bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and characterizations of polycaprolactone/green coconut fiber composites
Authors: Wu Chin‐San 
Published: September 2009

AbstractThe mechanical, thermal, and morphological properties of polycaprolactone (PCL) and green coconut fiber (GCF) composites were evaluated. Blends containing acrylic acid‐grafted PCL (PCL‐g‐AA/GCF) exhibited noticeably better mechanical properties due to better compatibility between the two components. The dispersion of GCF in the PCL‐g‐AA matrix was significantly more homogeneous due to the creation of branched and cross‐linked macromolecules via reactions between carboxyl groups in PCL‐g‐AA and hydroxyl groups in GCF. The tensile strength of the PCL‐g‐AA/GCF composites at break was considerably greater than that of PCL/GCF composites. In addition, the PCL‐g‐AA/GCF blend was more easily processed due to lower melt viscosity. Biodegradation tests were performed with each composite in an Acinetobacter baumannii BCRC 15556 environment. The mass of both composites was reduced by the GCF content within 4 weeks. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Accelerated aging versus realistic aging in aerospace composite materials. V. The effects of hot/wet aging in a structural epoxy composite
Authors: Dao B. , Hodgkin J. , Krstina J. , Mardel J. , Tian W. 
Published: September 2009

AbstractSamples of an aerospace‐grade, carbon‐fiber epoxy composite (Hexcell 8552/IM7) were subject to long‐term (≈ 1 year) hot/wet aging and thermal spiking under different humidity levels and temperature conditions related to the “in‐service” conditions seen in military aircraft. Changes to the chemical and physico‐chemical structure of the composite were analyzed by a range of experimental techniques including gravimetric analysis, FTIR, and DMA, to compare the effects of the various aging conditions. The results indicated that, while the chemical changes (as seen by FTIR) in this well cured composite appeared to be only significant at the surface, they did appear to have a deeper influence on some of the major physical property changes observed, such as microcracking, glass‐transition‐temperature (Tg) variations, and Tan δ curves. These physical changes could not be fully explained by standard water‐absorption effects alone but could also be influenced by chemical changes similar to those seen at the surface. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Preparation and characterization of nanocomposites based on polylactides tethered with polyhedral oligomeric silsesquioxane
Authors: Lee Jong Hyun , Jeong Young Gyu 
Published: September 2009

AbstractA series of polylactides tethered with polyhedral oligomeric silsesquioxane (POSS–PLAs) were synthesized via the ring‐opening polymerization of L‐lactide with 3‐hydroxypropylheptaisobutyl polyhedral oligomeric silsesquioxane (3‐hydroxypropylheptaisobutyl POSS) at a concentration of 0.02–2.00 mol % in the presence of a stannous(II) octoate catalyst.1H‐NMR spectra and a composition analysis of the POSS–PLA hybrids confirmed that 3‐hydroxypropylheptaisobutyl POSS served as an initiator for L‐lactide in the ring‐opening polymerization. X‐ray diffraction patterns evidenced that polyhedral oligomeric silsesquioxane (POSS) molecules of POSS–PLA hybrids were well dispersed without the formation of their crystalline aggregates. The POSS–PLA hybrid with 0.50 mol % POSS content was solution‐blended with a neat polylactide (PLA) homopolymer to obtain PLA/POSS–PLA nanocomposites with various POSS–PLA contents of 1–30 wt %. The X‐ray diffraction results of the PLA/POSS–PLA nanocomposites demonstrated that the POSS–PLA was well dispersed in the neat PLA matrix. The thermal and thermooxidative degradation properties of the nanocomposites were found to be improved at POSS–PLA contents of 1–20 wt %, compared to the neat PLA. The crystallization rates and crystallinities of the PLA/POSS–PLA nanocomposites were faster and higher, respectively, with increasing POSS–PLA content because of the nucleation effect of the POSS molecules in the neat PLA matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Interfacial aspects of adhesion in polymer nanocomposite thin‐film devices
Authors: Murugaraj P. , Mainwaring D. E. , Chen L. G. , Sawant P. , Al Kobaisi M. , Yek W. M. 
Published: September 2009

AbstractNanoscale polymeric composites are important in many new electronic technologies, including lightweight and flexible devices and sensors. The influence of surface chemical treatments, which particularly affect the adhesion properties of carbon–polyimide nanocomposite thin films, was studied with infrared spectroscopy, electron microscopy, atomic force microscopy, and contact angle measurements with respect to corresponding polyimide thin films. The contact angles showed that the inclusion of carbon initially increased the hydrophilicity, whereas a potassium hydroxide treatment increased the hydrophilicity of the pure polyimide film and the polyimide component of the nanocomposite surface without increasing the hydrophilicity of the carbon nanoparticle component. Friction‐force atomic force microscopy was shown to be a powerful technique for confirming the relative wetting characteristics at the nanoscale. The lower hydrophilicity and activity of the carbon nanoparticles during adhesion reactions reduced the load at break, and this suggests that this conventional modification used for polyimides is less effective for their nanocomposite counterparts. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Synthesis and characterization of a novel covalently functionalized organoclay and its polypropylene nanocomposite
Authors: Du Xiaohua , Zhang Zhenjiang , Yu Haiou , Wan Dong , Xing Haiping , Tang Tao 
Published: September 2009

AbstractA covalently functionalized organoclay was synthesized successfully through a condensation reaction of SiOH groups on the edge of montmorillonite (MMT) with acryloyl chloride followed by modification with hexadecyltrimethylammonium bromide (CTAB) via an ion‐exchange reaction. Fourier transform infrared confirmed that CC groups had been grafted to MMT sheets. Wide‐angle X‐ray diffraction measurements showed that CTAB had intercalated into MMT interlayers. The content of bonded acryloyl chloride was 2.42 wt % in the functionalized organoclay according to thermogravimetric analysis. Polypropylene (PP) nanocomposites were prepared by melt mixing. Rheological measurements and morphology observations confirmed that PP nanocomposites containing the organoclay bearing CC groups exhibited improved interfacial interaction between PP chains and MMT sheets. Thus, the PP nanocomposites showed not only higher storage modulus and complex viscosity values at low frequencies but also enhanced mechanical properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Studies on the self‐assembly of neat DBS and DBS/PPG organogels
Authors: Lai Wei‐Chi , Wu Chia‐Hui 
Published: September 2009

AbstractThe self‐assembly behavior of neat 1,3:2,4‐dibenzylidene‐D‐sorbitol (DBS) and DBS/poly(propylene glycol) (PPG) organogels has been investigated by scanning electron microscopy, polarizing optical microscopy, and rheological measurements. DBS molecules are capable of self‐organizing into fibrils and exhibit the birefringent spherulitic textures during cooling from the melt. On the other hand, DBS can self‐assemble into a fibrillar network in PPG to produce organogels. DBS/PPG organogels also reveal a spherulite‐like morphology. When a small amount of DBS is dispersed into a PPG matrix, we find that the spherulite sizes are much smaller than those of neat DBS. This is because the dilution of DBS causes DBS to self‐assemble in PPG at a lower temperature. Therefore, more nucleation sites and smaller spherulite sizes are found in the DBS/PPG organogel system. The rheological measurements demonstrate that the elastic modulus (G′) in DBS/PPG organogels increases as the DBS concentration increases. However, the increase in G′ is less obvious, as the DBS content exceeds 3 wt %. suggesting that the DBS networks become saturated. Also, it is found that these organogels require a certain period of time to reach thermodynamic equilibrium, depending on DBS concentrations. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Nucleation effect of inclusion complexes with different polyolefin as guest molecules on the crystallization of polypropylene
Authors: Li Chun , Isshiki Naoe , Saito Hiromu , Kohno Kazufumi , Toyota Akinori 
Published: September 2009

AbstractThe γ‐cyclodextrin (γ‐CD) inclusion complexes (ICs) with four kinds of polyolefin (PO) as guest molecules were prepared. The crystallization behavior of isotactic polypropylene (iPP) blended with the γ‐CD and γ‐CD–PO ICs was investigated by differential scanning calorimetry, polarized optical microscopy, and light scattering. The iPP blended with the ICs was found to exhibit higher crystallization temperature (TC), smaller spherulites, and faster crystallization rate than those of neat iPP, indicating that the ICs play a role of nucleating agent on the crystallization of iPP and induce accelerated crystallization. The IC with PO having higher TC as guest molecules showed higher nucleation effect than the IC with PO having lower TC as guest molecules. The results suggest that the nucleation effect of these ICs was affected by the kinds of the guest molecules. The higher TC guest molecules could result in higher nucleation effect. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Polyacrylamide‐g‐alginate‐based electrically responsive hydrogel for drug delivery application: Synthesis, characterization, and formulation development
Authors: Kulkarni Raghavendra V. , Setty Chitrali Mallikarjun , Sa Biswanath 
Published: September 2009

AbstractAn electrically responsive hydrolyzed polyacrylamide‐grafted‐sodium alginate (H‐PAAm‐g‐SA)‐based membrane‐controlled transdermal drug delivery systems were developed and evaluated. The grafting reaction was confirmed by Fourier transform infrared spectroscopy, elemental analysis, and thermogravimetric analysis. On application of electric stimulus, the swollen H‐PAAm‐g‐SA hydrogel was deswelled in the vicinity of electrodes. The drug release was greater in the presence of electric stimulus when compared with passive diffusion, and it was found to be dependent on the applied electric current strength, concentration of H‐PAAm‐g‐SA copolymer in the reservoir, and cross‐link density of rate‐controlling membrane. A pulsatile pattern of drug release was observed when the electric stimulus was switched “on” and “off.” The skin histopathology study suggested that, after application of an electrical stimulus, changes were in the structure of stratum corneum. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Hybrid emulsifiers enhancing polymerization stabilities and properties of pressure sensitive adhesives
Authors: Bai Yong‐Ping , Zhao Liang , Shao Lu 
Published: September 2009

AbstractIn this study, a series of (anionic and nonionic) emulsifiers were investigated to prepare acrylic pressure sensitive adhesives (PSA) with core‐shell structure by semicontinuous emulsion polymerization. The cloud point of different emulsifiers was characterized to explain the emulsifier effects on the emulsification ability. It was interestingly found that the hybrid emulsifiers (anionic coupling with nonionic) with optimized compositions could enhance the stability of emulsion system and improve the properties of PSA compared with the mono‐emulsifier. The stability of emulsion polymerization, the appearance of the emulsion system and the properties of PSA were studied in details by changing the proportion and the content of hybrid emulsifiers. When the ratio of sodium dodecyl sulfate (SDS: anionic emulsifier) to polyoxyethylene alkyl phenyl ether (OP‐10: nonionic emulsifier) reached 2 : 1, the content of hybrid emulsifiers reached 3 wt % and the reaction temperature was around 80°C, a better emulsion system was obtained in terms of comprehensive properties. At this condition, the synthesized PSA demonstrated the good holding power and 180° peel strength properties with fair tacky property, which was promising for industrial applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Electrospinning of waterborne polyurethanes
Authors: Buruaga Lorea , Sardon Haritz , Irusta Lourdes , González Alba , Fernández‐Berridi María José , Iruin Juan José 
Published: September 2009

AbstractPolyurethane (PU) fibers were obtained by electrospinning of waterborne PU dispersions. As dispersion cannot be electrospun, a water‐soluble polymer (poly (ethylene oxide) (PEO)) was dissolved in the PU dispersion and fibers were obtained from electrospinning the resulting mixture. Pure PU fibers were obtained after removing PEO with water extraction. Continuous PU fibers were obtained using a PU/PEO weight ratio higher than 2.5. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Atomic force microscopy and contact angle studies of polymerizable gemini surfactant admicelles on mica
Authors: Asnachinda Emma , O'Haver John H. , Sabatini David A. , Khaodhiar Sutha 
Published: September 2009

AbstractAtomic force microscopy (AFM) was used to directly observe and characterize a polymer‐modified mica surface prepared using a polymerizable gemini surfactant. Normal tapping mode and contact mode AFM were used to image the treated mica surface morphologies in air and liquid environments, respectively. The root mean square (RMS) roughness of mica surfaces before and after surface modification and polymerization was analyzed from these scans. To determine the effect of styrene adsolubilization on the surfactant‐modified mica, AFM measurements of the modified mica were made at various styrene concentrations. Contact angle measurements were also made to further characterize the nature of the surfactant‐modified mica surface. The surface morphology and surface hydrophilicity were observed to be different for the modified mica after polymerization. In addition, the polymerized surface maintained its morphology after washing/desorption studies demonstrating the stability of the polymerized surfactant film. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
The effect of incorporation of POSS units on polymer blend compatibility
Authors: Li Shuyan , Simon George P. , Matisons Janis G. 
Published: September 2009

AbstractIn this work, the compatibility of poly(methyl methacrylate) (PMMA) and polystyrene (PS) polymers with their polyhedral oligomeric silsesquioxane (POSS) copolymers combined by solution blending is investigated, to determine the effect of incorporation of the POSS unit on polymer compatibility. The morphology of these tethered POSS copolymer/polymer blends was studied by electron microscopy, thermal analysis, and density. Although the basic PS/PMMA blend was clearly immiscible, it was also found that the incorporation of POSS into the PS chain led to incompatibility when the POSScoPS copolymer was blended with PS homopolymer. However, conversely, in the case where the POSS moiety was included as part of a copolymer with PMMA, the copolymer was miscible with the PMMA homopolymer. The presence of isobutyl units on the corners of POSS cage is clearly sufficient to encourage miscibility with PMMA. Interestingly, blends of the two different POSS copolymers led to an immiscible structure, despite having the common POSS units, the interactions between the POSS moieties clearly not being sufficient to drive compatibility. The POSS copolymers have also been used as interfacial agents in immiscible PS and PMMA blend, and it has been found that the appearance of the interface bonding is improved, although the phase morphology is only slightly changed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Degradable poly(ester amine) based on poly(ethylene glycol) dimethacrylate and polyethylenimine as a gene carrier
Authors: Yu Jia‐Hui , Huang Jin , Nah Jae‐Woon , Cho Myung‐Haing , Cho Chong‐Su 
Published: September 2009

AbstractDegradable poly(ester amine) (PEA) based on poly(ethylene glycol) dimethacrylate (PMEG) and polyethylenimine (PEI) were synthesized by Michael addition reaction. The ratios of PEI to PMEG in PEAs were 0.99, 1.02, and 1.07 with corresponding number‐average molecular weight of 1.3 × 104, 1.2 × 104, and 0.9 × 104, respectively. Degradation rate of PEA at pH 7.4 was higher than that at pH 5.6. Good plasmid condensation and protection ability was shown when N/P molar ratio of PEA to DNA was above 15 (N: nitrogen element in PEA, P: phosphate in DNA). PEA/DNA complexes had positive zeta potential, narrow size distribution, good dispersity, and spheric shape with size below 250 nm when N/P ratio was above 30, suggestion of their endocytosis potential. Compared with PEI 25 KDa, the PEAs showed essential nontoxic to HeLa, HepG2 and 293T cells. With an increase in the molecular weight of PMEG, the transfection efficiency of PEAs in HeLa, HepG2 and 293T showed a tendency to decrease as well as the percent decrease of gene transfection efficiency with serum. The mechanism of PEA‐mediated gene transfection was attributed to “proton sponge effect” of PEI in the PEA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Kinetic rate equation combining ultraviolet‐induced curing and thermal curing. I. Bismaleimide system
Authors: Lin Rong‐Hsien , Huang Ru‐Yu , Yen Fu‐Shan , Chen Yi‐Hung , Ho Tzung‐Han 
Published: September 2009

AbstractA novel and general kinetic rate equation combining ultraviolet‐induced (UV‐induced) curing and thermal curing was successfully derived from the conventional thermal‐kinetic rate equation. This proposed novel kinetic rate equation can be applicable to the curing system either simultaneously or individually by UV‐induced and thermal cure methods. This general kinetic rate equation is composed of the reaction order n, activation energy Ea, curing temperature T, energy barrier of photoinitiation EQ, intensity of UV radiation Q, concentration of photoinitiator [I], and a few other parameters. The proposed equation was supported by experimental data based on the curing systems of 4,4′‐bismaleimidodiphenylmethane (BMI) and 2,2‐bis(4‐(4 maleimido phenoxy) phenyl propane (BMIP). The BMI and BMIP systems were isothermally cured at various temperatures, or simultaneously cured with varying intensity of UV radiation (wavelength 365 nm). Conversion levels for the various cured samples were subsequently measured with a FTIR spectrometer. The reaction order n = 1.2, activation energy Ea = 40,800 J/mol, and EQ = 7.5 mW/cm2 were obtained for curing BMI system. The reaction order n = 1.3, activation energy Ea = 53,000 J/mol, and EQ = 9.1 mW/cm2 were obtained for curing BMIP system. The values of n and Ea in the same curing system (BMI or BMIP) are irrespective of the curing method (either simultaneously or individually by UV‐induced and thermal cure methods). The salient results of this study show that UV radiation only enhances the initiation rate and UV ration do not influence the activation energy Ea. The experimental results are reasonably well represented by these semi‐empirical expressions.© 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Divergences without probability vectors and their applications
Authors: Sachlas Athanasios , Papaioannou Takis 
Published: September 2009

AbstractIn general, divergences and measures of information are defined for probability vectors. However, in some cases, divergences are ‘informally’ used to measure the discrepancy between vectors, which are not necessarily probability vectors. In this paper we examine whether divergences with nonprobability vectors in their arguments share the properties of probabilistic or information theoretic divergences. The results indicate that divergences with nonprobability vectors share, under some conditions, some of the properties of probabilistic or information theoretic divergences and therefore can be considered and used as information measures. We then use these divergences in the problem of actuarial graduation of mortality rates. Copyright © 2009 John Wiley & Sons, Ltd.
Response Adaptive Designs with a Variance‐penalized Criterion
Authors: Yi Yanqing , Wang Xikui 
Published: September 2009

AbstractWe consider a response adaptive design of clinical trials with a variance‐penalized criterion. It is shown that this criterion evaluates the performance of a response adaptive design based on both the number of patients assigned to the better treatment and the power of the statistical test. A new proportion of treatment allocation is proposed and the doubly biased coin procedure is used to target the proposed proportion. Under reasonable assumptions, the proposed design is demonstrated to generate an asymptotic variance of allocation proportions, which is smaller than that of the drop‐the‐loser design. Simulation comparisons of the proposed design with some existing designs are presented.
TNF‐α, a potent lipid metabolism regulator
Authors: Chen Xiuping , Xun Keli , Chen Lidian , Wang Yitao 
Published: September 2009

AbstractAs a multifunctional cytokine, tumor necrosis factor alpha (TNF‐α) exerts a series of biological actions in different cells, tissues, organs, and species and has been demonstrated to regulate and interfere with energy metabolism, especially lipid homeostasis. A large body of researches suggested that the effects of TNF‐α on lipid metabolism mainly include five aspects: (1) suppresses free fatty acid (FFA) uptake and promotes lipogenesis; (2) induces lipolysis; (3) inhibits lipid‐metabolism‐related enzymes activity; (4) regulates cholesterol metabolism; (5) regulates other adipocyte‐derived adipokines. The molecular mechanisms underlying these actions are complex and several signal transduction pathways might be involved. Regulation of metabolism‐related gene expression at transcriptional and protein levels and impact on enzymes activity might be of importance. Identification and verification of these pathways might provide novel potential strategies and drug targets for dyslipidemia therapy. However, the inconsistent and even conflict conclusions on lipid profile drawn from human subjects after infliximab therapy poses the possibility that the effect of TNF‐α on lipid metabolism might be more complicated than it appeared to be. Copyright © 2009 John Wiley & Sons, Ltd.
Phytoremediation of Sb, As, Cu, and Zn from Contaminated Water by the Aquatic Macrophyte Eleocharis acicularis
Authors: Ha Nguyen Thi Hoang , Sakakibara Masayuki , Sano Sakae 
Published: September 2009

AbstractSb, As, Cu, and Zn toxicity and contamination have become a growing concern in recent years. Phytoremediation, a plant based and cost effective technology, may be an effective approach in the cleanup of water contaminated by these metals. In this study, the aquatic macrophyte Eleocharis acicularis was used in laboratory and field experiments to assess its capability to accumulate Sb, As, Cu, and Zn, and thereby investigate its potential application in phytoremediation. The results showed that E. acicularis adapted well to water contaminated by these metals. The removal rates of Sb, As, Cu, and Zn in the laboratory experiment were 3.04, 2.75, 0.417, and 1.49 μg/L/day, respectively. The highest concentrations of these metals accumulated in E. acicularis after 10 days of the laboratory experiment were 6.29, 6.44, 20.5, and 73.5 mg/kg dry weight, respectively. Only 8% of As, 12% of Sb, 87% of Cu and 93% of Zn removed from the water were used by E. acicularis. The highest concentrations of Sb, As, Cu, and Zn accumulated in E. acicularis after 10 wk of the field experiment were 76.0, 22.4, 33.9, and 266 mg/kg dry weight, respectively. The results indicate that E. acicularis has the ability to accumulate Sb, As, Cu, and Zn from contaminated water.