bluuebunny/crossref_metadata_2025 huggingface dataset:
Wild capuchins (cebus capucinus) fail to use tools
Authors: Garber P.A. , Brown E.
Published: March 2004

From September through November 2000 we conducted an experimental field study of tool use in a group of 15 wild white‐faced capuchins (Cebus capucinus) in Costa Rica. The problem presented to the capuchins involved the use of wooden dowels as probes to obtain a food reward (two bananas) located inside a clear Plexiglas box. Specifically, the task required the capuchins to manually insert a dowel into any of six holes drilled into the box in order to push the bananas off a shelf. The banana could then be retrieved through a large opening at the bottom of the box. The capuchins visited the tool‐use platform 702 times over the course of 55 consecutive days and under several experimental conditions. During the first 21 days of the study, they explored the box but made no attempt to touch or pick up the dowels. Even after we placed the dowels in the holes, the capuchins only occasionally manipulated them. Overall, the results indicate that the capuchins did not use a tool to solve this novel foraging problem. Am. J. Primatol. 62:165–170, 2004. © 2004 Wiley‐Liss, Inc.
Use of spatial, visual, and olfactory information during foraging in wild nocturnal and diurnal anthropoids: A field experiment comparing Aotus, Callicebus, and Saguinus
Authors: Bicca‐Marques Júlio César , Garber Paul A.
Published: March 2004

Early in their evolution, the ancestors of anthropoid primates radiated from a nocturnal to a diurnal niche. Foraging during the night differs from foraging during the day in terms of the availability of light and color cues, and in the movement of odor molecules through the canopy. In this study, we compared the ability of nocturnal and diurnal New World monkeys to use perceptual cues (i.e., the sight or smell of food) and spatial information (place predictability) in within‐patch foraging decisions. An experimental field study was conducted on wild groups of night monkeys (Aotus nigriceps), tamarins (Saguinus imperator imperator and S. fuscicollis weddelli), and titi monkeys (Callicebus cupreus) at the Zoobotanical Park/UFAC, Rio Branco, Brazil. Our research design included the construction of feeding stations located in the home range of the study groups. Each feeding station consisted of eight visually identical feeding platforms located in a circular arrangement. In all test settings, two platforms at each feeding station contained a food reward (banana), and the remaining six platforms contained a sham reward (yellow plastic or inaccessible banana). In the night‐monkey experiments, each feeding platform was illuminated by a 40‐W red bulb to aid the researcher in observing their behavior. When the location of reward sites was predictable over time, individuals in all four species successfully relocated food rewards based solely on spatial information. Each species was also successful in using visual information to distinguish real from sham food rewards. However, only night monkeys and one group of emperor tamarins used olfactory information alone to locate food rewards. Overall, the species' performances did not clearly differentiate Aotus from diurnal New World primates in these experiments. Am. J. Primatol. 62:171–187, 2004. © 2004 Wiley‐Liss, Inc.
Significance of color, calories, and climate to the visual ecology of catarrhines
Authors: Dominy Nathaniel J. , Lucas Peter W.
Published: March 2004

Here we describe correlations among visual ecology and the physiochemical properties of fruits and leaves consumed by four species of catarrhine primate:Cercopithecus ascanius,Colobus guereza,Pan troglodytes, andPiliocolobus badius. Collectively, their diet was diverse, with each species relying on fruits and leaves to different extents. The mean chromaticity of both foods, as perceived by the green‐red and yellow‐blue signals that catarrhines decode, was distinct from background foliage. However, selection on the basis of color was evident only for leaves. Primates consumed leaves with higher green‐red values than the leaves they avoided–sensory mechanism that correlated with key nutritional variables, such as increased protein and reduced toughness. Moreover, the monkeys ingested leaves near dusk, when reddish targets may be more salient. Similar patterns were never observed with respect to edible fruits, the chromaticities of which did not differ from unconsumed fruits or correlate with nutritional properties. We also found that primate biomass is higher in seasonal sites. We conclude that these findings are consistent with the notion that routine trichromatic vision evolved in a context where seasonal folivory was pivotal to survival. Am. J. Primatol. 62:189‐207, 2004. © 2004 Wiley‐Liss, Inc.
Paleoenvironmental basis of cognitive evolution in great apes
Authors: Potts Richard
Published: March 2004

A bias favoring tree‐dominated habitats and ripe‐fruit frugivory has persisted in great ape evolution since the early Miocene. This bias is indicated by fossil ape paleoenvironments, molar morphology, dental microwear, the geographic pattern of extinctions, and extant apes' reliance on wooded settings. The ephemeral aspect of high‐quality fruit has placed a premium on cognitive and social means of finding and defending food sources, and appears related to great apes' affinity since the Miocene for wooded, fruit‐rich environments. These habitats have, however, undergone a severe withdrawal toward the low latitudes of Africa and Southeast Asia since the late Miocene, corresponding to a decline in the diversity of great apes beginning 9.5 million years ago. Plio‐Pleistocene records imply that wooded settings of Africa and SE Asia were prone to substantial fragmentation and coalescence. Once apes were confined to equatorial settings, therefore, habitat instability heightened the spatial/temporal uncertainty of ripe‐fruit sources. Prolonged learning, the assignment of attributes to distant places, mental representation, and reliance on fallback foods were all favored in this dynamic environmental context. These abilities helped sustain forest frugivory in most lineages. Fluid social grouping afforded the animals opportunities to locate ephemeral foods in continuous and fragmented forests. Fission‐fusion grouping also magnified the problems of object impermanence (of individuals) and dispersion manifested by food sources in the ecological realm. Thus the spatial and temporal dynamics of fruit and wooded habitats since the Miocene are reflected in important components of great ape cognition, foraging, and sociality. In contrast to great apes, cercopithecoid monkeys have increased their plant dietary options and diversified in seasonal environments since the late Miocene. Early hominins eventually severed the habitat bias that characterized the evolution of great apes, and later expanded into diverse environments. Am. J. Primatol. 62:209‐228, 2004. © 2004 Wiley‐Liss, Inc.
Human cognitive ecology: an instructive framework for comparative primatology
Authors: Keller Janet Dixon
Published: March 2004

In this review, research on human cognitive ecology is compared with studies of the cognitive ecologies of apes–especially the common chimpanzee. The objective was to assess the feasibility of extending an activity‐theory framework developed in studies of humans to an integrated approach for studying the cognitive accomplishments and skills of other primates living in the wild. Six generalizations were abstracted from studies of humans: 1) Social and material environments are arranged to facilitate production. 2) Human activity is shaped by conceptual and cultural principles that provide underlying logic for working knowledge and practice. 3) Schemata (multimodal, mental representations of procedures, strategies, and techniques) govern performance in a domain. 4) Working knowledge, skills, and social identities are coconstructed in communities of practice. 5) Rehearsal improves skilled performances, from which reputations as well as material products are derived. 6) Planning and emergence are in productive tension in human practices. These generalizations are applied to findings in the literature regarding the behavior of chimpanzees and other apes in the wild to assess the potential utility of a situated‐activity approach for comparative studies of primate cognition. It is argued in the Discussion that schemata constitute a common core of higher primate intelligence. Planning, emergence, and alterations of the environment to facilitate production further characterize human and chimpanzee or gorilla behaviors to varying degrees. Less apparent in the nonhuman‐primate literature is evidence of governing principles, rehearsal, and skill‐based reputations or identities entailing theories of mind. Nonetheless, recent observations in the wild suggest that further research is warranted to explore the rudiments of each of these components to enhance our understanding of the ecology of primate cognition and its evolutionary history. Am. J. Primatol. 62:229‐241, 2004. © 2004 Wiley‐Liss, Inc.
Effective enhancement of anticorrosive properties of polystyrene by polystyrene–clay nanocomposite materials
Authors: Yeh Jui‐Ming , Liou Shir‐Joe , Lin Chih‐Guang , Chang Yen‐Po , Yu Yuan‐Hsiang , Cheng Chi‐Feng
Published: March 2004

A series of polymer–clay nanocomposite (PCN) materials consisting of polystyrene (PS) and layered montmorillonite (MMT) clay was prepared by effectively dispersing the inorganic nanolayers of MMT clay in the organic PS matrix via in situ thermal polymerization. Organic styrene monomers were first intercalated into the interlayer regions of organophilic clay hosts, followed by a typical free radical polymerization with BPO as the initiator. The as‐synthesized PCN materials were characterized by infrared spectroscopy (IR), wide‐angle powder X‐ray diffraction (XRD) and transmission electron microscopy (TEM). PCN coatings with low clay loading (1 wt %) on cold‐rolled steel (CRS) were found to be superior in anticorrosion to those of bulk PS, based on a series of electrochemical measurements of corrosion potential, polarization resistance and corrosion current in a 5 wt % aqueous NaCl electrolyte. The molecular weights of PS extracted from PCN materials and bulk PS were determined by gel permeation chromatography (GPC) with tetrahydrofuran (THF) as the eluent. The effects of material composition on molecular barrier and thermal stability of PS and PCN materials, in the form of both free‐standing films and fine powders, were also studied by molecular permeability analysis, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1970–1976, 2004
One‐pot synthesis of polymeric bead bearing surface charge
Authors: Kusuktham Boonsri , Srikulkit Kawee
Published: March 2004

Preparation of polymeric bead bearing surface charge was carried out by using one‐pot suspension polymerization of styrene and divinylbenzene (DVB) in the presence of cationic functional monomer, 3‐methacryloylamino) propyl trimethyl ammonium chloride (MAPTAC), by using K2S2O8 and AIBN as initiators. First, polymerization of MAPTAC in aqueous solution using K2S2O8 initiator was performed for the determined time to generate a PMAPTAC radical. Second, the mixture of styrene, DVB, and AIBN initiator was fed into the solution of PMAPTAC radicals and then allowed the polymerization to proceed for another specified time. During the stage of polymerization of styrene and DVB, incorporation of PMAPTAC radicals onto the bead surface took place, resulting in the final bead particle comprising two layers (from SEM results): the inner core of the poly(styrene‐co‐DVB) support and the outer layer of copolymerization adduct of styrene, DVB, and PMAPTAC radical revealed by FTIR analysis. Factors affecting particle size, size distribution, and surface functionality (PMAPTAC segment) were investigated. Of all synthetic parameters, types of surfactants and amounts of DVB were found to play an important role in controlling the particle size and the surface functionality, respectively. Nonionic surfactant (cetyl alcohol) tended to produce large particle size with a majority of the population falling in the range of 500‐1800 μm. Replacement of nonionic surfactant with cationic surfactant (CTAB) resulted in better control of particle size and size distribution because of its effective electrostatic stabilizer. An increase in the amount of DVB led to smoother bead surface as a result of less availability of styrene on bead surface, reducing surface charge density. The results of dye adsorption isotherm further confirmed that the cationic functional group was incorporated into the outer shell of the polymer bead. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1375–1387, 2004
Studies of polypropylene–intumescent flame‐retardant composites based on etched polypropylene as a coupling agent
Authors: Ma Zhi‐Ling , Gao Jun‐Gang , Bai Li‐Gai
Published: March 2004

The ammonium polyphosphate (APP)–pentaerythritol (PT)–melamine (M) system was selected as an intumescent flame retardant (IFR). The influence of dichromic acid–etched polypropylene (EPP) on the properties and compatibility of IFR/polypropylene (PP) composites was studied. The results obtained from mechanical tests and SEM showed that EPP was a true coupling agent for IFR/PP blends, but without changing the necessary flame retardancy. The cocrystallization between bulk PP and PP segments of EPP was confirmed by WAXD analysis. Flow tests showed that the flow behavior of composites in the melt is that of a pseudoplastic liquid, which is significant for EPP's effect on the rheological behavior of IFR/PP composite. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1388–1391, 2004
Thermal oxidation of self‐degradable composite films based on low‐density polyethylene
Authors: Ol'Khov A. A. , Shibryaeva L. S. , Lordanskii A. L. , Zaikov G. E.
Published: March 2004

The effect of the structure of composite extrusion films based on a mechanical blend of low‐density polyethylene and poly(hydroxybutyrate) on the service characteristics and the kinetics of thermooxidative destruction was investigated. The aggregate state of the polymers affected the value of the boundary surface in the blend films. An increase in the latter affected the conformation states of both polymers in the blends. In this case, the strength decreased, the steam permeability increased, and the thermooxidative destruction of the polyethylene matrix during the beginning stages was accelerated. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1392–1396, 2004
Polyester binders for wood containing benzotriazole and HALS light stabilizers
Authors: Sundell P. , Sundholm F.
Published: March 2004

Three new polyester binders containing either benzotriazole‐type or hindered amine light stabilizers (HALS)‐type light stabilizers were synthesized. The binders were characterized by 13C and 1H NMR, FTIR, UV‐VIS spectroscopy, and size exclusion chromatography. It was found that it was possible to bind a benzotriazole‐type light stabilizer to the polymer backbone of the binder if a suitable group was present in the stabilizer. However, there was no proof that the HALS‐type stabilizer was bound to the binder. The average penetration depth of the binders into the radial surface of pine wood was mainly below 480 μm into earlywood and below 2500 μm into latewood. The average penetration depth into the tangential surface was around 1000 μm in the earlywood and around 2500 μm in the latewood. Artificial weathering causes a binder‐treated wood surface to darken independently of the binder used. The yellowness of the irradiated pine samples increased at the beginning of the exposure but decreased during longer exposure times. The benzotriazole stabilizer, Tinuvin 213, protected the surface of wood quite well; the other stabilizers were poor. The wood surface became rougher in appearance, cracks along the microfibril orientation became pronounced, and the bordered pits were degraded in the weathered samples. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1413–1421, 2004
Reduced copper diffusion in layered silicate/fluorinated polyimide (6FDA‐ODA) nanocomposites
Authors: Jiang Liang‐You , Wei Kung‐Hwa
Published: March 2004

The copper diffusion barrier properties of layered silicate/fluorinated polyimide nanocomposites were analyzed by transmission electron microscopy (TEM) and secondary ion mass spectrometry (SIMS). It was found that the particles of copper are effectively retarded from penetrating into the polyimide matrix by layered silicates. The diffusion coefficients of layered silicate/polyimide nanocomposites are lower than that of the pure polyimide. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1422–1425, 2004
Bulk polymerization of styrene in the presence of polybutadiene: Effect of initiator type and prepolymerization conditions on particle morphology
Authors: Soto G. , Nava E. , Rosas M. , Fuenmayor M. , González I. M. , Meira G. R. , Oliva H. M.
Published: March 2004

In this study, we investigated the synthesis of high‐impact polystyrene through a series of (batch and bulk) polymerizations of styrene in the presence of 6 wt % polybutadiene. The reactions with rubber involved three stages: dissolution, prepolymerization, and finishing. The prepolymerizations were isothermal (at 70°C) and nonisothermal (with an initial heating period from 70 to 120°C). Purely thermal reactions were compared with chemically initiated polymerizations involving tert‐butyl peroctoate (TBPO), 2,2′‐azobisisobutyronitrile (AIBN), and their mixtures. Most prepolymerizations involved a stirring rate of 125 rpm. The particle morphology was mainly determined by the evolution of the grafting efficiency, stirring rate, and system viscosity during prepolymerization. In the nonisothermal prepolymerizations with pure AIBN, the grafting efficiency was lower than in equivalent prepolymerizations without an initiator, yielding unstable emulsions and a poor final morphology. In the nonisothermal prepolymerizations with pure TBPO, a large amount of graft copolymer was produced early in the prepolymerization, yielding a submicrometer core–shell morphology. The particle size and morphology could be controlled by the appropriate adjustment of the recipe and the prepolymerization conditions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1397–1412, 2004
Rheological properties of water solutions of syndiotactic poly(vinyl alcohol) of different molecular weights
Authors: Kim Sam Soo , Seo In Seok , Yeum Jeong Hyun , Ji Byung Chul , Kim Joon Ho , Kwak Jin Woo , Yoon Won Sik , Noh Seok Kyun , Lyoo Won Seok
Published: March 2004

To precisely identify the effect of the molecular weight of syndiotacticity‐rich poly(vinyl alcohol) (s‐PVA) on the rheological properties of s‐PVA/water solutions, we prepared four s‐PVAs with a syndiotactic dyad content of 57%, a degree of saponification (DS) of 99.9%, and number‐average degrees of polymerization (Pn's) of 300, 1300, 2700, and 4000. Through a series of experiments, we found that the molecular weight of poly(vinyl alcohol) had a significant influence on the rheological properties of s‐PVA/water solutions. Over a frequency range of 10−1 to 102 rad/s, the s‐PVA/water solution with the highest Pn value showed the largest values of the complex viscosity, storage modulus, and loss modulus at similar syndiotacticity and DS values of s‐PVA, and this suggested that the higher Pn was, the stronger the internal ordered structure was in the molecules. All the s‐PVA/water solutions showed shear‐thinning behavior, which implied heterogeneity. In a modified Casson plot, Bingham flow behaviors, which gave rise to non‐zero yield stress, were evident. This suggested that some pseudostructure existed in the s‐PVA/water solutions. The yield stress increased with Pn, and this implied that the pseudostructure was developed as Pn increased. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1426–1431, 2004
Design of organic electroluminescent displays with ultraviolet‐shielding filters
Authors: Lee Rong Ho , Huang Chen Yang , Chen Chin‐Ti
Published: March 2004

The electroluminescence properties of polymer light‐emitting devices with and without an ultraviolet (UV)‐shielding filter were studied. The polymer light‐emitting devices were fabricated with poly(2‐methoxy‐5,2′‐ethyl‐hexyloxy‐1,4‐phenylene vinylene) as the light emitter and poly(ethylenedioxy thiophene) as the hole‐transporting material. The UV‐shielding filter was composed of alternating TiO2 and SiO2 dielectric multilayers made by a physical vacuum deposition process. The current density, brightness, and photometric efficiency decreased significantly for the polymer light‐emitting device without the UV‐shielding filter after irradiation by UV light. The decay of PLEDs due to UV degradation was greatly reduced by the UV‐shielding filter. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1432–1436, 2004
Preparation and properties of hydrophilic–hydrophobic chitosan derivatives
Authors: Yang Hua , Zhou Shaobing , Deng Xianmo
Published: March 2004

Hydrophilic–hydrophobic chitosan derivatives were obtained through the attachment of lactose and alkyl groups to the amino group of chitosan with potassium borohydride. The carboxymethylation of the chitosan derivatives was completed. They had excellent solubility in water. When they were prepared as hydrogels, the hydrogels had adjustable hydrophobicity and excellent hydrophilicity according to swelling measurements. All of them showed potential for applications in medical fields. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1625–1632, 2004
Dynamically cured polypropylene/epoxy blends
Authors: Jiang Xueliang , Huang Hua , Zhang Yong , Zhang Yinxi
Published: March 2004

The dynamic vulcanization process, usually used for the preparation of thermoplastic elastomers, was used to prepare polypropylene (PP)/epoxy blends. The blends had crosslinked epoxy resin particles finely dispersed in the PP matrix, and they were called dynamically cured PP/epoxy blends. Maleic anhydride grafted polypropylene (MAH‐g‐PP) was used as a compatibilizer. The effects of the reactive compatibilization and dynamic cure were studied with rheometry, capillary rheometry, and scanning electron microscopy (SEM). The crystallization behavior and mechanical properties of PP/epoxy, PP/MAH‐g‐PP/epoxy, and dynamically cured PP/epoxy blends were also investigated. The increase in the torque at equilibrium for the PP/MAH‐g‐PP/epoxy blends indicated the reaction between maleic anhydride groups of MAH‐g‐PP and the epoxy resin. The torque at equilibrium of the dynamically cured PP/epoxy blends increased with increasing epoxy resin content. Capillary rheological measurements also showed that the addition of MAH‐g‐PP or an increasing epoxy resin content increased the viscosity of PP/epoxy blends. SEM micrographs indicated that the PP/epoxy blends compatibilized with PP/MAH‐g‐PP had finer domains and more obscure boundaries than the PP/epoxy blends. A shift of the crystallization peak to a higher temperature for all the PP/epoxy blends indicated that uncured and cured epoxy resin particles in the blends could act as effective nucleating agents. The spherulites of pure PP were larger than those of PP in the PP/epoxy, PP/MAH‐g‐PP/epoxy, and dynamically cured PP/epoxy blends, as measured by polarized optical microscopy. The dynamically cured PP/epoxy blends had better mechanical properties than the PP/epoxy and PP/MAH‐g‐PP/epoxy blends. With increasing epoxy resin content, the flexural modulus of all the blends increased significantly, and the impact strength and tensile strength increased slightly, whereas the elongation at break decreased dramatically. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1437–1448, 2004
Nylon 6 microfiber prepared by carbon dioxide laser heating
Authors: Suzuki Akihiro , Kamata Kaori
Published: March 2004

A nylon 6 microfiber was easily obtained through carbon dioxide laser heating. The laser heating was carried out in two steps: the first laser heating was performed under an applied tension of 36.7 MPa at a power density of 17.3 W cm−2, and the second was performed under 0.18 MPa at 51.81 W cm−2. The microfiber was obtained by the second laser heating of the fiber. The microfiber prepared under the optimum thinning conditions had a diameter of 1.9 μm and a birefringence of 46.2 × 10−3. Its draw ratio, estimated from the diameter, was 9895× (so far, it has been impossible to achieve such a high draw ratio by drawing). A (200) reflection and a (002/202) doublet due to an α form were observed on the equator, but no (200) reflection due to a γ form was observed. The morphology of the crystallites existing in the microfiber was only the α form. Laser heating made the microfiber more easily than conventional technologies, such as conjugate spinning, melt blowing, and flash spinning. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1449–1453, 2004
Nylon 6 microfiber obtained by a continuous‐thinning method with a carbon dioxide laser
Authors: Suzuki Akihiro , Kamata Kaori
Published: March 2004

We succeeded in producing nylon 6 microfibers with a continuous‐thinning method with a carbon dioxide (CO2) laser. A laser‐thinning apparatus used to continuously prepare microfibers was developed in our laboratory; it consisted of spools supplying and winding the fibers, a continuous‐wave CO2‐laser emitter, a system supplying the fibers, and a traverse. The laser‐thinning apparatus produced microfibers in the range of 100–2500 m min−1. The diameter of the microfibers decreased as the winding speed increased, and the birefringence increased as the winding speed increased. When microfibers, obtained through the laser irradiation (at a power density of 19.8 W cm−2) of the original fiber supplied at 0.32 m min−1, were wound at 848 m min−1, they had a diameter of 3.2 μm and a birefringence of 47 × 10−3. The draw ratio calculated from the supplying and winding speeds was 2650×. Scanning electron microscopy showed that the microfibers obtained with the laser‐thinning apparatus had smooth surfaces not roughened by laser ablation that were uniform in diameter. Wide‐angle X‐ray diffraction photographs of the microfibers wound at 566 and 848 m min−1 showed equatorial and meridional reflections due to the γ from. These reflections gradually became clear as the winding speed increased. The developed apparatus more easily produced microfibers than conventional technologies, such as conjugate spinning, islands‐in‐a‐sea fiber spinning, melt blowing, and flash spinning. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1454–1458, 2004
Hyperbranched conjugated polymers for photovoltaic applications
Authors: Qiao Jing , Yang Chunhe , He Qingguo , Bai Fenglian , Li Yongfang
Published: March 2004

Three hyperbranched phenylene vinylenes (HPVs)—H‐mn, H‐es, and H‐py—were used in fabricating polymer photovoltaic cells (PVCs). PVCs with photoactive layers composed of pure HPV, a blend of HPV and C60, and a blend of HPV, poly(2‐methoxyl‐5,2′‐ethylhexyoxyl‐1,4‐phenylene vinylene) (MEH‐PPV), and C60, were fabricated, and their current–voltage characteristics were measured and investigated. The PVC with photoactive layers composed of H‐es and C60 showed promising photovoltaic characteristics, with an energy‐conversion efficiency of 0.035%, when illuminated under 85 mW/cm2 white light. The short‐circuit current and energy‐conversion efficiency of the PVCs based on H‐mn/C60 and H‐py/C60 were greatly improved when they were blended with a small amount of MEH‐PPV. The incident photon‐to‐collected‐electron efficiency of the HPV/MEH‐PPV/C60 PVCs indicated that both HPVs and MEH‐PPV contributed to the photocurrent. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1459–1466, 2004
Pseudo‐first‐order kinetic studies of the sorption of acid dyes onto chitosan
Authors: Wong Y. C. , Szeto Y. S. , Cheung W. H. , McKay G.
Published: March 2004

The adsorption of five acid dyes onto chitosan, derived through the deacetylation of crab‐shell chitin, from aqueous solutions was studied. The equilibrium isotherms were measured and analyzed with the Langmuir, Freundlich, and Redlich–Peterson equations; the results correlated well with the Langmuir equation. Kinetic studies were also performed in an agitated batch adsorber to study the effect of the initial dye concentration and the mass of chitosan. The kinetics were analyzed with the pseudo‐first‐order rate equation, and the rate constants were determined. The first‐order kinetic model correlated the experimental concentration and time data at short times and even up to 60% of the total adsorption period in a number of systems. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1633–1645, 2004
Characterization of the water state of hyaluronic acid and poly(vinyl alcohol) interpenetrating polymer networks
Authors: Kim Seon Jeong , Lee Chang Kee , Kim Sun I.
Published: March 2004

Interpenetrating polymer networks (IPNs) composed of hyaluronic acid and poly(vinyl alcohol) hydrogels were prepared, and the influence of water and the drying kinetics were investigated. The IPN hydrogels were characterized with thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The glass‐transition temperatures of the IPN hydrogels decreased with increasing water content. The bound water was the sum of the nonfreezing bound water and freezing bound water. From the DSC melting curves, the values of the total water and freezing bound water were evaluated for IPN hydrogels containing large amounts of water. At the same time, the bound water value was estimated with TGA. In the TGA curves, one‐step and two‐step weight losses, corresponding to free water and nonfreezing bound water, were observed. The bound water of the hydrophilic polymers broke the hydrogen bonding between the hydroxyl groups of the polymers. The swollen IPN hydrogels exhibited relatively high bound water contents (43.04–59.17%) by DSC and TGA. The bound water contents of the dry IPN hydrogel films were 10.2–15.29% by TGA. The drying reaction rate constant of the IPN hydrogel increased with increasing temperature. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1467–1472, 2004
Electrostimulus responsive behavior of poly(acrylic acid)/polyacrylonitrile semi‐interpenetrating polymer network hydrogels
Authors: Kim Seon Jeong , Lee Ki Jung , Kim Sun I.
Published: March 2004

Interpenetrating polymer network (IPN) hydrogels composed of poly(acrylic acid) and polyacrylonitrile were prepared with UV irradiation, and their bending behaviors between two electrodes were studied under various conditions. The swelling ratio of the IPN hydrogels decreased with an increasing NaCl concentration in an aqueous solution. The fastest bending speed was observed in a gel synthesized in a 0.6 wt % NaCl aqueous solution. As the applied voltage increased, the bending speed increased. The deformation of the IPN hydrogels was reversible when the applied voltage was turned on and off. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1473–1477, 2004
Preparation of novel semihomogeneous cation‐permeable membranes from blends of sulfonated poly(phenylene sulfide) and sulfonated phenolphthalein poly(ether ether ketone)
Authors: Hu Keyan , Xu Tongwen , Fu Yanxun , Yang Weihua
Published: March 2004

A series of semihomogeneous cation‐exchange membranes were prepared with binary blend systems, such as sulfonated phenolphthalein poly(ether ether ketone) (SPEEK‐C)/sulfonated poly(phenylene sulfide) (SPPS), or ternary blend systems, such as phenolphthalein poly(ether ether ketone) (PEEK‐C)/SPEEK‐C/SPPS, by solution blending and phase inversion, in which PEEK‐C and SPEEK‐C acted as binders and SPPS powder acted as a polyelectrolyte. Compared with homogeneous and heterogeneous membranes, the prepared semihomogeneous membranes had good electrochemical properties and mechanical strength as well as good dimensional stability. The fundamental properties of the membranes, such as the ion‐exchange capacity, water content, electrical resistance, transport number, diffusion coefficient of the electrolytes, and streaming potential, were largely dependent on both the loading of the SPPS resin and the sulfonation degree of PEEK‐C. Through the adjustment of these two important parameters, a series of semihomogeneous membranes with the desired conductivity and selectivity and the proper water content for different industrial purposes, such as electrodialysis, diffusional dialysis, and proton exchange, were achieved. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1478–1485, 2004
Fundamental study of the effect of the fiber wall thickness and inner diameter on the structure of polyamide and polypropylene hollow fibers
Authors: Petrulis Donatas
Published: March 2004

Some properties of the structure of polyamide (PA) and polypropylene (PP) hollow fibers were investigated in a theoretical fashion. These fibers were simultaneously compared with solid fibers. The structural indices of the hollow fibers, that is, the wall thickness and inner diameter, were systematically examined with the aim of determining their effect on the four conventional structural indices suitable for hollow fibers and for solid fibers. The fiber outer diameter and fiber outer lateral area were examined as well, and the ratio of the fiber outer lateral area to the fiber whole volume and the ratio of this area to the fiber mass were considered. Under assumptions about the fixed level and equal values of the linear density of PA and PP fibers, comments on the aforementioned effect were presented. The structural properties of these fibers with different wall thicknesses and inner diameters were examined. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2017–2022, 2004
Surface modification of silicone rubber with poly(ethylene glycol) hydrogel coatings
Authors: Vladkova T.
Published: March 2004

Hydrogel coatings of monoacrylated poly(ethylene glycol) (PEG) methyl ethers of different molecular weights were attached to silicon rubber surfaces and crosslinked with hexanediol diacrylate or ethoxylated trimethylolpropane diacrylate by UV polymerization. The wetting, evaluated with the water contact angles, correlated with the surface oxyethylene chain density, which was evaluated with the ESCA >CO/CH2 ratio obtained from the C(1s) peak. As measured by the ESCA N(1s) peak, bovine serum albumin formed very thin protein adsorbates on the PEG‐coated surfaces. A strong correlation was found between low protein adsorption and a high >CO/CH2 ratio of the PEG‐coated substrate. The PEG‐coated silicon rubber also demonstrated very low cell and platelet adhesion. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1486–1492, 2004
In situ atomic oxygen erosion study of fluoropolymer films using X‐ray photoelectron spectroscopy
Authors: Gonzalez Rene I. , Phillips Shawn H. , Hoflund Gar B.
Published: March 2004

The surfaces of a homologous series of fluoropolymers were characterized in situ using X‐ray photoelectron spectroscopy before and after a 15‐min exposure to the flux produced by a unique hyperthermal atomic oxygen (AO) source, which produces a flux of about of 1015 atoms cm−2 s−1. The linear polymers investigated in this study include high‐density polyethylene (HDPE), poly(vinyl fluoride) (PVF), poly(vinylidene fluoride) (PVdF), and poly(tetrafluoroethylene) (PTFE). They possess a similar base structure with increasing fluorine‐to‐carbon ratios of 0, 1 : 2, 1 : 1, and 2 : 1, respectively. No interaction of the AO with the nonfluorine‐containing linear polymer HDPE was detected over this short exposure. However, a correlation exists between the chemical composition of the fluorinated polymers and the induced chemical and structural alterations occurring in the near‐surface region as a result of exposure to AO. The data indicate that AO initially attacks the fluorine portion of the polymers, resulting in a substantial decrease in the near‐surface fluorine concentration. The near‐surface fluorine‐to‐carbon ratios of PVF, PVdF, and PTFE decreased during the 15‐min AO exposure by 68, 39, and 18.5%, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1977–1983, 2004
Raman spectroscopic study of CdS, PVA composite films
Authors: Badr Y. A. , Abd El‐Kader K. M. , Khafagy Rasha M.
Published: March 2004

A new material, which can be used in solar energy utilization, is obtained here by adding different weights of poly(vinyl alcohol) (PVA) to the semiconducting material CdS. The effect of this addition was studied by using FT‐Raman spectrometer (based on 1500 mW Nd : YAG laser at 1064 nm), UV–Vis‐IR (190–800 nm) spectrophotometer, and X‐ray diffractometer. Our experimental results indicated the appearance of several new Raman bands, which have not existed in both CdS and PVA. Some of the bands which are already existing in the Raman spectra of PVA showed an unexpected systematic increase in their intensities after the addition of CdS to the matrix. On the other hand, some of the new Raman bands appeared in special concentrations of PVA only, whereas some of the Raman bands of CdS were found to disappear after adding PVA. Finally, shifts in some bands associated with random increase in their intensities after adding PVA to CdS was detected in the FT‐Raman analysis. The experimental evidence given here might be attributed to the occurrence of new bonds, indicating that the produced mixture is a new material. The assignment of the new bands as well as an interpretation of the obtained variations is given here. Our X‐ray diffraction data confirmed the interpretation introduced here. Moreover, the UV–Vis spectra confirmed the existence of new absorption bands in the Visible region. The I‐V characteristic curve was measured for a selected concentration of the new composite material, showing a remarkable increase in the values of the conduction current of about two orders of magnitude as compared with the pure PVA material. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1984–1992, 2004
Preparation and evaluation of chitosan‐coated polyphosphazene hydrogel beads for drug controlled release
Authors: Qiu Liyan
Published: March 2004

Chitosan‐coated polyphosphazene‐Ca2+ hydrogel beads were fabricated by dropping polyphosphazene into CaCl2/chitosan gelling solution. Polyphosphazene used here was a water‐soluble degradable polyanion (PCPAP), which carried almost two carboxylatophenamino groups on each phosphorus atom of the polymer backbone. Two kinds of turbidimetric titration were applied in this study to reveal the interaction between PCPAP and chitosan within the pH range of 4.57≈7.14. The effect of gelling solution pH on the properties of chitosan‐coated PCPAP beads was especially emphasized. It was found that the PCPAP/chitosan complex prepared at relatively high pH (pH 6.5) dissociated most slowly in pH 7.4 phosphate‐buffered solution (PBS). The erosion of chitosan‐coated beads and the release of model drug (Coomassie brilliant blue and myoglobin) in PBS were both obviously prolonged with the increase of gelling solution pH, exhibiting perfect accordance with the behavior of complex dissociation. In addition, the coating of PCPAP/chitosan complex on the bead surface facilitated the improvement of drug loading efficiency. The higher the gelling solution pH, the more the drug loading efficiency improved. At pH 6.5 (PCPAP 5%, CaCl2 7%, chitosan 0.3%), the loading efficiency of myoglobin in beads reached as high as 93.2%. These results indicate that the chitosan‐coated polyphosphazene‐ Ca2+ bead is a potential formulation for drug controlled release. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1993–1999, 2004
Silica‐reinforced dynamically vulcanized ethylene–propylene–diene monomer/polypropylene thermoplastic elastomers: Morphology, rheology, and dynamic mechanical properties
Authors: Bazgir S. , Katbab A. A. , Nazockdast H.
Published: March 2004

Attempts were made to prepare dynamically crosslinked ethylene–propylene–diene monomer/polypropylene (EPDM/PP, 60/40 w/w) blends loaded with various amounts of silica as a particulate reinforcing agent. The dispersion of silica between the two phases under mixing conditions, and also extent of interaction, as the two main factors that influence the blend morphology were studied by scanning electron microscopy. Increasing the silica concentration led to the formation of large‐size EPDM aggregates shelled by a layer of PP. Dynamic mechanical thermal analysis performed on the dynamically cured silica‐loaded blend samples showed reduction in damping behavior with increasing silica content. Higher rubbery‐like characteristics under tensile load were exhibited by the silica‐filled EPDM/PP‐cured blends. However, increasing the silica level to 50 phr led to the enhancement of interface, evidenced by increases in the tensile modulus and extensibility of the blend compared with those of the unloaded sample. Addition of a silane coupling agent (Si69) into the mix improved the mechanical properties of the blend, attributed to the strengthening of interfacial adhesion between the PP matrix and silica‐filled EPDM phase. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2000–2007, 2004
Effect of supercritical carbon dioxide dyeing conditions on the chemical and morphological changes of poly(ethylene terephthalate) fibers
Authors: Hou Aiqin , Xie Kongliang , Dai Jinjin
Published: March 2004

Commercially available regular denier poly(ethylene terephthalate) (PET) fabrics were used in this investigation. PET fabric samples were wound on a bobbin and then exposed to supercritical CO2 under conditions representing a typical supercritical CO2 dyeing cycle. Infrared spectroscopy, X‐ray diffraction, differential scanning calorimetry, and scanning electron microscopy were used to characterize the chemical and morphological changes of the PET fibers. The results showed that exposure to supercritical CO2 did not cause chemical changes in the fibers; the crystal size and the Tmp of the PET fabric after treatment in supercritical CO2 did not significantly change; the crystallinity decreased; and the treatment in supercritical CO2 at higher temperature caused surface morphology changes (increased oligomer migration). However, there was no pitting, cracking, or crazing on the surface of the treated fibers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2008–2012, 2004
Preparation of silicon dioxide/polyurethane nanocomposites by a sol–gel process
Authors: Zhu Yan , Sun Duo‐Xian
Published: March 2004

Aqueous emulsions of cationic polyurethane ionomers, based on poly(ϵ‐caprolactone glycol) as soft segment, isophorone diisocyanate as hard segment, 3‐dimethylamino‐1,2‐propanediol as chain extender and potential ionic center, and hydrochloric acid as neutralizer, were mixed with tetraethoxysilane to prepare silicon dioxide–polyurethane (SiO2/PU) nanocomposites by a sol–gel process during which the inorganic mineral is deposited in situ in the organic polymer matrix. The sizes and distributions of the particles were measured by dynamic light scattering, and the structure and morphology of the nanocomposites were observed by transmission electron microscope and FTIR spectrum. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2013–2016, 2004
Study on the mechanical properties of hybrid reinforced rigid polyurethane composite foam
Authors: Yang Zhen‐Guo , Zhao Bin , Qin Sang‐Lu , Hu Zheng‐Fei , Jin Zhong‐Kao , Wang Jian‐Hua
Published: March 2004

The mechanical properties of hybrid reinforced rigid polyurethane (PU) foams were investigated with the reinforcing agent SiO2 and fibers. The effect of content of SiO2 and fibers and the effect of length of fibers on the properties of the PU composite foam were emphatically analyzed. The experiment results show that the tensile strength of the PU composite foam is optimal when the content of SiO2 and glass fiber is 20 and 7.8%, respectively. Furthermore, the reinforcing effect of glass fiber, Nylon‐66 fiber, and PAN‐matrix carbon fiber were compared and the results show that the tensile strength of the PU composite foam reinforced with 3–5% carbon fiber is optimal. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1493–1500, 2004
Synthesis of functionalized phenolformaldehyde polymer resins by the reaction of 2,4‐dihydroxyacetophenone formaldehyde resin with various amines and their metal ion uptake properties
Authors: Reddy A. Ravikumar , Reddy K. Hussain
Published: March 2004

A series of functionalized phenolformaldehyde polymer resins have been synthesized by the reaction of 2,4‐dihydroxyacetophenone‐formaldehyde resin with the amines, such as ethanolamine, aminophenol, ethylenediamine, and propylenediamine in dichloromethane. The Schiffbase polymers were characterized by IR and 1H‐NMR spectroscopic techniques. Thermal stabilities of the polymers were determined by TG and DTA studies. Heavy and toxic metal ions viz., Pb(II), Hg(II), Cd(II), and Cr(VI) have been removed using these polymer resins. Metal uptake efficiency, reusability, effect of pH, effect of time, and effect of initial concentration on the metal uptake were also studied. Amount of metal removed by the resin was determined using atomic absorption spectrophotometry. The retention properties were also tested under competitive conditions and were found to be depend strongly on the pH. Elution of metal ions were investigated in acid media. The uptake behaviour of the resins was approximately described by Freundlich's equation. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1501–1509, 2004
Sorbents for removal surfactants from aqueous solutions: Surface modification of natural solids to enhance sorption ability
Authors: Łukaszczyk Jan , Łękawska Ewa , Lunkwitz Klaus , Petzold Gudrun
Published: March 2004

Particulate materials of natural origin, sulfite cellulose and two kaolinite clays, were modified by the formation of nonstoichiometric polyelectrolyte complex on the surface of particles. This resulted in positive surface charge on cellulose and clays. Modified materials as well as selected commercial polymers were used as sorbents for removal of anionic, nonionic, and cationic surfactants from aqueous solutions. It was stated that cationic surface modification of cellulose and kaolinite clays resulted in a significant increase of sorption rate and degree of removal of oppositely charged anionic surfactants. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1510–1515, 2004
Synthesis of new soluble aromatic poly(amide imide)s from unsymmetrical extended diamine containing phthalazinone moiety
Authors: Cheng Lin , Jian Xi Gao
Published: March 2004

The preparation of a new unsymmetrical kink non‐coplanar heterocyclic diamine, 1,2‐dihydro‐2‐(4‐aminophenyl)‐4‐[4‐(3‐phenyl‐4‐aminophenoxy)phenyl]‐(2H)phthalazin‐1‐one (3), from a readily available unsymmetrical phthalazinone bisphenol‐like (1) was described. The diamine can be directly polymerized with various aromatic bis(trimellitimide)s (4a–e) by using triphenyl phosphite and pyridine as condensing agents to give a series of new aromatic poly(amide imides) (5a–e) containing the kink non‐coplanar phthalazinone heterocyclic units with inherent viscosities of 0.57–1.06 dL/g. The polymers were readily soluble in a variety of solvents such as N,N‐dimethylformamide, N,N‐dimethylacetamide, dimethylsulfoxide, N‐methyl‐2‐pyrrolidinone, and even in pyridine and m‐cresol and could be cast to form flexible and tough films. The glass transition temperatures were in the range of 315–340°C, and the temperatures for 5% weight loss in nitrogen were in the range of 487–512°C. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1516–1520, 2004