bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polyurethane elastomers based on polymer polyols
Authors: Mitzner Elke , Goering Harald , Becker R. 
Published: April 2003

AbstractLinear polyurethane elastomers based on polymer polyols were synthesized by the one‐shot technique. The hard‐segment content of the polyurethanes, the chain length of the base polyether, and the styrene/acrylonitrile content and/or the ratio of the polymer polyols were varied. The mechanical properties and the results of the dynamic mechanical analysis are discussed and compared with those of equivalent crosslinked polyurethane elastomers.
Surface modification of polypropylene by chromylchloride
Authors: Novák Igor , Pollák Vladimír 
Published: April 2003

AbstractThe changes of the adhesion properties of isotactic polypropylene (iPP) modified by chromylchloride (CrCl) have been studied. The free surface energy (FSE) of the iPP increases with the time of the modification and reaches a constant value after the time which strongly depends on the temperature of the modification. A similar trend has been observed for the dependences of the FSE vs. concentration of carbonyl groups. The molecular weight of the modified iPP decreases with the temperature of modification. The decrease of the FSE with time is negligible. It was found that after modification of iPP with CrCl the increase of mechanical work of adhesion was higher by 36% than that with chromosulfuric acid.
Herstellung und eigenschaften von cellulosebenzoat
Authors: Braun D. , Bahlig K. H. 
Published: April 2003

AbstractCellulosebenzoate mit Substitutionsgraden von 2,8–2,9 wurden in einer einstufigen Reaktion durch Umsetzung von Cellulose mit Benzoylchlorid in Gegenwart von Pyridin als Base hergestellt. Die Molekulargewichte der Cellulosebenzoate lagen zwischen 140000 und 100000; die mittels DSC gemessene Glastemperatur Tg betrug 155°C, die Schmelztemperatur TS 274°C. Die Ester sind gut löslich in organischen Lösungsmitteln wie N,N‐Dimethylformamid, Chloroform und Dichlormethan und besitzen ferner eine gute thermische Beständigkeit bis ca. 250°C. Filme und nacharbeitbare Preßlinge aus Cellulosebenzoat lassen sich aufgrund der hohen Sprödigkeit nur durch Zumischen eines Weichmachers (Diethylphthalat) herstellen. Dabei bleibt das hart‐spröde Verhalten, wie Zug‐Dehnungs‐Versuche und Schlagzähigkeitsmessungen zeigten, bis zu einem Weichmacheranteil von 20 Gew.‐% bestehen.
Copolymers of methyl methacrylate and N‐cyclohexyl maleimide: Preparation and properties
Authors: Usha V. , Varma I. K. , Bhayani G. G. , Sinha T. J. M. 
Published: April 2003

AbstractCopolymers of methyl methacrylate (MMA) and N‐cyclohexyl maleimide (NCM) with low intrinsic viscosity were obtained when free‐radical copolymerization was carried out in benzene solution. Copolymers containing 0–30 wt.‐% NCM were also prepared by bulk polymerization as cast acrylic sheets and had much higher intrinsic viscosity. An increase in NCM content in copolymers resulted in an increase in thermal stability and modulues and a decrease in tensile strength, strain at break, impact strength of unnotched specimen and light transmittance. The increase in haze was marginal up to 15 wt.‐% of NCM. A decrease in water absorption was observed with an increase in NCM content.
An example of free radical graft polymerization where the mechanism from‐to applies
Authors: Casinos Ismael 
Published: April 2003

AbstractFree‐radical grafting on natural and synthetic polymers is a method widely used to modify these polymers chemically. A number of these chemical systems show an unexpected behaviour of the polymerization rate when the monomer concentration is sufficiently high: it decreases and sometimes it increases afterwards. Here, the effect of varying the monomer concentration on the graft yield when grafting methyl acrylate, vinyl acetate and a mixture of both monomers onto cellulose initiated by ceric ions is discussed, considering a three‐component mechanism of grafting (mechanisms from, onto and from‐to). It is suggested that the unexpected behaviour indicated above is accounted for by the presence of the grafting mechanism from‐to. Some knowledge about the copolymer structure can be reached by using this mechanistic approach.
Investigations on thermal properties of triazinestilbene optical brightening agents and their copolymers with styrene and acrylonitrile
Authors: Konstantinova T. , Grabchev I. , Konstantinov H. 
Published: April 2003

AbstractThe effect of four optical brightening agents, chemically incorporated into polystyrene and polyacrylonitrile, on the molecular weight and polydispersity of the polymers has been investigated. Thermal analysis of the 1,3,5‐triazine‐stilbene brighteners has been carried out and the effect on the thermal and thermooxidative destruction of their copolymers with styrene and acrylonitrile has been studied.
Preparation of polymeric diketones and their conversion to polymeric hydroxy acids in crosslinked polymeric matrices
Authors: Kuriakose Sunny , Rajasekharan Pillai V. N. 
Published: April 2003

AbstractSupports of polystyrene (PS) crosslinked with divinylbenzene (DVB) with varying crosslink densities were prepared and furnished with 1,2‐diketo functions through a series of polymer‐analogous reactions. Crossed benzoin condensation between polymeric aldehyde (formylated polystyrene) and substituted low‐molecular aldehydes gives a set of mixed α‐hydroxy ketones. These polymeric benzoin analogues were converted to α‐diketones by oxidation. The polymeric systems containing α‐diketo functions were subjected to rearrangement under basic conditions into hydroxy acids. The products were characterized by IR and 13C CP‐MAS NMR spectroscopy and by chemical methods. The rearrangement was observed to be facile in these highly crosslinked networks in spite of the environmental constraints imposed by the rigid and high‐molecular‐weight polymeric backbone.
Damping materials based on simultaneously grafted interpenetrating polymer networks from castor oil
Authors: Xie Hong‐Quan , Wang Gui‐Gui , Guo Jun‐She 
Published: April 2003

AbstractFour kinds of grafted interpenetrating polymer networks (IPNs) were synthesized from castor oil (CAS), toluene diisocyanate (TDI), monohydroxy terminated acrylic (or methacrylic) prepolymer and/or acrylic (or methacrylic) monomer in the presence of dibutyltin dilaurate and redox initiators. Formation rates of soluble and insoluble polymers were investigated in the course of synthesis of the grafted IPN from NCO‐terminated CAS precursor, butyl acrylate prepolymer, CAS and ethyl methacrylate monomer. Mechanical properties of the IPNs were studied as well. Studies of the dynamic mechanical properties of the various grafted IPNs showed that certain IPNs (from CAS/TDI/butyl methacrylate and butyl acrylate prepolymers, CAS/TDI/butyl acrylate monomer/ethyl methacrylate prepolymer, CAS/TDI/ethyl methacrylate monomer/butyl methacrylate prepolymer) exhibit high damping behavior over wide temperature ranges for tan δ ≥ 0.3 (ΔThd from 88°C up to 133°C) and maximum tan δ values higher than 1.1.
Electroinitiated polymerization of some new monomers with schiff's base structure and pyrrole moieties
Authors: Simionescu C. I. , Grovu‐Ivanoiu M. , Grigoras M. , Cianga I. 
Published: April 2003

AbstractPyrrole‐2‐aldehyd azine, N,N'‐bis(2‐pyrrolylmethylene)‐1,4‐diaminobenzene and N,N'‐bis(2‐pyrrolylmethylene)‐4,4′‐diaminobiphenyl were polymerized by electro‐chemical precipitating oxidation reaction in 1,2‐dichloroethane and acetonitrile, respectively, in the presence of electrolytes like tetrabutylammonium perchlorate, tetrabutylammonium tetrafluoroborate and sodium p‐toluene sulfonate. The doped resulted polymers were characterized by elemental analysis, IR spectroscopy and thermal analysis.
Polymerization of ethylene and 1‐hexene with Cp2ZrCl2‐methylaluminoxane catalyst in a heat balance reaction calorimeter
Authors: Koivumäki Jari , Lahti Mikko , Seppälä Jukka V. 
Published: April 2003

AbstractA heat balance reaction calorimeter was used to obtain information about the typical process parameters such as viscosity and heat transfer properties in polymerizations carried out with Cp2ZrCl2‐methylaluminoxane catalyst. The rate enhancement upon comonomer addition was of particular interest. The viscosity of the reaction mixture was found to increase dramatically during the homopolymerization of ethylene but to increase only a little in the copolymerization of ethylene and 1‐hexene even though the final slurry concentration was six times as high as in the homopolymerization. The explanation offered for this unexpected result is the much smaller particle size in the copolymerization. In part, this might also explain the higher activity in the copolymerization.
Polyelectrolyte complexes of binary and ternary systems containing poly(sodium styrene sulfonate), poly(sodium styrene sulfonate), poly(sodium phosphate), and poly(N‐ethyl‐4‐vinylpyridinium bromide)
Authors: Trinh Cam Khon , Schnabel Wolfram 
Published: April 2003

AbstractPolyelectrolyte complexes (PECs) were prepared by precipitation upon mixing solutions of poly(N‐ethyl‐4‐vinylpyridinium bromide), PVPE, and poly(sodium styrene sulfonate), PSS, and/or poly(sodium phosphate), PP. The chemical composition of the PECs was determined as a function of the initial polyelectrolyte (PE) concentration ratio. With binary systems water‐insoluble PECs being 1:1 stoichiometrically composed were formed in the case of the system PP/PVPE at ϕPP = [PP]0/ = 0.8 to 4.0. In the case of the system PSS / PVPE, water‐insoluble PECs were formed at all ϕPSS = [PVPE]0 ratios. Up to ϕPSS = 1.0 the PEC composition was stoichiometric. At ϕPSS = 1.0–8.0 non‐stoichiometric PECs containing surplus PSS were formed. With ternary systems, water‐insoluble PECs were formed regardless of the initial PE concentration ratio. The PEC composition was stoichiometric up to ϕPSS = 1.0, but preferntial binding of PSS became increasingly important with rising ϕPSS. At ϕPSS 2.5, PP was totally replaced by PSS and non‐stoichiometric PECs containing surplus PSS were formed.
Styrol‐maleinsäure‐copolymere als korrosionsinhibitoren für aluminiumpigmente in wäußrigen medien
Authors: Müller Bodo , Mebarek Denise 
Published: April 2003

AbstractStyrol‐Maleinsäure‐Copolymere (Molmassen 1600‐2500 g mol‐1) inhibieren die Korrosion von Aluminiumpigmenten in Wasser/Butylglykol‐Gemischen bei pH 10 sehr effektiv (Schutzwerte bis 99%), wie durch gasvolumetrische Bestimmung des Korrosionsproduktes Wasserstoff nachgewiesen wurde. Es existiert ein Zusammenhang zwischen der Zusammensetzung der Copolymeren und ihrer Wirkung: Je geringer die Säurezahl des Styrol‐Maleinsäure‐Copolymeren ist, desto besser ist ihre korrosionsinhibierende Wirkung. Dieser Zusammenhang gilt allerdings nur innerhalb der hier untersuchten Gruppe von Styrol‐Maleinsäure‐Copolymeren. Ein zum Vergleich geprüftes Styrol‐Acrylsäure‐Copolymeres mit vergleichbarer Molmasse und Säurezahl erwies sich dagegen als deutlich deutlich schlechterer Korrosionsinhibitor.Aus Messungen der Konzentration von gelöstem Aluminium(III) mit Hilfe der Atomabsorptionsspektroskopie wurde auf die Bildung von (zumindest teilweise) löslichen Polymer‐Aluminium(III)‐Komplexen geschlossen.
Triazine‐based polymers, 2. Synthesis and characterization of polyethers
Authors: Braun D. , Most D. , Ziser T. 
Published: April 2003

AbstractTriazine‐based polyethers can be synthesized by phase transfer catalysed interfacial polycondensation at room temperature and reaction times of about 1 to 3 h. In this way, more than 20 polyethers were synthesized and solubilities, glass transition temperatures, thermogravimetric data, elongations at break, tensil strengths, elasticity moduli and impact strengths were determined. In addition, the degree of crystallinity was investigated for the polymer obtained from of 2,4‐dichloro‐6‐diethylamino‐s‐triazine and bisphenol A by wide angle X‐ray diffraction. The increment of the 1,3,5‐triazinetriyl ring was determined, which made it possible to calculate the glass transition temperatures of some polyethers according to van Krevelen.
Ionic polymers, I. Poly(vinyltoluene‐co‐divinylbenzene) networks and some chemical transformations
Authors: Luca Cornelia , Neagu Violeta , Poinescu Ignat , Simionescu Bogdan C. 
Published: April 2003

AbstractDifferent poly(vinyltoluene‐co‐divinylbenzene) networks, precursors for ionic polymers, were synthesized and characterized. The influence of diluent nature and divinylbenzene (DVB) content on copolymer properties is discussed. Both expanded and porous structures can be easily prepared. Expanded structures are formed when good or poor diluents are used for low DVB content, i. e. less than 20 wt.‐% with respect to vinyltoluene. Higher DVB content yields macroporous structures. Also, the possibility of obtaining strong base anion exchangers from poly(vinyltoluene‐co‐divinylbenzene) networks as precursors was investigated. Therefore, the above‐mentioned networks were transformed by the chlorination reaction with NaOCI/phase transfer catalyst system, followed by the amination reaction with trimethylamine or N,N‐dimethyl‐2‐hydroxyethylamine.
Effect of mixer rotor speed on interfacial crosslinking of epoxidized natural rubber and poly(acrylic acid)
Authors: Mallick A. , De S. K. , Pfeiffer D. G. 
Published: April 2003

AbstractIt is evident from Monsanto rheometric studies, dynamic mechanical analysis (DMA), physical property measurements and scanning electron microscopy (SEM) that the mixer rotor speed has an effect on the crosslinking of poly(acrylic acid) (PAA)/epoxidized natural rubber (ENR) blends. These studies reveal that mixing at high rotor speed deteriorates the crosslinking process between PAA and ENR. Infrared (IR) spectroscopic studies suggest that during mixing at high rotor speed ENR elastomer chains suffer breakdown through mechanochemical reactions.
Microemulsion polymerization of butyl acrylate. 1. Effect of initiator type and concentration
Authors: Potisk Pavol , Capek Ignác 
Published: April 2003

AbstractThe oil‐in‐water‐type (o/w) microemulsion polymerizations of butyl acrylate initiated by a water‐ (ammonium peroxodisulfate, AP)—and oil‐soluble (dibenzoyl peroxide, DBP, and 2,2′‐azoisobutyronitrile, AIBN) radical initiators were investigated. Polymerizations with AP were faster than those with DBP or AIBN. The rate of polymerization shows initiation and termination intervals, but no constant interval. The rate of polymerization is found to be proportional to the 0.46th, 0.53rd and 0.24th power of the AP, AIBN and DBP concentration. The rate per particle is found to be proportional to the 0.29th, 0.32nd and 0.37th power of the AP, AIBN and DBP concentration. The number of radicals per particle was found to increase with increasing the initiator concentration. The most pronounced increase in the number of particles with increasing the initiator concentration was observed with AP, much less with AIBN and the slight decrease with DBP. The molecular weights of polymers were found to vary only slightly with increasing the initiator concentration. The formation of radicals proceeds in the aqueous phase (AP and a water‐soluble fraction of AIBN or DBP) and the monomer‐swollen micelles (AIBN or DBP) as well. The polymer particles grow by recruiting monomer and emulsifier from the free monomer‐swollen emulsifier micelles.
A biomaterial‐based carbon fiber
Authors: Zhang Mingqiu , Zhu Shiping , Zeng Hanmin , Lu Yun 
Published: April 2003

AbstractAn attempt to convert natural sisal fiber into low cost carbon fibrous materials was made. The pretreatment, pyrolysis and carbonization processes of raw sisal fiber as well as structure and properties of the resultant product were investigated. It was found that the sisal‐based carbon fiber with moderate mechanical performance can be manufactured under the conditions applied. In addition, the application of the obtained sisal‐based carbon fiber serving as functional material is presented.
Zerstörungsfreie Prüfung von Polymeren mittels photothermischer Meßmethoden. 3. Einfluß von mikroskopischen und makroskopischen Oberflächenrauheiten auf das photoakustische Signal,
Authors: Schloßer Uwe , Bahners Thomas , Schollmeyer Eckhard 
Published: April 2003

AbstractFür die textile Analytik stellt sich die photoakustische Spektroskopie durch ihre Eigenschaften als vorteilhaftes Verfahren zur Farbstoff‐ und Farbstoffkonzentrationsbestimmung dar. Eingeschränkt wird dieses Verfahren besonders durch die Oberflächengestalt der Proben. In dieser Arbeit wird der Einfluß von mikroskopischen und makroskopischen Oberflächenstrukturen auf das photoakustische Signal untersucht. Der Beitrag einzelner unterschiedlicher Probenschichten zum photoakustischen Signal wird über die Modulationsfrequenz der einfallenden Strahlung reguliert. Dabei wird festgestellt, daß nur die mikroskopische Rauheit einen signifikanten qualitativen Einfluß auf das photoakustische Signal zeigt. Die makroskopische Oberflächenstruktur bestimmt die Intensität des Signals durch eine „effektive Oberfläche”︁, zeigt aber keinen Einfluß auf die Frequenzabhängigkeit des photoakustischen Signals.
Alkane als initiatoren zur radikalischen polymerization
Authors: Braun Dietrich 
Published: April 2003

AbstractAlkanes with highly substituted carbon‐carbon bonds can be cleaved in free radicals by homolytic dissociation under the influence of thermal energy. The energy of dissociation is mainly determined by the type and size of the respective substituents. For tetraarylbutane dinitriles the temperatures of decomposition are in the range of other technically used initiators. But nevertheless, these compounds are up to now rather seldom used to initiate free radical polymerizations. This is connected with the special mechanism of initiation: the formed highly substituted alkyl radicals are relatively stable and show only a rather low reactivity against the usually used monomers. Therefore, in the beginning of the polymerization the radical concentration is rather high which leads not only to addition to monomers but also to a pronounced primary radical termination. In some cases this termination process is reversible which results in an unusual polymerization kinetics. Depending on the type of monomer and the degree of reversibility of the primary radical termination, either a period of “dead‐end” polymerization follows or the cleavage of the oligomers at the chain end results in a re‐initiation process with a “normal” polymerization with increased rate. The reaction mechanism, kinetics and some possible applications of such initiating alkanes are reported.
Copolymers with periodic comonomer sequences
Authors: Eisenbach Claus D. , Lieberth Wolfgang , Sperlich Bernd 
Published: April 2003

AbstractThe free radical copolymerization and multipolymerization of olefins with acrylic monomers in the presence of acids has been studied. It was found that Brönsted acids are as suitable complexing agents for the acrylic comonomer as the up to now exclusively used Lewis acids. The effectiveness of the Brönsted acids, e.g. carboxylic acids, for obtaining alternating copolymers increased with the pKs value, and trifluoroacetic acid turned out to be the acid of choice. The variation of the Lewis acid‐type complexation agents was extended by the zinc chloride diethylether complex which is advantageous over ZnCl2 or other Lewis acids because of its good solubility and recycling practicability, which is also a feature of the Brönsted acids. The versatility of the new complexing agent systems was demonstrated in a series of co‐ and multipolymerizations, and ethyl cyanoacrylate was employed for the first time as electron acceptor comonomer. The properties of the copolymers with periodic comonomer sequences varied systematically with their composition, e.g. the glass transition temperature and the degree of crystallinity.
Propylene polymerization with metallocene catalysts in industrial processes
Authors: Langhauser F. , Kerth J. , Kersting M. , Kölle P. , Lilge D. , Müller P. 
Published: April 2003

AbstractProduct demands for polypropylene polymers cover a wide range of properties. Metallocene catalysts open up the way to influence the molecular properties of polypropylene by altering the ligand system of the metallocene complexes. This leads to new products with application properties which are not available with conventional catalysts. Concepts are presented to adapt metallocenes to modern, industrial polymerization processes. Some examples illustrate the particular advantages of this new generation of catalysts.
Funktionalisierte Kammpolymere: Synthesen, modifizierung und anwendungen
Authors: Ritter Helmut 
Published: April 2003

AbstractThe present paper deals with the synthesis and modification of functionalized polymers characterized by a special molecular architecture. The reactivity of a functionalized polymer with comb‐like structure can be controlled in a significant manner by the crystalline order of the side chains. In contrast, photocrosslinking of comblike polymers containing cinnamic components in the side chains influences the crystallization process. The air drying process of a modified polybutadiene system with comb‐like structure was shown to depend sensitively on the side chain order. Enzymatic synthesis of new monomers and polymers is briefly reviewed. The complexing capability of cyclodextrines were used to synthesize polyrotaxanes. Finally, the synthesis of a chiral polymerizable dendrimer containing eight estergroups in the monomer unit is presented.
Hochmolekulare lösliche polymere mit coronandenstruktur‐synthese und eigenschaften
Authors: Klemm Elisabeth , Kottner Nils , Alhakimi Gamil 
Published: April 2003

AbstractNew polymers with an alternating sequence of aliphatic chains and coronands were synthesized via Diels‐Alder addition polymerization of bis(2‐pyrones) with bismaleimides. The chemical structures of these polymers 6 are supported by NMR spectra, model reactions and crystal X‐ray structure analysis. The tetrafunctional maleimide 5 was synthesized and the cyclization of 5 to the bicycle 9 with 2 mol monopyrone 8 was carried out.
Polyoxazoline auf fettchemischer Basis
Authors: Beck M. , Birnbrich P. , Eicken U. , Fischer H. , Fristad W. E. , Hase B. , Krause H.‐J. 
Published: April 2003

AbstractA new, economic technique was developed for the production of 2‐alkyl‐2‐oxazolines with saturated, unsaturated or OH‐functionalized alkylrests. In the process the fatty acids are changed into polymerizable monomers.The cationic polymerization of fattyalkyl‐2‐oxazolines was investigated in unpolar solvents and in bulk. It reacts in a living mechanism. The polymerization is remarkable inert against impurities like water or ethanolamide. A reaction enthalpy of ΔH = 85,9 kJ/mol was found for the bulk polymerization of 2‐pentadecyl‐2‐oxazoline.
Optimization of mechanical strength of reinforced composites. 1. Study on the effect of reactive bismaleimide on the mechanical performance of CaCo3‐filled polypropylene
Authors: Khunova V. , Sain M. M. 
Published: April 2003

AbstractThe effect of 3‐phenylene bismaleimide on the mechanical performance of an inorganic filler‐based polypropylene composite was studied. The selection of processing temperature played a significant role in the preparation of such composites. A positive effect of the bismaleimide compound was obtained for a processing temperature above the decomposition temperature of bismaleimide. The chemical composition of the modified composite was correlated to its mechanical strength by experimentation involving a rotatable design. An interaction between polymer and CaCO3 has been proposed based on ESCA analysis.