Showing papers in "Polymer Bulletin in 1986"
TL;DR: In this paper, a new family of initiating systems has been discovered that efficiently induces the truly living polymerization of isobutylene (IB), the initiating systems are complexes of organic tertiary esters e.g., cumyl acetate, 2,4,4-trimethylpentane-2-acetate, with BCl3.
Abstract: A new family of initiating systems has been discovered that efficiently induces the truly living polymerization of isobutylene (IB). The initiating systems are complexes of organic tertiary esters e.g., cumyl acetate, 2,4,4-trimethylpentane-2-acetate, with BCl3. Living polymerizations proceed very rapidly in a variety of solvents, i.e., CH3Cl, CH2Cl2, C2H5Cl, and mixtures of chlorinated solvents plus n-hexane, in the range from −10° to −50°C. The living nature of the polymerizations was demonstrated by linear ¯Mn versus WPIB (g of polymer formed) plots starting at the origin and horizontal N (number of PIB chains) versus WPIB plots. The DPn of the products obeys [Mo]/[Io] where [Mo] and [Io] are initial monomer and initiator concentrations, respectively. Conversions and initiator efficiencies are ∼100%. In carefully controlled experiments narrow molecular weight distribution polyisobutylenes (PIB) have been obtained, i.e., Mw/Mn=1.17 − 1.3. A mechanism is outlined that helps rationalize the findings. It is postulated that the living polymerization of IB initiated by organic tertiary ester·BCl3 complexes most likely proceeds by a two-component group transfer polymerization process.
246 citations
TL;DR: In this article, a method has been developed which provides very pure alkyl methacrylate monomers for anionic polymerization, taking advantage of the chemistry of trialkylaluminum compounds.
Abstract: A method has been developed which provides very pure alkyl methacrylate monomers for anionic polymerization. This method takes advantage of the chemistry of trialkylaluminum compounds-their reactivity with alcohols and moisture, and their complex formation with methacrylic esters which facilitates titration of impurities. When coupled with previously known polymerization techniques, this purification methodology allows for both the synthesis of narrow distribution poly(alkyl methacrylates) of controlled and predictable molecular weight and for the utilization of a wide variety of methacrylate monomers. The procedure described herein should be equally applicable to group transfer polymerization.
177 citations
TL;DR: In this paper, liquid crystalline polymers with mesogenic groups laterally attached to the polymer backbone were investigated by polarizing microscopy with respect to their optical properties, and the nematic polymers were macroscopically oriented in a magnetic or electric field.
Abstract: Liquid crystalline polymers with mesogenic groups laterally attached to the polymer backbone were investigated by polarizing microscopy with respect to their optical properties. The nematic polymers were macroscopically oriented in a magnetic or electric field. Polarization microscopic investigations with convergent polarized light show optical biaxial behavior of the nematic phase.
103 citations
TL;DR: In this paper, a trityl group was found to be bonded at its α-chain end, which could further dissociate into propagating and trithl radicals, and was used as a thermal iniferter for polymerization of methyl methacrylate.
Abstract: Radical polymerization of methyl methacrylate (MMA) with phenylazotriphenylmethane (PAT) was found to give the polymer with a trityl group bonded at its α-chain end which could further dissociate into propagating and trityl radicals. Therefore, it was confirmed that PAT served as a thermal iniferter for polymerization of MMA, which proceeded via a living radical mechanism, i.e. yield and molecular weight of the polymers increased with reaction time. When the polymer thus obtained was used as a polymeric iniferter for the polymerization of styrene (St), the block copolymer was obtained.
80 citations
TL;DR: In this paper, living cationic polymerization of isobutyl vinyl ether was achieved by EtAlCl2 in the presence of ethyl acetate at rather high temperatures up to + 25°C in toluene.
Abstract: Living cationic polymerization of isobutyl vinyl ether was achieved by EtAlCl2 in the presence of ethyl acetate at rather high temperatures up to +25°C in toluene. In the absence of the ester additives, neither living nor long-lived propagating species were formed under these conditions. Similarly, living propagating species of vinyl ethers with an ester unit in the pendant (2-vinyloxyethyl benzoate and methacrylate) were obtained with EtAlCl2 alone. The obtained polymers showed a very narrow molecular weight distribution (¯Mw/¯Mn<1.2) and the ¯Mn was directly proportional to the monomer conversion.
73 citations
TL;DR: A new family of high performance, miscible polymer blends based on aromatic polybenzimidazoles and aromatic polyimides has been discovered in this paper, and the results indicated that polymers of these generic types may be miscible over a wide range of compositions and structural variations.
Abstract: A new family of high performance, miscible polymer blends based on aromatic polybenzimidazoles and aromatic polyimides has been discovered. Preliminary evidence, obtained with commercially available, soluble polymers suggests that polymers of these generic types may be miscible over a wide range of compositions and structural variations. Blend miscibility was evidenced in the form of single Tg1s and well-defined single tan δ relaxations intermediate to those of the component polymers, the formation of clear films and, in one case, enhanced solvent resistance.
70 citations
TL;DR: In this paper, it was found that 5 wt% solutions of UHMWPE in paraffin oil can be extruded through a conical die at a rate of 100 m/min without the appearance of filament irregularities due to elastic solution fracture.
Abstract: This communication is concerned with the gel-spinning of ultrahigh molecular weight polyethylene (UHMWPE) at speeds up to 1500 m/min. It was found that 5 wt% solutions of UHMWPE in paraffin oil could be extruded through a conical die at a rate of 100 m/min. without the appearance of filament irregularities due to elastic solution fracture. These elastic turbulences occur at extrusion speeds of about 5 m/min. Without the addition of 1 wt% of Aluminium-stearate the spinline could be stretched at most to 60 m/min at 170°C but at 210°C it did not break at a speed of 1500 m/min. These high-speed gel-spinning experiments at temperatures around 200°C yielded polyethylene fibers with a tensile strength of 3.5 GPa. It was observed that drying of the as-spun fiber containing n-hexane at constant length led to excessive crazing.
69 citations
TL;DR: Two acrylate side chain polymers in which the mesogenic moiety is a 4′-cyano-biphenyl-4-yl group have been synthesized and characterized by d.s.c., optical microscopy and X-ray diffraction as mentioned in this paper.
Abstract: Two acrylate side chain polymers in which the mesogenic moiety is a 4′-cyano-biphenyl-4-yl group have been synthesized and characterized by d.s.c., optical microscopy and X-ray diffraction. If the mesogenic moiety is linked to the polymer backbone by a -O-CO-(CH2)-5 group, the resultant polymer is nematic. For a -O-(CH2)-6 group, the unusual NSANre sequence is observed. X-ray diffraction has shown that the SA phase has a partially bilayer structure : the molecules are arranged in an antiparallel, overlapping interdigitated structure with a layer spacing of about 1.4 times the length of the side chains. Monolayer fluctuations are also observed in this SA phase.
67 citations
TL;DR: In this article, the efficiency of crosslinking was found to be dependent on the degree of neutralization of the sample and the concentration of the irradiated polymer solution and the extent of water uptake of the gel was shown to be related to the degree to neutralization by titration of acid groups within the gel subsequent to cross-linking.
Abstract: Samples of poly(acry1ic acid) (PAA) neutralized to varying degrees with sodium hydroxide were subjected to γ-irradiation to yield insoluble crosslinked polyacrylate hydrogels. The efficiency of crosslinking was found to be dependent on the degree of neutralization of the sample and the concentration of the irradiated polymer solution. The extent of water uptake of the gel was shown to be related to the degree of neutralization by titration of acid groups within the gel subsequent to cross-linking. Lightly crosslinked gels exhibited a maximum degree of swelling at a particular neutralization level. This was ascribed to a maximum in the long-range forces exerted cooperatively by the polymeric charges. The presence of simple electrolyte ions reduces swelling by screening these forces.
63 citations
TL;DR: In this paper, laser light scattering was used to study the miscibility behavior of PMMA/SAN blends and the region of stability of this structure was determined, and the binary interactional parameter was estimated.
Abstract: Laser light scattering was used to study the miscibility behavior of PMMA/SAN blends. These systems tend to phase separation at elevated temperatures, Above the lower critical solution temperature (LCST) a regular highly interconnected two-phase morphology is displayed. The region of stability of this structure is determined. Finally, the binary interactional parameter is estimated. It is negative due to the sufficiently repulsive intramolecular interactions relative to the repulsive intermolecular interactions.
55 citations
TL;DR: In this article, the hydroxyl content of a series of commercial poly(ethylene glycol)monomethy1 ethers was analyzed by means of 360 MHz 1H NMR spectroscopy of the trichloroacetyl isocyanate modified polymers.
Abstract: Analysis of the hydroxyl content of a series of commercial poly(ethylene glycol)monomethy1 ethers by means of 360 MHz 1H NMR spectroscopy of the trichloroacetyl isocyanate modified polymers has shown that some compounds contain considerable amounts of poly(ethylene glycol).
TL;DR: The freezing of the concentrated PVA water solutions results in obtaining hydrogels of non-covalent nature in the course of a single freezing-thawing cycle with no any noticeable destruction or covalent cross-linking of PVA macromolecules.
Abstract: The freezing of the concentrated PVA water solutions results in obtaining (after thawing) hydrogels of non-covalent nature. In the course of a single freezing-thawing cycle there is no any noticeable destruction or covalent cross-linking of PVA macromolecules.
TL;DR: In this paper, the relative reactivities of poly(ethylene oxide) macromonoraers (M2) carrying p-vinylbenzyl or methacryloyl group at α-end and methyl or dodecyl group at ω-end were prepared, and radical-copolynerized with benzyl metha-rylate or styrene (M1), and they were found to be significantly smaller than those of the corresponding model monomers of low molecular weights.
Abstract: Poly(ethylene oxide) macromonoraers (M2) carrying p-vinylbenzyl or methacryloyl group at the α-end and methyl or dodecyl group at the ω-end were prepared, and radical-copolynerized with benzyl methacrylate or styrene (M1). Relative reactivities of the macroraonomers (1/r1), were found to be significantly smaller than those of the corresponding model monomers of low molecular weights in all cases where the macromonomer (M2) and the homopolymer of the comonomer(poly-M1), are incompatible, supporting our previous suggestion of a repulsion between M2 and poly-M1, radical as a factor for retarding their mutual reaction.
TL;DR: In this article, the authors observed that the alteration of specific interactions rather than this entropic effect appears to be much more important in polystyrene with poly(vinyl methyl ether).
Abstract: Extensional flows can induce miscibility in a polymer blend of polystyrene with poly(vinyl methyl ether). Miscibility is observed as a change from turbidity to optical clarity when a phase separated blend flows isothermally in planar extension. In a start-up experiment at temperatures above the LCST, optical clarity does not appear instantaneously but after a time which depends on the rate of extension and the temperature, and it appears first near the region of highest extension. This effect is opposite to the observation for polymer solutions which exhibit shear-induced demixing. We attribute this to the fact that enthalpic effects largely determine blend miscibility, while the phase behavior of solutions is essentially controlled by entropic contributions. Since a deformation field decreases the configurational degrees of freedom of a polymer molecule, demixing is favored in solutions. However, the alteration of specific interactions rather than this entropic effect appears to be much more important in blends.
TL;DR: In this paper, the identification of coordination polymers has been carried out by the elementa W analysis and IR s pectrosoopy, and the results were obtained by using a mixture of interfaclal polycondensat|on of Cu,Ni,Co and Mn rezorcylaldehyde-ophe nylenedtamine sodium salt with terephthalic and tsophthalic d|chlworlde respeotP4ely, coordination pol-#~ers, as coloured powders, insoluble in organic solvents.
Abstract: SUMMARY By interfaclal polycondensat|on of Cu,Ni,Co and Mn rezorcylaldehyde-ophe nylenedtamine sodium salt with terephthalic and tsophthalic d|chlorlde respeotP4ely, coordination pol-#~ers, par~cularly ohelate plyesters, as coloured powders, insoluble in organic solvents, were obtained. The identification of coordination polymers has been carried out by the elementa W analysis and IR s pectrosoopy.
TL;DR: In this paper, the dependence of the intrinsic viscosities as a function of the ionic concentration (Cs) is discussed; the persistence length is given for Cs extrapolated to infinite.
Abstract: This paper concerns a series of experimental results obtained on sodium alginates with various molecular weights. The dependence of the intrinsic viscosities [η] as a function of the ionic concentration (Cs) is discussed; the persistence length is given for Cs extrapolated to infinite. The dependence of the specific viscosity as a function of the overlap parameter C [η] is discussed; it is independent of Cs as long as Cs is lower than 0.5 M.
TL;DR: In this paper, the structure of linear polyethylenes (HDPE) was investigated by GPC, C-13-NMR, and IR and it was shown that the strain hardening of the HDPE melts investigated here is not due to the short chain branches of the mainly linear molecules but influenced by a small amount of very long molecules of the molecular weight distribution.
Abstract: Different linear polyethylenes (HDPE) were elongated in the molten state at constant strain rates up to very large total strains (maximum stretch ratio λ=270). The structure of these polyethylenes was investigated by GPC, C-13-NMR, and IR. From the structural parameters it follows that the strain hardening of the HDPE melts investigated here is not due to the short chain branches of the mainly linear molecules but influenced by a small amount of very long molecules of the molecular weight distribution. For the influence of the temperature on the strain hardening phenomenon an unexpected result was found additionally.
TL;DR: Le macromere polyoxyde d'ethylene termine par un groupe p-vinylbenzyl est copolymerise avec le styrene dans le benzene, THF a 60°C as mentioned in this paper.
Abstract: Le macromere polyoxyde d'ethylene termine par un groupe p-vinylbenzyl est copolymerise avec le styrene dans le benzene, THF a 60°C
TL;DR: The solid state synthesis of a monosubstituted phthalocyanine 6 is described in this paper, which is obtained by cleavage with HBr/acetic acid.
Abstract: The solid state synthesis of a monosubstituted phthalocyanine 6 is described. 4-(4′-Hydroxyphenoxy)-1,2-benzenedicarbonitrile is polymer bound to a chloromethylated macroreticular polystyrene, yielding polymer 3. Reaction of 3 with 4-phenoxy-1,2-benzenedicarbonitrile in the presence of zinc salt results in the formation of covalently bound polymeric phthalocyanine 5. 6 is obtained by cleavage with HBr/acetic acid.
TL;DR: In this article, it has been found that polyethylene fibres were chlorosulfonated according to Kanig's technique, and that the tensile strength of the fibre decreases during chloroSulfonation, whereas the Young's modulus can be increased by more than fifty percent of its original value.
Abstract: Ultra-high strength polyethylene fibres were chlorosulfonated according to Kanig's technique. It has been found that the tensile strength of the fibre decreases during chlorosulfonation, whereas the Young's modulus can be increased by more than fifty percent of its original value. The interfacial bond-strength between polyethylene and gypsum plaster could be improved at least 4.8 times, amounting values of 6.3 MPa, making these fibres very suitable for use as a reinforcing material in gypsum plaster. SEM indicated that this improvement could be described to surface roughening of the fibre, due to chemical degradative stress-cracking during constrained chlorosulfonation.
TL;DR: In this article, a cyclohexane uptake overshoot was observed as a function of crosslinking ratio and geometric characteristics of the samples and it was attributed to molecular changes of polystyrene during swelling.
Abstract: Transport of liquid cyclohexane through well characterized, initially glassy, crosslinked polystyrene slabs was investigated as a function of time at 20, 30, 40, and 50 ° C. The samples used were produced by bulk polymerization of styrene and divinyl benzene using benzoyl peroxide as an initiator at 90 ° C for 48 hrs. The samples tested had initial crosslinking ratios, X, between 0.005 and 0.0250 mol DVB/mol styrene, their thickness varied from 0.025 to 0.180 cm, and the aspect ratio was maintained above 10 to achieve one-dimensional transport. A cyclohexane uptake overshoot was observed as a function of time. This overshoot was analyzed as a function of crosslinking ratio and geometric characteristics of the samples and it was attributed to molecular changes of polystyrene during swelling.
TL;DR: In this paper, a phase transfer catalyzed etherification and esterification of the chloromethyl groups with sodium 4-methoxy-4'-biphenoxide and potassium omega-(4-methyltebiphenyl)-alkanoates was used for the chemical modification of PECH.
Abstract: : Poly(epichlorohydrin) (PECH) containing pendant mesogenic units separated from the polymer main chain through spacers of zero to ten methylene units were synthesized and characterized. The synthetic pathway used for the chemical modification of PECH involved the phase transfer catalyzed etherification and esterification of the chloromethyl groups with sodium 4-methoxy-4'-biphenoxide and potassium omega-(4-methoxy-4'-ocybiphenyl)-alkanoates. All the resulting polymers, including that with no spacer, present thermotropic liquid crystalline mesomorphism.
TL;DR: In this article, thermal studies and microscopic observations on optically active liquid crystalline monomers having the following general formula were reported, with X = H (acrylates), CH3 (methacrylsates), Cl (chloroacryllates) and n=2, 6, 11 (flexible spacer groups) and corresponding side chain polymers.
Abstract: In this paper we report thermal studies and microscopic observations on optically active liquid crystalline monomers having the following general formula:
with X = H (acrylates), CH3 (methacrylates) and Cl (chloroacrylates) and n=2, 6, 11 (flexible spacer groups) and a few corresponding side-chain polymers.
TL;DR: In this article, Dodecyloxy poly(ethylene glycol) methacrylates with a degree of polymerization from 9 to 20 were used as comonomers in the dispersion polymerization of benzyl methacelate (BzRA) and styrene (St) to obtain soapless emulsions stabilized by the resulting graft copolymers.
Abstract: Summary Dodecyloxy poly(ethylene glycol) methacrylates with a degree of polymerization from 9 to 20 were used as comonomers in the dispersion polymerization of benzyl methacrylate (BzRA) and styrene (St) to obtain soapless emulsions stabilized by the resulting graft copolymers. In the aqueous dispersion with BzMA, the apparent reactivities of the macromonomers were essentially the same as those observed in the benzene solution, while in heptane they increased as also found in the case of the aqueous dispersion with St. The latter fact suggests a preferential polymerization near on the surface of the micellar particles where the macromonomers are enriched.
TL;DR: In this article, the reaction of polybutadiene avec la phenyl-4 triazoline-1,2,4 dione-3,5 conduit a l'addition de groupes urazole sur le polymere.
Abstract: La reaction de polybutadiene avec la phenyl-4 triazoline-1,2,4 dione-3,5 conduit a l'addition de groupes urazole sur le polymere. Etude de la formation des liaisons hydrogene entre les differents groupes urazole a differentes temperatures (entre 40 et 80°C)
TL;DR: In this paper, the reaction of diglycidyl ether of bisphenol A with methacrylic acid was carried out in the presence of an amine catalyst (imidazole) or a chromium chelate (chromium diisopropylsalicylate).
Abstract: The reaction of diglycidyl ether of bisphenol A with methacrylic acid was carried out in the presence of an amine catalyst (imidazole) or a chromium chelate (chromium diisopropylsalicylate). The resin products were analyzed by gel permeation chromatography and13C nuclear magnetic resonance spectroscopy. With both catalysts the reaction is characterized by an isomerization of the hydroxy-ester. The imidazole-catalyzed reaction product gave transesterification species in addition to isomerization product whereas these were absent with the chromium derivative catalyst.
TL;DR: In this article, reaction en presence du complexe tetramethyl 2,4, 4,6 heptane diacetate 2,6•BCl 3 dans CH 2 Cl 2 et C 2 H 5 Cl, entre −12 et −20°C
Abstract: Reaction en presence du complexe tetramethyl-2,4,4,6 heptane diacetate-2,6•BCl 3 dans CH 2 Cl 2 et C 2 H 5 Cl, entre −12 et −20°C
TL;DR: Melange d'homopolymeres identiques ou non quant a leur chimie. Prise en compte des interactions inter-and intramoleculaires.
Abstract: Melange d'homopolymeres identiques ou non quant a leur chimie. Prise en compte des interactions inter- et intramoleculaires
TL;DR: In this article, the possibility of group transfer polymerization of methyl methacrylate-terminated polystyrene macromer (MA-PSt) was explored by using 1-methoxy-1-(trimethylsiloxy)-2-methyl-1-propene and tris(dimethylamino)sulfonium difluorotrimethylsilicate as initiator and catalyst, respectively.
Abstract: The possibility of group transfer polymerization of methyl methacrylate-terminated polystyrene macromer (MA-PSt) was explored by using 1-methoxy-1-(trimethylsiloxy)-2-methyl-1-propene and tris(dimethylamino)sulfonium difluorotrimethylsilicate as initiator and catalyst, respectively. The results obtained at the polymerization temperature of 0°C were undesirable. However, the oligomerization at -78°C gave almost quantitatively oligo(MA-PSt) of which the degree of polymerization was in good agreement with the mole ratio of macromer to initiator. The GPC curve of oligo(MA-PSt) was sharp and symmetrical. In addition, it was shown by the copolymerization with methyl methacrylate that the polymerizability of the macromer was markedly enhanced in the presence of methyl methacrylate comonomer.
TL;DR: In this paper, a simple model is proposed to describe the miscibility of blends, which contain homo-and/or copolymers with tactic subunits, and directional-specific intermolecular interactions are assumed to be mediated by interactions caused by repulsive type intramolecular tacticity as well as chemical intersteps.
Abstract: A simple model is proposed to describe the miscibility of blends, which contain homo- and/or copolymers with tactic subunits. The directional-specific intermolecular interactions are assumed to be mediated by interactions caused by repulsive type intramolecular tacticity as well as chemical intersteps. Syndiotactic homopolymers are chosen as the reference state, for tactic as well as for mixed triads. The approximations developed in this paper include triad as well as diad treatment with respect to tacticity. Chemical intersteps are taken into account on a diad basis. Additive overlapping of tactic and chemical effects is assumed for mixed hetero- and isotactic triads.