Showing papers in "Polymer Bulletin in 1985"
TL;DR: In this paper, the conductivite ionique de sels de lithium dissous dans du polyoxyde d'ethylene, diminue par stockage, a temperature ambiante.
Abstract: La conductivite ionique de sels de lithium dissous dans du polyoxyde d'ethylene, diminue par stockage, a temperature ambiante. Ceci est du a une cristallisation qui peut etre inhibee par addition de caoutchouc nitrile et d'un macromere de polyoxyde d'ethylene
668 citations
TL;DR: In this paper, a method was developed to stop the crosslinking reaction of a polydimethylsiloxane system without disturbing the state of the sample, and the loss modulus and the storage modulus were found to be identical over several decades of frequency and for temperatures ranging between -50°C and +180°C.
Abstract: A method has been developed to stop the crosslinking reaction of a polydimethylsiloxane system without disturbing the state of the sample. Oscillatory shear experiments on samples just before and just beyond the gelation point demonstrated the transition of the material from a viscoelastic liquid to a viscoelastic solid. At the gel point the loss modulus and the storage modulus were found to be identical over several decades of frequency and for temperatures ranging between -50°C and +180°C. Both moduli were proportional to the square root of the frequency.
392 citations
TL;DR: A sol-gel process has been successfully utilized to produce hybrid materials incorporating polymeric/oligomeric components of polydimethyl siloxane (PDMS) with silicon glasses.
Abstract: A sol-gel process has been successfully utilized to produce hybrid materials incorporating polymeric/oligomeric components of polydimethyl siloxane(PDMS) with silicon glasses. All the samples made were transparent and flexible. Dynamic mechanical studies indicate that a portion of the siloxane species is phase-separated while the remainder is well dispersed. The effect of acid content were proven to be significant on the dispersion of the siloxane components and on the structure and properties of final products.
231 citations
TL;DR: In this article, bisphenol-A polysulfone (PSF) oligomers were used in the modification of Epon Resin 828/4,4′-diamino-diphenyl sulfone (DDS) network system.
Abstract: Functionally terminated bisphenol-A polysulfone oligomers were used in the modification of Epon Resin 828/4,4′-diamino-diphenylsulfone (DDS) network system. Phenolic hydroxyl terminated PSF oligomers were first capped with a large excess of bisphenol-A diglycidyl ether or Epon Resin 828 at both ends and then the resulting system was cured with DDS, in a two-step process. During these studies molecular weight and the amount of PSF oligomers incorporated into the network were varied and their effect on the overall properties of the resulting systems were investigated. The capping and curing reactions were followed by using FT-IR and NMR spectroscopy, GPC, HPLC and DSC techniques. As a function of the oligomer molecular weight, SEM studies showed the formation of two-phase structures with ductile PSF particles dispersed in the continuous epoxy matrix. Mechanical characterization and fracture toughness measurements showed a remarkable increase in KIC or gIC values of the modified networks over that of control, without significant loss in the modulus. This work would appear to be one of the first studies where well bonded ductile glassy modifiers have significantly improved the fracture toughness of highly crosslinked networks.
227 citations
TL;DR: A 180°C, seulement SnO and Sb 2 O 3 rendement superieur a 80% and une purete optique de l'ordre de 97% as discussed by the authors.
Abstract: A 180°C, seulement SnO et Sb 2 O 3 donnent un rendement superieur a 80% et une purete optique de l'ordre de 97%
178 citations
TL;DR: In this paper, the viscosity dependence of Xanthan as a function of polymer concentration, shear rate and molecular weight in the ordered conformation was investigated and a unique curve was obtained for the reduced specific visco-sensitivity.
Abstract: This paper concerns the viscosity dependence of Xanthan as a function of polymer concentration, shear rate and molecular weight in the ordered conformation. The different samples with various molecular weights are obtained by ultrasonication. A unique curve is obtained for the reduced specific viscosity (
$$\eta _{sp/} \eta _{sp_0 } $$
) as a function of γ · γ
r
−1
for the different molecular weight samples and polymer concentrations below an overlap concentration C [η]0⩽ 1.5. The master curve giving the relation
$$\eta _{sp_0 } $$
as a function of C [η]0 is drawn and compared with that of polystyrene in good solvent. The largest increase of
$$\eta _{sp_0 } $$
in semidilute solution may be due to larger interchain interactions and to larger stiffness of the Xanthan molecule.
138 citations
TL;DR: In this paper, a new class of liquid crystal side chain polymers has been synthesized, where the mesogenic groups are laterally attached to the polymer backbone, and the polymers are liquid crystalline in a broad temperature range above the glass transition temperature.
Abstract: A new class of liquid crystal side chain polymers has been synthesized, where the mesogenic groups are laterally attached to the polymer backbone. The monomeric liquid crystals are laterally substituted with an alkyl chain having a methacrylic ester group in the ω-position. While the monomers exhibit a metastable nematic phase with respect to the crystalline state, the polymers are liquid crystalline in a broad temperature range above the glass transition temperature.
119 citations
TL;DR: In this article, a simple and reproducible method of synthesizing enantiomers of benzyl malolactonate is described starting from optically active aspartic acid.
Abstract: A simple and reproducible method of synthesizing enantiomers of benzyl malolactonate is described starting from optically active aspartic acid. Chiral benzyl malolactonate is a β-substituted β-lactone monomer which can be readily polymerized anionically using triethylamine as the initiator to yield poly(benzyl β-malate) which is an optically active, semicrystalline polymer. Cleavage of protecting benzyl ester groups yields optically active poly(β-malic acid). The properties of the racemic and optically active monomers and polymers are compared. Optically active (−)poly(β-malic acid) shows one accessible positive CD band in the far UV.
118 citations
TL;DR: In this paper, a modification II-I transformation of polybutene-1 was investigated on oriented lamellae, which were melt-crystallized in the temperature gradient.
Abstract: Modification II-I transformation of polybutene-1 was investigated on oriented lamellae, which were melt-crystallized in the temperature gradient. WAXS photograph of as-grown specimen showed prefered orientation of [110] to the lamellar axis, and after transformation it showed “twelve point pattern” due to dual orientation of hexagonal lattice. By shear deformation parallel or perpendicular to lamellar axis, WAXS photograph showed the appearance of “six point pattern” due to single orientation of hexagonal lattice, and also the enhancement of transformation rate. These were explained by the growth of hexagonal nuclei formed by the slip in the tetragonal crystal.
81 citations
TL;DR: It is shown that the rate of degradation obeys first order kinetics at the begining and that poly(β-malic acid) degrades to malic acid at last.
Abstract: Poly(β-malic acid) is a new synthetic functional polyester of the poly(β-hydroxy-acid)-type whose properties are investigated in regard to possible uses as bioresorbable polyvalent drug-carrier. Degradation of polymer chains in 0.15 N phosphate buffer at pH=7.5 is monitored by aqueous GPC on SEPHADEX gels and by enzymatic titration of ultimate degradation products. It is shown that the rate of degradation obeys first order kinetics at the begining and that poly(β-malic acid) degrades to malic acid at last.
80 citations
TL;DR: In the absence of significant tranesterification, blends of poly(ethylene terephthalate) and poly(bisphenol-A carbonate) were found to be almost completely immiscible over the range of compositions studied as discussed by the authors.
Abstract: In the absence of significant tranesterification, blends of poly(ethylene terephthalate) and poly(bisphenol-A carbonate) were found to be almost completely immiscible over the range of compositions studied. Although the observed behavior was sometimes erratic, poly(bisphenol-A carbonate) appears to exert a significant influence on PET melting behavior and normalized heat of fusion.
TL;DR: In this paper, the authors show that the association of macromolecules is due to hydrogen bonding between sequences of vicinal carboxylic groups (minimum seven units) of the polyacid and polyether sequences.
Abstract: Complexation of polyacrylic acid and polyoxyethylene in aqueous solution has been examined for various degrees of neutralization of the polyacid, different molecular weights and concentrations of the polymers. Potentiometric and visometric measurements show that the association of macromolecules is due to hydrogen bonding between sequences of vicinal carboxylic groups (minimum seven units) of the polyacid and polyether sequences. In several systems we observed a very high viscosity. This effect may be explairned by a formation of highly branched structures, since the same polyacid molecule can be complexed with different polyether chains.
TL;DR: In this article, a 2-methyl-2-oxazoline (polyMeOZO) macromer having a styryl group as polymerizable function has been prepared via two methods.
Abstract: Poly(2-methyl-2-oxazoline) (polyMeOZO) macromers having a styryl group as polymerizable function have been prepared via two methods. The first one is to use an amine nucleophile having a styryl group to terminate the living cationic propagating species of MeOZO initiated by MeOTs (1), giving rise to a macromer (2) (“terminator method”). The second one is to induce the cationic ring-opening polymerization of MeOZO by an initiator of iodomethylstyrene to give a macromer (3)(“initiator method”). These macromers 2 and 3 can be used as a comonomer for the synthesis of copolymers with MeOZO graft chains.
TL;DR: In this article, a crystallite modulus of native cellulose along the chain axis has been calculated based on the X-ray analysed molecular conformation and the force constants used in the vibrational analysis.
Abstract: A crystallite modulus of native cellulose along the chain axis has been calculated based on the X-ray analysed molecular conformation and the force constants used in the vibrational analysis The calculated values are 1729 GPa and 708 GPa for the cases with and without the intramolecular hydrogen bondings taken into account, respectively The intramolecular hydrogen bondings have been found to play an important role on the determination of crystallite modulus and the chain deformation mechanism, based on the calculation of the strain energy distribution to the internal coordinates such as bond lengths, bond angles, and so on
TL;DR: Optically active liquid crystalline side chain polymers with dif ferent flexible spacer groups and different main chains (acry lates, methacrylates and α chloroacrylsates) are described in this paper.
Abstract: Optically active liquid crystalline side chain polymers with dif ferent flexible spacer groups (n=2–11) and different main chains (acry lates, methacrylates and α chloroacrylates) are described. (+)-2-methyl butyloxyphenyl esters of benzoic acid were chosen as the mesogenic group.
TL;DR: In this paper, the copolymerization of 2-methyl-2-oxazoline and N-phenyl maleimide in bulk or in solution, at 60°C or room temperature, is reported.
Abstract: The copolymerizations of 2-methyl-2-oxazoline and N-phenyl maleimide in bulk or in solution,at 60°C or room temperature are reported. The initiation is spontaneous and is due to the formation of zwitterion by interaction of the two monomers. The copolymers are statistical,more rich in maleimide units and propagation reaction can take place both by anions and zwitterions.
TL;DR: In this article, a pendant ether oxygens intramolecularly activate the growing end was found to have a very narrow molecular weight distribution (Mw/Mn ≤ 1.2); the oxyethylene units in the monomers hardly disturbed the polymerization.
Abstract: Vinyl ethers having oxyethylene units [CH2=CHO-(CH2CH2O)-nC2H5, n=1–4] were cleanly polymerized by the HI/I2 initiator in a nonpolar solvent (toluene) at low temperatures (−15 and −40°C) to yield living-like polymers with a very narrow molecular weight distribution (Mw/Mn ≤1.2); the oxyethylene units in the monomers hardly disturbed the polymerization. The number-average molecular weight of the polymers increased proportionally to monomer conversion and the monomer-to-HI feed ratio. The polymerization rates of the (poly)ether-containing vinyl ethers were much greater than those of alkyl vinyl ethers under similar conditions, and it is presumed that the pendant ether oxygens intramolecularly activate the growing end. The polymers were soluble in methanol (with n≥1) and in water (with n≥2), depending on the number of oxyethylene units in the pendant.
TL;DR: In this article, the complexation properties of poly(ethyleneimine) were investigated for cobalt, nickel, zinc, cadmium, and copper using membrane filtration.
Abstract: The complexation properties of poly(ethyleneimine) were investigated for cobalt, nickel, zinc, cadmium, and copper using membrane filtration. The elution curves of each metal were determined at different pH values in homogeneous phase. Poly(ethyleneimine) was found to be an effective complexing agent and suitable for retention and separation of metals in aqueous diluted solutions.
TL;DR: Polymerisation en masse a 120, 150 (principalement) and 180°C. Le rendement maximum (96%) est obtenu avec l'oxyde de magnesium as mentioned in this paper.
Abstract: Polymerisation en masse a 120, 150 (principalement) et 180°C. Le rendement maximum (96%) est obtenu avec l'oxyde de magnesium
TL;DR: Polymerisation du methacrylate de vinyl oxyethyle and du cinnamate de vinyl-2 oxyethyl-2 avec un melange iode/iodure d'hydrogene, dans le toluene, entre −15 and −40°C as discussed by the authors.
Abstract: Polymerisation du methacrylate de vinyl oxyethyle et du cinnamate de vinyl-2 oxyethyle avec un melange iode/iodure d'hydrogene, dans le toluene, entre −15 et −40°C
TL;DR: In this article, it has been established that all spectra of degraded PVC are showing two additional maxima resulting from a superposition of other polyene absorptions, and that the existing conception according to which all maxima are based on the most intensive longest-wave d-absorption of a definite polyene sequence could not be confirmed.
Abstract: UV-spectra of degraded PVC are put together in a complicated but surveyable way by superposition and deletion of the a-, b-, c-, and d-absorptions of individual polyenes. The existing conception according to which all maxima are based on the most intensive longest-wave d-absorption of a definite polyene sequence could not be confirmed. It has been established that all spectra are showing clearly two additional maxima resulting from a superposition of other polyene absorptions. Thus, counting all maxima for d-absorptions, in the literature a wrong assignment of the UV-maxima to the individual polyenes is reported.
TL;DR: Polymerisation dans le toluene a −15 and −40°C in presence du systeme HI/I 2, en composes solubles dans methanol (n≥1) and dans l'eau (n ≥ 2).
Abstract: Polymerisation dans le toluene a −15 et −40°C en presence du systeme HI/I 2 , en composes solubles dans le methanol (n≥1) et dans l'eau (n≥2)
TL;DR: In this paper, the reaction du methacrylate de vinyloxyethyle avec l'iodure d'hydrogene, est employe comme amorceur de la polymerisation de l'ethyl vinyl ether en presence d'une petite quantite d'iode.
Abstract: Le produit obtenu par reaction du methacrylate de vinyloxyethyle avec l'iodure d'hydrogene, est employe comme amorceur de la polymerisation de l'ethyl vinyl ether en presence d'une petite quantite d'iode
TL;DR: In this article, a mixture of acrylic acid and carbon dioxide (CO2) gas was investigated, and the polymer deposition rate in acrylic acid was increased by admixing CO2 gas, and polymers containing carboxyl groups were formed.
Abstract: Plasma polymerization in a mixture of acrylic acid and carbon dioxide (CO2) gas was investigated. The polymer deposition rate in plasma polymerization of acrylic acid increased by admixing CO2 gas, and polymers containing carboxyl groups were formed. The amount of carboxyl groups alterable to carboxylate anions by treating with 0.1 N KOH solution or NH3 gas reached twice of that formed in plasma polymerization without CO2 gas.
TL;DR: In this paper, the incorporation of starch hydrolysates in phenolic resins of the novolak and resol type via intermediate acid catalyzed dehydration to 5-hydroxymethylfurfural (HMF) has been investigated.
Abstract: The incorporation of starch hydrolysates in phenolic resins of the novolak and resol type via intermediate acid catalyzed dehydration to 5-hydroxymethylfurfural (HMF) has been investigated. The course of reaction was monitored by carbon-13-NMR and IR spectroscopy. Due to the formation of HMF/phenol condensates, savings of up to 40 % phenol and 50 % formaldehyde (by weight) are possible in comparison to commercial resins. Besides maintenance of essential property profiles, additional benefits may be achieved with respect to faster curing and lower amounts of free monomers.
TL;DR: In this article, different chemical structures of copolymers containing -S-CO-S-S and/or -O-CO -S groups have been obtained by reacting 1,3-benzene dithiol (BDT) with phosgene alone and with the products of BPA polycarbonate degraded with BDT; molecular weights were determined by viscometry and vapor pressure osmometry.
Abstract: Copolymers containing -S-CO-S-and/or -O-CO-S-groups have been synthesized mainly by interfacial polycondensation. Different chemical structures were obtained by reacting 1,3-benzene dithiol (BDT) respectively with phosgene alone, phosgene and bisphenol-A (BPA), bischloroformate of BPA, BPA polycarbonate oligomers and by reacting phosgene with the products of BPA polycarbonate degraded with BDT. The chemical structures of the copolymers were investigated by IR, 1H-NMR and 13C-NMR; molecular weights were determined by viscometry and vapor pressure osmometry. Although no attempt was made to find the optimum conditions for high molecular weight, some copolymers with fairly high mol. weight were obtained.
TL;DR: In this paper, the effect of ionic strength (0.1 M ≤ [Cl] ≤ 0.4M), pH (3.0 ≤ pH≤ 5.0) and shear rate (up to 1000 sec−1) on the rheological response of concentrated chitosan solutions have been studied.
Abstract: The effect of ionic strength (0.1 M ≤ [Cl] ≤0.4M), pH (3.0 ≤ pH≤ 5.0) and shear rate (up to 1000 sec−1) on the rheological response of concentrated chitosan solutions have been studied. It has been observed that viscosity increases with increasing chitosan concentration and that a shear thinning behavior is present for polymer concentrations above 0.50 g/dl. Also, it has been shown that the zero shear viscosity is independent of the ionic strength of the media, but increases as pH is increased. This behavior has been related to the role of the surface charge density on the chitosan backbone upon the intermolecular entanglement which control the rheological behavior of concentrated chitosan solutions.
[...]
TL;DR: Chitin was aminoalkylated with N,N-diethylaminoethyl chloride in organic solvents or aqueous solutions in the presence of sodium hydroxide as mentioned in this paper.
Abstract: Chitin was aminoalkylated with N,N-diethylaminoethyl chloride in organic solvents or aqueous solutions in the presence of sodium hydroxide. The substitution reactions in organic solvents occurred under heterogeneous conditions on dispersions of powdery chitin while those using alkali chitin solutions proceeded in solution. The latter reactions were more efficient and reproducible than the former ones due to the homogeneous reaction conditions. The resulting diethyl-aminoethyl-chitins showed much improved solubility in contrast to the insolubility of chitin. The derivatives prepared in aqueous solutions showed especially remarkable solubility; those with substitution degrees over 0.5 were readily soluble in water and highly swelled even in various common organic solvents.
TL;DR: In this paper, a modification of a theoretical model for the determination of the number average molecular weight between crosslinks, ¯Mc, is presented for the case of multifunctional junction functionalities in highly crosslinked, macromolecular systems.
Abstract: A modification of a theoretical model for the determination of the number average molecular weight between crosslinks, ¯Mc, is presented for the case of multifunctional junction functionalities in highly crosslinked, macromolecular systems.