bluuebunny/crossref_metadata_2025_split huggingface dataset:
Impact behaviour and fractographic analysis of rubber‐modified polybutyleneterephthalate obtained by reactive blending concurrently with polymerization process
Authors: Di Liello V. , Laurienzo P. , Malinconico M. , Martuscelli E. , Ragosta G. , Volpe M. G. 
Published: April 2003

AbstractRubber modification of polybutyleneterephthalate was accomplished by the addition of suitable functionalized ethylene‐propylene copolymers (EPR) concurrently with the high temperature polycondensation of 1,4‐butanediol and dimethylterephthalate.The impact properties of blends obtained with plain EPR, with ester or hydroxyl groups modified EPR were analyzed by Charpy tests performed at different temperatures with a Ceast fracture pendulum. The morphological features of fracture surfaces have also been investigated. An attempt has been made to correlate the morphology of the surfaces with the fracture analysis results.
Detailed reaction engineering as a basis of modern slurry technology for PE‐HD‐production
Authors: Böhm L. L. , Goebel P. , Schöneborn P.‐R. 
Published: April 2003

AbstractSaving product quality and quality consistency in polymer production needs a detailed knowledge of the polymerization process. A process model for the slurry polymerization of ethylene with high mileage Ziegler‐catalyst/cocatalyst systems has been developed. This model teaches which set of process parameters must be kept constant together with their acceptable deviations to keep product data within the required frame. The consequences for a technical production plant are also discussed.
Note on notch and unnotch toughness of PP‐CaCO3 composites: Influence of filler particle size and dispersion degree
Authors: Švehlová Vítězslava , Polouček Eduard 
Published: April 2003

AbstractThe influence of the filler particle size and dispersion degree on the Charpy notch toughness (U notch) and tensile impact strength (without notch) in the polypropylene‐microground calcium carbonate system was investigated. It was found that while the tensile impact strength was controlled by the content of particles and/or agglomerates coarser than about 10 µm (the strength decreased sharply with their increasing content), the Charpy notch toughness was not decreased even by large agglomerates (up to 100 µm), but dropped heavily with the increasing upper particle size of the filler measured before kneading into polymer. A model system polyethylene‐glass beads revealed even an increase of the notch toughness with the increasing upper diameter of the glass beads (the upper diameter being in the 50–400 µm range).
Polymerization of vinyl acetate in nonionic surfactant microemulsions
Authors: Donescu Dan , Anghel Dan Florin , Balcan Marieta 
Published: April 2003

AbstractThe rate of polymerization of vinyl acetate in microemulsions containing n‐propanol and ethoxylated nonylphenol with 30 moles of ethylene oxide (NP30) depends on the initial composition of the reaction mixture. The reaction is of first order with respect to the initiator (i. e. ammonium persulfate). The induction period increases and the polymer yield decreases by increasing the surfactant concentration. The maximum reaction rate is not affected by the surfactant concentration, but it decreases with the cosurfactant concentration. The rate of initiator decomposition increases with cosurfactant concentration and is lower in the presence of surfactant. The reaction order in case of n‐propanol is of 0.2 in presence of surfactant and of 0.3 in its absence.
Anhäufung von bruchstellen in polydispersen polymeren unter dauerbelastung
Authors: Goldman A. J. , Kestelman V. N. 
Published: April 2003

AbstractEs wird über die Untersuchungsergebnisse von Lebensdauer und Molmassenänderung an polydispersen Proben von HDPE und HDPE in einem breiten M̄v‐Bereich im Zugversuch in einem oberflächenaktiven Medium berichtet.Die Arbeit enthält auch die Darstellung der quantitativen Änderung der Molmasse von Hochdruck‐ und Niederdruck‐Polyethylen unter Dauerbeanspruchung und die Analyse der Lebensdauer in Abhängigkeit von den unterschiedlichen Molmassen (MM) (M̄w, M̄n, M̄v); die Unterschiede in Abhängigkeit von der Lebensdauer von M̄v für Proben und polydisperse Muster sowie die Vorstellungen über den dualen Einfluß der Polydispersität auf die Lebensdauer mit einer Interpretation der auftretenden Erscheinungen werden beschrieben.
Temperature dependence of proton spin‐lattice and spin‐spin relaxation times in isotactic polypropylene. Effect of atactic fraction
Authors: Tanaka Hiroshi , Kohrogi Fumie , Suzuki Kazuhiko 
Published: April 2003

AbstractThe temperature of the T1 minimum for the segmental motion in polypropylene containing a lot of atactic fraction is lower than that in isotactic polypropylene. A short T1, T1s, appears for both materials. As the temperature is raised, there is a large increase in T2a (T2 of the mobile amorphous regions), and a mild increase in T2m (T2 of the intermediate regions), while there is no substantial change in T2c (T2 of the rigid crystalline regions). T2a in polypropylene containing a lot of atactic fraction is longer than that in isotactic polypropylene.The mass fraction of crystalline regions, Fc, decreases and that of the amorphous regions, Fa, increases as the temperature is raised. There is a linear increase in the relaxation rate, 1/(T1min), as the amorphous fraction is increased, except for the sample extracted with boiling n‐heptane. With increase of the peak temperature of tanδ, T2a decreases nearly linearly, while the temperature of the T1 minimum increases.
Copolymerization of methyl methacrylate with maleic anhydride initiated by p‐toluenethiol
Authors: Kuramoto Noriyuki , Shibamura Tomoe , Iwaki Takeshi , Nagai Katsutoshi 
Published: April 2003

Abstractp‐Toluenethiol (PT) initiates the copolymerization of methyl methacrylate (MMA) with maleic anhydride (MAH) under various conditions. The kinetics of copolymerization of MMA with MAH initiated by PT was investigated in dioxane in the temperature range of 40–60°C, and the rates (Rp) of copolymerization and activation energy were determined. Rp was found to depend on [PT]0.4, ([MMA] + [MAH])2.0. The overall energy of activation was 45.2 kJ/molin the temperature range of 40–60°C. PT was found to be an effective initiating as well as transfer agent. PT induces chain transfer in the copolymerization of MMA with MAH to obtain marked reduction in molecular weight.
Partikelgrößenanalyse von dispersen farbstoffsystemen I. Grundlagen zur partikelgrößenanalyse mittels photonen‐korrelations‐spektroskopie
Authors: Brunger Harald , Schollmeyer Eckhard 
Published: April 2003

AbstractEine zur Beschreibung des Färbevorganges von Polyestermaterialien mit Dispersionsfarbstoffen wesentliche Größe stellt die Partikelgrößenverteilung im Farbebad dar. Partikelgrößen unterhalb eines Mikrometers lassen sich in situ nur mit wenigen Meßtechniken bestimmen. Dazu zählt u. a. die Photonen‐Korrelations‐Spektroskopie, die auf Streuung von Laserlicht an kleinen, in einer Flüssigkeit suspendierten Teilchen basiert. Die mathematischen und physikalischen Grundlagen dieser Meßtechnik werden in diesem Artikel erläutert.
Studies on rheological and mechanical properties of isotactic polypropylene‐olefine/styrene block copolymer blends
Authors: Żuchowska Danuta , Steller Ryszard 
Published: April 2003

AbstractExperimental studies of the blends consisting of isotactic polypropylene and olefine/styrene block copolymers have been carried out. Measurements of viscoelastic and mechanical properties as well as electron microscope observations have shown that the above system has a biphasic structure within the whole composition range. Olefine/styrene block copolymer is a good agent for polypropylene toughening, as the impact strength is increased by several hundred percent especially at low temperatures.
SAXS and WAXS investigations of the crystallinity in polymers
Authors: Rabiej Stanislaw , Wlochowicz Andrzej 
Published: April 2003

AbstractThe crystallinity of polyethylene, polyethyleneterephthalate, and polypropylene was measured with the aid of wide angle (WAXS) and small angle (SAXS) X‐ray scattering methods. The values of crystallinity evaluated using the latter method are distinctly larger than those ones given by the WAXS method. The differences are supposed to be associated with the transition layer existing between the amorphous and crystalline regions. It was concluded that small angle X‐ray scattering cannot be employed as an independent routine method of crystallinity determination.
The thermal decomposition of 2,2′‐azobis‐(2‐methyl‐5‐hydroxy‐valeronitril) and its phenyl isocyanate derivative
Authors: Yuruk H. , Jamil S. , Baysal B. M. 
Published: April 2003

AbstractThe thermal decomposition kinetics of 2,2′‐azo‐bis‐(2‐methyl‐5‐hydroxy‐valeronitrile) was studied in siobutyl methyl ketone, 1,4‐dioxane and cyclohexanone at 61, 71, and 81°C by applying ultraviolet absorption technique. The thermal decomposition of the phenyl isocyanate capped product of this azo‐compound was also studied in isobutyl methyl ketone at the same three temperatures. The overall rate expressions for decomposition of these azo‐initiators in various solvents are reported.
The influence of electron irradiation on the mechanical properties of polypropylene/EPDM rubber blends
Authors: Harnischfeger Peter , Kinzel Peter , Jungnickel Bernd‐Joachim 
Published: April 2003

AbstractBlends of isotactic polypropylene and EPDM rubber have been treated by electron irradiation in the composition range of rubber modification and in the thermoplastic rubber composition range as well. Mutual crosslinking of the components through the interface could be detected. This intercrosslinking caused a remarkable improvement of the mechanical properties particularly of the thermoplastic rubber.
Fast separation of stabilizers from polyolefins by microwave heating
Authors: Freitag Wolfgang , John Oswaldo 
Published: April 2003

AbstractThe application of microwave heating for the separation of stabilizers from polypropylene and polyethylene was studied. Additives examined were the antioxidants IRGANOX 1010 and IGRAFOS 168 and the light stabilizer CHIMASSORB 81. The polymer samples were kept in sealed vessels and irradiated in a laboratory microwave oven. Fairly quantitative (>90% of the expected content) extraction of the stabilizers from powered polymer was achieved within 3 to 6 minutes using 1, 1, 1 ‐trichloroethane or the 1:1 mixture of acetone and n‐heptane as the extracting solvent.
Eigenverstärkung von thermoplasten im schmelze‐deformationsprozeß
Authors: Ehrenstein Gottfried W. 
Published: April 2003

AbstractDurch gezielte Beeinflussung der Verarbeitungsprozesse können besonders bei PE, aber auch bei PP erhebliche Selbstverstärkungseffekte erreicht werden. Die Steifigkeit, die Festigkeit und der Verschleißwiderstand werden bis zum 5‐fachen (Spritzguß), sogar teilweise bis zum 20‐fachen (Extrusion) gegenüber normal verarbeitetem Material angehoben. Die Verstärkungswirkung wird durch Shish‐Kebab‐Strukturen erreicht. Sie ist mehrachsig, was für Bauteile grundsätzlich wichtig ist. Erreicht wird dieses durch Begünstigung einer strömungs‐ und druckinduzierten Kristallisation. Die Verfestigung des Materials erfolgt nicht wie üblich durch Abkuhlen sondern ebenfalls druckinduziert. Das Verfahren ist auf konventionellen Verarbeitungsmaschinen realisierbar. Die Strukturen sind sehr stabil.
Mechanisms of photooxidation of polyolefins
Authors: Gugumus F. 
Published: April 2003

AbstractThe mechanisms of photooxidation usually envisaged, are perfected by taking into account photoreactions of peroxy radicals. They involve interaction of a peroxy radical with the polymer to yield a hydroperoxy radical and a pair of macroradicals. After peroxidation, this pair will usually undergo bimolecular termination. The influence of such a reaction on photooxidation kinetics is particularly important for polyethylene. Then, chain termination occurs mainly by interaction of two hydroperoxy radicals or of a hydroperoxy radical with a macroperoxy radical. The reaction does not only affect kinetics of photooxidation but also the nature of the photooxidation products. The latter is more important for polypropylene than for polyethylene.
Investigation of the thermal ageing of polyethylene and polystyrene with the purpose of predicting their shelf‐life
Authors: Trifonova Maria , Evtimova Sonya , Peeva Lili 
Published: April 2003

AbstractThe aim of the present work is to predict the warehouse storage life of polyethylene low‐density, polyethylene high‐density and polystyrene impact‐resistent, using the method of temperature‐time superposition. The properties, most representative for thermal ageing, are the relative elongation at break for polyethylene and the impact resistance for polystyrene. The validity of the predicted shelf‐life is verified by estimating the change of these properties under real conditions of warehouse storage.
Competition between degradation and orientation in semicrystalline polymers
Authors: Raab Miroslav , Mantia Francesco La , Pospíšil Jan 
Published: April 2003

AbstractThis lecture summarizes some recent results and ideas about interrelations between degradation and mechanical behaviour of polyolefins. Aspects of the heterogeneous nature of oxidative degradation in the solid state, the feedback mechanism in degradation, effects of morphology, particularly orientation, on the degradation process, and the influence of degradation on plasticity and on the ultimate mechanical behaviour are discussed.
Thermal and UV degradation of impact‐resistant polystyrene (II)
Authors: Mlinac‐Mišak M. , Jelenčić J. , Bravar M. , Dejanović R. 
Published: April 2003

AbstractA commercial type of impact‐resistant polystyrene was investigated. Two types of antioxidants, Irganox 245 and Irganox PS‐800 were added to polystyrene in ammounts of 0,05 to 0.20%. Films, dumbbells and straight test pieces were subjected to thermal and u.v. ageing. Films of 250 μ thickness were thermally treated at 100°C and separately u.v. irradiated at 360 nm for 24, 72, 120 and 168 hours. Dumbbells and straight test pieces were only thermally aged at 100°C for 7, 14, 21, 28 and 35 days. Mechanical properties were determined. The spectra of samples were recorded using Perkin‐Elmer, model 1750 FTIR and Perkin‐Elmer data station 7700. Colour changes of all dumbbells were measured using Elrepho apparatus in u.v.‐visible region. (Changes of the content of carbonyl and hydroxyl groups, as well as of polybutadiene (PB) unsaturation in films were recorded on i.r. spektrophotometer Perkin‐Elmer 257 between 4000 and 625 cm−1 and were published in the first part of this study1).
Structural and mechanical changes of polyacrylate systems in correlation with their composition in degradative conditions
Authors: Cerovečki Z̈eljko , Kovačević Vera , Bešić Zdravka , Stanojević Duško 
Published: April 2003

AbstractThermal and photodegradation of copolymer system based on styrene, butyl acrylate, acrylic acid and N‐methylolacrylamide (S/BA/AA/MAA) shows mechanical, but no structural changes in examined temperature range and after 320 h of UV irradiation (simultaneously with 256 and 366 nm lamps). Content of acrylic acid is a very important factor for the mechanical stability of these systems which can be very successfully used as the coatings in the practice. Found correlations indicate mechanism and factors having influence on the excellent stability of copolymer films.
Properties of adhesive polymer compositions in ageing conditions
Authors: Kovačević Vera , Šmit Ivan , Kljajič‐Malinović Ljiljana , Sućeska Muhamed , Bravar Mladen 
Published: April 2003

AbstractIn our work the degradative changes in properties of polyurethane adhesives based on aliphatic isocyanates were defined and compared with similar changes occurring when using aromatic isocyanates. The readily observed PUR adhesive discolouration in situations of its contact with leather does imply the necessity for the establishing the real proportions of the polyurethane constituents responsible for this ever‐present problem. The structure‐property relationship of hydroxylterminated polyester‐based segmented aliphatic polyurethanes, as a component in adhesive composition were studied using wide angle X‐ray diffraction spectroscopy (WAXD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) as well as attenuated total reflectance infrared spectroscopy (ATR‐IR) and nuclear magnetic resonance spectroscopy (NMR). The results show that crystalline phase in segmented PUR component influence on morphological and structural properties in degradative conditions.
Kinetic characteristics of the light ageing of rubbers based on polydieneurethanes and polyetherurethanes
Authors: Ivanov V. B. , Kavun S. M. , Tikhonova T. M. 
Published: April 2003

AbstractThe influence of light wavelength and intensity, as well as the temperature, on photooxidation has been studied for rubbers based on polydieneurethane (PDU) or polyetherurethane (PEU). Photooxidation is shown to proceed by the chain free‐radical mechanism with bimolecular (for PDU) or linear (for PEU) kinetic chain termination. The PDU oxidation kinetic parameter is equal to 0.02 [mole/(kg·s)]1/2 and does not depend on temperature. In PEU photooxidation the kinetic chain length is constant in a wide range of light intensities and is equal to 7, while the activation energy is ca 18 kJ/mole. In distinction to PEU, PDU is sensitive not only to UV but also to visible light, with this sensitivity being preserved up to high oxidation levels. The dependences of photooxidation quantum yieldes on wavelength and irradiation time have been determined.
The investigation of structural and morphological changes after the chlorination of rubber surfaces
Authors: Hace Drago , Kovačević Vera , Manojlović Darko , Šmit Ivan 
Published: April 2003

AbstractThe samples of vulcanized rubber compounds with natural rubber (NR) and styrene‐butadiene rubber (SBR) were prepared. The surface chlorination of samples was performed by immersion of strips in aqueous solution of sodium hypochlorite and in hydrochloric acid in dependence of time and in temperature range from 20 °C to 80°C. The changes of chemical structures, thermal stability and morphological properties of chlorinated vulcanizates were recorded by IR‐FMIR spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), wide angle X‐ray diffraction (WAXD) and scanning electron microscopy (SEM). Extremely heterogeneous complex mechanisms of chlorination and parallel degradation processes in dependence on time and temperature above all were indicated and compared to NR and SBR vulcanizates. At higher temperatures the structural changes in elastomeric matrix in connection with selective separation and surface migration of multicomponent filler due to agressive media were observed.
The effect of degradation degree of the dispersed phase on the ozone aging of rubbers filled with crushed rubber powder
Authors: Bořuta Jaroslav , Běhal Miroslav 
Published: April 2003

AbstractThe effect of crushed rubber powder as a filler of rubber compounds on the ozone aging of vulcanizates has been investigated. It has been shown that the ozone resistance depends significantly both on the concentration and the degradation degree of the dispersed phase. Results of laboratory and atmospheric aging tests are summarized.
Influence of small amount dispersive additives on the weather ability of PVC‐films
Authors: Genova Penka , Gancheva Tamara , Marinova Atanasija 
Published: April 2003

AbstractThree types of transparent PVC‐films before and after exposition in the weather conditions are studied. The first film (the control) is plasticized and stabilized; the second is similar to the first but 1 part of cuprous oxide (CuzO) is incorporated in it, while in the third 1 part of aluminium (A1) powder is added. It is found that the light transparency decreases by 2‐7% upon adding Cu2O and by 17‐36% upon adding Al‐powder. UV‐visible measurements, colourimetric measurements and microscopic investigations are used for examining PVC‐samples properties during weathering. The surface layer chemical changes are studied by means of MIR‐IR‐spectroscopy. The total colour variation (ΔE*ab) in the case of 12 months aged PVC‐film, containing Cu2O, shows 11 relative units in comparison with 37 relative units for the other two materials. A retarding action of Cu2O and an accelerated effect of Al‐powder on the weather degradation of clear soft PVC‐films are established. The influence of the chemical properties and different size distribution of the dispersive additives on photooxidative behaviour of PVC‐compositions are discussed.
Antioxidative efficiency of N‐(arylamine) imides in thermal oxidation of polypropylene
Authors: Matisová‐Rychlá L. , Rychlý J. , Csomorová K. , Velikov A. A. , Kluge R. , Schulz M. 
Published: April 2003

AbstractElectron‐donating substituents of N‐(arylamine) phthalimides and succinimides promote antioxidative efficiency of these compounds in thermooxidation of polypropylene (190°C, oxygen), while electron‐withdrawing substituents contribute to a reduced volatilization of the polymer. 2,6‐Ditert.butyl‐4‐methylphenol (ionol) raises the antioxidative efficiency of 4‐methoxy and 4‐methyl substituted derivatives displaying a distinct synergism.
Stabilization of linear polyethylene crosslinked by irradiation
Authors: Kiss Peter , Nyitrai Zsuzsanna , Wein Tibor , Bődy Mária , Sipos Csaba 
Published: April 2003

AbstractOur experiments have shown that after a complex degradative effect, such as processing, irradiation and ageing, the effects of antioxidants and their mixtures are very different.The results of our investigation support the opinion, expressed by many researchers of stabilization, that there does not exist any universally practicable antioxidative system. The optimal effect has to be determined, for each system, in the knowledge of the quality and quantity of the given oxidative load.For polyethylene crosslinked by irradiation a satisfactory stability can be attained with the aid of the usual stabilizers; however, they must be used in relatively larger quantities owing to the additional degradative action of the irradiation. There are noticeable differences between the stabilizers not only in their stabilizing action, but also in influencing the degree of discoloration and in the dose number required to produce the same degree of crosslinking.
Studies in ageing of flame retardant high impact polystyrene
Authors: Rosík Ladislav , Virt Jaromír , Masařík Ivo , Horák Zdeněk 
Published: April 2003

AbstractHigh impact polystyrene modified with various flame retardants (decabromodiphenyl ether, hexabromocyclododecane, antimony trioxide) and other additives has been prepared. The ageing behaviour and the permanence of the flame retardance were tested. The ageing processes did not appreciably affected the flammability characteristics of the flame retardant high impact polystyrenes although other important material properties (impact strength, gloss, colour) were already considerably deteriorated.
Stabilization of polyacetals
Authors: Stohler Felix R. , Berger Kurt 
Published: April 2003

AbstractA brief introduction describes the main differences between homo, and copolymer polyacetals and their main degradation mechanisms. A short overview describes the importance of stabilization and the necessity of using antioxidants and costabilizers during manufacturing, processing and end use of polyoxymethylene(polyacetals). Various stabilizer systems are presented and studies on the interaction of antioxidants with costabilizers added. The criteria for testing the performance of these additives are discussed and demonstrated by many examples.In a second part the increasing importance of light stabilized polyacetal is mentioned and investigations on the performance of light stabilizer systems are highlighted.