bluuebunny/crossref_metadata_2025 huggingface dataset:
No evidence for linkage by transmission disequilibrium test analysis of microsatellite marker D22S278 and schizophrenia in a Palestinian Arab and in a German population
Authors: Dobrusin M. , Corbex Marilys , Kremer I. , Murad I. , Muhaheed M. , Bannoura I. , Müller D.J. , Schulze T.G. , Reshef A. , Blanaru M. , Gathas S. , Rietschel M. , Belmaker R.H. , Maier W. , Ebstein Richard P.
Published: August 2002

Linkage for a schizophrenia susceptibility locus on chromosome region 22q12–q13 was initially suggested by independent studies from two groups and confirmed in a combined analysis of data for the microsatellite marker D22S278 in multiply affected schizophrenic families derived from 11 independent research groups worldwide. In addition to these reports of linkage to schizophrenia on chromosome 22, bipolar disorder has also been linked to markers in this chromosomal region. We now report results from an analysis of 223 Palestinian Arab trios from three different centers in Israel and Palestine using the allele‐wise extended transmission disequilibrium test for multiallelic markers. No evidence for linkage is observed in the entire group or in any of the three centers (entire group: chi‐square = 5.59, P = 0.78, df = 9; Afula: chi‐square = 6.51, P = 0.48, df = 7; Bethlehem: chi‐square = 14.11, P = 0.12, df = 9; Beersheva: chi‐square = 7.04, P = 0.32, df = 6). Additionally, we examined D22S278 in a group of 114 schizophrenic German triads and failed to observe evidence for linkage (chi‐square = 8.13, P = 0.42, df = 8df). © 2001 Wiley‐Liss, Inc.
A family study of Tourette syndrome in Japan
Authors: Kano Yukiko , Ohta Masataka , Nagai Yoko , Pauls David L. , Leckman James F.
Published: August 2002

Although the mode of inheritance remains in doubt, twin and family studies conducted mostly in the United States and western Europe suggest that genetic factors play an important role in the transmission and expression of Tourette syndrome (TS). In an effort to evaluate population‐based genetic differences, we generated risk estimates for first‐degree relatives of TS probands in Japan using methods similar to those utilized in recent Western studies. The subjects were 52 TS probands seen at an outpatient clinic of Tokyo University Hospital and their 165 first‐degree relatives. All probands and one or more first‐degree relatives in each family were interviewed concerning the presence of tic and obsessive‐compulsive symptoms by expert clinicians. The age‐corrected rates of TS, chronic motor tics, obsessive‐compulsive disorder, and subclinical obsessive‐compulsive symptoms in the first‐degree relatives were 2.0%, 12.0%, 1.6%, and 7.0%, respectively. Rates of TS and related disorders in Japan appear to be much lower than those in recent Western family studies. If replicated, these data suggest that there may be differences in the nature and frequency of vulnerable alleles for TS and related disorders in the Japanese compared to European populations. © 2001 Wiley‐Liss, Inc.
Geographic distribution and abundance of woolly (Lagothrix cana) and spider (Ateles chamek) monkeys in southwestern Brazilian Amazonia
Authors: Iwanaga Simone , Ferrari Stephen F.
Published: August 2002

Two species of frugivorous atelids,Ateles chamekandLagothrix cana, occur in southwestern Brazilian Amazonia. Populations were surveyed at 36 sites in the state of Rondônia.Ateles chamekis widespread, but the distribution ofL. canais limited by a combination of riverine barriers and ecological factors, possibly including competition withA. chamek. Groups ofL. canawere generally larger and more abundant than those ofA. chamek, even in syntopy. The transitional forest that predominates in the extreme south of Rondônia (Hylea‐cerrado) is not a barrier to either species, with both species being tolerant of habitat disturbance when hunting pressure is low. Am. J. Primatol. 56:57–64, 2002. © 2002 Wiley‐Liss, Inc.
Egarapithecus narcisoi, a new genus of Pliopithecidae (primates, catarrhini) from the Late Miocene of Spain
Authors: Moyà‐Solà Salvador , Köhler Meike , Alba David M.
Published: August 2002

Pliopithecid remains from the Spanish locality of Torrent de Febulines (Late Vallesian, MN 10), consisting of right and left mandibular fragments with partial tooth rows and an isolated P3 probably belonging to the same individual, are described and assigned to Egarapithecus narcisoi gen. et sp. nov. (Pliopithecidae, Crouzeliinae). This is a highly derived species dated at around 9 Ma (Ma = 106 years), representing the latest appearance of the family in the European continent. Morphologically it is the most distant member from the inferred primitive pliopithecid morphotype, displaying many autapomorphies that notably accentuate those of the remaining Crouzeliinae. A cladistic analysis based on lower cheek teeth, performed in order to tentatively assess the phylogenetic relationships of Egarapithecus within the Crouzeliinae, indicates that several equally parsimonious cladograms are possible in the light of current evidence. This is due to uncertainties regarding the position of Plesiopliopithecus and Crouzelia (here considered distinct genera), as a result of missing characters and the significant degree of homoplasy apparently involved in crouzeliine dental evolution. Whether Egarapithecus is more closely related to Crouzelia or to Anapithecus (the latter hypothesis tentatively favored here) cannot be definitively resolved with the currently available material and deserves further investigation. It is clear, however, that Egarapithecus is one of the more derived and specialized members of the Pliopithecidae. Am J Phys Anthropol 114:312–324, 2001. © 2001 Wiley‐Liss, Inc.
Three‐dimensional analysis of nonhuman primate trabecular architecture using micro‐computed tomography
Authors: Fajardo R.J. , Müller R.
Published: August 2002

Until recently, detailed analyses of the architecture of nonhuman primate cancellous bone have not been possible due to a combination of methodological constraints, including poor resolution imaging or destructive protocols. The development of micro‐computed tomography (μCT) and morphometric methods associated with this imaging modality offers anthropologists a new means to study the comparative architecture of cancellous bone. Specifically, μCT will allow anthropologists to investigate the relationship between locomotor behavior and trabecular structure. We conducted a preliminary study on the trabecular patterns in the proximal humerus and femur of Hylobates lar, Ateles paniscus, Macaca mulatta, and Papio anubis to investigate the quantitative differences in their trabecular architecture and evaluate the potential of μCT in anthropological inquiry. μCT allows the researcher to evaluate variables beyond simple two‐dimensional orientations and radiographic densities. For example, this methodology facilitates the study of trabecular thickness and bone volume fraction using three‐dimensional data. Results suggest that density‐related parameters do not reliably differentiate suspensory‐climbing species from quadrupedal species. However, preliminary results indicate that measurements of the degree of anisotropy, a measure of trabecular orientation uniformity, do distinguish suspensory‐climbing taxa from more quadrupedal species. The μCT method is an advance over conventional radiography and medical CT because it can accurately resolve micron‐sized struts that make up cancellous bone, and from these images a wide array of parameters that have been demonstrated to be related to cancellous bone mechanical properties can be measured. Methodological problems pertinent to any comparative μCT study of primate trabecular architecture are discussed. Am J Phys Anthropol 115:327–336, 2001. © 2001 Wiley‐Liss, Inc.
Transected neurites, apoptotic neurons, and reduced inflammation in cortical multiple sclerosis lesions
Authors: Peterson John W. , Bö Lars , Mörk Sverre , Chang Ansi , Trapp Bruce D.
Published: August 2002

Multiple Sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system that causes motor, sensory, and cognitive deficits. The present study characterized demyelinated lesions in the cerebral cortex of MS patients. One hundred twelve cortical lesions were identified in 110 tissue blocks from 50 MS patients. Three patterns of cortical demyelination were identified: type I lesions were contiguous with subcortical white matter lesions; type II lesions were small, confined to the cortex, and often perivascular; type III lesions extended from the pial surface to cortical layer 3 or 4. Inflammation and neuronal pathology were studied in tissue from eight and seven patients, respectively. Compared to white matter lesions, cortical lesions contained 13 times fewer CD3‐positive lymphocytes (195 vs 2,596/mm3 of tissue) and six times fewer CD68‐positive microglia/macrophages (11,948 vs 67,956/mm3 of tissue). Transected neurites (both axons and dendrites) occurred at a density of 4,119/mm3 in active cortical lesions, 1,107/mm3 in chronic active cortical lesions, 25/mm3 in chronic inactive cortical lesions, 8/mm3 in myelinated MS cortex, and 1/mm3 in control cortex. In active and chronic active cortical lesions, activated microglia closely apposed and ensheathed apical dendrites, neurites, and neuronal perikarya. In addition, apoptotic neurons were increased significantly in demyelinated cortex compared to myelinated cortex. These data support the hypothesis that demyelination, axonal transection, dendritic transection, and apoptotic loss of neurons in the cerebral cortex contribute to neurological dysfunction in MS patients.
Structure and mechanical properties of nanocrystalline boron nitride thin films
Authors: Ossi Paolo M. , Miotello Antonio
Published: August 2002

Boron nitride thin films have been deposited on (100) Si wafers, kept at low temperature, by radio frequency (r.f.) magnetron sputtering. The r.f. target power was fixed at 150 W and the substrate bias voltage ranged between −50 and −130 V. Film composition was checked by Auger electron spectroscopy; the structure was investigated by Fourier transform IR spectroscopy, glancing‐angle X‐ray diffraction and micro‐Raman spectroscopy. Film hardness and Young's modulus were measured by nanoindentation. Film composition is nearly equiatomic, with a low degree of gaseous contamination. All samples are very fine grained, and nanocrystalline. Film coordination is mixed sp2–sp3, and the fraction of tetrahedral coordination depends critically on the bias voltage value. In hexagonal sp2‐bonded films the hardnesses and Young's moduli are low and increase considerably with the content of sp3‐coordinated cubic phase. Copyright © 2001 John Wiley & Sons, Ltd.
Solid‐state NMR and FT IR studies of the preparation of Si–B–C–N ceramics from ­boron‐modified polysilazanes
Authors: Schuhmacher Jörg , Berger Frank , Weinmann Markus , Bill Joachim , Aldinger Fritz , Müller Klaus
Published: August 2002

Multinuclear (29Si,13C,11B,15N,1H) solid‐state NMR and FT IR spectroscopy is employed to investigate the thermolysis of boron‐modified polyhydridovinylsilazane, [B(C2H4SiHNH)3]n, from which a high‐temperature stable Si–B–C–N ceramic can be formed. The study is focused primarily on the characterization of the amorphous intermediates on the atomic scale, where such spectroscopic techniques have demonstrated their particular suitability. In addition, data are provided for the transformation from the amorphous to the crystalline ceramic. It is shown that the transformation of the polymeric precursor to the (amorphous) pre‐ceramic network is completed at around 500 °C. At this temperature the BN domains and Si–C–N units of mixed composition are formed. Above this temperature a continuous transformation to the ceramic takes place. At 1050 °C the amorphous ceramic consists of three main components: (i) amorphous (graphite‐like) carbon; (ii) planar BN domains; and (iii) an Si–C–N matrix (SiCxN4−xunits withx = 0, 1, 2). In addition, a considerable amount of hydrogen is present even at this temperature. The NMR studies have further shown that above 1700 °C the amorphous ceramic demixes, along with the formation of crystalline silicon nitride and silicon carbide. Likewise, structural changes for BN domains have been registered that are attributed to the formation of turbostratic BN(C) interface layers. In summary, the present study has demonstrated that the combination of multinuclear solid‐state NMR and FT IR spectroscopy is a powerful method to probe the thermolytic preparation of ternary and quaternary ceramic materials. Copyright © 2001 John Wiley & Sons, Ltd.
Synthesis, characterization of diorganotin(IV) complexes of N‐(2‐hydroxyarylidene)amino‐acetic acid and antitumour screening in vivo in Ehrlich ascites carcinoma cells
Authors: Basu Baul Tushar S. , Dutta Sushmita , Rivarola Eleonora , Scopelliti Michelangelo , Choudhuri Soumitra
Published: August 2002

Some new diorganotin(IV) complexes have­been prepared by reacting potassium N‐(2‐hydroxyarylidene)aminoacetate with R2SnCl2(R =­Me,nBu,Ph). The complexes have been characterized by 1H,13C,119Sn NMR, IR and 119mSn Mössbauer spectroscopic techniques in combination with elemental analysis. In the solid state, the complexes possess penta‐ and hexa‐coordinated tin centres. The hexa‐coordinated tin complexes were found to dissociate in solution, giving rise to penta‐coordinated species­as revealed by 119Sn NMR spectroscopy. Antitumour screening in vivo of the complexes L4SnPh2,L4SnPh2·Ph3SnCl and L4SntBu2·t Bu2SnCl2 (L4 = N‐(2‐hydroxyacetophenone)aminoacetate) is also reported. Copyright © 2001 John Wiley & Sons, Ltd.
Emission to air of volatile organotins from tributyltin‐contaminated harbour sediments
Authors: Vella Alfred J. , Vassallo Roderick
Published: August 2002

An analytical method for determining the presence in air of volatile forms (e.g. chlorides) of tributyltin (TBT) and that of methylbutyltins Me
nBu(4−n)Sn (n = 1–3) was developed and used to establish whether dredged harbour sediments contaminated with TBT served as sources of air pollution with respect to organotin compounds. The method was based on active sampling of the air being analysed and sorption of analytes onto Poropak‐N. Sorbed methylbutyltins were extracted with dichloromethane and analysed by gas chromatography using flame photometric detection. Other butyltins were converted into butyltin hydrides prior to analysis by gas chromatography. It was shown that TBT‐contaminated sediments from Marsamxett Harbour, Malta, placed in 0.5 l chambers through which air was displaced by continuous pumping for 11 days released mainly methylbutyltins, with concentrations (as tin) reaching maximum 48 h mean values of 8.7 (Me3BuSn), 22.1 (Me2Bu2Sn) and 93.0 ng m−3(MeBu3Sn) being measured. Other volatile forms of TBT, dibutyltin and monobutyltin were detected in the headspace air, but very infrequently and at much lower tin concentrations (<2 ng m−3). It was also shown that methylbutyltins dissolved in sea‐water ([Sn] = 0.2 to 400 ng l−1) were very difficult to exsolve from this medium, even on prolonged evaporation of the solutions using mechanical agitation and active ventilation. The results suggest that emission of methylbutyltins from contaminated sediments probably occurs only from the surface of the material. The environmental implications of these findings in the management of TBT‐polluted harbour sediments are discussed. Copyright © 2002 John Wiley & Sons, Ltd.
Synthesis and single crystal X‐ray determination of the Schiff base 1‐[(2‐isopropyl‐5‐methylphenoxy)hydrazono] ethyl ferrocene
Authors: Baghlaf Ahmad O. , Ishaq M. , Bakhiswein Khalid H. , Al‐Harbi Adil H.
Published: August 2002

The reaction of acetylferrocene [Fe(η‐C5H5)(η‐C5H4COCH3)] (1) with (2‐isopropyl‐5‐methylphenoxy) acetic acid hydrazide [CH3C6H3CH(CH3)2OCH2CONHNH2] (2) in refluxing ethanol gives the stable light‐orange–brown Schiff base 1‐[(2‐isopropyl‐5‐methylphenoxy)hydrazono] ethyl ferrocene, [CH3C6H3CH(CH3)2OCH2CONHNC(CH3)Fe(η‐C5H5)(η‐C5H4)] (3). Complex 3 has been characterized by elemental analysis, IR, 1H NMR and single crystal X‐ray diffraction study. It crystallizes in the monoclinic space group P21/n, with a = 9.6965(15), b = 7.4991(12), c = 29.698(7) Å, β = 99.010(13) °, V = 2132.8(7) Å3, Dcalc = 1.346 Mg m−3; absorption coefficient, 0.729 mm−1. The crystal structure clearly shows the characteristic [NH···O] hydrogen bonding between the two adjacent molecules of 3. This acts as a bidentale ligand, which, on treatment with [Ru(CO)2Cl2]
n, gives a stable bimetallic yellow–orange complex (4). Copyright © 2002 John Wiley & Sons, Ltd.
Complexation of CH3Hg+ with chloride, sulfate and carbonate in NaClO4: construction of thermodynamic models
Authors: Sanz J. , Raposo J. C. , de Diego A. , Madariaga J. M.
Published: August 2002

The complexation of CH3Hg+ with major ions present in sea and estuary waters (Cl−, SO42− and CO32−) was studied potentiometrically in an NaClO4 medium in the ionic strength range 0.1–3.0 mol dm−3 at 25 °C. The potentiometric data, treated with non‐linear least squares computer programs, led us to establish the formation of the species CH3HgCl in equilibrium with chloride, CH3Hg(SO4)− species with sulfate and no complex with carbonate. The stoichiometric stability constants obtained at the different ionic strengths were correlated by means of the modified Bromley methodology (MBM) to determine the corresponding thermodynamic constants and interaction parameters. This study is the second of a series designed to simulate, using the MBM thermodynamic model, the behaviour of methylmercury in different conditions of sea and estuary waters. In the first study of the series, the hydrolysis equilibria of methylmercury in NaClO4 ionic media were established. Copyright © 2002 John Wiley & Sons, Ltd.
Synthesis and characterization of ABA triblock and novel multiblock copolymers from ethylene glycol, L‐lactide, and ϵ‐caprolactone
Authors: Mohammadi‐Rovshandeh J. , Farnia S. M. F. , Sarbolouki M. N.
Published: August 2002

Three types of copolymers were synthesized and characterized. First, triblock ABA copolymers [where A is a homopolymer of ϵ‐caprolactone and B is poly(ethylene glycol)] were prepared by the ring‐opening polymerization of poly(ethylene glycol) with ϵ‐caprolactone in the presence of stannous octoate (Sn(Oct)2). The spectral, thermal, and mechanical properties of one sample of these copolymers were studied, and it was discovered that these types of copolymers were more hydrophilic, possessed lower melting points, and had superior mechanical properties (greater toughness) than poly(ϵ‐caprolactone). Second, triblock ABA copolymers [where A is a homopolymer of L‐lactide and B is poly(ethylene glycol)] were prepared by the ring‐opening polymerization of poly(ethylene glycol) with L‐lactide in the presence of Sn(Oct)2. The mechanical properties of these copolymers were studied, and it was found that they were tougher and softer than poly(L‐lactide). Third, novel ABA triblock copolymers [where A is a copolymer of ϵ‐caprolactone and L‐lactide and B is poly(ethylene glycol)] were prepared, and 1H‐NMR and 13C‐NMR spectra of these copolymers indicated a microblock structure for the two end blocks. The stress–strain behavior revealed low yields and high toughness for these copolymers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2072–2081, 2002
Morphology/behavior relationship and recyclability of composites based on PP/EPDM blends and short aramid fibers
Authors: Arroyo M. , Bell M.
Published: August 2002

The effect of short aramid fibers on the mechanical behavior of polypropylene (PP) and ethylene‐propylene‐diene (EPDM) and their blends has been investigated by means of an experimental design. The results have shown that aramid fibers are very effective reinforcing agents for composites when the continuous phase of the matrix is constituted by PP, so sensible increments in tensile modulus and strength are obtained as fiber content in the composites increases. An optimal matrix composition and fiber content has been observed that produced high abrasion resistance compounds. However, the abrasion resistance of very rich EPDM matrices is hardly affected by fibers content. The addition of fibers to EPDM rich (>50%) matrices gives rise to a sensible decrease of the impact strength of this polymer. However, at PP contents above 50% in the polymer matrix, an increase of impact strength is observed at fiber percentages in the composites above 10%. The different behavior of the fibers depending on matrix type can be attributed to a better affinity of these fibers for PP matrix. Morphological studies of the composites have been carried out by scanning electron microscopy. Finally, the price and recyclability of these materials have been analyzed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2474–2484, 2002
Hybrids of cellulose acetate and sol–gel silica: Morphology, thermomechanical properties, water permeability, and biodegradation evaluation
Authors: Zoppi R. A. , Gonçalves M. C.
Published: August 2002

Hybrids based on cellulose acetate (CA) and SiO2 were prepared by hydrolysis of tetraethoxysilane (TEOS). More rigid films were obtained with an inorganic phase incorporation. The thermal stability of the hybrids was similar to pure CA. Composite membranes were prepared by casting of CA/TEOS mixtures onto a poly(vinylidene fluoride) support. The water permeation decreased with the incorporation of the inorganic phase. Hybrid membranes were able to retain solutes with a molar mass of ≅9000 g/mol (≅98% retention). Hybrids were submitted to biodegradation tests. The presence of the inorganic phase did not inhibit the growth of Thricoderma harzianum fungi. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2196–2205, 2002
Mathematical modeling of rheological properties of hydroxyl‐terminated polybutadiene binder and dioctyl adipate plasticizer
Authors: Bandgar B. M. , Krishnamurthy V. N. , Mukundan T. , Sharma K. C.
Published: August 2002

Solid composite propellants contain 80–90% of a crystalline oxidizer like ammonium perchlorate and powdery metallic fuel like aluminum with 10 to 15% organic binders like HTPB or CTPB, to bind the solids together and maintain the shape under severe stress and strain environment. Also, the propellant must not crack or become brittle at subzero temperatures. Formulating and processing of the highly filled composite propellants are difficult tasks and need a thorough understanding of rheology, even apart from a knowledge of propellant chemistry, particulate technology, manufacturing methods, and safe handling of explosives and hazardous materials. The flow behavior or rheology of the propellant slurry determines the ingredients and some of the abnormalities of the motor during firing. The propellant viscosity and mechanical properties are determined by the binder system, and the unloading viscosity of the propellant slurry is dependent on the initial viscosity of the binder system, solid loading, particle size, and its distribution, shape, temperature, and pressure. In the present report an attempt is made to study the dependency of viscosity of the HTPB binder system on temperature, plasticizer level (composition), and torque (angular velocity of spindle). The viscosity measurements were made using a Brookfield viscometer model DV III at different plasticizer levels (10–50%), temperatures (30–65°C), and torques (50–100%). The data indicate that the viscosity of HTPB, DOA, and their mixture decreases with increasing temperature and is constant with torque. The Arrhenius equation gives the energy for viscous flow to be ≅35 kcal/mol for HTPB. The variation of viscosity with temperature of HTPB/DOA and their mixture follows a mathematical model expressed as where T is the temperature and a1, a2, a3, a4, and a5 are the constants. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1002–1007, 2002
Dispersion polymerization of n‐butyl acrylate
Authors: Wang Danni , Dimonie Victoria L. , Sudol E. David , El‐Aasser Mohamed S.
Published: August 2002

The dispersion polymerization of n‐butyl acrylate (BA) was investigated using alcohol/water mixtures as the dispersion medium, 4,4′ ‐azobis‐(4‐cyanopentanoic acid) as the initiator, and polyvinylpyrrolidone (PVP) as the stabilizer. The effects of polymerization parameters, such as the alcohol/water ratio in the medium and the type and concentration of the polymeric stabilizer, on the resulting particle size and size distribution were studied. The final particle size and the stability of the dispersion system were found to be greatly influenced by the type of alcohol used in the mixture; that is, methanol or ethanol, even though the apparent solubility parameters are almost the same for the two types of mixtures. Poly(butyl acrylate) particles with controlled size and size distribution (monodisperse), and gel content were successfully prepared in a 90/10 methanol/water medium. It was found that the particle size decreased with increasing initiator concentration. This is the opposite of what was previously reported in the dispersion polymerizations of styrene and methyl methacrylate. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2692–2709, 2002
Disperse dyeing of polyester fibers: Kinetic and equilibrium study
Authors: Georgiadou K. L. , Tsatsaroni E. G. , Eleftheriadis I. C. , Kehayoglou A. H.
Published: August 2002

The effect of temperature on the dyeing rate constant k, diffusion coefficient D, and time of half‐dyeing t1/2 was evaluated for the dyeing of polyester fibers with two disperse dyes, an azo and an anthraquinone dye. Activation energies of diffusion E were calculated. The polyester dyeing equilibrium was also studied and the partition coefficient K and standard affinity Δμ° at various temperatures were determined for the anthraquinone dye. Standard enthalpy ΔH° and standard entropy ΔS° of dyeing were also obtained. The same equilibrium parameters were not obtained for the azo dye because of its dyeing behavior. A similar kinetic and equilibrium study was made for the pure azo and anthraquinone compounds free from the dispersing agents present in the commercial dyes and the results are discussed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 123–128, 2002
Characterization of alkali‐treated jute fibers for physical and mechanical properties
Authors: Ray Dipa , Sarkar B. K.
Published: August 2002

Changes occurring in jute fibers when treated with a 5% concentration of a NaOH solution for 0, 2, 4, 6, and 8 h were characterized by weight loss, linear density, tenacity, modulus, FTIR, and X‐ray measurements. A 9.63% weight loss was measured during 2 h of treatment with a drop of hemicellulose content from 22 to 12.90%. The linear density value showed no change until 2 h of treatment followed by a decrease from 33.0 to 14.5 denier by 56% after 6 h of treatment. The tenacity and modulus of the fibers improved by 45 and 79%, respectively, and the percent breaking strain was reduced by 23% after 8 h of treatment. X‐ray diffractograms showed increase in crystallinity of the fibers only after 6 h of treatment, while FTIR measurements showed much of the changes occurring by 2 h of treatment with an increased amount of OH groups. By measuring the rate of change of the modulus, tenacity, and percent breaking strain with the time of treatment, a clear transition was apparent at 4 h of treatment with the dissolution of hemicellulose, causing a weight loss and drop in the linear density before and development of crystallinity with an improvement in the properties after the transition time. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1013–1020, 2001
Polymers from renewable resources. XIII. Interpenetrating polymer networks derived from castor oil–hexamethylene diisocyanate and polymethacrylamide
Authors: Nayak P. , Mishra D. K. , Sahoo K. C. , Pati N. C. , Jena P. K. , Lenka S. , Nayak P. L.
Published: August 2002

Several castor oil‐based polyurethanes (PUs) samples were synthesized using various diisocyanates such as hexamethylene diisocyanate (HMDI) with varying NCO/OH ratios. All the PUs were reacted with methacrylamide (MAM) using an ethylene glycol dimethacrylate (EGDM) crosslinker and benzoyl peroxide as an initiator. Thermogravimetric analysis of the polymers was followed using a computer analysis method for assigning the kinetic mechanism. The degradation steps are discussed in the light of kinetic parameters. The scanning electronic microscopy of some of the interpenetrating polymer networks (IPNs) were studied and the morphology was examined. The samples were subjected to wide‐angle X‐ray diffraction analysis. Ruland and Vonk's method was used to calculate the degree of crystallinity. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1349–1353, 2001
Polymer‐based self‐lubricating material
Authors: Shiao Shin Jen , Fu Wei Shung , Tuo Chin Lin , Cheng Un I
Published: August 2002

A low‐friction coefficient material with color based on proper selection of polar conditions of pigment and liquid lubricant was developed. Bush‐type bearings were made from poly oxymethylene reinforced with inorganic fillers, including polar compounds of white carbon and glass powder, and nonpolar compounds of carbon black and graphite. The fillers were coated with different levels of titanate, and with polar lubricants such as cetyl alcohol and palmitic acid, and nonpolar lubricants of motor oil, and paraffin. The frictional properties at constant velocity and at constant loading, and the relationships between materials polarity are discussed. An excellent self‐lubricating material of frictional coefficient less than 0.02 was obtained. That is superior to the most current commercial products claiming μ = 0.05 ∼ 0.06. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1514–1519, 2001
Grafting of poly(acrylic acid) on polyamide yarn
Authors: Bucheńska Jadwiga
Published: August 2002

Graft copolymerization of acrylic acid onto PA6 yarn was examined in this study. Prior to the grafting process, the fibers were activated with a benzene solution of benzoyl peroxide. Next, the fibers were put into a bath containing acrylic acid, a dispersing agent, and the activator of reaction. The effects of the main process parameters and auxiliary additives on the degree of grafting, quantity of the homopolymer formed during grafting, effectiveness of grafting, extent of conversion, and grafting ratio were determined. Using calculation factors such as the reaction efficiency, the extent of reaction, and the ratio of grafting, the conditions of grafting were found that made possible the reduction or elimination of the by‐product. Also determined were the influence of the degree of grafting on the moisture sorption and the swelling of modified fibers. In addition, the value of apparent activation energy was calculated (49.123 kJ/mol). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1914–1919, 2001
Compatibilization of PA6/PPO blend with carboxylated poly(styrene) compounds
Authors: Kelnar I. , Stephan M. , Jakisch L. , Janata M. , Fortelný I.
Published: August 2002

PA6/PPO 70/30 blends were reactively compatibilized using carboxylated polystyrene (PS) and poly(styrene‐block‐4‐methylstyrene) with various degrees of carboxylation. The high carboxylation of PS (up to about 50%) caused a decrease of dispersed PPO dimensions with a simultaneous deterioration of properties, especially of toughness and elongation. The best mechanical behavior was found for PS with 1% degree of carboxylation and for neat PS. On the other hand, degrees of carboxylation higher than 50% caused an increase in particle size. This was most significant for block copolymers, where a marked change in size and shape occurred, from spherical particles of about 1 μm in size to large, elongated particles about 50 μm long or a similar rough cocontinuous structure. The deteriorated mechanical behavior is tentatively explained by unsuitable properties of the reactively formed compatibilizer and thus of the interface. The enhanced rigidity of highly carboxylated poly(4‐methylstyrene) chains (and its product of grafting with PA6), causing its decreased emulsification ability together with the expected rigid interface, which probably suppresses breakup of the PPO phase, may be responsible for the increase of the dispersed PPO dimensions found. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2273–2280, 2001
Preparation and characterization of polyurethane flame‐retardant coatings using pyrophosphoric lactone‐modified polyesters/isophorone diisocyanate–isocyanurate
Authors: Park Hong‐Soo , Kim Dae‐Won , Hwang Kyu‐Hyun , Yoon Byung‐Seon , Wu Jong‐Pyo , Park Jin‐Woo , Hahm Hyun‐Sik , Im Wan‐Bin
Published: August 2002

Pyrophosphoric lactone‐modified polyester containing two phosphorous functional groups in one structural unit of base resin was synthesized to prepare a nontoxic, reactive flame‐retardant coatings. Then, the pyrophosphoric lactone‐modified polyester was cured at room temperature with isocyanate and isophorone diisocyanate (IPDI)–isocyanurate to get a two‐component polyurethane flame‐retardant coatings (TAPPU). Comparing the physical properties of the films of TAPPU with the film of nonflame‐retardant coatings, no deterioration of physical properties was observed with the incorporation of a flame‐retarding component into the resin. Three kinds of flame retarding tests were conducted, including the 45° Meckel burner method, limiting oxygen index method (LOI method), and oxygen combustion method with Cone calorimeter. It was observed that the char lengths were 3.1∼4.5 cm and LOI values were 27∼30%. These results indicate that the prepared coatings are good flame‐retardant ones. It was also found that the flame retardancy of those coatings was increased with the contents of phosphorous. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2316–2327, 2001
Crystallization of poly(ethylene terephthalate) modified with codiols
Authors: Bouma Krista , Regelink Marc , Gaymans Reinoud J.
Published: August 2002

The nucleation of poly(ethylene terephthalate) (PET) by codiols and olefinic segments was studied. The codiols 1,5‐pentanediol, 1,8‐octanediol, 2,5‐hexanediol, and 1,3‐dihydroxymethyl benzene were copolymerized into PET in a concentration range of 0–10 mol %. The melting (Tm), crystallization (Tc), and glass‐transition (Tg) temperatures were studied. These codiols were found to be able to nucleate PET at low concentrations, probably by lowering the surface free energy of the chain fold. However, the codiols also disturbed the structural order of the polymer, resulting in a decrease in both the Tm and Tc values. The optimum codiol concentration was found to be at around 1 mol %, which is lower than previously reported. A diamide segment N,N′‐bis(p‐carbo‐methoxybenzoyl)ethanediamine (T2T) was found to be a more effective nucleator than the codiols; however, no synergy was observed between the nucleating effect of the diamide segment T2T and that of the codiol. An olefinic diol (C36‐diol) with a molecular weight of 540 g/mol was also copolymerized into PET in a concentration range of 0–21 wt %. Only one Tg was observed in the resulting copolymers, suggesting that the amorphous phases of PET and the C36‐diol are miscible. The main effect of incorporating the C36‐diol into PET was the lowering of the Tg; thus, the C36‐diol is an internal plastifier for PET. The C36‐diol had little effect on the Tm value; however, the Tc value actually increased in the 11.5 wt % copolymer. As the Tg decreased and the Tc increased, the crystallization window also increased and thereby the likelihood of crystallization. Therefore, the thermally stable C36‐diol appears to be an interesting compound that may be useful in improving the crystallization of PET. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2676–2682, 2001
Ring‐opening metathesis polymerization of dicyclopentadiene catalyzed by titanium tetrachloride adduct complexes with oxygen‐containing ligands
Authors: Qian Yanlong , Dono Keleypette , Huang Jiling , Ma Haiyan
Published: August 2002

Ring‐opening metathesis polymerization of dicyclopentadiene catalyzed by TiCl4 · 2L/CH3Li system [where L is tetrahydropyran (1), dioxane, 2,5‐dimethylfuran, or tetrahydrofurfyl alcohol] is reported. The obtained polymer was characterized by IR and 1H‐NMR. These catalytic systems effectively promoted the polymerization reaction. Seven influencing factors are discussed. When the aging temperature was 0°C, the aging time was 90 min, the polymerization temperature was 60°C, Li/Ti was 1.5–2, and the monomer/catalyst molar ratio ranged between 30 and 50, the polymerization reaction catalyzed by complex 1 yielded better results within a shorter period of time. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 662–666, 2001
Miscibility and phase structure of binary blends of poly(L‐lactide) and poly(vinyl alcohol)
Authors: Shuai Xintao , He Yong , Asakawa Naoki , Inoue Yoshio
Published: August 2002

Blend films of poly(L‐lactide) (PLLA) and poly(vinyl alcohol) (PVA) were obtained by evaporation of hexafluoroisopropanol solutions of both components. The component interaction, crystallization behavior, and miscibility of these blends were studied by solid‐state NMR and other conventional methods, such as Fourier transform infrared (FTIR) spectra, differential scanning calorimetry (DSC), and wide‐angle X‐ray diffraction (WAXD). The existence of two series of isolated and constant glass‐transition temperatures (Tg's) independent of the blend composition indicates that PLLA and PVA are immiscible in the amorphous region. However, the DSC data still demonstrates that some degree of compatibility related to blend composition exists in both PLLA/atactic‐PVA (a‐PVA) and PLLA/syndiotactic‐PVA (s‐PVA) blend systems. Furthermore, the formation of interpolymer hydrogen bonding in the amorphous region, which is regarded as the driving force leading to some degree of component compatibility in these immiscible systems, is confirmed by FTIR and further analyzed by 13C solid‐state NMR analyses, especially for the blends with low PLLA contents. Although the crystallization kinetics of one component (especially PVA) were affected by another component, WAXD measurement shows that these blends still possess two isolated crystalline PLLA and PVA phases other than the so‐called cocrystalline phase. 13C solid‐state NMR analysis excludes the interpolymer hydrogen bonding in the crystalline region. The mechanical properties (tensile strength and elongation at break) of blend films are consistent with the immiscible but somewhat compatible nature of these blends. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 762–772, 2001
Blends of vinylic copolymer with plasticized lignin: Thermal and mechanical properties
Authors: Feldman D. , Banu D. , Campanelli J. , Zhu H.
Published: August 2002

The article presents an investigation into the use of plasticizers for reducing the degree of association existing within lignin molecules, in order to overcome adverse effects on the mechanical properties of its blends with a vinyl chloride–vinyl acetate (VC–VAc) copolymer. Infrared spectroscopy and differential scanning calorimetry were performed to examine the effect of the plasticizer type and concentration in plasticizing Alcell, an organosolv lignin. The results show that the compatibility and efficiency of a plasticizer are strongly influenced by the solubility parameter, which should be close to that of the lignin. Polyblends prepared with several plasticizers, Alcell lignin, and the VC–VAc copolymer were also investigated by thermal analysis and mechanical testing. Variations in the mechanical properties of these blends were found to correlate with the lignin dispersion quality and with the plasticizer efficiency in Alcell lignin. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 861–874, 2001
Synthesis, characterization, and glass transition temperature of poly(styrene‐b‐butyl methacrylate) block copolymers by stable free radical polymerization
Authors: Fernández‐García M. , Cuervo‐Rodríguez R. , Madruga E. L.
Published: August 2002

The synthesis of controlled polystyrenes with different molecular weights has been performed in the presence of 1‐phenyl‐1‐(2,2,6,6‐tetramethyl‐1‐piperidinyloxy)ethane (PETEMPO). The polystyrenes have served as macroinitiators for the formation of poly(styrene‐b‐butyl methacrylate) block copolymers. Using differential scanning calorimetry (DSC) it has been shown that all block copolymers synthesized do not present phase segregation. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 14–21, 2001
Thermal degradation of flax and jute fibers
Authors: Gassan Jochen , Bledzki Andrzej K.
Published: August 2002

The thermal degradation of jute and flax fibers under temperatures between 170 and 210°C for a maximum of 120 min was studied in detail. This article will analyze the effects of the thermal exposure on mechanical properties (tenacity) as well as on fiber fine structure (degree of polymerization and degree of crystallinity). It was found that temperatures below 170°C only slightly affects fiber properties, while temperatures above 170°C significantly dropped tenacity and degree of polymerization. Because of chain scissions, a slight increase in degree of crystallinity was observed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1417–1422, 2001
Glass‐transition behavior of poly(methacrylonitrile)
Authors: Katircioğlu T. Y. , Güven O.
Published: August 2002

The glass‐transition temperatures (Tg) of some polymers reported in the literature have always been a source of great uncertainty. The values reported for poly(methacrylonitrile) (PMAN, 100 and 120°C) are well above the value determined in this study (67°C). It is clearly shown by FTIR and DSC work that formation of cyclic structures during the drying of PMAN, even at low temperatures, is the main reason for the high Tg values observed. The contributions of naphthydrine type cyclic structures and intermolecular crosslinks in the increase of the Tg are determined over an aging temperature interval of 90–300°C. The combined effects of intra‐ and intermolecular linking cause an increase in the Tg from 67 to 116°C. The hardness measurements also confirm the value determined by DSC. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1936–1943, 2001
Utilization of cellulose‐triacetate‐blended membranes for carrier‐mediated transport of some metal ions
Authors: Abdelaal Magdy Youssef
Published: August 2002

In this study, cellulose triacetate was used as a suitable base polymer for polymer‐blended membranes for ion sensing and separation. Polymer‐blended membranes were prepared with the solvent casting technique in the presence of mixed plasticizer and a metal ion carrier known as an ionophore. 7‐Dodecenyl‐8‐hydroxy‐quinoline and N,N′‐diphenylethyl Kemp's triacid diamide, in addition to the newly synthesized 8‐[N‐acetyl‐O‐(4‐tert‐butyl benzyl)‐L‐tyrosylamino] quinoline, were used as representative examples for ionophores. The membranes were evaluated through the transport of copper and lead ions into 0.1M nitric acid as the receiving phase. The concentrations of the investigated metal ions in both phases were assayed by atomic absorption spectrometry. From this study, it can be concluded that the efficiency of the membrane, either as an ion‐transporting or as an ion‐extracting condidate, is controlled by the amount of the immobilized ionophore, the immobilization time within the membrane matrix while in contact with the receiving phase, the nature of the ionophore–metal ion complex, and so on. The carrier‐mediated transport mechanism was also investigated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2008–2015, 2001
Effects of glass‐fiber content and coolant temperature on temperature and crystallinity profiles of PP melt during cooling
Authors: Sombatsompop N. , Tangsongcharoen A.
Published: August 2002

This investigation studied the temperature gradients and degree of crystallinity of polypropylene melt across a circular duct during the cooling process, where the coolant used was chilled water. The effects of glass‐fiber content, varying from 0 to 44 wt %, and coolant temperature, varying from 5 to 20°C, were our main interest. The results suggested that the rate of cooling of the polymer of each position across the duct was not significantly affected by the temperature of the coolant and glass‐fiber contents, although the rate of cooling was influenced by the size of the duct. The crystallization temperature and degree of crystallinity of the polymer increased with increasing glass fiber contents and the coolant temperature. These phenomena were associated with the heat transfer between the coolant and the polymer, crystallization temperature, exothermic crystallization process, and thermal properties of the polymer. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2087–2097, 2001
Quantitative characterization of dispersed particle size, size distribution, and matrix ligament thickness in polypropylene blended with metallocene ethylene–octene copolymers
Authors: Premphet K. , Paecharoenchai W.
Published: August 2002

The average rubber particle size, size distribution, and matrix ligament thickness between particles in polypropylene blends containing metallocene catalyzed ethylene–octene copolymers have been quantitatively analyzed, as functions of blend composition and phase viscosity ratio. Comparison has been made between experimental data and those predicted from a number of theoretical models. All blends showed two‐phase morphology, with interestingly a bimodal distribution of the rubber particle size. The ranges and averages of rubber particle size were mainly determined by blend composition and viscosity ratio between the phases, irrespective of comonomer content along the rubber chains. The logarithmic relationship between the matrix ligament thickness and rubber concentration was observed. The values of ligament thickness obtained from the experiments and theoretical models were not in agreement. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2140–2149, 2001
Sulfonation of poly(ether ether ketone)(PEEK): Kinetic study and characterization
Authors: Huang R. Y. M. , Shao Pinghai , Burns C. M. , Feng X.
Published: August 2002

Hydrophobic poly(ether ether ketone) (PEEK) were modified by sulfonation at different temperatures (22, 36, 45, and 55°C) and varying period of time with concentrated sulfuric acid used as solvent. A kinetic study was carried out based on the assumption that sulfonation reaction is a second‐order reaction, which takes place preferentially in the aromatic ring between the two ether (O) links (the first type substitution), and there is only one substituent attached to each repeat unit of the PEEK before the complete substitution of this preferred aromatic ring. More than 100% substitution was observed in experiment. All the data with substitution degree less than 95% agree fairly well with the kinetic behavior of the second‐order reaction. The reaction rate coefficient and activation energy for first type substitution were obtained. The sulfonated PEEK samples were characterized in terms of ion‐exchange capacity (IEC), 1H‐NMR, contact angle, and solubility. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2651–2660, 2001
Crystallization behavior of polytetrafluoroethylene (PTFE)
Authors: Wang Xiao Qun , Chen Da Rong , Han Jie Cai , Du Shan Yi
Published: August 2002

For some polymers such as PTFE, the crystallization is so rapid that it is difficult to observe isothermal crystallization by differential scanning calorimetry (DSC). In this investigation, first, isothermal crystallization kinetics of PTFE was followed by DSC and the results were analyzed by the Avrami method, which showed that PTFE crystallizes one‐dimensionally from preexisting nuclei, presumably impurities. Furthermore, the crystallization activation energy, the equilibrium melting point, and the nucleation rate parameter Kg were calculated in the isothermal crystallization. Second, nonisothermal crystallization was also studied and the result was in accordance with the results of isothermal crystallization. Then, the Kissinger method was used to investigate the activation energy of PTFE in the nonisothermal crystallization. Third, the effect of glass fiber (used as filling) was investigated on crystallization of PTFE matrix. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 990–996, 2002