bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modification of poly(epichlorohydrin) with nadimide derivatives and their curing reaction
Authors: Galià M. , Mantecón A. , Cádiz V. , Serra A. 
Published: April 2003

AbstractChemical modification of poly(epichlorohydrin) (PECH) with nadimide derivatives using 1,8‐diazabicyclo (5.4.0)−7 undecene to catalyze the substitution of the chlorine atom by acid compounds (DBU method) was accomplished. The linear polyethers obtained showed a degree of substitution from 5–80%, depending on time and temperature reaction. The Tg of modified polymers and Ea, calculated in the cure reactions, increases with substitution degree. Residual enthalpies were observed in all cases, which suggests that the curing reaction is incomplete. TGA measurements showed that the degradation has a greater dependence on the modification degree than on the introduced pendant group. © 1994 John Wiley & Sons, Inc.
Polymers incorporating backbone thiophene, furan, and alcohol functionalities formed through chemical modifications of alternating olefin–carbon monoxide copolymers
Authors: Jiang Zhaozhong , Sanganeria Siddharth , Sen Ayusman 
Published: April 2003

AbstractThe reaction of the alternating ethylene–carbon monoxide copolymer with Lawesson's reagent resulted in the conversion of 75% of the carbonyl groups to thiophene units. A few thioketone groups were also present in the derived polymer. A polymer with furan units in the backbone was formed upon treatment of the alternating propylene–carbon monoxide copolymer with P2O5. Depending on the reaction conditions, up to 90% of the carbonyl groups were converted. Finally, 1,4‐polyalcohols were prepared from the alternating propylene‐carbon monoxide copolymer by reduction. Hydrogenation using Raney nickel as catalyst resulted in the reduction of 60% of the carbonyl groups, whereas reaction with LiAlH4 at room temperature caused the reduction of 85% of the carbonyl groups. The glass transition temperature was found to increase monotonically with increasing concentration of hydroxyl groups in the polymer backbone. © 1994 John Wiley & Sons, Inc.
Synthesis of graft copolymers having phospholipid polar group by macromonomer method and their properties in water
Authors: Ishihara Kazuhiko , Tsuji Tsuyoshi , Sakai Yuko , Nakabayashi Nobuo 
Published: April 2003

AbstractWater‐soluble graft copolymers with phospholipid polar group were synthesized by the macromonomer method and their properties in water were investigated by surface tension and fluorescence spectroscopic measurements. At first, 2‐methacryloyloxyethyl phosphorylcholine (MPC) was polymerized in the presence of 3‐mercapt propionic acid as a chain transfer agent and carboxyl group‐terminated oligo (MPC) was obtained. The oligo (MPC) reacted with glycidyl methacrylate to convert the carboxyl group to a polymerizable methacryloyl group. The MPC macromonomer obtained was copolymerized with hydrophobic n‐butyl methacrylate (BMA) and a graft copolymer was obtained. The graft copolymer, poly(MPC‐graft‐BMA), was water‐soluble when the MPC unit mole fraction was above 0.40. The surface tension of the aqueous solution of poly(MPC‐graft‐BMA) did not depend on the polymer concentration below 0.1 wt %. This tendency was the same as that which appeared in aqueous poly(MPC) solution. The fluorescence intensity of hydrophobic probes observed in an aqueous solution of the poly (MPC‐graft‐BMA) was also the same level as that observed in the case of poly(MPC). These results clearly indicated that the poly(MPC‐graft‐BMA) took a domain structure like micelle in water, i.e., the hydrophobic poly(BMA) backbone was in the core part and the hydrophilic poly(MPC) chain formed the shell part of the micelle. © 1994 John Wiley & Sons, Inc.
Synthesis and characterization of new aromatic polyesters and polyethers derived from 1,2‐bis(4‐hydroxyphenyl)‐1,2‐diphenylethylene
Authors: Watanabe Shinji , Kobayashi Atsushi , Kakimoto Masa‐Aki , Imai Yoshio 
Published: April 2003

AbstractNew polyarylates and aromatic polyethers were synthesized from 1,2‐bis(4‐hydroxyphenyl)‐1,2‐diphenylethylene, and aromatic dicarboxylic acid chlorides and aromatic dihalides, respectively. The polyarylates having inherent viscosities of 0.28–1.05 dL/g were synthesized by either the two‐phase method or the high‐temperature solution method. All the polymers were easily soluble in N‐methyl‐2‐pyrrolidone, N,N‐dimethylformamide, pyridine, m‐cresol, 1,4‐dioxane, and 1,1,2,2‐tetrachloroethane. They have glass transition temperatures in the range of 217–250°C and showed no weight loss below 315°C in both air and nitrogen atmospheres. Aromatic polyethers with inherent viscosities of 0.85–1.21 dL/g were obtained by the polycondensation of 1,2‐bis(4‐hydroxyphenyl)‐1,2‐diphenylethylene and aromatic difluorides in the presence of potassium carbonate. These polymers having glass transion temperatures of 193–220°C were also soluble in the aforementioned solvents and stable up to around 350deg;C in both atmospheres. © 1994 John Wiley & Sons, Inc.
Phenolic materials via ring‐opening polymerization: Synthesis and characterization of bisphenol‐A based benzoxazines and their polymers
Authors: Ning Xin , Ishida Hatsuo 
Published: April 2003

AbstractCompounds with bifunctional benzoxazine groups in their molecular structures form crosslinked structures characteristic of phenolic materials through a ring‐opening reaction mechanism. This family of compounds offers greater flexibility than conventional novolac or resole resins in terms of molecular design. It is also superior to conventional phenolic resin in process control since it releases no by‐product during curing reactions. The materials thus obtained exhibit excellent mechanical integrity with glass transition temperatures over 200°C. The synthesis, composition, and structural analysis of precursors based on bisphenol‐A are discussed herein. © 1994 John Wiley & Sons, Inc.
Comparative characterization of MgCl2/ethyl benzoate/TiCl4 and MgCl2/2,2,6,6 tetramethylpiperidine/TiCl4 Ziegler‐Natta precatalysts
Authors: Ferreira Maŕia L. , Damiani Daniel E. 
Published: April 2003

AbstractIn this article we present the results of the preparation and characterization of two Ziegler–Natta precatalysts: MgCl2/Ethyl benzoate (EB)/TiCl4 and MgCl2/2,2,6,6 tetramethylpiperidine (TMPiP)/TiCl4 by means of FTIR, X‐ray diffraction, SEM, BET surface area measurements, and other techniques applied at different steps of their preparation procedures.The precatalysts were prepared by impregnating with TiCl4 a given amount of MgCl2, which was previously ball‐milled with the electron donor chosen.Prior to impregnation, the ball‐milled material presented different surface compounds depending on the electron donor used: [(MgCl2)2] · 2EB, MgCl2 · EB, or a salt of the amine. The solid milled with EB is more homogeneous than the one milled with the TMPiP.Titanium is better retained in the solid milled with EB. This precatalyst has better morphological properties and larger BET surface area. By means of FTIR, we found evidences that an adequate surface structure for the formation of stereospecific sites in MgCl2/TMPiP/TiCl4 was formed. © 1994 John Wiley & Sons, Inc.
Curing of epoxidized natural rubber with p‐phenylenediamine
Authors: Hashim A. S. , Kohjiya S. 
Published: April 2003

AbstractThe curing of epoxidized natural rubber with p‐phenylenediamine catalyzed by bisphenol A was investigated. The curing reaction was found to be first order with respect to the amine and to have an activation energy of 67.5 kJ/mol. Vulcanizates of tensile strength 12.5–16.0 MPa were obtained at cure times of 30–75 min at 180°C. The amine‐cured vulcanizate was observed to be more rigid than the sulfur‐cured one at room temperature consistent with its relatively high Tg. Stress‐strain analysis and dynamic mechanical properties indicated that the high Tg of the amine‐cured vulcanizate could be attributed to the bulky amine crosslinks and hydrogen bonding effect of bisphenol A. © 1994 John Wiley & Sons, Inc.
Thermodynamic studies of some complexation systems involving methacrylic acid‐acrylamide copolymer, poly(vinyl pyrrolidone) and poly(ethylene oxide)
Authors: Chatterjee S. K. , Chhabra Mamta , Johri Shalini 
Published: April 2003

AbstractInterpolymer complexes of methacrylic acid‐acrylamide copolymer have been prepared by the interaction of its comonomer units with two different homopolymers, and also with a single homopolymer. The stability constants and related thermodynamic parameters (e.g., ΔH0 and ΔS0) of the mixed complex were found to be significantly different from the single homopolymer complexes. This has been attributed to neighboring group influence and destabilization of various interacting forces at different temperatures. © 1994 John Wiley & Sons, Inc.
Thermally initiated frontal polymerization of transition metal nitrate acrylamide complexes
Authors: Savostyanov V. S. , Kritskaya D. A. , Ponomarev A. N. , Pomogailo A. D. 
Published: April 2003

AbstractThe effect of the thermally initiated frontal polymerization of acrylamide complexes of transition metal nitrates such as those of Mn(II), Co(II), Ni(II), and Zn(II) was disclosed. The rate of the polymerization front propagation was found to be 2−9 × 10−2cm/c, depending appreciably on sample diameter and density, as well as the presence of radical inhibitor additives. The rate was found to decrease in the series: Co(II) > Ni(II) > Mn(II) > Zn(II). Polymerization was shown to occur directly in the melting region of a complex at 80–100°C to give three‐dimensional polymers. A mechanism of the polymerization being initiated with the products of the partial nitrate group decomposition was proposed. © 1994 John Wiley & Sons, Inc.
The effect of the nature of organoaluminium compound and the catalytic system preparation procedure on molecular characteristics of 1,4‐Cis‐polybutadiene
Authors: Kozlov V. G. , Sigaeva N. N. , Nefedjev K. V. , Savel'eva I. G. , Marina N. G. , Monakov Yu. B. 
Published: April 2003

AbstractThis study investigated the effect produced by the preparation procedure of a 2‐component lanthanide catalytic system and by the nature of organoaluminium compound on 1) the molecular characteristics of 1,4‐cis‐polybutadiene (PB), 2) the regularities of its average molecular weight (MW), and 3) molecular weight distribution (MWD). The kinetic parameters of the polymerization process were calculated. The principal regularities of variations in PB molecular characteristics with respect to the polymerization conditions, i.e., OAC and monomer concentrations and temperature, are retained with different procedures of the lanthanide catalytic system, and those present distinctive features of the catalytic complexes studied in this article. But as for differences in MW and its patterns of dependence on monomer conversion rate and OAC nature, these are due to changes in kinetic parameters of the polymerization, which occur with the use of the catalyst prepared by a different procedure. © 1994 John Wiley & Sons, Inc.
Kinetics of polymerization of 1‐octene with Mgcl2‐supported Ticl4 catalysts
Authors: Kothandaraman H. , Devi M. Saroja 
Published: April 2003

AbstractA number of TiCl4 catalysts supported on MgCl2 which was activated by the recrystallization method using different alcohols were prepared with ethyl benzoate or dibutyl phthalate as the internal electron donor. All the catalysts were characterized by BET, x‐ray diffraction, and hydrolysis–GC analysis. Kinetics of polymerization of 1‐octene was studied with three of the above catalysts (having different internal electron donors) activated by AlEt3. The rate of polymerization increased linearly with increasing temperature, and catalyst and monomer concentrations. From the Arrhenius plot, the overall activation energies of polymerization were determined and the dependence of rate on the AlEt3 concentration could be explained by the Langmuir‐Hinshelwood mechanism. 13C‐NMR was used to study the effect of internal electron donors on the % isotacticity of poly(1‐octene). The catalytic activities of all the catalysts were compared in 1‐octene polymerization. © 1994 John Wiley & Sons, Inc.
Electrical conductivity of iodine‐doped pseudo interpenetrating polymer networks of poly‐(carbonate‐urethane) and natural rubber
Authors: Frisch H. L. , Chen Z. J. 
Published: April 2003

AbstractRecent DC conductivity measurements on iodine‐doped full and psuedo IPNs of poly (carbonate‐urethane) (PCU) and natural rubber (NR) reveal that these materials possess a modest conductivity. Both such full and pseudo IPNs (with linear NR chains) are single‐phased materials if the NR is of sufficiently high molecular weight derived from Brazilian Manihot glaziovii. On iodine doping the electrical conductivity rises eight orders of magnitude of both the full IPN (to ca. 10−5S cm−1) and the pseudo IPN (to ca. 10−4 S cm−1). A simple theory based on the assumption that conduction occurs essentially along the linear NR chains, composing a percolation cluster, in the iodine‐doped pseudo IPNs of PCU and NR accounts for the observed electrical conductivity dependence on temperature, iodine molality, and weight fraction of NR. As temperature decreases the DC conductivity falls and the material becomes essentially an insulator. At sufficiently low temperature (ca. 115 K) this trend reverses and the DC conductivity rises by two orders of magnitude with further decreasing temperature up to that of liquid helium. © 1994 John Wiley & Sons, Inc.
Chemical modification of poly(2,6‐dimethyl‐1,4‐phenylene oxide) by bromination‐alkynylation
Authors: Bonfanti C. , Lanzini L. , Roggero A. , Sisto R. 
Published: April 2003

AbstractThe chemical modification of poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) by bromination of the aromatic ring, followed by displacement of bromine with substituted acetylenes, has been investigated. This pathway leads to a series of novel copolymers containing substituted alkynes on the aromatic ring. The degree of bromination and alkynylation, determined by 1H‐NMR, was in the range of 20–85 and 15–80%, respectively. 13C‐NMR and FT‐IR unambiguously elucidated the structure of the alkynylated polymers. Finally, thermal properties and permeation properties of substituted PPO to carbon dioxide, methane, oxygen, and nitrogen are reported. © 1994 John Wiley & Sons, Inc.
A multi‐technique study of the spontaneous oxidation of N‐hexane plasma polymers
Authors: Gengenbach Thomas R. , Vasic Zoran R. , Chatelier Ronald C. , Griesser Hans J. 
Published: April 2003

AbstractLong‐term compositional changes were observed when n‐hexane plasma polymers were stored in air at ambient temperature. These post‐deposition changes were monitored over periods exceeding one year using XPS, grazing angle FTIR, and SEM. A rapid initial increase in the oxygen content was followed by a slower oxygen uptake, which continued for many months. In contrast to the reported autocatalytic acceleration of the oxidation of polyolefins, the rate of oxidation of n‐hexane plasma polymers was found to decrease continuously, and it did not proceed to the same extent toward higher oxidation states. The plasma polymer coatings did not show physical manifestations of oxidative degradation such as cracking, reduction in thickness, or loss of physical integrity. Comparison of the XPS and FTIR data suggested that the top few nanometers of the plasma polymer coatings oxidized at a faster rate than the “bulk.” The experimental data were interpreted using a model comprising reactions known from the oxidative degradation of polyolefins: carbon‐centered radicals, trapped in the course of the plasma deposition, combine with atmospheric oxygen to form metastable peroxy radicals and hydroperoxides, which decompose to generate a variety of stable product groups such as hydroxyl, carbonyl, and carboxylic groups. There was broad agreement between the XPS data and the time dependence of particular species in model calculations. © 1994 John Wiley & Sons, Inc.
Synthesis and characterization of poly(urethane‐sulfone)s
Authors: Zhang Tianhong , Litt Morton H. , Rogers Charles E. 
Published: April 2003

AbstractEight poly(urethane‐sulfone)s were synthesized from two sulfone‐containing diols, 1,3‐bis(3‐hydroxypropylsulfonyl)propane (Diol‐333) and 1,4‐bis(3‐hydroxypropylsulfonyl)butane (Diol‐343), and three diisocyanates, 1,6‐hexamethylene diisocyanate (HMDI), 4,4′‐diphenylmethane diisocyanate (MDI), and tolylene diisocyanate (TDI, 2,4‐ 80%; 2,6‐20%). As a comparison, eight polyurethanes were also synthesized from two alkanediols, 1,9‐nonanediol and 1,10‐decanediol, and three diisocyanates. Diol‐333 and Diol‐343 were prepared by the addition of 1,3‐propanedithiol or 1,4‐butanedithiol to allyl alcohol and subsequent oxidation of the resulting sulfide‐containing diols. The homopoly(urethanesulfone)s from HMDI and MDI are semicrystalline, and are soluble in m‐cresol and hot DMF, DMAC, and DMSO. The copoly(urethane‐sulfone)s from a 1/1 molar ratio mixture of Diol‐333 and Diol‐343 with HMDI or MDI have lower crystallinity and better solubility than the corresponding homopoly(urethane‐sulfone)s. The poly(urethane‐sulfone)s from TDI are amorphous, and are readily soluble in m‐cresol, DMF, DMAC, and DMSO at room temperature. Differential scanning calorimetry data showed that poly(urethane‐sulfone)s have higher glass transition temperatures and melting points than the corresponding polyurethanes without sulfone groups. The rise in glass transition temperature is 20–25°C while the rise in melting temperature is 46–71°C. © 1994 John Wiley & Sons, Inc.
Polymerization photoinitiated by carbonyl compounds. X. Methyl methacrylate polymerization photoinitiated by fluorenone in the presence of triethylamine
Authors: Encinas M. V. , Lissi E. A. , Rufs A. M. , Previtali C. M. 
Published: April 2003

AbstractThe photoinitiation efficiency of the fluorenone/triethylamine (TEA) system in the polymerization of methylmethacrylate (MMA) has been evaluated as a function of the monomer concentration, the amine concentration, and the polarity of the reaction medium. The polymerization proceeds readily in low polarity media (benzene/monomer), but it is negligible in more polar solvents (acetonitrile/monomer). The polymerization rate increases with the amine concentration up to 0.01 M TEA. Further increase in amine concentration produces a decrease in the polymerization rate. A similar behavior was observed for the fluorenone photoreduction yield and the yield of fluorenone derived radicals. All these processes are considered to involve the excited triplet, while quenching of the excited singlet by the amine decreases the rate of these processes. However, the decrease in photoinitiation efficiency observed at high amine concentration is larger than that expected from the singlet quenching extent, as estimated from the effect of the amine on the fluorescence yield under the same experimental conditions. This discrepancy indicates that other process(es) must contribute to the protection afforded by high amine concentrations. Quenching of the charge transfer intermediate by the amine is postulated as a competitive process that could explain the above mentioned effects. © 1994 John Wiley & Sons, Inc.
Surface modification of polyethylene fiber by graft polymerization
Authors: Mori Masaru , Uyama Yoshikimi , Ikada Yoshito 
Published: April 2003

AbstractTo improve the wettability and adhesion, graft polymerization of acrylamide (AAm) and glycidyl methacrylate (GMA) was performed onto the surface of ultra‐high modulus polyethylene (UHMPE) fiber pretreated with Ar plasma. Following the plasma treatment and the subsequent exposure to air to introduce peroxides onto the fiber surface, graft polymerization onto the UHMPE fiber was allowed to proceed from the polymer peroxides either in deaerated monomer solution at an elevated temperature (degassing method), or in aerated monomer solution containing riboflavin at 30°C under UV irradiation (photoinduction method). The monomer solution was prepared from water and dioxane for AAm and GMA, respectively. After rigorous removal of homopolymers, surface analysis of the grafted fibers was performed with ATR‐FTIR and XPS, which revealed that PAAm and PGMA chains were grafted in the surface region of fibers. The grafting rate of PAAm by the photoinduction method was much higher than that by the degassing method when compared at the same concentration of the AAm solution. The amount of PGMA grafted was greatly affected by UV irradiation time, but depended on plasma treatment time to an insignificant extent if the treatment was carried out for longer than 30 s. Reaction of propylamine with the PGMA‐grafted surface resulted in the appearance of a nitrogen peak in the XPS spectrum, suggesting the presence of epoxy groups on the surface of PGMA grafted fiber. © 1994 John Wiley & Sons, Inc.
Polymerizability of norbornene in ring‐opening metathesis polymerization initiated by Mo‐based complexes
Authors: Heroguez Valérie , Fontanille Michel 
Published: April 2003

AbstractConcerning the study on the relation between structural parameters and reactivity in ring‐opening metathesis polymerization of cyclo‐olefins, the “living” polymerization of norbornene initiated by Schrock's‐type complexes was considered as a reference and studied from the kinetic point of view. First kinetic orders with respect to both monomer and active species allow the values of absolute rate constants of propagation to be determined. The thermodynamic parameters obtained from kinetic experiments performed at different temperatures seem to indicate that monomer coordination and metallacycle formation are rate‐determining steps in the process studied. © 1994 John Wiley & Sons, Inc.
Primary thermal degradation processes occurring in poly(phenylenesulfide) investigated by direct pyrolysis–mass spectrometry
Authors: Montaudo Giorgio , Puglisi Concetto , Samperi Filippo 
Published: April 2003

AbstractThe thermal degradation Processes which occur in poly(phenylenesulfide) (PPS) have been studied by direct pyrolysis‐mass spectrometry (DPMS). The structure of the compounds evolved in the overall temperature range of PPS decomposition (400–700°C) suggests the occurrence of several thermal decomposition steps. At the onset of the thermal degradation (430–450°C) this polymer decomposes with the formation of cyclic oligomers, generated by a simple cylization mechanism either initiated at the—SH end groups or by the exchange between the inner sulfur atoms along the polymer chain. At higher temperature (> 500°C) another decomposition reaction takes over with the formation of aromatic linear thiols. The formation of thiodibenzofuran units by a subsequent dehydrogenation reaction occurs in the temperature range of 550–650°C; in fact, pyrolysis products with a quasi‐ladder structure have also been detected. Ultimately, above 600°C, extrusion of sulfur from the pyrolysis residue occurs with the maximum evolution at the end of decomposition (about 700°C). It appears, therefore, that the residue obtained at high temperature tends to have a crosslinked graphite‐like structure from which the bonded sulfur is extruded. © 1994 John Wiley & Sons, Inc.