bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface modification of calcium carbonates studied by inverse gas chromatography and the effect on mechanical properties of filled polypropylene
Authors: Price Gareth J , Ansari Deeba M 
Published: March 2004

AbstractInverse gas chromatography (IGC) has been used to characterize the surfaces of a pure calcitic calcium carbonate as well as samples that had been treated with sodium polyacrylate and/or stearic acid. The dispersive components of the surface free energy for the pure material agreed well with related literature data. Polar contributions to the surface interactions with a range of probes were determined. The results show that the surface treatments reduced the polarities of the surfaces and that modification with stearic acid produced a non‐polar, low‐energy surface. Some mechanical properties of the polypropylene composites containing the modified calcium carbonates were found to correlate well with the filler surface energies. Copyright © 2004 Society of Chemical Industry
Performance of an intumescent‐flame‐retardant master batch synthesized by twin‐screw reactive extrusion: effect of the polypropylene carrier resin
Authors: Wang Qi , Chen Yinghong , Liu Yuan , Yin Huan , Aelmans Nico , Kierkels Rene 
Published: March 2004

AbstractA novel way of preparing an intumescent flame retardant (IFR) and its master batch by the reactive extrusion of melamine phosphate and pentaerythritol, together with a polypropylene (PP) carrier, in a twin‐screw extruder has been established. The effect of the PP carrier resin on the flame retardancy and water resistance of the intumescent‐flame‐retarding PP materials was investigated by using the limited oxygen index (LOI), UL94 test, elemental analysis (EA), thermogravimetric analysis (TGA) and water solubility testing, respectively. In addition, the mechanism of the carrier effect was analysed by melt flow index (MFI), scanning electron microscopy (SEM), and TGA. The experimental results show that with increasing content of carrier resin (PP) in the IFR master batch from 0 to 15 wt%, the flame retardancy LOI of the PP/IFR (25 wt% loading) blend increased from 29.5 to 32, and the UL94 level at 1.6 mm thickness was improved from failure to a V‐0 rating. In addition, the water resistance of a flame‐retarded composite at 25 wt% IFR loading was greatly improved, i.e. after treatment with hot water at 70 °C for 168 h, the reducing rate of element N in the IFR/PP blend decreased from 18.3% with 5 wt% carrier resin to 12.9% with 15 wt% carrier resin, and the LOI reduction rate decreased from 15.3% without any carrier resin to 10.9% with 15 wt% carrier resin, while the flame‐retarded PP with an IFR master batch containing 10–15 wt% carrier resin maintained its UL94 V‐0 rating at 3.2 mm thickness. The improvement in flame retardancy was attributed to the improved flame‐retardant (FR) dispersion due to the carrier resin, while the improved water resistance was explained by the lowered water solubility of the IFR, the improved FR dispersion and the improved compatibility of the FR with the matrix resin due to the carrier resin. Reactive extrusion is a novel way to obtain pelletissed IFRs without powder pollution and their corresponding flame‐retarding materials with a number of desired properties. Copyright © 2004 Society of Chemical Industry
Ethylene–(vinyl acetate) copolymer/carbon fiber conductive composite: effect of polymer–filler interaction on its electrical properties
Authors: Di Wei‐hua , Zhang Guo , Zhao Zhu‐Di , Peng Yi 
Published: March 2004

AbstractEthylene–(vinyl acetate) (EVA)/carbon fibre (CF) composites were prepared by changing the content of CF in the composite. To investigate the effect of the interaction between EVA and CF on the electrical properties of the composite, the CF was treated in nitric acid. The interaction between EVA and CF was examined by a solvent‐extraction method. It was found that the interaction of EVA with CF was enhanced due to the chemical absorption of EVA on CF. The correlation of CF content, electrical properties and the formation of polymer–filler gel for the composite with oxidized CF was studied. Although the composites filled with treated CF exhibit a slightly higher resistivity than those filled with untreated CF at room temperature, they show the improved electrical properties, including elimination of the negative‐temperature‐coefficient (NTC) effect, high electrical reproducibility after thermal cycles, and independence of the conductivity on time, which improves the practical applications of positive‐temperature‐coefficient (PTC) materials. Copyright © 2004 Society of Chemical Industry
Modelling of the interactions between a photochromic naphthopyran and a poly(methyl methacrylate) matrix through the variation of the glass transition temperature and application of the energy/volume/mass (EVM) model
Authors: Rauzy Evelyne , Berro Charles , Morel Sébastien , Herbette Gaétan , Lazzeri Véronique , Guglielmetti Robert 
Published: March 2004

AbstractA quantitative structure property relationship (QSPR) model, called the EVM (energy, volume, mass) model, to calculate the glass transition temperature (Tg) of a poly(methyl methacrylate) matrix as a support of a naphthopyran photochromic pigment, as a function of the concentration of this pigment, is described. The interactions between the photochromic pigment and the polymer matrix, and especially the van der Waals non‐bonding interactions, are important for the photochromic behaviour of the optical material and the commercial availability of glasses. The prediction of Tg through a multiparametric relationship is interesting for the choice of the best conditions of formulation of the couple photochromic pigment–polymer matrix Copyright © 2004 Society of Chemical Industry
Morphology and thermal properties of two polymethacrylates modified by a polymer liquid crystal
Authors: Brostow Witold , Gargallo Ligia , Hormazabal Andrea , Jaklewicz Magdalena , Menard Kevin P , Opazo Alejandra , Radic Deodato 
Published: March 2004

AbstractWe have studied blends of a polymer liquid crystal (PLC) with poly(cyclohexylethyl methacrylate) (PCHEMA) or poly(cyclohexylpropyl methacrylate) (PCHPMA). The PLC is PET/0.6PHB where PET = poly(ethylene terephthalate), PHB = p‐hydroxybenzoic acid and 0.6 is the mole fraction of the latter in the copolymer. The microstructure was studied by scanning electron microscopy (SEM). PCHEMA + PLC (20 wt% of the latter, blend E) has a fine texture with LC islands evenly distributed in the matrix and good adhesion between the phases resulting from their partial miscibility. The PCHPMA + PLC (20 wt% of the latter, blend P) shows only limited compatibility. The SEM results are confirmed by values of the glass transition temperatures Tg determined via thermal mechanical analysis. The Tg value of the blend E is shifted towards the Tg of PLC; Tg of blend P is practically equal to that of PCHPMA. The linear isobaric expansivity αL values for both blends are lower than the respective values for pure PCHPMA and PCHEMA. Thermal stabilities of the blends determined by thermogravimetry are also better than those of pure polymethacrylates. The temperature of 50% weight degradation for blend E is higher than that for pure PCHEMA by more than 60 K Copyright © 2004 Society of Chemical Industry
Soluble aromatic poly(ether amide)s containing aryl‐, alkyl‐, and chloro‐substituted phthalazinone segments
Authors: Zhu Xiuling , Jian Xigao 
Published: March 2004

AbstractA series of novel aromatic diamines (2–4) containing the alkyl‐, aryl, or chloro‐substituted group of phthalazinone segments were synthesized via two synthetic steps starting from 4‐(3‐R‐4‐hydroxyphenyl)‐2,3‐phthalazinone‐1 (R = Ph, CH3, Cl). Three series of aromatic polyamides containing phthalazinone moieties were prepared through diamines 2–4 reacting with different aromatic dicarboxylic acids via a direct Yamazaki–Higashi phosphorylation polycondensation reaction. The resulting aromatic polyamides had inherent viscosities in the range of 0.40–0.76 dL/g. The thermal property of the polyamides was examined with DSC and thermogravimetric analysis. The glass‐transition temperatures of these polyamides ranged from 298 to 340 °C. The 10% mass‐loss temperature was above 405 °C under nitrogen. Structures of monomers 2–4 and the polymers were confirmed by Fourier transform infrared spectroscopy, 1H NMR, and mass spectrometry. Good solubility of these polymers in polar solvents such as N‐methylpyrrolidone, dimethylformamide, dimethylacetamide (DMAc), and m‐cresol was observed, and tough, flexible films were obtained from the polymer's DMAc solutions. The effect of the substituted group on the physical property of polymers was also investigated. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2026–2030, 2004
Synthesis and characterization of polyaniline doped with organic acids
Authors: Kulkarni Milind V. , Viswanath Annamraju Kasi , Marimuthu R. , Seth Tanay 
Published: March 2004

AbstractSpectroscopic [UV–visible and Fourier transform IR (FTIR)] and thermal properties of chemically synthesized polyanilines are found to be affected by varying the protonation media (acetic, citric, oxalic, and tartaric acid). The optical spectra show the presence of a greater fraction of fully oxidized insulating pernigraniline phase in polyaniline doped with acetic acid. In contrast, the selectivity in the formation of the conducting phase is higher in oxalic acid as a protonic acid media. The FTIR spectra of these polymers reveal a higher ratio of the relative intensities of the quinoid to benzenoid ring modes in acetic acid doped polyaniline. Scanning electron micrographs revealed a sponge‐like structure derived from the aggregation of the small granules in acetic acid and oxalic acid doped polyaniline. A three‐step decomposition pattern is observed in all the polymers, regardless of the protonic acid used for the doping. The second step loss related to the loss of dopant is found to be higher in the oxalic acid doped polymer. In accordance with these results the conductivity is also found to be higher in oxalic acid doped material. The temperature dependent conductivity measurements show the thermal activated behavior in all the polymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2043–2049, 2004
Polymerization of isoprene with η5‐C5H4(tert‐Bu)TiCl3/MAO catalyst
Authors: Miyazawa Akira , Kase Toshio , Shibuya Tomohiro 
Published: March 2004

Abstractcis‐Selective polymerizations of isoprene with the catalysts composed of η5‐C5H4(R)TiCl3 (1; RH, 2; tert‐Bu) and methylaluminoxane were investigated. Both catalysts showed remarkable catalytic activities for the polymerization of isoprene. The polymerization activities were strongly affected by the substituent introduced on cyclopentadienyl ring. Introduction of bulky tert‐butyl group was found to be effective for enhancement of polymerization activity, but the cis‐content of polyisoprene prepared by the 2/MAO catalyst was lower than that by 1/MAO catalyst. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1841–1844, 2004
Green‐emitting poly[(1,3‐phenylenevinylene)‐alt‐ (1,4‐phenylenevinylene)]s: Effect of the substitution patterns on the optical properties
Authors: Liao Liang , Pang Yi , Ding Liming , Karasz Frank E. 
Published: March 2004

AbstractGreen‐emitting substituted poly[(2‐hexyloxy‐5‐methyl‐1,3‐phenylenevinylene)‐alt‐(2,5‐dihexyloxy‐1,4‐phenylenevinylene)]s (6) were synthesized via the Wittig–Horner reaction. The polymers were yellow resins with molecular weights of 10,600. The ultraviolet–visible (UV–vis) absorption of 6 (λmax = 332 or 415 nm) was about 30 nm redshifted from that of poly[(2‐hexyloxy‐5‐methyl‐1,3‐phenylenevinylene)‐alt‐(1,4‐phenylenevinylene)] (2) but was only 5 nm redshifted with respect to that of poly[(1,3‐phenylenevinylene)‐alt‐(2,5‐dihexyloxy‐1,4‐phenylenevinylene)] (1). A comparison of the optical properties of 1, 2, and 6 showed that substitution on m‐ or p‐phenylene could slightly affect their energy gap and luminescence efficiency, thereby fine‐tuning the optical properties of the poly[(m‐phenylene vinylene)‐alt‐(p‐phenylene vinylene)] materials. The vibronic structures were assigned with the aid of low‐temperature UV–vis and fluorescence spectroscopy. Light‐emitting‐diode devices with 6 produced a green electroluminescence output (emission λmax ∼ 533 nm) with an external quantum efficiency of 0.32%. Substitution at m‐phenylene appeared to be effective in perturbing the charge‐injection process in LED devices. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1820–1829, 2004
Stereoselective nucleophilic substitution of poly(vinyl chloride) with potassium 4‐acetamidothiophenolate
Authors: Martínez Gerardo , Millán José Luis 
Published: March 2004

AbstractThe nucleophilic substitution reaction of poly(vinyl chloride) (PVC) with potassium 4‐acetamidothiophenolate was performed in a cyclohexanone solution. The quantitative microstructural analysis, as a function of the conversion, was followed by 13C NMR spectroscopy. Through a comparison of the microstructural changes with the degree of substitution, a small fraction of mmr tetrads was found to react occasionally with the central chlorine of the mr triad instead of the mm, such as for sodium benzenethiolate (NaBT). This conclusion was confirmed by Fourier transform infrared results. However, unlike NaBT, the evolution of the glass‐transition temperature (Tg) with the degree of conversion changed with the degree of substitution similarly to the ratio of the extents to which mmr and rrmr structures intervened in the substitution reaction. From these studies, it followed that the specific interactions due to the polar nature of the nucleophile enhanced the molecular‐microstructure‐based mechanisms, which were responsible for Tg. Such a novel quantitative correlation, compared with more tentative ones obtained previously, presents valuable insight into the role of the stereochemical microstructure in the glass‐transition process in PVC. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1857–1867, 2004
Synthesis and characterization of novel aryl‐ethynylene polymers of tuned rigidity/flexibility
Authors: Winter Dominik , Eisenbach Claus D. 
Published: March 2004

AbstractNew poly(aryl‐ethynylene) polymers of tuned rigidity/flexibility were synthesized by a palladium‐catalyzed polycondensation. The Sonogashira–Hagihara‐type coupling reaction of 2,5‐diethynyl‐4‐dodecyltoluene with 2,5‐ and/or 3,5‐dibromopyridine led to polymers of different rigidity/flexibility simply by varying the ratio of 2,5‐ to 3,5‐dibromopyridine charged in the polycondensation reaction. The ratio of para–meta linkages at the pyridine moiety in the polymer backbone was determined by NMR spectroscopy. The combination of molecular weight data obtained from vapor pressure osmometry and the use of oligomeric model compounds allowed us to establish a polymer‐specific gel permeation chromatography calibration. Information about the molecular conformation of the polymers in solution were obtained by small‐angle X‐ray scattering (SAXS) experiments. The glass‐transition and melting temperatures varied systematically with the degree of rigidity/flexibility and could be directly related to the conformational changes as reflected from the SAXS data. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1919–1933, 2004
Parallel kinetic investigation of 2‐oxazoline polymerizations with different initiators as basis for designed copolymer synthesis
Authors: Hoogenboom Richard , Fijten Martin W. M. , Schubert Ulrich S. 
Published: March 2004

AbstractThe systematical kinetic investigations of four 2‐substituted‐2‐oxazoline monomers with four initiators at two temperatures and four monomer/initiator ratios are described. To cover this broad range of variables (128 different combinations), an automated synthesizer was used to accelerate the investigations and to provide highly comparable results. With both gas chromatography and gel permeation chromatography, the livingness and the polymerization rates were determined for the different polymerizations. The resulting insights in the kinetics were used for the directed synthesis of truly random copolymers and copolymers with composition drift. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1830–1840, 2004
Initiation process of L‐lactide polymerization carried out with zirconium(IV) acetylacetonate
Authors: Dobrzynski Piotr 
Published: March 2004

AbstractLactide polymerization using zirconium(IV) acetylacetonate [Zr(acac)4] as an initiator was investigated. In the reaction between Zr(acac)4 and the monomer molecule, lactide deprotonation and the release of acetylacetone occurred. The structures of the obtained complexes were analyzed with high‐resolution NMR spectroscopy. A computational method was used to calculate the hypothetical structures. The role of the obtained complexes in the initiation of polymerization and the reaction of chain growth was proposed. The influence of the reaction temperature on the structures of the complexes was investigated. Polylactide chain growth proceeded by an insertion‐coordination mechanism. The polymer chain grew on one ligand, which was formed in advance from a deprotonated lactide. The molecular masses of the obtained polymers were the same as the theoretical masses and were directly proportional to the reaction conversion. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1886–1900, 2004
High‐throughput experimentation in atom transfer radical polymerization: A general approach toward a directed design and understanding of optimal catalytic systems
Authors: Zhang Huiqi , Marin Veronica , Fijten Martin W. M. , Schubert Ulrich S. 
Published: March 2004

AbstractHigh‐throughput experimentation (HTE) was successfully applied in atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) for the rapid screening and optimization of different reaction conditions. A library of 108 different reactions was designed for this purpose, which used four different initiators [ethyl 2‐bromoisobutyrate, methyl 2‐bromopropionate, (1‐bromoethyl)benzene, and p‐toluenesulfonyl chloride], five metal salts (CuBr, CuCl, CuSCN, FeBr2, and FeCl2), and nine ligands (2,2′‐bipyridine and its derivatives). The optimal reaction conditions for Cu(I) halide, CuSCN, and Fe(II) halide‐mediated ATRP systems with 2,2′‐bipyridine and its 4,4′‐dialkyl‐substituted derivatives as ligands were determined. Cu(I)‐mediated systems were better controlled than Fe(II)‐mediated ones under the examined conditions. A bipyridine‐type ligand with a critical length of the substituted alkyl group (i.e., 4,4′‐dihexyl 2,2′‐bipyridine) exhibited the best performance in Cu(I)‐mediated systems, and p‐toluenesulfonyl chloride and ethyl 2‐bromoisobutyrate could effectively initiate Cu(I)‐mediated ATRP of MMA, resulting in polymers with low polydispersities in most cases. Besides, Cu(I) halide‐mediated ATRP with 4,5′‐dimethyl 2,2′‐bipyridine as the ligand and p‐toluenesulfonyl chloride as the initiator proved to be better controlled than those with 4,4′‐dimethyl 2,2′‐bipyridine as the ligand, and polymers with much lower polydispersities were obtained in the former cases. This successful HTE example opens up a way to significantly accelerate the development of new catalytic systems for ATRP and to improve the understanding of structure–property relationships of the reaction systems. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1876–1885, 2004
Tetrakis Sn(IV) alkoxides as novel initiators for living ring‐opening polymerization of lactides
Authors: Kalmi Mikko , Lahcini Mohammed , Castro Pascal , Lehtonen Olli , Belfkira Ahmed , Leskelä Markku , Repo Timo 
Published: March 2004

AbstractThe use of tetrakis Sn(IV) alkoxides as highly active initiators for the ring‐opening polymerization of D,L‐lactide is reported. The activities of prepared Sn(IV) tetra‐2‐methyl‐2‐butoxide, Sn(IV) tetra‐iso‐propoxide, and Sn(IV) tetra‐ethoxide were compared to a well‐known ring‐opening polymerization initiator system, Sn(II) octoate activated with n‐butanol. All polymerizations were conducted at 75 °C in toluene. The activities of tetrakis Sn(IV) alkoxides grew in order of increasing steric hindrance, and the bulky Sn(IV) alkoxides showed higher activity than the Sn(II) octoate/butanol system. The living character of the polymerization was demonstrated in homopolymerization of D,L‐lactide and in block copolymerization of L‐lactide with ϵ‐caprolactone. 1H, 13C, and 119Sn NMR were used to characterize the prepared Sn(IV) alkoxides and the polymer microstructure, and size exclusion chromatography was used to determine the molar masses as well as the molar‐mass distributions of the polymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1901–1911, 2004
Synthesis and characterization of new polybenzimidazopyrrolones derived from pyridine‐bridged aromatic tetraamines and dianhydrides
Authors: Liu Jin‐Gang , Wang Li‐Fang , Yang Hai‐Xia , Li Hong‐Shen , Li Yan‐Feng , Fan Lin , Yang Shi‐Yong 
Published: March 2004

AbstractA series of new polybenzimidazopyrrolones (polypyrrolone, PPy) were synthesized by polycondensation of pyridine‐bridged aromatic tetraamines, including 2,6‐bis (3′,4′‐diaminophenyl)‐4‐phenylpyridine and 2,6‐bis(3′,4′‐ diaminophenyl)‐4‐(3″‐trifluoromethyl)phenyl pyridine, with various aromatic dianhydrides. Experimental results indicated that the PPys, multiaromatic conjugated and semiladder polymers, showed good thermal stabilities with thermal‐decomposition temperatures of about 500 °C and residual weight retention at 750 °C as high as 84%. PPy films could be obtained by casting the precursor solution, poly(amide amino acid) on glass substrate, followed by thermal dehydrating at elevated temperatures. The polymer films exhibited excellent alkaline hydrolysis resistance, which retained their original shapes and toughness after boiling 7 days in 10% sodium hydroxide solution. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1845–1856, 2004
N,N,N′,N′,N″‐penta(methyl acrylate)diethylenetriamine: A novel ligand for atom transfer radical polymerization of methyl methacrylate
Authors: Chu Juan , Chen Jin , Zhang Keda 
Published: March 2004

AbstractA novel ligand, N,N,N′,N′,N″‐penta (methyl acrylate) diethylenetriamine (MA5‐DETA), was synthesized by the reaction of diethylenetriamine with methyl acrylate in almost quantitive yield. The polymerizations of methyl methacrylate with MA5‐DETA as the ligand and α,α‐dichlorotoluene (DCT) and ethyl 2‐bromoisobutyrate (2‐EBiB) as the initiators, respectively, under different conditions were examined. The polymerization with CuCl/MA5‐DETA/DCT was closely controlled in bulk and gave polymers with quite narrow molecular weight distributions (Mw/Mn's) of 1.16–1.29. The polymerization with the system CuBr/MA5‐DETA/EBiB in bulk gave high activity. However, the system was not well controlled and gave the polymers with Mw/Mn = 1.35–1.53. The solution polymerization in anisole with CuBr/MA5‐DETA/EBiB showed a better‐controlled nature. Moreover, the addition of CuBr2 into the aforementioned system can further improve its controllability. The Mw/Mn's of the resulting polymers ranged from 1.11 to 1.21. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1963–1969, 2004