latter may be rate‐determining. The kinetic expression of this reaction was determined as ‐d[Cu(II)‐PVA]/dt = k[Cu(II)‐PVA] [H+] [PVA]/[Ca(II)‐EDTA], where k = k1 + k′2[H+], k1 = 3.85 × 10−2 sec−1, k2 = k′2 · K−HCu(II)‐H‐PVA 9.59 × 105 1 mol−1 sec−1.
Functionalization of silica (II) ‐ oxidation of cyclohexanes in the presence of functionalized silica complexed by iron and copper
Authors: Kurusu Yasuhiko 
Published: March 2011

AbstractSilica gel was modified with (N,N‐dimethyl‐3‐ aminopropyl)trimethoxysilane and the functionalized silica catalysts thus prepared complexed with iron and copper to produce FS‐1{Fe},FS‐1{Cu}. 11.2% of methylcyclohexane was oxidized in the presence of oxygen with FS‐1(Fe) at 60°C. 2‐Hydroxymethylcyclohexane was obtained in 59% yield. The structural differences between FS‐1 (Fe)and FS‐1 {Cu} are discussed.
Evidence of polyphenols nitrosation by computer aided ESR spectroscopy
Authors: Marchettini Nadia , Pogni Rebecca , Basosi Riccardo 
Published: March 2011

AbstractPolyphenols play an important role as model systems in transition metal derivatives for the preparation of macromolecular systems. Among the metal ions ironnitrosyl coordination chemistry has received much attention in the past because of its important role in inorganic and biological processes. In the case of Fe(I)(NO)2 complexes with polyphenols ligands in solution, difficulties in the interpretation of the ESR spectra arise from complicated patterns due to simultaneous presence of different nitrogen nuclei directly bound to the metal ion or due to the presence of equilibria between species under slow exchange conditions. In order to overcome these difficulties the investigations reported here were carried out using computer simulation of ESR spectra combined with selective isotopic substitution of 14NO with 15NO. Resorcinol displays an unexpected nine lines ESR pattern at g=2.018 which can be explained only by considering more than two nitrogen atoms interacting with the unpaired electron delocalized over the metal complex.
Polymers with indane units by cationic polymerization
Authors: Nuyken Oskar , Maier Gerhard , Yang Dazhong , Leitner Michael B. 
Published: March 2011

AbstractIn spite of the difunctionality of the monomers, cationic polymerization of 1,3‐ and 1,4‐diisopropenylbenzene does not lead to branched or cross‐linked products. Instead, soluble polymers are obtained, containing the 1,1,3‐trimethylindane system as repetitive unit along the backbone. These polymers are interesting materials because of their high glass transition temperature (200°C‐250°C) and good thermal stability in air (2% weight loss at 450°C). Although the molar mass of the polyindanes seems to be limited due to a side reaction, it is possible to produce telechelic polyindanes. Substitution of an alkyl side chain onto the isopropenyl groups of 1,4‐diisopropenylbenzene leads to monomers which yield substituted polyindanes with glass transition temperatures as low as 26°C. Such polymers still exhibit good thermal stability: at 340°C a weight loss of only 2% occurs. 1,4‐Diisopropenylbenzene can even be anionically polymerized to linear polymers. In this case, the resulting polymer possesses isopropenyl phenyl side groups, which can be used as initiators for cationic polymerization of isobutene to obtain grafted copolymers.
Carbenium ions, onium ions, and covalent species in the cationic polymerization of alkenes
Authors: Matyjaszewski Krzysztof 
Published: March 2011

AbstractThe importance of exchange reactions between various types of active species present in the cationic polymerization of alkenes is addressed. Reactivities of carbocations, corresponding ion pairs, onium ions, and covalent species are discussed for model systems and in real polymerization. The influence of various parameters on the equilibria between carbenium ions, onium ions, and covalent species is described. Rate constants of the isomerization of active sites are estimated and correlated with polydispersities. General ways to improve control of cationic polymerization of alkenes are discussed.
The role of N‐acyllactam in polymerizations of lactams
Authors: Puffr Rudolf , Stehlíček Jaroslav , Šebenda Jan 
Published: March 2011

AbstractIn anionic, cationic and non‐catalyzed polymerizations of lactams, highlyreactive N‐acyllactams are formed in slow initiation steps. These imides enter then the propagation and termination reactions. All types of lactam polymerizations can be accelerated by an intentional addition of N‐acyllactams or other acylating agents, including the polymerizations where N‐acyllactams are not spontaneously formed. The rate data of the initiation, propagation, transacylation and side reactions and of N‐acyllactam hydrolyses, alcoholyses, acidolyses and aminolyses are surveyed.
Determination of highly resolved particle size distributions in the submicron range by ultracentrifugation
Authors: Mächtle Walter 
Published: March 2011

AbstractTwo methods, the H2O/D2O‐analysis and the Coupling‐Particle‐Size‐Distribution(PSD)‐Technique, to determine the distribution of the density and the sire of sub‐micron particles by means of an ultracentrifuge, are outlined. Either of them base only on Stokes' equations and on Mie's light scattering theory. Because of the possibility to measure seven samples simultaneously and to raise the rotor speed exponentially from 0 to 40,000 rpm, particle diameters from 10 to 3000 nm can be measured at high resolution. The H2O/D2O‐analysis supplies a density distribution and also a size distribution, provided the sample is chemically homogeneous. The Coupling‐PSD‐Technique allows to determine highly resolved size distributions of extremely broad distributed dispersions by only one single run. Several examples applying either method are given.
Size exclusion chromatography of polyelectrolytes with aqueous elution solvents
Authors: Bruessau Rudolf J. 
Published: March 2011

AbstractSize exclusion chromatography (=SEC) is a widly used method for determining the molecular weight distribution of polymer samples. But using aqueous elution solvents, this method is even today combined with numerous problems, mostly caused by the polyelectrolyte structure of water soluble polymers. Therefore we will firstly give a survey of this special features and discuss preventive measures. From this view then some working rules will be derived with special regard to the devices, columns and calibration standards available today. Finally we will give some remarks about the specific experimental conditions for ultrahigh molecular weight samples.
Characterization of copolymers by high performance liquid chromatography
Authors: Glöckner Gottfried 
Published: March 2011

AbstractSize exclusion chromatography (SEC) is capable of evaluating the molecular weight distribution (MWD) of a sample. Information about the chemical composition distribution can be gained by gradient high performance liquid chromatography (gradient HPLC), where a poor starting eluent is, in the course of the separation, substituted by another one of increasing elution strength. Both normal‐phase and reversed‐phase systems can be employed. The combination of SEC and gradient HPLC enables chromatographic cross‐fractionation to be performed efficiently.
Determination of persistence lengths and mark‐houwink constants of aromatic polyesters from GPC‐differential viscometric coupling
Authors: Schmitt R. , Bolle B. , Greiner A. , Heitz W. 
Published: March 2011

AbstractThe introduction of lateral substituents and/or twisted biphenylylene units increase the solubility of aromatic para‐linked polyesters. Two polyesters of this type of structure were characterized by gel permeation chromatography (GPC), low angle laser light scattering (LALLS) and viscometry. From the molecular weights and limiting viscosity numbers obtained by universal calibration and LALLS/viscometry the Mark‐Houwink constants and persistence lengths were determined. The values of these parameters indicated that the polyesters can be described as wormlike chains in dilute solution.
Molar mass determination of macromolecular compounds by matrix‐assisted laser desorption ionization mass spectrometry
Authors: Karas Michael , Bahr Ute , Deppe Andreas , Stahl Bernd , Gießmann Ulrich 
Published: March 2011

AbstractMatrix‐assisted laser desorption ionization is a recently developed new ionization technique which enables macromolecular compounds to be investigated by mass spectrometry. The general features of the technique are described, they have so far mainly been worked out for biopolymers such as proteins. Fast and precise molecular weight determination is possible up to 400,000 Dalton. First examples described in this paper indicate that the technique also holds great promise for the investigation of synthetic polymers.
Molar mass determination by end group analysis ‐ amino group determination in aliphatic and partially aromatic polyamides with 1‐fluoro‐2,4‐dinitrobenzene in benzyl alcohol
Authors: Rossbach Volker , Leumer Gerhard , Böhme Sigrid 
Published: March 2011

AbstractEnd group analysis is the most important absolute method of obtaining number‐average molar mass values for polymers of the step‐growth polymerization type. A great number of methods are available which primarily differ in the detection of the end group concerned. Special chemical methods based on the formation of covalent derivatives of the end groups (e.g. introduction of UV/VIS chromophores) are important if there is a need to demonstrate, with the aid of gel permeation chromatography, that damage to the polymer (e.g. onset of cross‐linking) has occurred.In the case of fibre‐forming polycondensation products, the applicability of end group analysis is often restricted by the lack of suitable reagents and solvents. This is also true of the determination of amino end groups in polyamides by means of 1‐fluoro‐2,4‐dinitrobenzene, as is already contained in the German Standards specification (DIN 54 274) ‐ albeit only for polyamide 6 and 6,6. This contribution describes a modified version of the 1‐fluoro‐2,4‐dinitrobenzene method. The analytical principle and practical procedure correspond to those of DIN 54 274, but the solvent used for the reaction with the reagent is benzyl alcohol, and that for the photometric evaluation is 1,1,1,3,3,3‐hexafluoro‐2‐propanol. The scope of the method is thus increased. Examples of applications for this method are commercial products based on aliphatic polyamides (6; 11; 12; 6,6; 6, 12), partially aromatic polyamides (2,4,4‐trimethylhexamethylenediamine, terephthalic acid; copolyamides with bis‐(4‐aminocyclohexyl)propane(2), isophthalic acid, ω‐aminododecanoic acid) and multicomponent systems with the abovementioned polyamides (bicomponent fibres, blends). It is shown that large differences may arise between the value determined by titration and the actual amino end group content. In addition, the presence of secondary amino groups can be demonstrated in polyamides of the Trogamid T type.
Neutron reflection studies at polymer‐polymer interfaces
Authors: Fernandez M. L. , Higgins J. S. , Penfold J. 
Published: March 2011

AbstractThe application of the neutron reflectivity technique to the study of polymer‐polymer interfaces is described and several examples given. The high resolution of the technique allows the details of the interface during early stages of mixing to be resolved for a partially miscible blend. The results are discussed in terms of recent theories.
Thin film order of symmetric diblock copolymers
Authors: Russell Thomas P. , Menelle Alain , Anastasiadis Spiros H. , Satija Sushil K. , Majkrzak Charles F. 
Published: March 2011

AbstractThe ordering in thin films of symmetric diblock copolymers of polystyrene and poly(methyl methacrylate) has been investigated by neutron reflectivity as a function of film thickness and temperature. The order‐disorder transition in the thin films was found to lose its first order character in that the transition occurs in a continuous manner without the correlation length becoming infinite. In addition, a transition from a partially to fully ordered state was observed which was fully reversible. This transition depended in a power law manner on the film thickness and extrapolates to the bulk order‐disorder transition temperature for thick films.
Surface modification of polymers by photoinitiated graft polymerization
Authors: Rånby Bengt 
Published: March 2011

AbstractTwo methods for modification of polymer surfaces by photoinitiated grafting have been developed and applied to films and fibers of synthetic polymers, e.g. polyethylene and polypropylene with acrylic monomers. In the batch process the substrate is enclosed in a cell containing initiator and monomer vapor. UV light through a quartz window initiates the grafting reaction by exciting the initiator (e.g. benzophenone). The grafting reaction is slow (1 to 3 min) due to the inefficient transfer of initiator and monomer through vapor phase. In the continuous process the substrate is presoaked in a solution of initiator and monomer and then drawn into a reactor “on line” where the substrate is irradiated by UV light through a quartz window. The grafting takes place in the very thin surface layer of solution on the substrate. The grafting efficiency is high (70–80% of the polymer formed is grafted) and the process is rapid (5–15 s due to the efficient transfer of initiator and monomer through the liquid phase. The continuous surface grafting process is promising for industrial applications.
Kinetic behavior of propagating radical in bulk polymerization of styrene
Authors: Shen Jia‐Cong , Wang Guo‐Bin , Zheng Ying‐Guang , Yang Mei‐Lin 
Published: March 2011

AbstractHigh resolution ESR spectra of polystyrene radical at various conversion in the bulk polymerization have been determined. The propagation and termination rate coefficients during the whole process of polymerization were evaluated from the conversion and the propagating radical concentration determined by ESR. It was found that the propagating radical has two stable conformations. The reduction of the radical activity with the conversion is partly resulting from the wrapping effect which is due to the far slower segment relaxation and the very rapid propagation.
Some newer concepts on ethylene/α‐olefin copolymerization on heterogeneous Ziegler‐Natta catalysts
Authors: Wang Jian‐Guo , Zhang Wen‐Bin , Huang Bao‐Tong 
Published: March 2011

AbstractUnsteady diffusion kinetics, recently advanced by this laboratory, is applied to the examination of some polymerization and molecular chain structure problems. Hitherto deemed “anomalous” phenomena, such as the faster rate of copolymerization of ethylene/α‐olefin than the homopolymerization of ethylene and the enrichment in the incorporation of a higher α‐olefin in its copolymerization with ethylene by a lower α‐olefin, are reasonably explained by unsteady diffusion of monomers. Molecular chain structure of copolymers, such as compositional heterogeneity and its dependence on comonomer incorporation originates from the difference in diffusion coefficients of the monomers. A copolymer composition equation taking into consideration the unsteady diffusion was developed. In cases where simulated curves were compared with experimental curves, good agreements were found.
Ring‐opening metathesis polymerization of exo‐dicyclopentadiene: Reversible crosslinking by a metathesis catalyst
Authors: Fisher Richard A. , Grubbs Robert H. 
Published: March 2011

Abstractexo‐Dicyclopentadiene has been polymerized by several well characterized, single‐component metathesis catalysts to provide soluble, linear, poly exo‐dicyclopentadiene. Under the best circumstances the polymerizations proceed in a living manner. The crosslinking of polymer chains which can occur under high monomer concentration has been investigated and determined to result from the secondary metathesis of the cyclopentene substituent.