Showing papers in "Polymer Bulletin in 1987"
TL;DR: In this article, the crystallinity of six cellulose samples with different origin and treatment was determined using x-ray diffraction and nuclear magnetic resonance with cross polarization and magic angle sample spinning (CP/MAS NMR) methods.
Abstract: The crystallinity of six cellulose samples with different origin and treatment was determined using x-ray diffraction (XDR) and nuclear magnetic resonance with cross polarization and magic angle sample spinning (CP/MAS NMR) methods. The numerical results for crystallinity obtained by using curve fitting methods in both cases correlated very well. It was concluded that the values for the crystallinity can be determined from NMR spectra when CP times not exceeding 0.5 ms are used. The range of order of the samples was further characterized calculating the radial atomic density function from the x-ray diffraction patterns and determining the greatest distances with significant deviations from the average density.
117 citations
TL;DR: In this article, a simplified morphological model has been suggested to describe these new hybrid systems, based on the experimental results, and the molecular weight of PTMO has been varied to study its effect on the structure-property behavior of these hybrid materials.
Abstract: Novel transparent hybrid materials incorporating triethoxysilane endcapped poly(tetramethylene oxide) with tetramethoxysilane have been successfully prepared by a sol-gel process. The molecular weight of PTMO has been varied to study its effect on the structure-property behavior of these hybrid materials. Mechanical properties and dynamic mechanical behavior have been measured; small angle X-ray scattering (SAXS) has been utilized to obtain structural information. Based on the experimental results, a simplified morphological model has been suggested to describe these new hybrid systems.
92 citations
TL;DR: In this article, Terthienyl and pyrrole, substituted with alkylsulfonate side chains, can be polymerized electrochemically without the addition of a conduction salt.
Abstract: α — Terthienyl and pyrrole, substituted with alkylsulfonate side chains, can be polymerized electrochemically without the addition of a conduction salt. This gives rise to self-doped conducting polymers that are soluble in water in the doped state.
68 citations
TL;DR: In this article, the bulk polymerization of methyl methacrylate (MMA) with 1,2-disubstituted tetraphenylethanes (TPSN), tetra(p-methoxyphenyl)succinodinitrile (TMPSN), and pentaphenylthane (PPE) was investigated.
Abstract: The bulk polymerization of methyl methacrylate (MMA) with 1,2-disubstituted tetraphenylethanes, tetraphenylsuccinodinitrile (TPSN), tetra(p-methoxyphenyl)succinodinitrile (TMPSN), and pentaphenylethane (PPE), was investigated. These compounds were found to serve as thermal iniferters to induce living radical polymerization via a mechanism close to the model proposed previously (see Eq. 2). However, the living nature was not so high, because undesirable side reactions occurred. The oligomer with molecular weight of 2500 was isolated from the reaction mixture of MMA with TPSN, which was found to cause further polymerization of MMA. From the polymerization of styrene (St) with the polymers obtained by these iniferters, the block copolymers were produced.
63 citations
TL;DR: In this article, a three-arm telechelic liquid polyisobutylenes PIB carrying exactly three -CH2C(CH3)2Cl end groups have been synthesized by living carbocationic polymerization using C6H3(C(C)2OCH 3)3/BCl3 complexes in CH3Cl and CH2Cl2 diluents in the 0° to −30°C range.
Abstract: SummaryThree-arm star telechelic liquid polyisobutylenes PIB carrying exactly three -CH2C(CH3)2Cl end groups have been synthesized by living carbocationic polymerization using C6H3(C(CH3)2OCH3)3/BCl3 complexes in CH3Cl and CH2Cl2 diluents in the 0° to −30°C range. The living nature of the polymerizations was demonstrated by linear Mnversus WPIB (g PIB) formed plots starting at the origin and horizontal N (moles of PIB) versus WPIB plots. Initiating efficiency (Ieff) was close to ∼100% and Mn was determined by the [monomer]/[initiator] ratio. Polymerizations guenched by methanol yield tert.-chlorine end groups which have been quantitatively converted to isopropylidene (-CH2C(CH3)=CH2) termini.
52 citations
TL;DR: In this article, it was concluded that the propagating carbocation is stabilized not by the counteranion but by an externally added basic compound (dioxane) that strongly interacts with the active end.
Abstract: Well-defined living polymers of isobutyl vinyl ether were obtained in the polymerization initiated with ethylaluminum dichloride (EtAlCl2) in conjunction with a stoichiometric excess of dioxane (5–10 vol%) in n-hexane at 0°C. Under these conditions, the number-average molecular weight of the polymers increased in direct proportion to monomer conversion, while the molecular weight distribution stayed narrow (Mw/Mn = 1.1–1.25). In sharp contrast, the EtAlCl2-initiated polymerization in the absence of dioxane led to non-living polymers with a broad molecular weight distribution. It was concluded that the propagating carbocation is stabilized not by the counteranion but by an externally added basic compound (dioxane) that strongly interacts with the active end.
52 citations
TL;DR: Differential scanning calorimetry (DSC) measurements have been carried out on a number of poly(butylene terephthalate) (PBT)/BPA polycarbonate (PC) blends prepared by melt compounding and solution casting from hexafluoroisopropanol (HFIP).
Abstract: Differential scanning calorimetry (DSC) measurements have been carried out on a number of poly(butylene terephthalate) (PBT)/BPA polycarbonate (PC) blends prepared by melt compounding and solution casting from hexafluoroisopropanol (HFIP). The results clearly indicate that appreciable mixing of the two polymers takes place in the melt phase whereas complete separation is observed in cast films. The failure of the casting procedure to mimic the melt blending results is related in part to liquid-liquid phase separation and to crystallization of both polymers from the casting solvent.
50 citations
TL;DR: In this paper, a scaling analysis of the rubber-like elastic behavior of a cross-linked polymer network is presented which incorporates the two most salient contributions to the free energy of deformation: the chain connectivity of the segments and the restrictions on the chain configurations due to entanglements.
Abstract: A scaling analysis of the rubber-like elastic behavior of a cross-linked polymer network is presented which incorporates the two most salient contributions to the free energy of deformation: the chain connectivity of the segments and the restrictions on the chain configurations due to entanglements. The affine deformation of the junction points is assumed and a tube model is used to discuss the deformation dependence of the entanglement constraint parameter.
49 citations
TL;DR: In this article, reaction dans CH 3 Cl ou CH 2 Cl 2 en presence de di (methoxy-2 propyl-2)-1,3-t-butyl-5 benzene associe a BCl 3
Abstract: Reaction dans CH 3 Cl ou CH 2 Cl 2 en presence de di (methoxy-2 propyl-2)-1,3-t-butyl-5 benzene associe a BCl 3
45 citations
TL;DR: In this paper, a −80°C was reported for CH 3 Cl/nC 6 H 14, with an average temperature of − 80°C dans CH 3 C 6 h 14.
Abstract: Reaction a −80°C dans CH 3 Cl/nC 6 H 14 . Influence de la temperature sur la structure du polymere
45 citations
TL;DR: The functionality of divinyl-terminated poly(dimethylsiloxane) (PDMS) was greatly increased by a substitution reaction to give PDMS with triethoxysilyl chain ends.
Abstract: The functionality of divinyl-terminated poly(dimethylsiloxane) (PDMS) was greatly increased by a substitution reaction to give PDMS with triethoxysilyl chain ends. Samples having number-average molecular weights of 720 and 17.6 × 103 g mol−1, and mixtures thereof, were added to tetraethoxysilane (TEOS) or a related silane. The functionalized PDMS-silane mixtures were hydrolyzed in the usual sol-gel technique to give polymer-modified silica glasses. The hardness of the glasses was measured, and then related to the molecular weight of the PDMS, its molecular weight distribution, the composition of the PDMS-silane mixtures, and the nature of the silane.
TL;DR: In this article, the temperature of the transition from Regimes I and II has been analyzed for several systems for which data is available for both overall crystallization rates and the direct growth rate of supermolecular structures.
Abstract: The temperature of the transition from Regimes I and II has been analyzed for several systems for which data is available for both overall crystallization rates and the direct growth rate of supermolecular structures. The same transition temperature is observed irrespective of the experimental method. In addition it is found that the Regimes do not serve as boundaries between distinct morphological forms.
TL;DR: In this article, butadienes were modified by an "ene' reaction using 4-phenyl-1, 2,4-triazoline-3,5-dione (1), 3-nitro-4-hydroxyphenyl (3-NH) and 4-hexyl-polyphenyl (4-RH) groups.
Abstract: Poly(butadienes) were modified by an ‘ene’-reaction using 4-phenyl-1, 2,4-triazoline-3,5-dione (1) 3′-nitro-4′-hydroxyphenyl-1, 2,4-triazoline-3,5-dione (2) and 4′-hydroxyphenyl1, 2,4-triazoline-3,5-dione (3). The resulting hydrogen bond complexes between urazole groups act as thermoreversible crosslinks and alter the melt rheological behaviour. While dimeric chelate-like complexes are formed in polymers modified with 1 or 2, a three dimensional structure of hydrogen bond complexes is formed if 3 is used as the modifying agent. The thermorheologically complex behaviour of the latter material is interpreted by structural changes in the three dimensional structure with temperature.
TL;DR: In this paper, four stable families of low energy conformers are found; three correspond to conformations observed in linear and cyclic maltodextrins in the crystalline state.
Abstract: An understanding of the molecular changes occurring during polymorphic transformations of amylose is sought through the use of energy calculations Four stable families of low energy conformers are found; three of these correspond to conformations observed in linear and cyclic maltodextrins in the crystalline state Upon change of solvent, significant variations have been shown to occur in the relative abundance of amylose conformers This, in turn, influences properties such as chain extension The relevance of the stable conformers with respect to helical structures of amylose is analyzed Whereas one of the conformers would generate a V type shallow helix, another one would give rise to a 6 fold left-handed strand having a 36 A advance per residue This would generate a double helical stranded structure
TL;DR: The Tg-composition curves of the five miscible blend systems can be described by the Gordon-Taylor and the Kwei equations as mentioned in this paper, and they show a positive deviation in their glass transition temperatures.
Abstract: Poly(p-vinyl phenol) is miscible with poly(methyl methacrylate), poly(ethyl methacrylate), poly(n-propyl methacrylate), poly(isopropyl methacrylate), and poly(tetrahydrofurfuryl methacrylate), but is immiscible with poly(n-butyl methacrylate). Except for poly(p-vinyl phenol)/ poly(methyl methacrylate) blends, the other miscible blends show pronounced positive deviations in their glass transition temperatures. The Tg-composition curves of the five miscible blend systems can be described by the Gordon-Taylor and the Kwei equations.
TL;DR: In this article, a ring-substituted aniline residue was added to the end-functionalized poly(isobutyl vinyl ether) and the resulting polymers exhibited a narrow molecular weight distribution.
Abstract: End-functionalized poly(isobutyl vinyl ether) (2) with a terminal amine, carboxylic acid, or ester group was prepared by quenching the HI/I2-initiated living polymer ends with ring-substituted anilines (H2N-C6H4-X, p or m; X = NH2, COOH, COOC2H5). The living polymerization of isobutyl vinyl ether and the subsequent end-capping reaction were carried out at −15°C in methylene chloride. The resulting polymers exhibited a narrow molecular weight distribution
$$(\bar M_W /\bar M_n = 1.1 - 1.2)$$
and carried one terminal function (aniline residue) per chain, according to 1H NMR structural analysis.
TL;DR: In this article, the results of a series of recent studies of the morphology and deformation behavior of toughened poly(butylene terephthalate) (PBT)/BPA polycarbonate (PC) blends are briefly summarized.
Abstract: In this communication the results of a series of recent studies of the morphology and deformation behavior of toughened poly(butylene terephthalate) (PBT)/BPA polycarbonate (PC) blends are briefly summarized. Several papers containing a more detailed account are currently in press (1–3). Among the unique morphological features of these blends are the consistent isolation of the core/shell impact modifier (IM) in the PC phase and the crystallization and phase separation of the PBT from the partially miscible PBT/PC melt on slow cooling. DSC studies provide corroborating evidence for melt miscibility of the two resins. The blends deform through a combination of cavitation and shear processes. In all cases cavitation occurs exclusively within the IM particles and is suppressed at higher PC concentrations and elevated temperatures.
TL;DR: In this paper, the curing reaction of diglycidyl ether of Bisphenol A (DGEBA) with triethylene tetramine (TETA) was studied by the differential scanning calorimetry (DSC).
Abstract: The curing reaction of diglycidyl ether of Bisphenol A(DGEBA) with triethylene tetramine(TETA) was studied by the differential scanning calorimetry(DSC). The reaction was affected as the vitrification occurred when the glass transition temperature(Tg) of the reaction mixture exceeded the curing temperature. In order to describe the curing reaction in the rubbery state as well as in the glassy state, the reaction kinetic equation containing the generalized WLF equation term was proposed and the parameters were determined from the DSC data.
TL;DR: In this paper, the synthesis and characterization of side-chain liquid crystalline polysiloxane and copolysiloxanes containing trans 5-(n-undecanyl)-2-(4-methoxyphenyl)-1,3-dioxane and respectively trans 2-(ndecanyl)-5-(4)-methoxide polysiloxide side groups is presented, in most cases the resulting polymers exhibit two glass transition temperatures, i.e., one due to the independent motion of the main chain, and the other due to independent but cooperative motion of
Abstract: The synthesis and characterization of side-chain liquid crystalline polysiloxanes and copolysiloxanes containing trans 5-(n-undecanyl)-2-(4-methoxyphenyl)-1,3-dioxane and respectively trans 2-(n-decanyl)-5-(4-methoxyphenyl)-1,3-dioxane side groups is presented. In most cases the resulting polymers exhibit two glass transition temperatures, i.e., one due to the independent motion of the main chain, and the other due to the independent but cooperative motion of the side chains.
TL;DR: In this paper, the effect of temperature and solvent composition (polar/nonpolar) on the polymer structure has been investigated by rapid living polymerization using aromatic di-tert.-ether/BCl3 initiator system in CH3Cl at −70°.
Abstract: SummaryThe efficient synthesis of symmetrical telechelic polyisobutylenes carrying ∼ CH2C(CH3)2Cl groups at either end of the molecule,
$$\\mathop - \\limits^t Cl - PIB - Cl\\mathop - \\limits^t$$
, has been accomplished by rapid living polymerization using aromatic di-tert.-ether/BCl3 initiator system in CH3Cl at −70°. The living nature of the polymerization was demonstrated by linear Mn versus amount of PIB formed (WPIB) plots starting at the origin. The effect of temperature and solvent composition (polar/nonpolar) on the polymer structure has been investigated. Undesirable indanyl end groups which form during polymerizations carried out at −30° and −50°C can be eliminated by decreasing the temperature to −70°C. The apparent activation energy differences have been determined in the −30 to −70°C range at different polar/nonpolar solvent compositions: ΔEa of
$$\\mathop - \\limits^t Cl - PIB - Cl\\mathop - \\limits^t$$
decreases from 2.6 to 1.0 kcal/mole by decreasing the polarity of the medium from 100% CH3Cl to a 60/40 v/v CH3Cl/hexanes mixture.
TL;DR: In this article, the authors forecast quantitatively molecular weight, gel point and modulus from the conversions of >SiH, >C=CHf2 and the chain entanglement concentration reported for polyisobutene in the literature.
Abstract: A liquid polyisobutene oligomer with unsaturated chain ends undergoes hydrosilylation with HMe2SiOMe2SiOMe2SiH or Si(OMe2SiH)4 to give higher molecular weight polymers or elastomers. A major side reaction consumes SiH to give redistributed siloxane in the resulting polymers and gaseous silanes and siloxanes as by-products. A second side reaction results in loss of reactivity in the oligomer due to a shift of the terminal double bond to an internal position. If the side reactions are taken into account, it is possible to forecast quantitatively molecular weight, gel point and modulus from the conversions of >SiH, >C=CHf2 and the chain entanglement concentration reported for polyisobutene in the literature.
TL;DR: In this paper, the technique developed for precipitating reinforcing silica into an elastomer is extended to titania fillers by hydrolyzing a titanate instead of a silicate.
Abstract: The technique developed for precipitating reinforcing silica into an elastomer is extended to titania fillers by hydrolyzing a titanate instead of a silicate. Of the three catalysts studied, namely HCl, NH4OH, and (C2H5)2NH, the NH4OH was the most efficient, introducing as much as 65 wt % titania into a poly(dimethylsiloxane) network in twelve hours. Stress-strain measurements in elongation showed the nature and extent of the reinforcement to be very similar to that obtained from insitu precipitated silica.
TL;DR: The nonconjugated poly (3,3-dimethyl-1-butyne) and poly (1-trimethylsilyl)-1-propyne were prepared by metathesis catalysts and the polymerization was monitored for molecular weight by GPC and monomer conversion by GC.
Abstract: The non-conjugated poly (3,3-dimethyl-1-butyne) and poly (1-trimethylsilyl)-1-propyne were prepared by metathesis catalysts and the polymerization was monitored for molecular weight by GPC and monomer conversion by GC. Both the 1-(trimethylsilyl)-1-propyne and 3,3-dimethyl-1-butyne gave a linear relationship with number average molecular weight versus conversion and number average molecular weight versus monomer to initiator ratio. The 1-(trimethylsilyl)-1-propyne failed to polymerize beyond 100% conversion. The 3,3-dimethyl-1-butyne, however, gave conversion to 300%, with GPC data clearly showing the continuation of propagation from the living polymer chain. The living character of these polymerizations seems to be the result of both the lack of backbiting which can occur only from a cis-cisoidal growing chain, and the lack of interchain reactions. Both the cis-cisoidal configuration and the interchain reactions are prohibited for steric reasons.
TL;DR: Relation entre temperature and the SANS for des solutions and des reseaux du polymere ou pour le copolymere ayant 5% de methacrylate de sodium dans l'eau deuteriee.
Abstract: Relation entre la temperature et la SANS pour des solutions et des reseaux du polymere ou pour le copolymere ayant 5% de methacrylate de sodium dans l'eau deuteriee
TL;DR: In this paper, the authors observed significant piezoelectric activity in cast films of poly(1-bicyclobutanecarbonitrile) and showed that it is possible to construct a cast film with poly( 1-bicycleclobutaine) carbonitrile.
Abstract: We observed significant piezoelectric activity in cast films of poly(1-bicyclobutanecarbonitrile).
TL;DR: In this article, a humidity sensor was fabricated by depositing gold electrodes on both sides of the grafted polyethylene film, measured as a function of humidity for the acid and alkali salts of sulfonate.
Abstract: Inside a microporous polyethylene film, 2-acrylamido-2-methylpropane sulfonic acid was graft polymerized by ultraviolet irradiation. A humidity sensor was fabricated by depositing gold electrodes on both sides of the grafted film. The impedance was measured as a function of humidity for the acid and alkali salts of sulfonate. The sensor has long term stability and is resistant to water.
TL;DR: In this article, the authors clarified the mechanism of living radical polymerization of methyl methacrylate (MMA) with tetraphenylsuccinodinitrile (TPSN) as a thermal iniferter.
Abstract: To clarify the mechanism of living radical polymerization of methyl methacrylate (MMA) with tetraphenylsuccinodinitrile (TPSN) as a thermal iniferter, a model compound for the end group of the poly(MMA) produced, methyl 2,2-dimethyl-3,3-diphenyl-3-cyanopropionate (2), was synthesized and found to initiate a living radical polymerization of MMA, indicating that the hexa-substituted C-C bond in 2 dissociated into radicals. The poly(MMA) thus obtained further initiated the radical polymerization of styrene (St) to give a block copolymer.
TL;DR: In this article, a thin film of poly(L-glutamate) containing 6′-nitroindolinospiropyran was exposed to uv light (mainly 365nm), and measurable change in the optical rotatory power was observed, accompanied with the coloration due to the formation of the photo-merocyanine.
Abstract: When the thin film of poly(L-glutamate) containing 6′-nitroindolinospiropyran was exposed to uv light(mainly 365nm), measurable change in the optical rotatory power was observed, accompanied with the coloration due to the formation of the photo-merocyanine. The change was reversible upon exposure to visible light(>480nm). The extent of the reversible change of the optical rotatory power was found to depend on the concentration of the spiropyran as well as casting concentration. Discussion was made on the mechanism of the appearance of the optical rotatory power.
TL;DR: In this article, a new model was derived to calculate the solute diffusion coefficient through heterogeneous membranes consisting of a crosslinked, swollen phase and an impermeable, crystalline phase.
Abstract: A new model is derived to calculate the solute diffusion coefficient through heterogeneous membranes consisting of a crosslinked, swollen phase and an impermeable, crystalline phase. The solute diffusion coefficient is shown to depend on various structural characteristics of the amorphous permeable phase and on the volume fraction of the impermeable phase.
TL;DR: In this paper, high strength polyethylene fibres, with a tensile strength at break of 3.0 and 3.4 GPa, were irradiated, at various temperatures in a hydrogen atmosphere, by means of high energy electrons.
Abstract: Ultra-high strength polyethylene fibres, with a tensile strength at break of 3.0 and 3.4 GPa, were irradiated, at various temperatures in a hydrogen atmosphere, by means of high energy electrons. When the fibres were not annealed, the tensile strength at break was found to decrease upon irradiation, while the Young's modulus remained unchanged. A maximal obtainable tensile strength of 22 GPa was calculated from the decrease in tensile strength and the gel-sol measurements. Gel contents upto 100% were obtained for fibres irradiated in the hexagonal phase.