bluuebunny/crossref_metadata_2025_split huggingface dataset:
Peculiar features of emulsion copolymerization with functionally substituted water‐soluble comonomers
Authors: Yeliseyeva V. I. , Petrova S. A. , Zuikov A. V. 
Published: June 2010

AbstractDespite the considerable interest displayed by industry in latex polymers with functional groups, the study of the process of producing such latexes by the method of emulsion polymerization has just started. It should be expected that the introduction of functional groups into the interphase layer will entail a change in the course of the colloid and polymerization processes in the reaction system. In this work, the authors studied precisely this aspect of the process of emulsion copolymerization. Correlation between the polarity of a monomer (or monomer composition) on the one hand, and the kinetics of polymerization and adsorption of the emulsifier, on the other, has been shown in the case of alkyl acrylates and their copolymerization with functional monomers differing in their solubility in water. It has also been shown that localization in the interphase layer of functional groups capable of interaction, for instance, owing to the formation of hydrogen bonds, sharply intensifies the effect of these groups on the mechanical and thermomechanical properties of a polymer obtained through emulsion polymerization. The same fact leads to localization of crossing processes in interglobular regions in a latex polymer.
Self‐condensation of aromatic tetraamines and their polycondensation with some tetrachloro compounds
Authors: Banihashemi A. , Marvel C. S. 
Published: June 2010

AbstractSeveral ladder and partial ladder polymers have been synthesized by self‐condensation reactions of 1,2,4,5‐tetraaminobenzene, 3,3′,4,4′‐tetraaminodiphenylether, 3,3′‐diamino‐benzidine and 3,3′, 4,4′‐tetraaminodiphenyl sulfone in polyphosphoric acid. These products are highly colored and have good thermal stability. Polyquinoxaline or dihydrophenazine or a mixture of these two recurring units seem to form these compounds. These compounds are slightly soluble in methanesulfonic acid and concenterated sulfuric acid and have inherent viscosities in the 0.2–0.4 range. Also, new ladder and partial lader aromatic heteropolymers have been obtained from 1,2,5,6‐tetraaminoanthraquinione with 2,3,7,8‐tetrachloro‐1,4,6,9‐tetraazaanthracene, 2,2′,3,3′‐tetrachloro‐6,6′‐diquinoxaline, 2,2′,3,3′‐tetrachloro‐6,6′‐di‐quinoxalylether and 2,2′,3,3′‐tetrachloro‐6,6′‐diquinoxalyl sulfone. In these cases poly‐condensation was carried out both in solution and in melt. Their inherent viscosities were in the range of 0.1–0.44. These polymers were also highly colored, have good thermal stability, and were soluble in methanesulfonic acid and concentrated sulfuric acid.
Copolymerization of unsaturated 1,3‐diox‐ane derivatives with maleic anhydride
Authors: Maśalińaska‐Solich Jolanta , Jedlińaski Zbigniew 
Published: June 2010

AbstractThe copolymerization of unsaturated 1,3‐dioxane derivatives and maleic anhydride in the presence of α, α azobisisobutyronitrile was investigated and alternating copolymers have been obtained. It has been shown that unsaturated 1,3‐dioxane derivatives form a charge‐transfer complex with maleic anhydride. The equilibrium constants of the charge‐transfer complexes were determined by NMR spectroscopy. The mechanism of the polymerization was discussed.
Radical copolymerization of maleic anhydride with organotin acrylates
Authors: Rzaev Z. M. , Sadykh‐Zade S. I. 
Published: June 2010

AbstractCopolymerization of maleic anhydride (MA) with trialkylstannylmethacrylates has been studied. Copolymerization constants (r1 r2) have been determined for maleic anhydride and trialkylstannylmethacrylates, the parameters Q2 and e2 have been calculated for (CH3)3Sn‐ (C2H7)3 Sn‐ and (n‐C4H9)3Sn‐ and (n‐C4H9)3Sn‐ methacrylic acid derivatives: Q2 = 0.31, 0.27, 0.23 and 0.18; e2 = − 0.64, − 0.75, − 0.81 and − 0.88. Kinetic regularities of the reaction have been studied. It has been shown that organotin copolymers composition, as well as their model compound structures, are characterized by the occurrence of coordinate bonds of type. There has been revealed the effect of internal complexation in radical copolymerization responsible for both monomer links laternation along macromolecular chain and possible stereodirection of the reaction. The reactivity of complexomers MA‐TBSM and MA‐ Styrene (St) has been studied by means of terpolymerization.
Paracrystallinity of hot stretched linear polyethylene cut in slices parallel to the fiber axis and graft copolymerized with styrene
Authors: Čačković H. , Loboda‐Čačković J. , Hosemann R. 
Published: June 2010

AbstractLinear polyethylene (PE), hot stretched 10‐fold at 80°C and cut into 0.1 mm‐thick slices parallel to the fiber axis was annealed for 102 min at 120°C and then graft copolymerized in styrene by varied doses of 60Co up to 0.4 Mrad. The ungrafted styrene was washed out and the sample then vaccum dried for 24 hr. Again, by a combined analysis of small and wide angle x‐ray scattering (SAXS and WAXS), characteristic changes can be observed during the first 40% increase of weight ΔG. The diffraction analysis proves with the help of the theory of paracrystals, that microslices parallel to the plane of cutting are produced, within them the g13‐value of the paracrystalline superlattice decreases till ΔG = 20% by 4% and reaches its old value g13 = 28% again at ΔG = 45%, while g23, orthogonal to the slices, till ΔG = 20% increases by 2% and then decreases by 4% to the value g23 = 30% at ΔG = 45%. The graft copolymerization up to ΔG = 20% mainly takes place in the “amorphous” layers of the ultrafibrils, until the shortest PE tie molecules are stretched to such an amount that families of adjacent microparacrystals build up common backfolding surfaces. Above ΔG = 20% all styrene graft copolymerizes in the lateral grain boundaries of the ultrafibrils. At ΔG = 40% they reach a main thickness of ∼ 30 Å. Then the adhesive forces between adjacent microparacrystals are so weakened that they are pushed back into their old position with larger g13‐values, by which g23 automatically reaches a 4% smaller values. At ΔG = 200% the lateral grain boundaries are 140 Å thick in the average and can not grow more at higher doses, since now the PE tie molecules between lateral microparacrystals are stretched out too. The importance of these grain boundaries between adjacent ultrafibrils is pointed out. Though contrary to “amorphous” layers they practically have the same electron density as the microparacrystals they play an important role for the physico chemical behavior of the polymers which can not be understood by the conventional two phase model. Some new observations of distortions in the microparacrystals depending on the degree of graft copolymerization are described. They give hints about kinks and kink blocks in the microparacrystallites.
Polymerization of vinyl chloride by organometallic compounds III. Characterization of the structure of poly (vinyl chloride) samples prepared by various methods
Authors: Kolínský M. , Jíšová V. , Lím D. 
Published: June 2010

AbstractThe polymerization of vinyl chloride by various organo‐lithium compounds, either alone or engaged in various complexes, yields polymers which show higher thermal stabilities than polymers resulting from polymerizations initiated by customary radical catalysts. By comparing various samples prepared under different conditions, an attempt has been made to find out what the structural factors are which have such a significant effect on the improvement of the properties of these more thermostable polymers.
Ion exchange of polyacrylic acid grafted on polypropylene
Authors: Pegoraro Mario , Penati Amabile 
Published: June 2010

AbstractSamples of polypropylene grafted with polyacrylic acid, homopolymer free, containing different amounts of polyacid and having different physical formation (moldings, powders, membranes, films) have been put into contact with solutions at various NaCl concentrations. The exchange kinetic has been followed through pH measurements; the kinetic is influenced by the diffusion; at the end it is possible to come to an equilibrium state, the constant of which has been calculated by several measurement cycles. The value of the constant is not dependent on the physical state of the examined samples and is practically the same determined using polyacrylic acid homopolymer insolubilized by the presence of NaCl.
The influence of supermolecular structure on linear polyethylene drawing
Authors: Korsukov V. E. , Marichin V. A. , Miasnikova L. P. , Novak I. I. 
Published: June 2010

AbstractThe influence of the supermolecular structure type of linear polyethylene films on the relationship between the strengthening process and loss of strength at drawing has been studied by the infrared spectroscopy technique. It has been found that the progress of the strengthening process (which is connected with the macromolecular segments orientation in the microfibril amorphous region), as well as the loss of strength process (which is caused by macromolecules scissions), is strongly influenced by the initial supermolecular structure.
Effect of orientation on radiation behavior of polyolefins
Authors: Yurkevich V. G. , Karpov V. L. , Zverev B. I. , Aleksandrova L. B. 
Published: June 2010

AbstractThe fundamental radiation‐chemical reactions under irradiation, destruction and crosslinking of macromolecules, primarily depend on the molecular structure. However, the action of radiation on polymeric fibers (anomalous deterioration of strength properties) obtained out of the same polymer occurs depending on the dose. This results from the character of the conformation of the macromolecules in the stretched polymer. To solve this question, the change of solubility, characteristic viscosity, and gelation under irradiation were studied.The orientation parameter was studied by the optical microscope, and isometrical heating, the radiothermoluminescence and roentgen‐structure were analyzed, also. The obtained dependences were compared with the change in tensile strength of polyolefin fibers (polyethylene, polypropylene) under irradiation. It was determined that the degree of orientation of the polymer has an essential influence upon the radiation yield of the reaction of destruction and crosslinking of macromolecules. Structure changes in polyethylene fibers exposured to a radiation dose of from 0 to 2000 Mrads were studied. The influence of the postirradiation treatment on the structure was studied, too. The behavior of fibrous material after irradiation is predominantly influenced by its chemical shructure; the behavior of a fiber is not very different from that of the base polymer in some other form. The rather remarkable effects that have been observed with some materials (e.g., polyethylene) during irradiation have stimulated research toward finding improved fibers for use in textiles. This trend is reflected in much of the literature that deals with radiation effects on fibrous materials.The modification of textile fiber properties by radiation per se to produce improved products does not appear promising. As a gross effect, the properties of all textile materials are harmed by exposure to radiation under ordinary conditions. Hence the action of radiation on polymeric fibers obtained from the same polymer causes the anomalous deterioration of strength depending on the dose.This investigation was concerned with the effect of orientation on the radiation behavior of polymers, and was carried out on manufactured polyolefin fibers (polyethylene (PE), and polypropylene (PP)). The change of solubility, characteristic viscosity, and gelation mechanical properties by radiation were studied. The orientation parameter by the optical microscope, the isometrical heating, the radiothermoluminescence, and roentgen structure were analyzed, too.
Isothermal crystallization of low density polyethylene and chlorinated polyethylenes by calorimetry
Authors: Erä Väinö , Venäläinen Heikki 
Published: June 2010

AbstractIsothermal crystallization of LDPE and CPE with varying chlorine contents has been studied by differential scanning calorimetry. The effect of chlorine on the crystallization kinetics is shown by varying shapes of the crystallization isotherms as well as by variations of the slopes of the straight lines representing the plot of the maximum crystallinities against the crystallization temperatures.
Viscoelastic and high‐elastic properties of solutions of “monodisperse” polybutadienes in the region of critical concentrations
Authors: Ya. Malkin A. , Berezhnaya G. V. , Vinogradov G. V. 
Published: June 2010

AbstractThere occurs a transition from the local to the continuum viscoelasticity of polymer solutions at the critical concentration, and this affects the change of the form of the concentration dependence of all the characteristics of the viscoelasticity of the solution. For polymers of different molecular weight, the concentration dependences of their viscoelastic properties over the entire range of concentrations are determined by the volume filling of the system.
Light scattering on optically active polythiol esters. determination of molecular weight and optical anisotropy of poly‐(s) (‐)‐α‐para‐toluenesulfonamido‐β‐propiothio‐lactones
Authors: Šegudović N. , Deželić G. J. , Fleš D. 
Published: June 2010

AbstractOptically active polythiol esters (PTE) were prepared by polymerization of (S)‐a‐p‐toluenesulfonamido β‐propiothiolactone in bulk, in dimethylformamide (DMF) solution, and from benzene‐water interface. By the light scattering method the optical anisotropy of the polymers dissolved in DMF was studied. In the determination of molecular weights it was found necessary to correct the Rayleigh ratios for the anisotropic scattering. The optical anisotropies of the PTE samples were found to be significantly higher than those recorded for ordinary flexible polymers. The possible secondary structure of the polymer in solution is discussed in view of the light scattering data.
The optical properties of chiral centers used as tools for studying irreversible or reversible reactions of synthetic polymers in solution
Authors: Vert Michel , Selegny Eric 
Published: June 2010

AbstractThe optically active manifestations (ORD and CD) of asymmetric centers of synthetic macromolecules are discussed. Well known for conformational studies, they can also detect or give quantative information about the covalent or associative reactions of these polymers when important contributions of rigid or ordered structures are absent. The Moffitt equation can not only characterize the helical conformation of polypeptides but it is also, and in a more general manner, satisfied when at least one of the Cotton effects of sufficient amplitude contributing to the ORD of the polymer is of opposite sign to the other ones. These contributions are met in several cases which are classified and illustrated. An example is given where the b0 constant of the Moffitt equation is used to determine the composition of a copolymer resulting from a chemical modification of some of the monomeric units of a polymer. The results are discussed.
Destruction of polymers with benzoxazole and imide fragments in the main chain
Authors: Tseitlin G. M. , Korshak V. V. , Rode V. V. , Vinogradov A. V. , Al‐Haidar L. T. 
Published: June 2010

AbstractThermal and thermooxidative destruction of polyimidobenzoxazoles having the same ratio of imide and benzoxazole cycles was studied. The benzoxazole cycle was shown to be more thermally stable than the imide cycle. It has been concluded from the composition of the products of polymer decomposition and the kinetics of their formation that both in vacuum and in the presence of oxygen decomposition of the polymer by a radical mechanism predominates. Above 550°C there is slight hydrolytic decomposition of the benzoxazole fragments of the chain.
On the mechanism of the thermal degradation of polyvinyl acetate
Authors: Troitskii B. B. , Razuvaev G. A. , Khokhlova L. V. , Bortnikov G. N. 
Published: June 2010

AbstractThe kinetics of deacetylation and benzene formation, and the polymer crosslinking and absorption spectra of PVAc during thermal degradation (in vacuo at 200–280°C with or without removal of volatile products) were studied. The effects of the molecular weight of PVAc samples and the addition of various substances such as acids, metal chlorides, amines, phenols, triphenylmethane, organic salts of Ca, and dialkyltin on the thermal decomposition of PVAc were investigated.Deacetylation kinetics of the polymer with continuous removal of volatile products can be described by the first order reaction equation with the rate constant ket = 9.6 × 1015 e−51400/RT sec−1. The PVAc degradation rate does not depend on the molecular weight of the polymer. During the thermal degradation of PVAc, polyenes having up to six conjugated double bonds form. A scheme is proposed for the thermal degradation of PVAc by the molecular mechanism.In the presence of volatile degradation products the kinetic curves of PVAc deacetylation have a distinct autocatalytic character. This is due to the accelerating effect of acetic acid. Degradation of PVAc is also accelerated by other acids. There is a certain correlation between the degradation rate and dissociation constants of acids. This indicates that acids accelerate the thermal degradation of PVAc by the ionic mechanism.A rapid crosslinking of the polymer takes place in the process of PVAc thermal decomposition. This evidently results from Diels‐Alder reactions between polyenes. The inhibitors of the free radical reactions, organic salts, have no effect on deacetylation rate of PVAc.
Degradation of polyethers containing in‐chain alicyclic ring structures
Authors: Kops Jørgen 
Published: June 2010

AbstractThe degradation of polymers prepared by ring‐opening polymerization of methyl substituted 7‐oxabicyclo‐[2.2.1]‐heptanes has been investigated. The thermal stability was found to be dependent upon the molecular weight up to a limiting value. For the polymers with high molecular weights the thermal stability with regard to initial weight loss was found to be comparable to that of the aromatic analog polyphenyleneoxide (PPO) when the degradation occurs in inert atmosphere. The thermal degradation proceeds differently for the different polymers and while PPO carbonizes with a substantial residue, the alicyclic polymers do not discolorize during a process where quantitative conversion to volatile products takes place. Gas‐liquid chromatography established that the monomer could not be found among the degradation products. The suitability of utilization of a combination of TGA and GPC measurements for studying the course of the degradation is demonstrated. Oxidative degradation was found to proceed at a much faster rate than that of the purely thermally induced process for both alicyclic and aromatic polymers. However, for PPO it was found that 20–30% of the initial weight is lost very quickly in an exothermic reaction after which the weight loss become very slow. The oxidative weight loss for the alicyclic polymers is essentially linear with time and occurs with a rate which is slower than the initial rate for PPO.
Stressed polymer ageing under irradiation and in chemically active media
Authors: Regel V. R. , Vershinina M. P. 
Published: June 2010

AbstractThe results of the experimental study of the lifetime of stressed polymers under the action of irradiation of various kinds and in chemically active media are summarized. The lifetime of polymers under the action of additional destructive factors is compared with the lifetime of the same polymers in the absence of these factors. The results of the experiments are interpreted within the framework of the kinetic concept of strength.
Radiation degradation of polymethylmeth‐acrylate in the presence of liquid organic additives
Authors: Dziedziela W. M. , Sudzik R. , Kroh J. 
Published: June 2010

AbstractThe effect of α‐methylstyrene, ethylbenzene, and 2‐mercaptoethanol on radiation induced degradation of polymethylmethacrylate (PMM) was investigated. The deaerated viscous mixtures containing from 11 to 33 w/w % of PMM were irradiated with 60Co gamma rays and molecular weight of polymers determined by osmometry.The degradation of PMM in the presence of additives proceeded with higher yield as compared with pure solid polymer. The yields of main chain scission G(s) were found dependent on the nature and concentration of additives. Sensibilization effect increased in the order: α‐methyl‐styrene, 2‐mercaptoethanol, and ethylbenzene as the most effective agent. Within the concentration range investigated G(s) increased linear with concentration of additives. The mechanism of processes occuring during irradiation of PMM in the presence of additives is discussed.
Influence of short‐term thermal pretreatment on the rate of acidolysis of cellulose
Authors: Rusznák I. , Tánczos I. 
Published: June 2010

AbstractCotton and regenerated cellulose had been hydrolyzed under acid conditions on thermally pretreated and untreated samples. Three to four times higher rate constants could be calculated from the loss in DP of the acid‐hydrolyzed thermally pretreated cellulose. Loss in humidity regain as well as dyestuff uptake could be observed on the same samples. Consequently the increase in the rate of hydrolysis cannot be ascribed to accessibility changes. No correlation could be found between the increased rate of reaction and the acid adsorption or the rate of its diffusion. Not enough chemical changes could be detected in the cellulose for the wanted explanation.
The conformational statistics of pectic acid
Authors: Whittington S. G. , Glover R. M. , Hallman G. M. 
Published: June 2010

AbstractThe effect of random insertions of 1,2‐linked a‐ and β‐L‐rhamnose units on the characteristic ratio of a 1,4‐linked poly‐a‐D‐galacturonic acid molecule was investigated. In each case the characteristic ratio decreases dramatically as the proportion of rhamnose units is increased, the effect being more marked with the β sugar than with the a sugar. The effect is interpreted in terms of kinks which are introduced into the chain by the insertion of the rhamnose units.
The initial stages of the heterogeneous degradation of alkali cellulose by oxygen in relation to the morphology of native cotton cellulose
Authors: Palma A. , Jovanović S. , Schulz G. V. 
Published: June 2010

AbstractTreatment of cotton cellulose with sodium hydroxide solutions of varying concentration over extended periods in the absence of oxygen markedly decreases the intrinsic viscosity of both the cellulose in cuoxam and its cellulose trinitrate derivative (CTN) in acetone. Light‐scattering measurements show that the molecular weight does not change while the radius of gyration decreases and the second virial coefficient increases. The narrow molecular weight distribution of the native cotton is still maintained. Mild oxidation first causes the intrinsic viscosity to increase. At more prolonged oxidation times the viscosity decreases. These results are interpreted by an intramolecular cross‐linking reaction in the folded cellulose chains with the formation of chemically resistent bonds. Cleavage of the resultant cyclic structures leads to molecules with a larger radius of gyration but the same molecular weight.
Conformational variation and versatility of the connective tissue hyaluronates
Authors: Atkins E. D. T. , Brown Jacqueline H. , Landsdall Julia M. , Nieduszynski I. A. , Sheehan J. K. 
Published: June 2010

AbstractFour distinct conformations for the hyaluronic acid backbone have been observed. A two‐fold helix with a projected disaccharide repeat of 9.8Å, a three‐fold helix with a repeat of 9.5Å, and two perturbed four‐fold helical conformations with projected disaccharide repeats of 9.3Å and 8.3Å. In addition the three‐fold conformations exist for both univalent and divalent salt forms in a number of two‐dimensional packing arrangements which may be described in tesselation notation.