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Showing papers in "Polymer Bulletin in 1980"


Journal ArticleDOI
TL;DR: This article showed that cyclization plays a decisive role already at the onset of the reaction and observed an apparent decrease in reactivity of the pendant double bonds in the interior of the chain.
Abstract: Analysis of experimental results on the chain (co) polymerization of bisunsaturated monomers suggests that cyclization plays a decisive role already at the onset of the reaction. At medium and elevated concentrations of the bisunsaturated compound, compact microgel-like particles are formed, which give rise to a gel mainly by participating in the polymerization reaction only with pendant double bonds in their surface layer, and not with double bonds in the interior. This mechanism is reflected in an apparent decrease in reactivity of the pendant double bonds.

103 citations


Journal ArticleDOI
TL;DR: In this paper, a method of confidence intervals for copolymerization reactivity ratios determined by the linear Kelen-Tudős method is described, both for low and high conversions.
Abstract: Calculation method of confidence intervals for copolymerization reactivity ratios determined by the linear Kelen-Tudős method is described, both for low and high conversions. The intervals as well as the confidence regions were compared with those obtained using non-linear estimation. No considerable deviations were found either in the parameter values or in their errors.

101 citations


Journal ArticleDOI

98 citations


Journal ArticleDOI
TL;DR: The possibility of using the phase-volume method for determining phase diagrams of polymer mixtures in a common solvent has been ascertained as mentioned in this paper, and the above method was used to determine a phase diagram of water-casein-soybean globulins system.
Abstract: The possibility of using the phase-volume method for determining phase diagrams of polymer mixtures in a common solvent has been ascertained. The above method was used to determine a phase diagram of water-casein-soybean globulins system.

70 citations


Journal ArticleDOI
TL;DR: In this paper, hot drawing at 150°C was applied to high molecular weight polyethylene fibers produced by flow induced crystallization in a Couette apparatus, referred to as the surface growth technique, and a distinct improvement of the tensile properties of the fibers was noticed upon drawing.
Abstract: Hot drawing at 150°C has been applied to high molecular weight polyethylene fibers produced by flow induced crystallization in a Couette apparatus, referred to as the ‘surface growth’ technique. A distinct improvement of the tensile properties of the fibers was noticed upon drawing. A tensile strength at break of 4.7 GPa was reached. Drawability is discussed in relation to fiber morphology. The shish-kebab like structure of the ‘surface growth’ fiber was transformed into a morphology consisting of smooth fibrils upon drawing.

67 citations


Journal ArticleDOI
TL;DR: The effect of water on the dynamic mechanical properties of chitin and chitosan as a function of temperature is reported.
Abstract: Recently, much attention in the many fields has been paid to chitin(Poly-N-acetyl-D-glucosamine), which is formally considered an aminocellulose derivative that occurs widely in nature, for example, in the hard shell of insect and crustaceans, cuttlefish bone, and the cell walls of fungi, and its derivative, chitosan (Poly-D-glucosamine), which is readily obtained from chitin by N-deacetylation with alkali. However, there has been few papers concerning the physical properties of these polysaccharides. FUKADA et ai.(1975) examined the piezoelectricity of highly crystalline s-chitin, and found that a temperature dispersion appears only around -95~ which has been assigned to the water strongly bound to s-chitin. More recently, BRADLEY et ai.(1976) studied dynamic mechanical properties of some polysaccharides such as cellulose, amylose, and dextran containing various amount of water, and have characterized four mechanical transitions. In this paper, we report the effect of water on the dynamic mechanical properties of chitin and chitosan as a function of temperature.

58 citations


Journal ArticleDOI
TL;DR: The polymerization of phenylacetylene induced by UV irradiation of W(CO)6 in carbon tetrachloride provided in high yield a polymer, whose molecular weight reached about 80,000 as discussed by the authors.
Abstract: The polymerization of phenylacetylene induced by UV irradiation of W(CO)6 in carbon tetrachloride provided in high yield a polymer, whose molecular weight reached about 80,000. The polymerization did not proceed without UV irradiation or in the absence of a halogen-donating agent such as carbon tetrachloride. On the other hand, the polymerization of 2-chloro-1-phenylacetylene was best effected by Mo(CO)6, and did not require any halogen-donating agent (polymer MW 400,000). Polymerization of other acetylene derivatives was also examined.

48 citations


Journal ArticleDOI
TL;DR: In this paper, hot drawing in a temperature gradient has been applied to porous high molecular weight polyethylene fibers and the porosity and tensile strength of a fiber were measured as a function of draw ratio.
Abstract: Hot drawing in a temperature gradient has been applied to porous high molecular weight polyethylene fibers. The porous fibers were produced by spinning a 5% solution in paraffin oil and subsequently extracting the paraffin oil in n-hexane. Spinning/drawing under appropriate conditions resulted in a fiber with a tensile strength at break of 4.1 GPa. The porosity and tensile strength of a fiber were measured as a function of draw ratio. The influence of spinning/drawing conditions is discussed in relation to fiber texture and entanglement topology.

43 citations


Journal ArticleDOI
TL;DR: In this article, the effect of HCl on the thermal degradation of PVC has been studied and it was shown that HCl is able to reinitiate the allyl-activated zip elimination by proton exchange with polyenes.
Abstract: The effect of HCl on the thermal degradation of PVC has been studied. Changes in UV and visible spectra and kinetics of HCl loss indicate that HCl is able to reinitiate the allyl-activated zip elimination by proton exchange with polyenes. Also polyene-consuming secondary reactions are accelerated by HCl.

41 citations



Journal ArticleDOI
TL;DR: In this article, unsaturated oxocarbenium salts were used to initiate the polymerization of THF and the macromers obtained were characterized carefully, and it was found that these species are well defined, of narrow molecular weight distribution, and fitted quantitatively with end standing polymerizable double bonds.
Abstract: Unsaturated oxocarbenium salts were used to initiate the polymerization of THF. The macromers obtained were characterized carefully, and it was found that these species are well defined, of narrow molecular weight distribution, and fitted quantitatively with end standing polymerizable double bonds.

Journal ArticleDOI
TL;DR: 2,6-Di-tert-butyl-4-methylpyridine effectively discriminates between the two major initiation mechanisms encountered in cationic polymerisation and provides a means of assessing the relative importance of each.
Abstract: 2,6-Di-tert-butyl-4-methylpyridine (DBMP) effectively discriminates between the two major initiation mechanisms encountered in cationic polymerisation. Whenever a protonic acid is involved in the formation of chain carriers, directly or through cocatalysis, addition of equivalent amounts of DBMP inhibits the process. If however direct electrophilic addition of a Lewis acid to the monomer is the source of active species, the hindered base cannot intervene to alter its course. When both pathways are operative DBMP only quenches the former and provides a means of assessing the relative importance of each. Examples are given of the three situations. The simplicity of the method is emphasised.

Journal ArticleDOI
TL;DR: In this paper, fast spectroscopy experiments have been performed upon the photoinitiation process of a vinyl polymerization with the benzophenone-amine derivative system and the rate constants of the processes in the excited states have been determined.
Abstract: Fast spectroscopy experiments have been performed upon the photoinitiation process of a vinyl polymerization with the benzophenone-amine derivative system. The rate constants of the processes in the excited states have been determined. The results make it possible to discuss the rate constant of the polymerization and to deduce the efficiency of the initiating radicals.

Journal ArticleDOI
TL;DR: In this article, a method for the preparation of cyclic polystyrene is described, which is terminated by addition of equimolar amounts of α, α′-dichloro-p-xylene under conditions of high dilution.
Abstract: A method for the preparation of cyclic polystyrene is described. Bifunctionally growing living polystyrene is terminated by addition of equimolar amounts of α, α′-dichloro-p-xylene under conditions of high dilution.

Journal ArticleDOI
TL;DR: In this paper, the kinetics and mechanism of crosslinking and chain scission have been studied on several PVC samples during thermal thermooxidative, dynamic, and HCl catalyzed degradation.
Abstract: The kinetics and mechanism of crosslinking and chain scission has been studied on several PVC samples during thermal thermooxidative, dynamic, and HCl catalyzed degradation. During pure thermal degradation crosslinking at a constant rate without scission occurs, while in the presence of oxygen and/or shear scission is not negligible. In the dynamic test, under shear both processes are fast, compared to static tests. The mechanism of benzene formation without main chain scission is discussed.

Journal ArticleDOI
TL;DR: The structural uniformity of polyphthalocyanines depends strongly on the starting compounds as mentioned in this paper, and the starting compound is a mixture of 1,2,4,5-tetracyanobenzene and metallic copper.
Abstract: The structural uniformity of polyphthalocyanines 3 depends strongly on the starting compounds. With 1,2,4,5-tetracyanobenzene (1) and metallic copper or octacyan-phthalocyanine 2 and copper salts structural uniform 3 are received. Polymers, obtained in a reaction of 1 and copper salts, contain structure elements of 3 and polyisoindolenines 4.

Journal ArticleDOI
TL;DR: In this paper, living poly(tetrahydrofuran) (PTHF) was coupled with sodium p-vinylbenzyloxide quantitatively to prepare a macromer of PTHF.
Abstract: Living poly(tetrahydrofuran) (PTHF) was coupled with sodium p-vinylbenzyloxide quantitatively to prepare a macromer of p-vinylbenzyloxyl poly(tetrahydrofuran) (VBO-PTHF). The radical polymerization of the macromer with AIBN was performed. From the GPC measurement the conversion of the macromer to poly-macromer was shown to be high percentage, but the degree of polymerization of poly-macromer was much lower than that expected in the case of regular monomers such as styrene.

Journal ArticleDOI
TL;DR: In this article, critical stoichiometric ratio necessary for gelation in polyurethane systems composed of poly(oxypropylene)triol and diol, trimethylolpropane and 4,4′-diphenylmethane diisocyanate revealed the effects of different functionality, reactivity of functional groups, tendency to cyclization and the course of the crosslinking process.
Abstract: Determination of critical stoichiometric ratio necessary for gelation in polyurethane systems composed of poly(oxypropylene)triol and diol, trimethylolpropane and 4,4′-diphenylmethane diisocyanate revealed the effects of a different functionality, reactivity of functional groups, tendency to cyclization and the course of the crosslinking process.

Journal ArticleDOI
TL;DR: In this paper, Nanosecond laser spectroscopy is applied to the determination of the rate constants of several processes involved in the photochemistry of a series of substituted benzophenones.
Abstract: Nanosecond laser spectroscopy is applied to the determination of the rate constants of several processes involved in the photochemistry of a series of substituted benzophenones. The results allow the initiation of a vinyl monomer polymerization to be discussed and reveal a peculiarity of the benzene/THF system.

Journal ArticleDOI
TL;DR: Silica surfaces have been modified by reaction with Cl-Si(CH 3)2-CH 2-CH2-C6H4-CH1Cl and the modified solids were subsequently used in conjunction with Et2AlCl or AlMe3 coinitiators to initiate the surface graft copolymerization of isobutylene-isoprene mixtures.
Abstract: Silica surfaces have been modified by reaction with Cl-Si(CH3)2-CH2-CH2-C6H4-CH2Cl and the modified solids were subsequently used in conjunction with Et2AlCl or AlMe3 coinitiators to initiate the surface graft copolymerization of isobutylene-isoprene mixtures The experimental conditions have been chosen such that the composition of the rubbery component of the surface-graft be close to that of commercial butyl rubber The overall composition of silica-grafted butyl rubbers have been characterized

Journal ArticleDOI
TL;DR: In this paper, the influence of Lewis acidity of homogeneous organozinc catalyst RZnEt on monomer distribution in maleic anhydride-propylene oxide copolymers produced by this catalyst has been investigated.
Abstract: The influence of Lewis acidity of homogeneous organozinc catalyst RZnEt (R=C2H5-, CH3O-, CH3COO-, 2-CH3OC6H4O-,3-CH3 OC6H4O- and CH3COCH=C(CH3)O-) on monomer distribution in maleic anhydride-propylene oxide copolymers produced by this catalyst has been investigated. It was found that increasing the acidity (electron-accepting properties) of the Zn atom in the catalyst molecule caused an increase in the number of propylene oxide units in the obtained copolymers and a decrease of their average molecular weight.

Journal ArticleDOI
TL;DR: In this paper, crosslinking and chain scission in thermooxidative PVC degradation have been studied and a linear Charlesby-Pinner plot was found to give linear plots consistent with the constant rate of crosslink and scission.
Abstract: Crosslinking and chain scission in thermooxidative PVC degradation have been studied. Gel formation was found to give linear Charlesby-Pinner plots, consistent with the constant rate of crosslinking and scission. Similarly to thermal degradation, partial reversibility of crosslinking was observed also in oxygen.

Journal ArticleDOI
TL;DR: In this paper, the formation of charged groups on network chains is connected with the age of polyacrylamide gels, and the presence of the electrostatic charges is required for the observation of the gel collapse.
Abstract: Ageing of polyacrylamide gels is connected with the formation of charged groups on network chains. The presence of the electrostatic charges is required for the observation of the gel collapse.

Journal ArticleDOI
TL;DR: This finding indicates the stoichiometric salt-linkage formation between the basic groups in the hemoglobin and the KOSO3-groups in KPVS.
Abstract: Colloid titrations of human carboxyhemoglobin were carried out at different pH. The total number of basic groups in the hemoglobin was 95, as evaluated by the titration with potassium poly (vinyl alcohol) sulfate (KPVS). The value estimated was comparable with that obtained from the amino acid sequence of human hemoglobin. This finding indicates the stoichiometric salt-linkage formation between the basic groups in the hemoglobin and the KOSO3-groups in KPVS.

Journal ArticleDOI
TL;DR: In this paper, the effect of the anisotropy of poly(p-phenyleneterephthalamide) solutions in concentrated sulphuric acid on the tensile properties of wet yarn was investigated.
Abstract: In this paper a description is given of series of experiments which demonstrate the effect of the anisotropy of poly(p-phenyleneterephthalamide) solutions in concentrated sulphuric acid on the tensile properties of wet spun yarn. It will be shown that, in agreement with the well-known rules for spinning processes, the orientation of the molecules produced by stretching essentially contributes to the mechanical properties of the spun yarn, whereas anisotropy tends to have an adverse effect on the formation of fibers.

Journal ArticleDOI
TL;DR: In this paper, a simple statistical calculation leads to a relation between crystallinity and concentration of defects (α) times crystallite thickness yielding the average inclusion of chain defects per crystalline chain segment as an independent parameter.
Abstract: A simple statistical calculation leads to a relation between crystallinity and concentration of defects (ɛ) times crystallite thickness yielding the average inclusion of chain defects per crystalline chain segment as an independent parameter. Comparison of X ray crystallinity data for branched isothermically crystallized polyethylene (PE) with buthyl or longer side sequences with our statistical predictions confirms inclusion of up to one defect per 100 carbon atoms (depending on ɛ) within the crystal lattice. These results are in good agreement with values derived from unit cell expansion measurements.

Journal ArticleDOI
TL;DR: In this paper, the behavior of PMMA in the polar binary mixture of chloroform and methyl acetate was studied and a conformational transition has been found for u2 = 40% methylacetate.
Abstract: In this paper, we study the behaviour of PMMA(3) in the polar binary mixture chloroform(1)/methyl acetate (2). I n this system chloroform is preferentially adsorbed by PMMA in the range 0 < u2< 88% methyl acetate. A conformational transition has been found for u2 = 40% methyl acetate. In order to characterize quantitatively the phenomenon the intra- and intermo1ecular interactions have been determined using viscometry and light scattering as experimental techniques.


Journal ArticleDOI
TL;DR: In this paper, preliminary results on plasma-induced bulk homopolymerization of styrene, acrylic acid, methacrylic acid, ethyl acrylate and N-vinyl carbazole, styrene and acrylamide are presented.
Abstract: Preliminary results on plasma-induced bulk homopolymerization of styrene, acrylic acid, methacrylic acid, ethyl acrylate and on plasma-induced solution homopolymerization of N-vinyl carbazole, styrene and acrylamide are presented. Experimental data suggest that a radical mechanism of polymerization has to be considered to explain this new approach to polymer synthesis.

Journal ArticleDOI
TL;DR: In this article, a study was made of the radiation-induced grafting of acrylic acid onto polyethylene, which was found to be steady state in character in the early stages, when carried out in a suitable medium.
Abstract: SummaryA study has been made of the radiation-induced grafting of acrylic acid onto polyethylene. Grafting was found to be steady state in character in the early stages, when carried out in a suitable medium. Evidence is presented showing that, in the later stages, autoacceleration becomes a feature of the grafting process. Thermal analysisprocedures were used in an attempt to show the occurrence of grafting.Immobilization using N-ethoxycarbonyl-2-ethoxy,-1,2-dihydroquinoline (EEDQ) as the coupling agent was attempted. This met with various levels of success. The copolymer-EEDQ-enzyme system was used to couple bovine serum albumin (65 mg protein/g of substrate) and phenyl propylamine (95 mg phenylpropylamine/g of substrate).