bluuebunny/crossref_metadata_2025 huggingface dataset:
Scalp EEG for the diagnosis of epilepsy and photosensitivity in the baboon
Authors: Ákos Szabó C. , Leland Michelle , Sztonák László , Restrepo Santiago , Haines Richard , Mahaney Michael A. , Williams Jeff T.
Published: February 2004

Spontaneous seizures have been observed in several baboon species housed at the Southwest National Primate Research Center (SNPRC), including Papio hamadryas anubis and cynocephalus/anubis, hamadryas/anubis, and papio/anubis hybrids. The goal of this study was to establish a noninvasive, reliable electroencephalographic technique to characterize epilepsy phenotypes and assess photosensitivity in these subspecies. Thirty baboons with witnessed seizures, and 15 asymptomatic baboons underwent scalp electroencephalograms (EEGs) with photic stimulation (PS). The sensitivity and specificity of surface EEG for identifying interictal epileptic discharges (IEDs) in baboons with witnessed seizures were examined. The morphology of IEDs, electroclinical features of seizures and responses to PS, reproducibility of EEG findings, and intrarater reliability were also evaluated. Twenty‐three seizure baboons (77%) demonstrated IEDs, predominantly with frequencies of 4–6 Hz in 18 baboons and 2–3 Hz in six baboons. Two seizure animals had a mixture of 2–3‐Hz and 4–6‐Hz IEDs. All animals with 2–3‐Hz IEDs were 3 years old or younger. Myoclonic seizures (MS) and generalized tonic‐clonic seizures (GTCS) were recorded in 13 baboons (43%). PS activated IEDs in 15 baboons (50%) and seizures in nine baboons. The presence of IEDs or seizures was not associated with a particular gender or species (Fisher exact test, α=0.05). Seizures were more common in animals >3 years old, while PS‐induced IEDs and seizures were more prevalent in P.h. anubis/cynocephalus crosses compared to P.h. anubis. In the asymptomatic controls, IEDs were recorded in five baboons (33%), and photoparoxysmal responses were observed in two (13%). Surface EEG is a sensitive and reliable instrument for characterizing the epilepsy encountered in Papio species. Electroclinically, the seizure animals had generalized epilepsy with photosensitivity. The variation in IED morphology may be age‐related or it may reflect different epileptic phenotypes. Ketamine provoked IEDs and seizures in most seizure animals and only in a few asymptomatic baboons; therefore, it may enhance the sensitivity of surface EEG for detecting a predisposition to epilepsy. Am. J. Primatol. 62:95–106, 2004. © 2004 Wiley‐Liss, Inc.
Hermann Staudinger und der Ursprung der Makromolekularen Chemie
Authors: Mülhaupt Rolf
Published: February 2004

Staudingers Visionen haben den Weg bereitet für die Entwicklung moderner Kunststoffe mit vielseitigen Eigenschaften und Anwendungen an der Schnittstelle zwischen Material‐ und Biowissenschaften. Dies belegt dieses Essay, das aus Anlass des 50. Jahrestages der Nobelpreisverleihung an Hermann Staudinger daran erinnert, dass sein damals revolutionäres und heftig umstrittenes Konzept den Zugang zum molekularen Design von polymeren Werk‐ und Effektstoffen eröffnete, deren Eigenschaftsprofile über die molekularen Architekturen anwendungsspezifisch maßgeschneidert werden.
Hermann Staudinger und die Zukunft der Polymerforschung Jubiläumsfeiern – selbstbestimmter Anlass kultureller Frömmigkeit
Authors: Ringsdorf Helmut
Published: February 2004

Die Chemie war sein Leben, aber die Träume Hermann Staudingers gehörten der Biologie und der Einheit von Chemie und Biologie. Das ist eine zentrale Aussage dieses Essays, das sich anlässlich der fünfzig Jahre zurückliegenden Verleihung des Nobelpreises an Staudinger zurück‐, aber auch dezidiert nach vorne schauend speziell auch mit der Bedeutung der Polymerwissenschaft und Staudingers Träumen gerade für die Biowissenschaften auseinandersetzt. Darüber hinaus geht es aber auch um Fragen der Wissenschaftsethik sowie um die enge Verflechtung und das Wechselspiel von Forschung, Politik und Verantwortung.
Titelbild: Nontoxic Membrane‐Active Antimicrobial Arylamide Oligomers (Angew. Chem. 9/2004)
Authors: Liu Dahui , Choi Sungwook , Chen Bin , Doerksen Robert J. , Clements Dylan J. , Winkler Jeffrey D. , Klein Michael L. , DeGrado William F.
Published: February 2004

Die amphiphile Natur eines hochselektiven antimikrobiellen Arylamid‐Oligomers zeigt sich in der Simulation seiner Konformation an einer Wasser‐Octan‐Grenzfläche. Arginin‐Endgruppen machen es zum amphiphilsten aller untersuchten Oligomere und erhöhen sein hydrophobes Moment. Ersteres korreliert gut mit seiner geringen Toxizität, letzteres hingegen mit seiner hohen antimikrobiellen Aktivität. Mehr darüber berichten DeGrado et al. in ihrer Zuschrift auf S. 1178 ff.
Nature or Petrochemistry?—Biologically Degradable Materials
Authors: Mecking Stefan
Published: February 2004

Naturally occurring polymers have been utilized for a long time as materials, however, their application as plastics has been restricted because of their limited thermoplastic processability. Recently, the microbial synthesis of polyesters directly from carbohydrate sources has attracted considerable attention. The industrial‐scale production of poly(lactic acid) from lactic acid generated by fermentation now provides a renewable resources‐based polyester as a commodity plastic for the first time. The biodegradability of a given material is independent of its origin, and biodegradable plastics can equally well be prepared from fossil fuel feedstocks. A consideration of the overall carbon dioxide emissions and consumption of non‐renewable resources over the entire life‐cycle of a product is not necessarily favorable for plastics based on renewable resources with current technology—in addition to the feedstocks for the synthesis of the polymer materials, the feedstock for generation of the overall energy required for production and processing is decisive.
Hermann Staudinger and the Origin of Macromolecular Chemistry
Authors: Mülhaupt Rolf
Published: February 2004

Staudinger's visions paved the way for the development of modern polymeric materials with very versatile properties and new opportunities at the interface of materials and life sciences. This is confirmed in this Essay, written to mark the 50th anniversary of the award of the Nobel Prize for Chemistry to Hermann Staudinger. His revolutionary concept, which initially attracted heavy opposition, marked the beginning of the new era of rational molecular design of structural and functional polymeric materials, whose property profiles are tailored by varying their molecular architectures.
Hermann Staudinger and the Future of Polymer Research Jubilees—Beloved Occasions for Cultural Piety
Authors: Ringsdorf Helmut
Published: February 2004

Chemistry was his life, but Hermann Staudinger's dreams belonged to biology and to the unity of chemistry and biology. That is the central theme of this Essay, which, on the occasion of the fiftieth anniversary of the award of the Nobel Prize to Hermann Staudinger, discusses the significance of Staudinger's discoveries for the biosciences, not only retrospectively, but deliberately also prospectively. General questions of science ethics and the interplay of research, politics, and responsibility are also considered.
Cover Picture: Nontoxic Membrane‐Active Antimicrobial Arylamide Oligomers (Angew. Chem. Int. Ed. 9/2004)
Authors: Liu Dahui , Choi Sungwook , Chen Bin , Doerksen Robert J. , Clements Dylan J. , Winkler Jeffrey D. , Klein Michael L. , DeGrado William F.
Published: February 2004

The amphiphilic nature of a highly selective antimicrobial arylamide oligomer is shown by the simulation of its conformation at a water/octane interface. Arginine end groups make this oligomer the most amphiphilic in the series studied and increase its overall hydrophobic moment. While the former property correlates with its low toxicity, the latter correlates with a high antimicrobial activity. More details are described in the Communication by DeGrado and co‐workers on page 1158 ff.
Monohydroxy‐hydrazone‐functionalized thermally crosslinked polymers for nonlinear optics
Authors: Singh Rajendra K. , Stoffer James O. , Flaim Tony D. , Hall David B. , Torkelson John M.
Published: February 2004

The synthesis and properties of six hydrazone‐functionalized crosslinked polymers possessing stable nonlinear optics (NLO) properties are presented. First, a series of six hydroxy‐functionalized, NLO‐active hydrazone chromophores were synthesized. These chromophores were then grafted via its hydroxy functionality on an epoxy polymer to obtain the six NLO‐active soluble prepolymers. The grafting reaction yielded multiple secondary hydroxyl sites, which were used for further crosslinking by formulation of the prepolymer with a blocked polyisocyanate crosslinker. This formulation was spin‐coated on glass slides to form 2–2.5 μ thick defect‐free transparent films. The films were corona‐poled above their glass‐transition temperatures to align the chromophores in a noncentrosymmetric fashion and were simultaneously cured. The thermal characteristics of the second‐order nonlinearity of the six polymers were compared to illustrate the key structure–property relationships underlying the performance of the films in terms of NLO activity and thermal stability. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 770–781, 2004
Properties of amine‐containing coatings prepared by plasma polymerization
Authors: Choukourov A. , Biederman H. , Kholodkov I. , Slavinska D. , Trchova M. , Hollander A.
Published: February 2004

Two monomers, ethylenediamine (EDA) and diaminocyclohexane (DACH), were plasma‐polymerized in continuous‐wave (CW) and pulse modes. The influence of different plasma parameters on the deposition rate and film composition were investigated in detail and the changes in aminofunctionalization with varying pulse parameters were examined by FTIR, ESCA, and chemical‐derivatization techniques. It was shown that a varying duty cycle does not produce a considerable effect on the retention of amine groups into the film, while power and ton play a significant role in the polymerization process. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 979–990, 2004
Development and characterization of hydrocarbon polyol polyurethane and silicone magnetorheological polymeric gels
Authors: Fuchs Alan , Xin Mei , Gordaninejad Faramarz , Wang Xiaojie , Hitchcock Gregory H. , Gecol Hatice , Evrensel Cahit , Korol George
Published: February 2004

Magnetorheological polymeric gels (MRPG) have been developed for use in semi‐active magnetorheological fluid (MRF) dampers and other magnetorheological (MR) devices. The novel MRPGs are prepared by suspending iron particles in polymeric gels. Off‐state (i.e, no applied magnetic field) viscosity and settling behavior can be controlled through the selection of polymeric gels. In this study, tunable rheological properties were investigated with a piston‐driven flow type rheometer with a shear rate varying from 20 s−1to 6,000 s−1. Silicone MRPG (with 84.5 wt % iron particles) has controllable viscosity and a high shear yield stress over a wide range of shear rates. Silicone MRPG (79.5 wt % iron particles) has the lowest viscosity of those studied. Polyurethane MRPG has the lowest settling rate. The order of addition of magnetic particles and polymer during the polymerization process affects the MRPG final off‐state apparent viscosity (80% increase in apparent viscosity for silicone MRPG polymerized after adding iron particles). This indicates that polymer gels modify the surface properties of the magnetic particles, causing interaction among particles. The dynamic shear yield stress is higher for fluids with better dispersion stability. Polyurethane MRPG, which has the lowest settling rate, has a high dynamic yield stress (23 kPa at 350 mT). Both dynamic and static shear stress values of the MRPGs were found to be similar in magnitude (5–8 kPa at 120 mT for silicone MRPG with 84.5 wt % iron particles and polyurethane MRPG), indicating that MRPGs can provide consistent performance in devices. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1176–1182, 2004
Preparation and properties of (BATB–ODPA) polyimide–clay nanocomposite materials
Authors: Yeh Jui‐Ming , Chen Chi‐Lun , Kuo Tai‐Hung , Su Wen‐Fen , Huang Hsi‐Ya , Liaw Der‐Jang , Lu Hsin‐Yi , Liu Chi‐Fong , Yu Yuan‐Hsiang
Published: February 2004

A series of polymer–clay nanocomposite (PCN) materials consisting of 1,4‐bis(4‐aminophenoxy)‐2‐tert‐butylbenzene–4,4′‐oxydiphthalic anhydride (BATB–ODPA) polyimide (PI) and layered montmorillonite (MMT) clay were successfully prepared by an in situ polymerization reaction through thermal imidization up to 300°C. The synthesized PCN materials were subsequently characterized by Fourier‐Transform infrared (FTIR) spectroscopy, wide‐angle powder X‐ray diffraction (XRD) and transmission electron microscopy (TEM). The effects of material composition on thermal stability, mechanical strength, molecular permeability and optical clarity of bulk PI and PCN materials in the form of membranes were studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), molecular permeability analysis (GPA) and ultraviolet‐visible (UV/VIS) transmission spectra, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1072–1079, 2004
Novel aliphatic polyketone fiber by a wet‐spinning method using aqueous composite metal salt solutions
Authors: Morita Toru , Taniguchi Ryu , Matsuo Teruhiko , Kato Jinichiro
Published: February 2004

Poly(1‐oxotrimethylene), obtained by the perfectly alternating polymerization of ethylene and carbon monoxide, was successfully dissolved in composite metal salt solutions such as zinc chloride and calcium chloride aqueous solutions. Certain poly(1‐oxotrimethylene) solutions exhibited a phase‐separation point of 0°C or greater; the different phase‐separation temperatures depended on the metal salt composition ratio, the polymer molecular weight, and the polymer concentration. When a solution with a phase‐separation point was used for wet spinning, a coagulation temperature below the phase‐separation point resulted in gelation of the filament, which was caused by a temperature jump during the coagulation process; this yielded a coagulated filament with a dense and homogeneous cross‐sectional structure. The hot drawing of the coagulated fiber produced a high‐performance polyketone fiber with high strength and high elastic modulus [tenacity = 18.5 cN/dtex (2.4 GPa); elongation = 5%; elastic modulus = 450 cN/dtex (59 GPa)].With a solution that exhibited no phase‐separation temperature, coagulation proceeded as the coagulant penetrated from the fiber surface into the filament inside, yielding a coagulated filament with a skin–core structure. The maximum tenacity achieved with this skin–core coagulated filament was as low as 15 cN/dtex (1.9 GPa). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1183–1189, 2004
Studies on Indian silk. I. Macrocharacterization and analysis of amino acid composition
Authors: Sen Kushal , Babu K Murugesh
Published: February 2004

This first in a series of articles characterized the different varieties of Indian silk for their macrostructural parameters, such as filament length, degumming loss, denier, cross section, moisture regain, and intrinsic viscosity, for example. The results of amino acid analysis using a reverse‐phase technique were also reported. Five Indian silk varieties—two mulberry (bivoltine and crossbreed) and three nonmulberry (tasar, muga, and eri)—were investigated. The differences existing between the different varieties and the extent of lengthwise variations within a cocoon in the dimensional and macrostructural parameters were discussed. It was observed that denier of the filament decreases considerably from the outer to the inner layers, whereas density showed an increasing trend in all the varieties. Both the mulberry silks demonstrated lower moisture regain. Electron micrographs of all the nonmulberry varieties showed microvoids in their cross section. Fraction studies showed the development of mushroom structure on the tips. In both types of mulberry silk, glycine, alanine, and serine constitute about 82% of the amino acids present. On the other hand, in nonmulberry silks, these constitute about 73% with a high proportion of alanine. The nonmulberry varieties showed a substantial proportion of amino acids with bulky side groups. Similarly, the higher hydrophilic to hydrophobic amino acid ratio (9.06–9.85) for nonmulberry silks, compared against that of the mulberry varieties (5.29–6.22), was shown to be responsible for the higher moisture content of nonmulberry silks. Cystine and methionine were present in all the varieties. The higher intrinsic viscosity of nonmulberry varieties suggested their higher molecular weight. Through amino acid analysis, it was shown that there is no difference in chemical architecture between the outer and the inner layers of cocoons. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1080–1097, 2004
Studies on Indian silk. III. Effect of structure on dyeing behavior
Authors: Sen Kushal , Babu K Murugesh
Published: February 2004

This third in a series of articles deals with the analysis of the dyeing behavior of two mulberry and three nonmulberry varieties of silk. The results of the dyeing tests carried out were discussed in relation to the physical and chemical structure of the silk fibers. Noticeable differences in the dye uptake were observed among the different varieties of silk. Mulberry varieties showed higher dye uptake compared to that of all three nonmulberry varieties. Among the nonmulberry varieties, tasar shows higher dye uptake followed by eri and muga. Interestingly, dye uptake reduces significantly within a variety from the outer to the inner layers. The reduction within a variety was found to correlate well with the morphological parameters. Determination of morphology of fibers confirmed significant differences in structural parameters such as crystallinity, orientation, density, and birefringence, for example, between and within varieties. An increase in all these parameters was observed as one moves from the outer to the inner layers within a variety. The differences in the dye uptake of different varieties of silk correlated well with the physical as well as chemical structure of silk fibers. Dye uptake differences between the varieties were found to correlate with the end amino groups. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1116–1123, 2004
Effects of acrylic‐based processing aids on processibility, rheology, thermal and structural stability, and mechanical properties of PVC/wood–sawdust composites
Authors: Sombatsompop N. , Phromchirasuk C.
Published: February 2004

Methyl methacrylate and ethylacrylate (MMA‐co‐EA) and methyl methacrylate and butylacrylate (MMA‐co‐BA) copolymeric processing aids were introduced into poly(vinyl chloride) (PVC)/33.3 wt % wood–sawdust composites containing 0.6 and 2.4 phr of calcium stearate lubricant. The properties of the composites were monitored in terms of processibility, rheology, thermal and structural stability, and mechanical properties. It was found that the mixing torque, wall shear stress, and extrudate swell ratio increased with increasing processing aid content because of increased PVC entanglement. MMA‐co‐BA (PA20) was found to be more effective than MMA‐co‐EA (K120 and K130), this being associated with the flexibility of the processing aids, and the dipole–dipole interactions between sawdust particles and polymeric processing aids. The sharkskin characteristic of the composite extrudate at high extrusion rate was moderated by the presence of processing aids. Adding the acrylic‐based processing aids and lubricant into PVC/sawdust composites improved the thermal and structural stability of the composites, which were evidenced by an increase in glass transition and decomposition temperatures and a decrease in polyene sequences, respectively. The changes in the mechanical properties of the composites involved a composite homogeneity, which was varied by degree of entanglement and the presence of wood sawdust, and un‐reacted processing aids left in the composites. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 782–790, 2004
Synthesis and tensile properties of a novel composite of Chlorella and polyethylene
Authors: Otsuki Toshi , Zhang Farao , Kabeya Hiroshi , Hirotsu Takahiro
Published: February 2004

A novel composite of the green microalga Chlorella sp. with polyethylene (PE) was synthesized through chemical modification of PE with maleic anhydride (MA), with respect to the biological fixation of CO2 with Chlorella sp. The interaction of Chlorella grains with a PE matrix is strikingly enhanced by the chemical modification of PE with MA. The tensile strength of a Chlorella–MA‐modified PE composite (Ch–MPE) with a Chlorella content of 40 wt % is more than 2 times greater than that of a composite derived from unmodified PE. The marked increase in tensile strength is attributed to the formation of chemical bonds between Chlorella grains and the PE matrix, from IR and SEM studies. Because of the satisfactory thermal plasticity of Ch–MPE, it can be easily shaped into plate and dishlike moldings by a heat‐pressurizing method. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 812–816, 2004
Studies on castor oil–based polyurethane/polyacrylonitrile interpenetrating polymer network for toughening of unsaturated polyester resin
Authors: Guhanathan S. , Hariharan R. , Sarojadevi M.
Published: February 2004

Tricomponent interpenetrating polymer network (IPN) systems involving castor oil, toluenediisocyanate (TDI), acrylonitrile (AN), ethylene glycol diacrylate (EGDA), and general‐purpose unsaturated polyester resin (GPR) were prepared with various compositions. The structures of the IPNs at various stages were confirmed using FTIR. The thermal stability of the IPNs was studied using TGA, which indicated that the polyurethane/polyacrylonitrile/GPR (PU/PAN/GPR) IPN underwent single‐stage decomposition, showing perfect compatibility at the IPN composition of 10 : 90 (PU/PAN : GPR). The mechanical properties such as tensile, flexural, impact, and hardness for the IPNs with various compositions were determined. It was found that the tensile strength of the GPR matrix was decreased and flexural and impact strengths were increased upon incorporating PU/PAN networks. The swelling properties in water and toluene were also studied. The morphology of the IPNs was studied using SEM. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 817–829, 2004
Reactive blends of epoxy resin (DGEBA) crosslinked by anionically polymerized polycaprolactam: Process of epoxy cure and kinetics of decomposition
Authors: Gupta Alka , Singhal Reena , Nagpal A. K.
Published: February 2004

The curing reactions, kinetics, morphology, and thermal stability of the reactive blends of diglycidyl ether of bisphenol‐A (DGEBA) and polycaprolactam were studied by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis. DSC studies showed that the heat of reaction (ΔH) increased when the DGEBA content was increased from 50 to 80 wt % and increased drastically above 70 wt % DGEBA content because of an increase in the extent of crosslinking. The activation energy and pre‐exponential factor of cure reactions increased drastically with an increase in the DGEBA content above 70 wt % because of a drastic increase in crosslink density. The extent of curing reaction of polycaprolactam with DGEBA is dependent on the blend composition. The nucleophilic attack on oxirane ring by amide nitrogen of polycaprolactam is a dominant curing reaction in low DGEBA compositions, and another type of curing reaction with relatively large activation energy and pre‐exponential factor also occurred, which becomes dominant when the DGEBA content reaches above 70 wt %. FTIR studies also revealed that two types of reactions do exist during the curing of polycaprolactam with DGEBA. It was observed during SEM studies that the reactive blends show multiphase system and on increasing the DGEBA content from 50 to 80 wt %, the mixing of the two phases increased. The reactive blend Ep80Ca20 with 80 wt % DGEBA content exhibits a single‐phase system because of better mixing of the two phases. The results of thermogravimetric analysis also indicate that the initial degradation temperature (Ti), activation energy (E), and pre‐exponential factor (Z) increased with increasing DGEBA content from 50 to 80 wt % in the reactive blends and increased drastically above 70 wt % DGEBA content due to the higher crosslink density. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 687–697, 2004
Synthesis and characterization of functional copolymer of Linalool and vinyl acetate: A kinetic study
Authors: Shukla Anjali , Srivastava A. K.
Published: February 2004

Linalool (LIN) and vinyl acetate (VA) were copolymerized by benzoyl peroxide (BPO) in p‐xylene at 60°C for 90 min. The system follows nonideal kinetics: Rpα[I]0.6[LIN]1.2[VA]1.1. It results in the formation of alternating copolymer as evidenced from reactivity ratios as r1 (VA) = 0.01, r2 (LIN) = 0.0015, which have been calculated by Kelen–Tudos method. The overall activation energy is 82 kJ/mol. The FTIR spectrum of the copolymer shows the presence of the band at 3425 cm−1 due to alcoholic group of LIN and at 1641 cm−1 due to >CO group of VA. The 1H‐NMR spectrum shows peaks at 7.0–7.7 δ due to hydroxy proton of LIN and at 1.0–1.4 δ due to acetoxy protons of VA. 13C‐NMR spectrum of copolymer shows peaks at 167 ppm due to acetoxy group and at 75–77 ppm due to COH group. The Alfrey–Price Q–e parameters for LIN has been calculated as Q2 = 1.24 and e2 = 3.11. The copolymer is highly thermally stable and has a glass transition temperature (Tg) of 85°C, evaluated from DSC studies. The mechanism of copolymerization has been elucidated. This article also reports measurement of Mark–Houwink constants in THF at 25°C by means of GPC as α = 0.8 and K = 3.0 × 10−4 dl/g. The thermal decompositions of copolymer are established with the help of TGA technique. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1134–1143, 2004
Synthesis of resol–layered silicate nanocomposites by reaction exfoliation with acid‐modified montmorillonite
Authors: Wang Hongsheng , Zhao Tong , Yan Yehai , Yu Yunzhao
Published: February 2004

Resol–layered silicate nanocomposites were prepared by the intercalative polymerization of phenol and formaldehyde in the presence of acid‐modified montmorillonite (HMMT). The nanocomposites were studied by means of X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, dynamic mechanical analysis (DMA), and rheological measurements. The exfoliation of HMMT was promoted by the intragallery reactions catalyzed by protons in the galleries of the clay, whereas the extragallery polymerization catalyzed by ammonia went on simultaneously. The nanocomposites showed higher glass‐transition temperatures in the DMA diagram compared with the resol counterparts. The impact strength was improved significantly by the incorporation of the clay. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 791–797, 2004
Synthesis and characterization of epoxidized styrene–butadiene rubber/silicon dioxide hybrid materials
Authors: de Luca Maria Augusta , Machado Taís Espíndola , Notti Renan Beretta , Jacobi Marly Maldaner
Published: February 2004

Hybrid materials were synthesized from epoxidized (68, 43, or 14%) styrene–butadiene rubber (SBR) and the hydrolysis product of tetraethoxysilane (TEOS) in situ under ultrasonic irradiation. The products were characterized with thermal analysis (differential scanning calorimetry and thermogravimetric analysis), stress–strain tests, scanning electron microscopy (including energy‐dispersive spectrometry), and swelling in tetrahydrofuran and water. The most transparent were those prepared from SBR with the highest degree of epoxidation, whereas those obtained from less epoxidized SBR and with larger amounts of TEOS showed distinct phases that could be considered two hybrid phases (one rich in TEOS and another rich in SBR). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 798–803, 2004
Preparation and properties of styrene–butadiene rubber based nanocomposites: The influence of the structural and processing parameters
Authors: Sadhu Susmita , Bhowmick Anil K.
Published: February 2004

Rubber‐based nanocomposites were prepared with octadecyl amine modified sodium montmorillonite clay and styrene–butadiene rubber with different styrene contents (15, 23, and 40%). The solvent used to prepare the nanocomposites, the cure conditions, and the cure system were also varied to determine their effect on the properties of the nanocomposites. All the composites were characterized with X‐ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM). The XRD studies revealed exfoliation for the modified clay–rubber composites. The TEM photomicrographs showed a uniform distribution of the modified clay in the rubber matrix. The thickness of the particles in the exfoliated composites was around 10–15 nm. Although the FTIR study of the unmodified and modified clays showed extra peaks due to the intercalation of the amine chains into the gallery, the spectra for the rubber–clay nanocomposites were almost the same because of the presence of a very small amount of clay in the rubber matrix. All the modified clay–rubber nanocomposites displayed improved mechanical strength. The styrene content of the rubber had a pronounced effect on the properties of the nanocomposites. With increasing styrene content, the improvement in the properties was greater. Dicumyl peroxide and sulfur cure systems displayed similar strength, but higher elongation and slightly lower modulus values were obtained with the sulfur cure system. The curing of the samples at four different durations at 160°C showed that the cure time affected the properties. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 698–709, 2004
Synthesis and coating characteristics of novel calcium‐containing poly(urethane ethers)
Authors: Jayakumar R. , Lee Y.‐S. , Nanjundan S.
Published: February 2004

Calcium salt of mono(hydroxypentyl)phthalate [Ca(HPP)2] was synthesized by the reaction of 1,5‐pentanediol, phthalic anhydride, and calcium acetate. Calcium‐containing poly(urethane ethers) (PUEs) were synthesized by the reaction of hexamethylene diisocyanate (HMDI) or toluylene 2,4‐diisocyanate (TDI) with a mixture of Ca(HPP)2 and poly(ethylene glycol) (PEG300 or PEG400) with di‐n‐butyltin dilaurate as a catalyst. We synthesized a series of calcium‐containing PUEs with different compositions by taking the molar ratio of Ca(HPP)2 : PEG300 or PEG400 : diisocyanate (HMDI or TDI) as 2 : 2 : 4, 3 : 1 : 4, and 1 : 3 : 4 to study the coating properties of the PUEs. Blank PUEs without a calcium‐containing ionic diol were also prepared by the reaction of PEG300 or PEG400 with HMDI or TDI. The PUEs were well characterized by fourier transform infrared spectroscopy, 1HNMR, −13C‐NMR, solid‐state cross‐polarity/magic‐angle spinning 13C‐NMR, viscosity, solubility, and X‐ray diffraction studies. The thermal properties of the polymers were also studied with thermogravimetric analysis and differential scanning calorimetry. The PUEs were applied as a top coat on acrylic‐coated leather, and their physicomechanical properties were also studied. The coating properties of PUEs, including tensile strength, elongation at break, tear strength, water vapor permeability, flexing endurance, cold crack resistance, abrasion resistance, color fastness, and adhesive strength, were better than the standard values. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 710–721, 2004
A novel method for the preparation of monocarboxyl‐end‐grouped polycaprolactam with an adjustable molecular weight
Authors: Zhang Yi , Zhang Quanling , Cheng Kailiang , Xu Jiarui
Published: February 2004

A novel method was used to synthesize adjustable‐molecular‐weight polycaprolactams with monocarboxyl end groups. The reaction device and conditions are discussed. The products were characterized by Fourier transform infrared spectroscopy, 1H‐NMR spectroscopy, high‐resolution pyrolysis gas chromatography–mass spectrometry, and wide‐angle X‐ray diffraction. The thermal properties were studied by differential scanning calorimetry and thermogravimetric analysis. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 722–727, 2004
Adsorption of Cu(II) ions from an aqueous solution by crosslinked amphoteric starch
Authors: Xu Shi‐Mei , Feng Shun , Yue Fan , Wang Ji‐De
Published: February 2004

The adsorption process of Cu(II) ions from aqueous solutions by crosslinked amphoteric starch with quaternary ammonium and carboxymethyl groups was investigated. The adsorption capacity was found to be dependent on the solution pH, the dose of the crosslinked amphoteric starch, and the initial concentration of Cu(II) ions. Moreover, the adsorption capacity increased with an increasing degree of substitution (DS) of the carboxymethyl groups. The adsorption followed a Freundlich adsorption isotherm. The adsorption process was endothermic, and the thermodynamic parameters were calculated at different DS values. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 728–732, 2004
Analysis of surface structure with regard to interfacial delamination in polyester films with incompatible polymers
Authors: Ito Katsuya , Nonomura Chisato , Yamashita Katsuhisa , Suzuki Toshitake , Chinwanitcharoen Charoen , Yamada Toshiro , Ishihara Hideaki
Published: February 2004

Poly(ethylene terephthalate) (PET) films containing incompatible polymer particles were analyzed, with particular reference to the relationship between the PET particle interfacial tension and the microvoids, or the protrusion that were formed when the composite material was stretched at 90°C. A model was developed to simulate void formation and surface protrusion due to interfacial delamination between PET and three types of dispersed incompatible polymers, poly(4‐methyl‐1‐pentene), polypropylene, and polystyrene. The numerical results, obtained with the finite element method, were compared with experimental data of the blends for both the internal and subsurface regions. The experimental measurements showed that the increase in the difference in the surface tension between PET and the added incompatible polymer was associated with the formation of larger voids. The protrusions were also generated in the stretching and delamination between PET and the incompatible polymers, but a decrease in the interfacial tension agreed with the formation of a larger protrusion. Modeling studies showed that increasing the interfacial tension between the two components in a blend causes a decrease in the critical stress for delamination. Interfacial tension values related qualitatively to the critical stress for void formation and protrusion calculated with the numerical analysis. A concavity was also necessary for understanding the surface structure of the films, along with protrusion. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1243–1251, 2004
Mechanical and dielectric properties of cured 1,2‐bis(vinylphenyl)ethane resin modified with poly(phenylene oxide)
Authors: Amou Satoru , Yamada Shinji , Takahashi Akio , Nagai Akira , Tomoi Masao
Published: February 2004

1,2‐Bis(vinylphenyl)ethane (BVPE) could be cured without curing agents at relatively low temperatures (∼ 180°) in a nitrogen atmosphere. Cured BVPE (CBVPE) resin showed exceptionally low dielectric constant (ϵ = 2.50 at 10 GHz) and low dielectric loss tangent (tan δ = 0.0012 at 10 GHz), and had excellent thermal resistance. Its 5 wt % weight‐loss temperature was 425°C in a nitrogen atmosphere and glass transition temperature was over 400°C. Poly(phenylene oxide) (PPO) was used to improve the toughness of CBVPE resin. PPO was an effective modifier to toughen CBVPE resin: when using 30 wt % of the modifier, the tensile strength and elongation of the modified CBVPE resin were 75 MPa and 26%, respectively. The modified CBVPE resin also showed excellent dielectric properties (ϵ = 2.45 at 10 GHz, tan δ = 0.0015 at 10 GHz). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1252–1258, 2004
Cure kinetics, microheterogeneity, and mechanical properties of the high‐temperature cure of vinyl ester resins
Authors: Li Peng , Yang Xiaoping , Yu Yunhua , Yu Dingsheng
Published: February 2004

A kinetic model has been developed that is based on the irreversible thermodynamic fluctuation theory, in which the conversion of comonomers is a function of the curing relaxation time, reaction time, and reaction temperature. This modified model permits a better prediction of the course of the high‐temperature cure reaction of vinyl ester (VE) resins under isothermal conditions. The microheterogeneity in cured resins was investigated through the measurement of the residual heat of isothermally cured samples with differential scanning calorimetry and through the observation of the fracture surfaces of samples under different cure conditions with scanning electron microscopy (SEM). The SEM photographs demonstrated the existence of clusters of microgels of about 20 μm in samples isothermally cured at 80°C for 3 h. The results of the dynamic mechanical thermal analysis of postcured samples verified the microheterogeneity in the cured samples and showed that the glass‐transition temperatures were not affected by the curing conditions. The effect of postcuring on the conversions of VE and styrene varied with the different cure schedules. The postcure for a sample isothermally cured at 80°C increased the tensile strength and flexural strength. On the contrary, the postcure for samples isothermally cured at 120°C reduced the tensile strength and flexural strength. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1124–1133, 2004
Effects of the blending sequence in polyolefin ternary blends
Authors: Ha M. H. , Kim M. S. , Kim B. K. , Kim W. , Lee M. C. , Kim H. D.
Published: February 2004

Ternary blends of isotactic polypropylene (PP), ethylene–octene copolymer (mPE), and high‐density polyethylene (HDPE) were prepared by melt mixing in a twin‐screw extruder with two different sequences of mixing: the simultaneous mixing of the three components (method I) and the premixing of mPE and HDPE followed by mixing with PP (method II). Regardless of the mixing sequence, mPE encapsulated HDPE in the PP matrix, although better mechanical properties were generally obtained with method II. The domain size was mainly determined by the viscosity ratio of mPE to PP in method I and by the viscosity ratio of the binary blend (mPE/HDPE) to PP in method II. Specimens prepared by injection molding gave much finer dispersions than compression‐molded specimens. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 804–811, 2004
Sorption studies of volatile organic compounds in a divinyl‐terminated poly(dimethylsiloxane)–oligo polymer
Authors: Zhen Hanfei , Jang Steven , Teo W. K.
Published: February 2004

The sorption equilibria and kinetics of three volatile organic compounds (VOCs)—benzene, chloroform, and acetone—in a newly developed divinyl‐terminated poly(dimethylsiloxane) (PDMSvi)–oligo polymer were studied. The PDMSvi–oligo polymer was prepared from a hexane solution consisting of PDMSvi as the polymer, oligosilylstyrene as the crosslinker, and a platinum–divinyltetramethyldisiloxane complex as the Karstedt catalyst. The sorption uptake of each VOC by the polymer was measured gravimetrically at different VOC partial pressures at a constant temperature and at different temperatures between 24 and 50°C. The rate of VOC sorption was monitored until equilibrium was established. The solubility coefficient increased when the VOC activity increased, and the results revealed that the PDMSvi–oligo polymer was a good sorbent for the three VOCs examined. Relatively high solubilities of these VOCs were obtained in this polymer in comparison with those reported for conventional silicone rubbers. The Flory–Huggins model fit the observed equilibrium sorption isotherms of the benzene and chloroform systems very well, whereas the Koningsveld–Kleinjtens variation law had to be combined with the Flory–Huggins model to describe the sorption isotherm of acetone in the polymer film. The rates of sorption of the three VOCs in the polymer samples were generally rapid and controlled by Fickian diffusion. The diffusivities of benzene, chloroform, and acetone at 24°C, determined with the diffusion equation, were approximately 10−6 cm/s. The sorption and diffusion data revealed that the newly developed PDMSvi–oligo polymer was an excellent sorbent for the three VOCs examined. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 920–927, 2004
Thermoplastic olefin/clay nanocomposites: Morphology and mechanical properties
Authors: Mehta Sameer , Mirabella Francis M. , Rufener Karl , Bafna Ayush
Published: February 2004

Thermoplastic olefin (TPO)/clay nanocomposites were made with clay loadings of 0.6–6.7 wt %. The morphology of these TPO/clay nanocomposites was investigated with atomic force microscopy, transmission electron microscopy (TEM), and X‐ray diffraction. The ethylene–propylene rubber (EPR) particle morphology in the TPO underwent progressive particle breakup and decreased in particle size as the clay loading increased from 0.6 to 5.6 wt %. TEM micrographs showed that the clay platelets preferentially segregated to the rubber–particle interface. The breakup of the EPR particles was suspected to be due to the increasing melt viscosity observed as the clay loading increased or to the accompanying chemical modifiers of the clay, acting as interfacial agents and reducing the interfacial tension with a concomitant reduction in the particle size. The flexural modulus of the injection moldings increased monotonically as the clay loading increased. The unnotched (Izod) impact strength was substantially increased or maintained, whereas the notched (Izod) impact strength decreased modestly as the clay loading increased. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 928–936, 2004
Preparation and characterization of hybrid organic–inorganic epoxide‐based films and coatings prepared by the sol–gel process
Authors: špírková Milena , Brus Jiří , Hlavatá Drahomíra , Kamišová Helena , Matějka Libor , Strachota Adam
Published: February 2004

Hybrid organic–inorganic coatings and free‐standing films were prepared and characterized. The hybrids were prepared from [3‐(glycidyloxy)propyl]trimethoxysilane, diethoxy[3‐(glycidyloxy)propyl]methylsilane, poly(oxypropylene)s of different molecular weights end‐capped with primary amino groups (Jeffamines D230, D400, and T403), and colloidal silica particles with hydrochloric acid as a catalyst for the sol–gel process and water/propan‐2‐ol mixtures as solvents. The structure evolution during the network formation was followed by NMR spectroscopy and small‐angle X‐ray scattering; the surface morphology was tested by atomic force microscopy. The influence of the reaction conditions (the organosilicon precursor, oligomeric amine, ratio of functional groups, and method of preparation) on the network buildup and product properties was studied and examined. The mechanical testing, based on stress–strain experiments, in combination with dynamic mechanical thermal analysis served as an effective instrument for the optimization of the reaction conditions for the preparation of products with desired properties. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 937–950, 2004
New postfunctional method to synthesize C60‐containing poly(ethylene oxide)
Authors: Li Zhen , Shao Pin , Qin Jingui
Published: February 2004

This article reports the detailed synthesis and structural characterization of two new C60‐containing poly(ethylene oxide)s by a new postfunctional method. A predesigned amino end‐functionalized poly(ethylene oxide) was prepared, and this reactive macromolecular intermediate was reacted with C60 molecules in chlorobenzene to yield the C60‐containing poly(ethylene oxide)s. The molecular structures of the polymers were characterized with 1H‐NMR, IR, and ultraviolet–visible spectra. The polymers exhibited good solubility in common organic solvents and water and were stable in air. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 867–870, 2004
On the use of extruders as chemical reactors
Authors: Natov Milcho , Mitova Violeta , Vassileva Stefanka
Published: February 2004

Composites of polyamide‐6 (PA‐6) and poly(butadiene acrylonitrile) (PBAN), varying in the quantity of the elastomer and the content of its nitrile groups, were examined during extrusion in a 45‐mm extruder at 225 ± 2°C and with a shear rate over 450 s−1. It was established that these two incompatible polymers can be mixed and the blends display solubility in formic acid. This fact is explained by chemical transformation of the nitrile groups followed by chemical interaction between the polyamide and elastomer components. As a result, graft copolymers were most probably formed. The reaction proceeds easily if the PA‐6 contains water. The extrusion leads to improved compatibility of the polymers and enhanced impact strength of the extrudates. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 871–877, 2004
Preparation of hyperbranched polyester photoresists for miniaturized optics
Authors: Feng Zongcai , Liu Minghua , Wang Yuechuan , Zhao Lin
Published: February 2004

Hyperbranched polymers containing carboxyl and acryloxyl groups were prepared through a one‐step synthesis with metatrimellitic anhydride, epichlorohydrin, and methylacrylic acid glycidic ester. The photo‐sensitivity coefficients of the polymer resists varied with the resin acid values and formulas. The linear depth was the reverse of the contrast. When the contrast was less than 0.49, the linear depth could reach 43 μm. The hyperbranched polyester resists were used to prepare microlens arrays. Moreover, there was a slight discrepancy between the element profile and simulated profile of the formed resists. The etching depth could reach 50 μm. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1259–1263, 2004
Preparation and release behavior of carboxymethylated chitosan/alginate microspheres encapsulating bovine serum albumin
Authors: Zhang Lina , Guo Ji , Peng Xianghong , Jin Yong
Published: February 2004

Microspheres were prepared from carboxymethylated chitosan (CM‐chitosan) and alginate by emulsion phase separation. Their structure and morphology were characterized with IR spectroscopy and scanning electron microscopy. Bovine serum albumin (BSA) was encapsulated in the microspheres to test the release behavior. The swelling behavior, encapsulation efficiency, and release behavior of BSA from the microspheres at different pHs and with a pH‐gradient condition were investigated. The BSA encapsulation efficiency was calculated to be 80%. The degree of swelling of the microspheres without BSA loaded at pH 7.2 was much higher than that at pH 1.0. The encapsulated BSA was quickly released in a Tris–HCl buffer (pH 7.2), whereas a small amount of BSA was released under acid conditions (pH 1.0) because of the strong electrostatic interaction between NH2 groups of CM‐chitosan and COOH groups of alginic acid and a dense structure caused by a Ca2+ crosslinked bridge. For the simulation of the processing of the drug under the conditions of the intestine, the microspheres were tested in a pH‐gradient medium, in which an acceleration of the release occurred at pH 7.4 after a lag time at a low pH (5.8–6.8). At pH 7.4, a large amount of BSA was released from the microspheres in a short time because of the rapid swelling of the microspheres. However, the release only depended on the diffusion of BSA at relatively low pHs, this resulted in a relatively low release. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 878–882, 2004