bluuebunny/crossref_metadata_2025 huggingface dataset:
Counter aggression and reconciliation in Assamese macaques (Macaca assamensis)
Authors: Cooper Matthew A. , Bernstein Irwin S.
Published: August 2002

Patterns of aggressive and affiliative behavior, such as counter aggression and reconciliation, are said to covary in the genus Macaca; this is referred to as the systematic variation hypothesis. These behavior patterns constitute a species dominance style. Van Schaik’s [1989] socioecological model explains dominance style in macaques in terms of within‐ and between‐group contest competition. Dominance style is also said to correlate with phylogeny in macaques. The present study was undertaken to examine phylogenetic and socioecological explanations of dominance style, as well as the systematic variation hypothesis. We collected data on counter aggression and reconciliation from a habituated group of Assamese macaques (Macaca assamensis) at the Tukeswari Temple in Assam, India. The proportion of agonistic episodes that involved counter aggression was relatively low. Counter aggression, however, occurred more often among males than among females, and it was most common when females initiated aggression against males. The conciliatory tendency for this group of Assamese macaques was 11.2%. The frequency of reconciliation was low for fights among males and for fights among females, but reconciliation was particularly rare for opposite‐sexed opponents. Female social relationships were consistent with the systematic variation hypothesis, and suggest a despotic dominance style. A despotic dominance style in Assamese macaques weakens the correlation between dominance style and phylogeny in macaques, but it is not inconsistent with the socioecological model. Male–female relationships were not well explained by the despotic‐egalitarian framework, and males may well have more tolerant social relationships than do females. Sex differences need to be considered when categorizing species according to dominance style. Am. J. Primatol. 56:215–230, 2002. © 2002 Wiley‐Liss, Inc.
Discerning evolutionary processes in patterns of tamarin (genusSaguinus) craniofacial variation
Authors: Rogers Ackermann Rebecca , Cheverud James M.
Published: August 2002

Quantitative genetic theory specifies evolutionary expectations for morphological diversification by genetic drift in a monophyletic clade. If genetic drift is responsible for the evolutionary morphological diversification of a clade, patterns of within‐ and between‐taxon morphological variance/covariance should be proportional. We tested for proportionality of within‐ and between‐species craniofacial morphological variation in 12 species of tamarins (genusSaguinus). We found that within‐ and between‐taxon morphological variations across the entire genus were not proportional, and hence not likely to be due to genetic drift alone. The primary deviation from proportionality is that size and size‐related shape in the cranium is more variable relative to other aspects of cranial morphology than expected under genetic drift, suggesting differential size selection between the two major clades, the small‐bodied and large‐bodied tamarins. Within each of these major clades, most of the interspecific variation is consistent with the pattern expected under genetic drift, although specific contrasts may indicate the involvement of differential selection. Morphological distances among taxa do not correspond very closely to the phylogeny derived from mtDNA. In particular,S. oedipusandS. geoffroyiare very distinct morphologically from the rest of the tamarins, although they are phylogenetically the sister clade to a clade containingS. midasandS. bicolor. Morphological similarity is not a good guide to phylogenetic affinity in the tamarins, especially with regard to deeper nodes in the phylogenetic tree. Am J Phys Anthropol 117:260–271, 2002. © 2002 Wiley‐Liss, Inc.
Testing isonymy with paternal and maternal lineages in the early Québec population: The impact of polyphyletism and demographic differentials
Authors: Gagnon Alain , Toupance Bruno
Published: August 2002

Isonymy is an ingenious and useful approach to studying kinship in human populations. However, it relies on assumptions that are difficult to verify. In this study, we provided a way to assess, in the early Québec population, the impact of factors such as polyphyletism, unbalanced sex‐ratio among founders, and age differentials between spouses. All data were taken from the Population Register of Early Québec, which contains births, marriages, and deaths (>712,000) recorded in parish registers from the beginning of colonization (in 1608) to 1800. More specifically, using the 70,869 marriages recorded during that period, we compared kinship estimates given by genealogies, surnames, and paternal and maternal lineages. We also calculated a fifth coefficient of kinship by combining paternal and maternal lineage, thus providing a new way to test the isonymy method. The results show a good agreement between genealogical and isonymous estimates. However, this good correspondence is due to counterbalancing biases. Some of the implications of our results are discussed in the context of colonial America. Am J Phys Anthropol 117:334–341, 2002. © 2002 Wiley‐Liss, Inc.
Chimpanzee right‐handedness reconsidered: Evaluating the evidence with funnel plots
Authors: Palmer A. Richard
Published: August 2002

Evidence for population‐level right‐handedness in nonhuman primates seems inconsistent and contradictory, and many hypotheses have been advanced to account for this volatility. Funnel plots (scatter plots of percent right‐hand use vs. sample size) offer a straightforward graphical technique for assessing: 1) the strength and consistency of handedness, 2) whether variability is consistent with normal sampling variation, and 3) how likely reports of statistically significant handedness might have arisen due to chance (i.e., type I error). They are informative for both within‐ and among‐population variation.

Reexamination of within‐population variation from a detailed and widely cited study reporting significant population‐level right‐handedness in 140 individual captive chimpanzees (Hopkins [1994] Dev. Psychobiol. 27:395–407) revealed several puzzling patterns: 1) funnel plots showed higher percent right‐hand use among individuals for which fewer observations were recorded, 2) when individuals with fewer than 25 observations were excluded, statistical support for population‐level right‐handedness either became marginal (P = 0.043, when computed as average percent use of the right hand) or disappeared (P = 0.62, when computed as proportion of individuals using the right hand more than the left, whether they did so significantly or not), and 3) the proportion of statistically ambilateral chimpanzees actually increased with increasing number of observations per individual, rather than decreased as would be expected for true population‐level right‐handedness. In addition, funnel plots of among‐population variation from an earlier meta‐analysis (McGrew and Marchant [1997] Yrbk. Phys. Anthropol. 40:201–232) suggested that the four reports of significant right‐handedness, out of 37 estimates from 14 studies, were likely those that achieved statistical significance simply due to chance. Funnel plots, and the more refined statistical tests they suggest, confirm that the current evidence for population‐level right‐handedness in chimpanzees remains equivocal. Am J Phys Anthropol 118:191–199, 2002. © 2002 Wiley‐Liss, Inc.
Dementia in hereditary cerebral hemorrhage with amyloidosis‐Dutch type is associated with cerebral amyloid angiopathy but is independent of plaques and neurofibrillary tangles
Authors: Natté Remco , Maat‐Schieman Marion L. C. , Haan Joost , Bornebroek Marjolijn , Roos Raymund A.C. , Van Duinen Sjoerd G.
Published: August 2002

Cerebral amyloid angiopathy is frequently found in demented and nondemented elderly persons, but its contribution to the causation of dementia is unknown. Therefore, we investigated the relation between the amount of cerebral amyloid angiopathy and the presence of dementia in 19 patients with hereditary cerebral hemorrhage with amyloidosis‐Dutch type. The advantage of studying hereditary cerebral hemorrhage in amyloidosis‐Dutch type is that patients with this disease consistently have severe cerebral amyloid angiopathy with minimal neurofibrillary pathology. The amount of cerebral amyloid angiopathy, as quantified by computerized morphometry, was strongly associated with the presence of dementia independent of neurofibrillary pathology, plaque density, or age. The number of cortical amyloid β‐laden severely stenotic vessels, vessel‐within‐vessel configurations, and cerebral amyloid angiopathy‐associated microvasculopathies was associated with the amount of cerebral amyloid angiopathy and dementia. A semiquantitative score, based on the number of amyloid β‐laden severely stenotic vessels, completely separated demented from nondemented patients. These results suggest that extensive (more than 15 amyloid β‐laden severely stenotic vessels in five frontal cortical sections) cerebral amyloid angiopathy alone is sufficient to cause dementia in hereditary cerebral hemorrhage with amyloidosis–Dutch type. This may have implications for clinicopathological correlations in Alzheimer's disease and other dementias with cerebral amyloid angiopathy.
N‐acetylaspartate is an axon‐specific marker of mature white matter in vivo: A biochemical and immunohistochemical study on the rat optic nerve
Authors: Bjartmar Carl , Battistuta Jan , Terada Nobuo , Dupree Erica , Trapp Bruce D.
Published: August 2002

Axonal pathology is a major cause of neurological disability in multiple sclerosis. Axonal transection begins at disease onset but remains clinically silent because of compensatory brain mechanisms. Noninvasive surrogate markers for axonal injury are therefore essential to monitor cumulative disease burden in vivo. The neuronal compound N‐acetylaspartate, as measured by magnetic resonance spectroscopy, is currently the best and most specific noninvasive marker of axonal pathology in multiple sclerosis. The possibility has been raised, however, that N‐acetylaspartate is expressed also by oligodendroglial lineage cells. In order to investigate N‐acetylaspartate specificity for white matter axons, transected rat optic nerves were analyzed by high‐performance liquid chromatography and immunohistochemistry. In transected adult nerves, N‐acetylaspartate and N‐acetyl aspartylglutamate decreased in concordance with axonal degeneration and were undetectable 24 days posttransection. Nonproliferating oligodendrocyte progenitor cells, oligodendrocytes, and myelin were abundant in these axon‐free nerves. At 24 days posttransection, N‐acetylaspartate was increased (42%; p = 0.02) in nontransected contralateral nerves. After transection at postnatal day 4, total N‐acetylaspartate decreased by 80% (P14; p = 0.002) and 94% (P20; p = 0.003). In these developing axon‐free nerves, 25 to 33% of oligodendrocyte progenitor cells were proliferating. These data validate magnetic resonance spectroscopy measurements of N‐acetylaspartate as an axon‐specific monitor of central nervous system white matter in vivo. In addition, the results indicate that neuronal adaptation can increase N‐acetylaspartate levels, and that 5 to 20% of the N‐acetylaspartate in developing white matter is synthesized by proliferating oligodendrocyte progenitor cells.
Inhibition of autoimmune encephalomyelitis by a tetracycline
Authors: Popovic Natalija , Schubart Anna , Goetz Brian D. , Zhang Su‐Chun , Linington Chris , Duncan Ian D.
Published: August 2002

We have explored the use of minocycline, a tetracycline with antiinflammatory properties, to treat chronic relapsing‐remitting experimental allergic encephalomyelitis, an animal model of multiple sclerosis. Therapeutic treatment with minocycline dramatically suppresses ongoing disease activity and limits disease progression. Disease suppression is associated with immune deviation in the periphery and with suppression of the inflammatory cascade in the central nervous system. This association is demonstrated by inhibition of microglial activation and metalloproteinase‐2 expression, which results in a concomitant decrease in inflammation and demyelination. As an established antiinflammatory drug with neuroprotective properties, minocycline may provide a novel therapeutic agent for relapsing‐remitting multiple sclerosis.
Subjective memory complaints: Objective neural markers in patients with Alzheimer's disease and major depressive disorder
Authors: Grön Georg , Bittner Daniel , Schmitz Bernd , Wunderlich Arthur P. , Riepe Matthias W.
Published: August 2002

Patients with probable Alzheimer's disease and depressive patients frequently present with subjective memory complaints. Objective distinction of underlying neuronal substrate malfunction and early cross‐sectional differential diagnosis have been elusive thus far. We used repetitive learning and free recall of abstract geometric patterns during functional magnetic resonance imaging to assess episodic memory in older subjects (ages 56–64 years) who sought first‐time medical attention with subjective memory complaints and were diagnosed with probable Alzheimer's disease (NINCDS‐ADRDA criteria; ages 51–67 years) or major depressive disorder (DSM‐IV; ages 50–65 years). Contrasting healthy seniors or depressive patients with Alzheimer's disease patients revealed superiority of hippocampal activation. Contrasting Alzheimer's disease patients with seniors showed bilateral prefrontal activity as a correlate of futile compensation of episodic memory failure. Contrasting patients who had major depressive disorder with seniors or patients who had Alzheimer's disease showed bilateral activation of the orbitofrontal cortex and the anterior cingulate. Subjective memory complaints may be classified objectively and very early with functional magnetic resonance imaging of episodic memory in groups of patients with Alzheimer's disease and depressive syndrome. This may facilitate drug trials with evaluation of specific treatments, but further studies will be needed to establish the differential diagnosis for the individual patient.
Speciation of some triorganotin compounds in sediments from the Anacostia and Potomac Rivers, Washington, DC, using Mössbauer spectroscopy
Authors: Eng George , Desta Dereje , Biba Edmond , Song Xueqing , May Leopold
Published: August 2002

Triorganotin compounds, namely the tributyltin (TBT) and triphenyltin (TPT) moieties, have been used as the active components in antifoulant marine paints. Mössbauer spectroscopy was used in this work to identify the products of speciation of these triorganotin compounds in various types of sediment from rivers around the Washington, DC, USA, area. Aerobic and anaerobic sediments from several sites in the Anacostia and Potomac Rivers were spiked with tributyl‐ and triphenyl‐tin chloride, bis‐(tri‐n‐butyltin) oxide and triphenyltin hydroxide. Mössbauer spectra were recorded for the resultant interactions of the species produced with the various sediments. The Mössbauer spectra of both types of sediment, aerobic and anaerobic, spiked with tributyltin chloride and bis‐(tri‐n‐butyltin) oxide were the same, suggesting that these compounds were converted to the same species, mostly likely the hydrated tributyltin cation, TBT+. The spectra of all triphenyltin chloride and triphenyltin hydroxide spiked sediment samples were the same, indicating again that these compounds were converted to the same species, in this case the hydrated triphenyltin cation, TPT+. Thus the species that interacts with the various sediments are the respective hydrated cations. The results also support the previous conclusion obtained with Chesapeake Bay sediments, that the product of triorganotin speciation depends on the nature of sediment. Copyright © 2001 John Wiley & Sons, Ltd.
Grafting of long‐chain unsaturated carboxylic acids onto acrylonitrile–butadiene–styrene terpolymer
Authors: Zhou Z. F. , Huang H. , Zhu C. Y. , Liu N. C.
Published: August 2002

The graft copolymerization of undecylenic acid, oleic acid, and crotonic acid onto acrylonitrile–butadiene–styrene terpolymer (ABS) was initiated by benzoyl peroxide (BPO) in 1,2‐dichloroethane solution. The infrared spectra confirmed that undecylenic acid, oleic acid, and crotonic acid were successfully grafted onto the ABS backbone. The grafting occurred at the butadiene region of the ABS. The grafting degree increased with increasing monomer concentration, but it decreased after monomer concentration, reaching 0.30 mol/L in undecylenic acid and oleic acid systems. The grafting degree increased rapidly with increasing initiator concentration, but slowed down at about 0.012 mol/L of initiator concentration. The grafting degree decreased considerably with increasing ABS concentration; however, the total amount of grafted monomer increased. Increasing reaction time and temperature led to an increase in grafting degree. The chain length of the monomer has a great influence on grafting. The grafting degree decreases with increasing the chain length due to a steric hindrance and monomer cage effect, which is in agreement with activation energy calculation. The overall activation energy of crotonic acid, undecylenic acid, and oleic acid systems are 118, 122, and 134 kJ/mol, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1934–1939, 2002
Modeling of high‐pressure ethylene polymerization. I. Kinetic parameters of oxygen initiation
Authors: Cerinski B. , Jelencic J.
Published: August 2002

A kinetic model of a high‐pressure, free‐radical ethylene polymerization is presented. The model of S. Goto, K. Yamamoto, S. Furui, and M. Sugimoto (J Appl Polym Sci, Appl Polym Symp 1981, 36, 21), developed for several common peroxides, was extended to be applicable for the oxygen initiation also. Small‐extent propylene copolymerization, as well as telomerization with isobutane and propylene, are included into the overall kinetic scheme. The model is based on a string of elemental continuously stirred tank reactors and is particularly suited for the tubular low‐density polyethylene reactors. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2043–2051, 2002
Formation and structure of polyacrylamide–silica nanocomposites by sol–gel process
Authors: Jang Jyongsik , Park Hwanseok
Published: August 2002

The formation of nanocomposites by the sol–gel reaction of tetraethoxysilane (TEOS) in polyacrylamide (PAAm) is studied. The nanocomposites are prepared in aqueous solution. Fourier transform IR spectroscopy shows that substantial hydrogen bonding occurs in the nanocomposites. The fracture surfaces of the nanocomposites are observed by atomic force microscopy (AFM) as a function of the TEOS content. The AFM images reveal that the PAAm–silica nanocomposite exhibits particle–matrix morphology. It is also found that aggregate formation is more dominant than the particle growth with the TEOS contents. The solution of composite precursor is also applied to spin coating. Furthermore, during the calcination there is an observable change in the silica networks, and then a microinterconnected structure is generated. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1817–1823, 2002
Grafting of a styrene–acrylonitrile binary monomer mixture onto cellulose extracted from pine needles
Authors: Chauhan Ghanshyam S. , Lal Harinder , Sharma Rajeev , Guleria Lalit , Sarwade B. D.
Published: August 2002

In an attempt to develop new reactive membrane materials, we graft‐copolymerized styrene (Sty) and acrylonitrile (AN) onto cellulose extracted from pine needles by a chemical initiation method. The optimum grafting reaction conditions for Sty onto cellulose were earlier evaluated as [Sty] = 656.25 mmol/L and [potassium persulfate–ferrous ammonium sulfate] = 146.3:12.75mmol/L in 20 mL of H2O with a reaction time of 3 h and a reaction temperature of 60°C for 1 g of cellulose. Under these conditions, Sty was graft‐copolymerized with AN at five different concentrations of the latter. Grafting parameters and different rates of concentration were evaluated. The effects of additives such as ZnCl2, LiNO3, and Cu(NO)3 were studied at the best comonomer concentration of Sty–AN. In the presence of ZnCl2, Sty–AN graft‐copolymerized in an alternate way, thus, making it evident that ZnCl2 coordinated to form a “complexomer,” or complex of monomers [Sty−AN+…ZnCl2], of two monomers. Evidence of the structural characteristics of grafted chains were provided by characterization with elemental analysis, thermal analysis, and Fourier transform infrared spectroscopy. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2000–2007, 2002
Study on N‐hydroxyphthalimide as blocking agent for isocyanates
Authors: Wei Wu‐Ji , Guo Zhi‐Rui , Zhang Yu‐Feng , Pan En‐Li
Published: August 2002

In this article, N‐hydroxyphthalimide (NHPH) has been prepared with phthalic anhydride and hydroxylamine hydrochloride. The blocked toluene diisocyanate (NTDI) by NHPH was synthesized also. The effects on the synthesis of NTDI were studied, and the deblocking temperature of NTDI was read by TG‐DSC and IR. In the meantime, actual crosslinking reaction conditions on the systems of polyhydroxy compounds were surveyed also. The stability of the mixture of NTDI and polyhydroxy compounds was observed by determining the viscosity of it. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1346–1352, 2002; DOI 10.1002/app.10242
Synthesis of chelating resins with iminodiacetic acid and its wastewater treatment application
Authors: Wang Cheng‐Chien , Chen Chuh‐Yung , Chang Chia‐Yuan
Published: August 2002

The chelating resins have high potential applications for the selective removal and recovery of metal ions from industrial waste solutions. The hydrophilic acrylate monomer with the iminodiacetic acid chelating group was prepared from glycidyl methacrylate and iminodiacetic acid at 60°C. The microbeads, prepared from acrylate monomer with the iminodiacetic acid chelating group, were employed by inversion suspension polymerization. In the pH range of 2–6, a reasonably good equilibrium sorption capacity is maintained for Cr3+ (ca. 2.7 mmol/g) and Cu2+ (ca. 1.8 mmol/g) in the chelating resins. The adsorption of Cd2+ and Pb2+ on microbeads is clearly affected by the pH of the solution, such that these ions' adsorption capacity increased with the pH of the aqueous solution. The adsorption of Cd2+ (ca. 1.25–1.87 mmol/g) and Pb2+ (ca. 0.99–1.89 mmol/g) showed a maximum at approximately pH = 5 and 6, respectively. The adsorption isotherms of Cr3+ and Cu2+ adsorbed on microbeads were following the Langmuir isotherm, but the adsorption behavior of Cd2+ and Pb2+ were not. The concentration of alkaline earth–metal cations on the range of 0–200 ppm had no influence on metal ions adsorbed capacity of chelating resins. Additionally, NTA (nitrilotriacetic acid) had no significant influence on metal ion adsorption by chelating resins. Furthermore, phenol pollutant can be adsorbed effectively by metal ions chelated microbeads; therefore, the microbeads were useful not only in recovering metal ions but also in the treating phenol pollutants in wastewater. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1353–1362, 2002; DOI 10.1002/app.10243
Crystallization behavior of PHA/PEDEA oligoester blends
Authors: Cui Yanjun , Wang Xinling , Hong Ling , Tang Xiaozhen
Published: August 2002

The crystallization behavior of oligoester blends prepared from crystalline poly(hexanediol adipate) (PHA) and amorphous poly(ethylene diethylene glycol adipate) (PEDEA) was studied using POM, WAXD, and DSC. The crystal form of both PHA and the blends are spherulites. The crystallinity, melting enthalpies, and crystallization rate increased with increased PHA content in the blends. Two sharp diffraction peaks of each blend were detected at the same position, where, respectively, 2θ = 21.3° and 24.1°. The research on the crystallization kinetics showed that the Avrami exponent of all the oligoester blends is approximately 4. It was demonstrated that the crystallization mechanism of PHA is not disturbed by amorphous PEDEA. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1363–1368, 2002; DOI 10.1002/app.10268
Variable‐frequency microwave curing of benzocyclobutene
Authors: Tanikella Ravindra V. , Bidstrup Allen Sue A. , Kohl Paul A.
Published: August 2002

Polymer dielectrics are widely used in the microelectronics industry for several applications including interlevel dielectrics, encapsulants, and passivating layers. To attain the desired properties, these materials need to be processed via lengthy cure cycles. Variable frequency microwave (VFM) processing has been investigated as a rapid curing alternative for the processing of thin‐film dielectrics. Previous studies on epoxies and polyimide‐based materials have shown significant reduction in cure time and improvement in properties on VFM processing. In this study, VFM curing of Dow Chemical Cyclotene™ 3022 benzocyclobutene (BCB) was investigated. The kinetics of the cure reaction were studied by Fourier transform infrared (FTIR) spectroscopy. FTIR studies indicated no significant differences in chemical structure between VFM and thermally cured films. The electrical, optical, mechanical, and chemical properties of VFM‐processed films were characterized and compared with thermally processed films to determine the effectiveness of microwave processing. The results showed that VFM curing of BCB is feasible, and properties comparable to thermally cured films can be attained. The residual stress of partially cured BCB was lower for VFM processing than for traditional thermal processing. The residual stress in fully cured BCB was similar. Improvements such as shorter cure times and lower processing temperatures than conventional thermal processing can be achieved. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3055–3067, 2002; DOI 10.1002/app.10286
Hygrothermal aging of rubber‐modified and mineral‐filled dicyandiamide‐cured DGEBA epoxy resin. III. Dielectric spectroscopy investigation
Authors: Ivanova Katya I. , Pethrick Richard A. , Affrossman S.
Published: August 2002

The effects of moisture absorption on the dielectric properties of a rubber‐modified, mineral‐filled, epoxy resin based on the diglycidyl ether of bisphenol A cured with dicyandiamide are reported. Samples of the resin were aged by immersing in deionized water, or 5% w/w NaCl solution, at elevated temperatures. Dielectric measurements were carried out over the frequency range 10−1 to 6 × 105 Hz. A featureless dielectric spectrum was observed with both real and imaginary dielectric permittivity increasing with the amount of absorbed water. The change in the dielectric properties with absorption of water was independent of presence of salt, temperature of exposure, and aging history, although a hysteresis of the hydration–dehydration process was observed at low frequencies. Two types of absorbed water were observed—water molecularly dispersed within the epoxy matrix and clustered water in spherical microcavities. The time dependence of the real dielectric permittivity measured at 10 kHz was found to closely resemble that of the water absorption, which allowed the activation energy of diffusion to be calculated from both dielectric and gravimetric data. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1011–1024, 2002; DOI 10.1002/app.10368
Study on the phase separation of thermoplastic‐modified epoxy systems by time‐resolved small‐angle laser light scattering
Authors: Zheng Qiang , Tan Kuitian , Peng Mao , Pan Yi
Published: August 2002

Reaction‐induced phase‐separation behavior of an epoxy (E‐ 51) system modified by thermoplastics, namely, polyetherimide (PEI) and polycarbonate (PC), isothermally cured with 4,4′‐ diaminodiphenylsulfone (DDS) at various temperatures, was investigated by the time‐resolved small‐angle laser light‐scattering (SALLS) technique. It was found that the morphology evolution of this E‐51 curing system was controlled by the competition between the curing reaction and the phase separation. It was verified that the phase separation of these systems followed the spinodal decomposition mechanism through analyzing the scattering pattern evolution and the cocontinuous morphology observed by optical microscopy. The curing temperatures and compositions of these epoxy systems were considered to be the determining factors for the domain size and the phase‐separation behavior. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 950–956, 2002
Swollen behavior of crosslinked network hydrogels based on poly(vinyl alcohol) and polydimethylsiloxane
Authors: Shin Mi‐Seon , Kim Seon Jeong , Kim In Young , Kim Nam Gyun , Song Chul Gyu , Kim Sun I.
Published: August 2002

Poly(vinyl alcohol) (PVA) was dissolved in the water to make a 10 wt % aqueous solution, and polydimethylsiloxane (PDMS) was mixed with 1 wt % 2,2‐dimethyl‐2‐phenylacetophenone (DMPAP) and 0.5 mol % methylenebisacrylamide (MBAAm) in isopropyl alcohol. This mixture was added to a PVA aqueous solution and heated at 90°C for 7 h. Various crosslinked networks were prepared at different molar ratios of PVA/PDMS (1:1, 1:3, and 3:1). The characterization of PVA/PDMS crosslinked networks was determined by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), a universal testing machine (UTM), and the equilibrium water content (EWC). The DSC melting endotherms showed, at 219.49°C, a sharp endothermic peak of PVA, and PVA/PDMS crosslinked networks had melting peaks close to this point. The value of EWC increased with the content of PVA in the crosslinked networks, simultaneously depending on the temperature. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 957–964, 2002
Manufacture and properties of chitosan/N,O‐carboxymethylated chitosan/viscose rayon antibacterial fibers
Authors: Li Zhi , Liu Xiaofei , Zhuang Xupin , Guan Yunlin , Yao Kangde
Published: August 2002

Chitosan/N,O‐carboxymethylated chitosan/viscose rayon antibacterial fibers (CNVFs) were prepared by blending chitosan emulsion, N,O‐carboxymethylated chitosan (N,O‐CMC), and viscose rayon together for spinning. The fibers were characterized by transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). TEM micrographs showed that chitosan microparticles dispersed uniformly along the oriented direction with the mean size ranging from 0.1 to 0.5 μm. DSC spectra of these fibers showed that no significant change in thermal property was caused by adding chitosan and N,O‐CMC into the viscose rayon. TGA spectra showed that the good moisture retentivity was not affected by the addition of chitosan and N,O‐CMC. Both DSC and TGA suggested that the decomposing tendency of the viscose rayon above 250°C seemed to be weakened by the chitosan. The fibers' mechanical properties and antibacterial activities against Escherchia coli,
Staphylococcus aureus, and Candida albicans were measured. Although the addition of chitosan slightly reduced the mechanical properties, the antibacterial fibers' properties were obtained and were found to meet commercial requirements. CNVF exhibited excellent antibacterial activity against E. coli,
S. aureus, and C. albicans. The antibacterial activity increased along with the chitosan concentration and was not greatly affected by 15 washings in water. Scanning electron microscopy (SEM) was used to observe the morphology of bacteria cells incubated together with the antibacterial or reference fibers. SEM micrographs demonstrated that greater amounts of bacteria could be adsorbed by the antibacterial fiber than by the reference fiber; these bacteria were overwhelmingly destroyed and killed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2049–2059, 2002; DOI 10.1002/app.10501
Interface modification on the properties of sisal fiber‐ reinforced polypropylene composites
Authors: Fung K. L. , Li R. K. Y. , Tjong S. C.
Published: August 2002

Short sisal fiber (SF)‐reinforced polypropylene (PP) composites were prepared by melt blending followed by injection molding. To improve the interfacial bonding between SF and PP, the PP matrix was maleated (MAPP) by blending PP and maleic–anhydride‐grafted‐PP in the weight ratio of 9/1. It was found that the SF/MAPP composites have lower melt viscosity (as reflected by torque rheometer measurements) than the SF/PP composites at the respective sisal fiber contents. In terms of mechanical properties, PP maleation has the effect of improving the tensile strength. This can be explained in terms of the improved SF/matrix interfacial bonding when MAPP was used. However, the impact strength was reduced when the PP matrix was maleated. The improved SF/matrix interfacial bonding prevented fracture mechanisms such fiber/matrix debonding and fiber pullout from taking place. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 169–176, 2002
Comparison of tetraethyl‐ and tetramethylthiuram disulfide vulcanization. I. Reactions in the absence of rubber
Authors: Gradwell M. H. S. , Grooff D.
Published: August 2002

The reactions of tetraethylthiuram di‐ and monosulfide (TETD and TETM, respectively) were investigated in the absence of rubber and compared with those reported previously for tetramethylthiuram compounds. The reactions of TETM, TETD, and zinc diethyldithiocarbamic acid with zinc oxide and sulfur were investigated by differential scanning calorimetry, and the reaction products analyzed by high performance liquid chromatography. TETM was shown to be more stable at vulcanization temperatures (±150°C), but also less reactive with sulfur than tetramethylthiuram disulfide (TMTD). The reactions of TETD are very similar to those of TMTD, the TETD reacting slower than the TMTD to form analogous products. In the presence of zinc oxide, the formation of the zinc compound of TETD, zinc diethyldithiocarbamic acid, occurred readily. TMTD does not react readily with zinc oxide. The reaction of TETD with sulfur lead to the formation of polysulfidic accelerator species, although the concentrations formed in the absence of rubber were considerably less than that formed by the corresponding TMTD system. These differences in reactivity would affect the vulcanization reactions that take place in the rubber. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2292–2299, 2001
Study on the tribological characteristics of solid lubricants embedded tin‐bronze bearings
Authors: Li Tongsheng , Tao Jiang , Cong Peihong , Liu Xujun
Published: August 2002

The friction and wear characteristics of graphite, MoS2, and PTFE embedded tin‐bronze bearings were studied using a pin‐on‐disc tester. The results indicated that solid lubricants decreased and stabilized the friction coefficient, and decreased the wear rate by two to three orders of magnitude. When the content of solid lubricants, PTFE mixed with graphite, was 20–40%, the performance of the solid lubricants embedded bearing (SLEB) was the best. Wear scar was analyzed by means of X‐ray diffraction (XRD), Auger electron spectroscopy (AES), and scanning electron microscopy (SEM). The results show that the transfer films of solid lubricants reduce adhesion between the SLEBs and the mating material, and the wear mechanism of SLEBs changes to fatigue and adhesive wear. The main reason for fatigue wear is microcracks expanding at Pb points in SLEBs. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2394–2399, 2001
Blends of acrylonitrile–butadiene–styrene/waste poly(ethylene terephthalate) compatibilized by styrene maleic anhydride
Authors: Paul S. , Kale D. D.
Published: August 2002

Waste poly(ethylene terephthalate) (PET) from thin bottles was blended with acrylonitrile–butadiene–styrene (ABS) copolymer in different proportions, up to 10 wt %. Styrene maleic anhydride (SMA) copolymer was used as a compatibilizer. The tensile strength and heat deflection temperature of the blend were higher than that of virgin ABS. Flexural modulus remained unaffected, although a slight decrease in impact property was observed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2593–2599, 2001
Mechanical properties of flame retardant filled polypropylene composites
Authors: Tai C. M. , Li Robert K. Y.
Published: August 2002

The flammability performance and mechanical behaviors for halogen‐based and non‐halogen‐based flame retardant (FR) filled polypropylene (PP) composites were investigated in this study. The halogen‐based FR system consisted of a mixture of brominated phosphate ester and antimony trioxide (BR), and the halogen‐free FR was a magnesium hydroxide (MH). It was found from limiting oxygen index measurements that 60 wt % of MH was needed in order to achieve the same degree of flammability as the composite containing only 30 wt % of BR. Scanning electron microscopy examinations of the fractured specimens indicated that the interfacial bond strength between PP and MH was stronger than that for PP and BR. The notched Charpy impact strength and the impact fracture toughness were measured and compared. The discrepancies between the two impact test results could be correlated after kinetic energy correction was applied to the Charpy impact strengths. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2718–2728, 2001
Properties of films made from ternary blends of metallocene and conventional polyolefins
Authors: Majumdar A. , Kale D. D.
Published: August 2002

Thin films were blown from a composition of 75% linear low density polyethylene (LLDPE) and 25% LDPE. The LLDPE content was made up of different % of metallocene‐based and conventional octene‐based LLDPE. Tensile strength, dart impact strength, hot tack strength, heat seal strength, and the barrier properties of these films were measured. All the properties showed significant improvement when conventional LLDPE (cLLDPE) was replaced by metallocene‐based LLDPE (mLLDPE), even to the extent of only 25%. The blends of 50% mLLDPE and 50% LDPE showed attractive properties. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 53–57, 2001
Electrical behavior and structure of polypropylene/ultrahigh molecular weight polyethylene/carbon black immiscible blends
Authors: Mironi‐Harpaz I. , Narkis M.
Published: August 2002

This study investigates the electrical behavior, which is the positive temperature coefficient/negative temperature coefficient (PTC/NTC), and structure of polypropylene (PP)/ultrahigh molecular weight polyethylene (UHMWPE)/carbon black (CB) and PP/γ irradiated UHMWPE (XL‐UHMWPE)/CB blends. As‐received UHMWPE or XL‐UHMWPE particles are chosen as the dispersed phase because of their unusual structural and rheological properties (extremely high viscosity), which practically prevent CB particles penetration. Because of their stronger affinity to PE, CB particles initially form conductive networks in the UHMWPE phase, followed by distribution in the PP matrix, thus interconnecting the CB‐covered UHMWPE particles. This unusual CB distribution results in a reduced electrical percolation threshold and also a double‐PTC effect. The blends are also investigated as filaments for the effect of shear rate and processing temperature on their electrical properties using a capillary rheometer. Because of the different morphologies of the as‐received and XL‐UHMWPE particles in the filaments, the UHMWPE containing blends exhibit unpredictable resistivities with increasing shear rates, while their XL‐UHMWPE containing counterparts depict more stable trends. The different electrical properties of the produced filaments are also related to differences in the rheological behavior of PP/UHMWPE/CB and PP/XL‐UHMWPE/CB blends. Although the flow mechanism of the former blend is attributed to polymer viscous flow, the latter is attributed to particle slippage effects. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 104–115, 2001
Evaluation of thermo‐viscosity parameters of dextran in polar and nonpolar solvent
Authors: Mahapatra A. P. , Samal R. K. , Samal R. N. , Roy G. S.
Published: August 2002

Some thermo‐viscosity parameters like Viscosity‐molecular weight constant (K), the short‐range parameter, (A) and long‐range parameter (B) have been evaluated for the polymer “Dextran” of three different molecular weights (M̄w = 19,500, 75,000, and 250,000) in three different solvents like 6 (M) aqueous urea, 2 (M) aqueous glycine, and 50% aqueous glucose at temperatures ranging from 25 to 50°C. The study reveals that the viscosity‐molecular weight constant (K) decreases with increase in temperature for polar solvents like aqueous urea and aqueous glycine. The value of “K” increases with the rise in temperature within the range of 25 to 35°C in case of a nonpolar solvent aqueous glucose and then “K” decreases with the increase in temperature within the range of 40 to 50°C for the nonpolar solvent aqueous glucose. The short‐range parameter (A) shows the same trend as shown by “K” and the long‐range parameter “B” exhibits no definite trend with the variation of temperature. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 440–452, 2001
Carbon black‐filled PET/HDPE blends: Effect of the CB structure on rheological and electric properties
Authors: Mallette Javier G. , Quej Luis M. , Marquez Alfredo , Manero Octavio
Published: August 2002

The rheological and electric properties of blends of poly(ethylene terephthalate) (PET) and high‐density polyethylene (HDPE) filled with various types of carbon black (CB) were analyzed in detail in this project. Four types of CB samples with available values of surface area, particle size, porosity, density, and maximum packing fraction were considered. Blends were prepared using an internal mixing chamber at two different rotational speeds, prior to mold compression of the samples. The rheological properties of the blends with varying polymer composition and a constant amount of CB were recorded in terms of torque variation with time for two shear rates (in terms of rotational speed). Rheological data were related to the resistivity of blends. Results show that the CB structure (porosity, surface area, apparent bulk density, and particle size) largely determine the resulting equilibrium torque and electrical properties. Furthermore, since CB is preferentially located in the HDPE phase, higher conductivity is observed as the PET content decreases, since the relative CB content in this phase increases. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 562–569, 2001
Curing of epoxy–urethane copolymers in a heated mold: Effect of the curing conditions on the phase‐separation process
Authors: Stefani P. M. , Moschiar S. M. , Aranguren M. I. , Marieta C. , Mondragon I.
Published: August 2002

The curing process of an epoxy–urethane copolymer in a heated mold was studied. The epoxy resin (DGEBA, Araldyt GY9527; Ciba Geigy), was coreacted with a urethane prepolymer (PU, Desmocap 12; Bayer) through an amine that acted as crosslinking agent (mixture of cycloaliphatic amines; Distraltec). The study focused on the effect of the curing condition and PU concentration on time–temperature profiles measured in the mold and the consequent final morphologies obtained. As the PU concentration increases, the maximum temperature reached in the mold decreases as a result of the dilution effect of the elastomer on reaction heat, whereas the Tg of the piece also decreases. Phase separation is a function of conversion and temperature reached in the curing part and was analyzed using experimental data and a mathematical model that predicts temperature and conversion throughout the thickness of the mold. Scanning electron microscopy and atomic force microscopy were used to determine the characteristics of the dispersed phase for the different formulations and conditions of curing. It was shown that the size of the dispersed phase increased with the initial PU concentration, whereas there were practically no differences in the separated phase as a function of position or temperature of curing (in the range of 70 to 100°C studied). The superposition of the phase diagrams with the conversion–temperature trajectories during cure provided an explanation of the morphologies generated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 889–900, 2001
Antimicrobial treatment of nylon
Authors: Lin Jian , Winkelman Catherine , Worley S. D. , Broughton R. M. , Williams J. F.
Published: August 2002

The preparation of an antimicrobial nylon material and its properties are discussed. Biocidal cyclic N‐chloramine moieties were covalently bonded to Nylon 66. These moieties, which included hydantoins, oxazolidinones, and imidazolidinones, were stable during at least 3 months of dry storage, and their antimicrobial activities, once lost by reaction with reducing sodium thiosulfate, could be regenerated by exposure to free chlorine. Biocidal swatch tests showed that the nylon fabrics containing N‐chlorinated hydantoin functional groups provided a 7.2 log reduction of Staphylococcus aureus and a 7.1 log reduction of Escherichia coli at a contact time of only 10 min. Antimicrobial nylon should find a variety of important uses such as in clothing, carpets, sutures, brushes, and so forth. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 943–947, 2001
Copolymerization of polypropylene and functionalized linear α‐olefin onto glass fibers
Authors: Barbosa Silvia E. , Ferreira María L. , Damiani Daniel E. , Capiati Numa J.
Published: August 2002

This work deals with a novel glass fiber surface modification and subsequent metallocenic propylene polymerization onto it. Experimental results are presented on methylaluminoxane (MAO) fixation at the fiber surface, followed by propylene–α‐olefin graft copolymerization catalyzed by EtInd2ZrCl2/MAO. First results indicate that part of the produced polymer is chemically bonded to the glass fiber. Scanning electron microscopy, Fourier transform infrared spectroscopy, and X‐ray disperse energy microanalysis characterization confirm the permanence of a thin polymer layer as well as aluminum and oxygen (from the MAO) on the glass surface, even after a severe solvent extraction treatment. From these results, the copolymerization of hydroxy‐α‐olefin, grafted on MAO pretreated glass fiber, is foreseen as a possible way to improve fiber–matrix adhesion in glass fiber thermoplastic composites. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1266–1276, 2001
Analysis of annealed thin polymer films prepared from dichloro(methyl)phenylsilane by plasma polymerization
Authors: Cech V. , Horvath P. , Trchova M. , Zemek J. , Matejkova J.
Published: August 2002

Thin plasma polymer films were deposited from a mixture of dichloro(methyl)phenylsilane (DCMPS) vapor and gaseous hydrogen in an rf (13.56 MHz) capacitive coupling deposition system on pieces of silicon wafers. Some of samples were annealed in a vacuum to temperatures ranging from 450 to 700°C. The chemical composition, structure, and surface morphology of the annealed samples and those stored in air at room temperature were studied by FTIR, XPS, SEM, and optical microscopy. The thermal stability and decomposition of the plasma polymer with increasing temperature were characterized using thermogravimetry together with mass spectrometry. The plasma polymer was stable to a temperature of 300°C. Above that temperature, the material started to decompose together with additional crosslinking due to the incorporation of extra oxygen atoms forming new siloxane bonds. The plasma polymer was tough at room temperature but much more brittle after annealing. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2106–2112, 2001