bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of substituted aromatic heterocyclic phosphate salts on properties, crystallization, and melting behaviors of isotactic polypropylene
Authors: Zhang Yue‐Fei , Xin Zhong
Published: March 2006

Nucleation effects of 2,2′‐methylene‐bis (4,6‐di‐tert‐butylphenyl) phosphate metal salts as a nucleating agent for isotactic polypropylene (iPP) were investigated with differential scanning calorimeter and polarized optical microscope, and their effects on mechanical, optical, and heat resistance properties of iPP were also studied. The results showed that monovalent metal salts of substituted aromatic heterocyclic phosphate such as sodium salt, lithium salt, and potassium salt had a good performance. With 0.2 wt % of sodium salt, lithium salt, or potassium salt incorporated into iPP, the crystallization peak temperature of iPP could be increased by 13.5, 13.6, and 15.0°C, respectively; the mass fraction of crystallinity of iPP could be increased by about 5%; and crystallization rate was enhanced increasingly. Meanwhile the tensile strength and flexural modulus of iPP could be increased by about 10 and 30%, respectively, and the clarity and heat distortion temperature of iPP could also be improved significantly. But bivalent and trivalent metal salts of substituted aromatic heterocyclic phosphate had little effect on properties of iPP. Meanwhile the morphology study showed that the addition of monovalent sodium salt could decrease the spherulite size of iPP significantly. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4868–4874, 2006
Effect of fluorinated hydrophobic monomer on the drug release behavior for the thermosensitive hydrogels
Authors: Lee Wen‐Fu , Liu Ta‐Ming
Published: March 2006

Three series of copolymeric gels based onN‐isopropylacrylamide (NIPAAm) and perfluoroalkyl methacrylate such as 2,2,3,3,4,4,5,5‐octafluoropentyl methacrylate (OFPMA), 4,4,5,5,6,7,7,7‐octafluoro‐2‐hydroxy‐6‐(trifluoromethyl)heptyl methacrylate (OFHHMA), and 3,3,4,4,5,6,6,6‐octafluoro‐5‐(trifluoromethyl)hexyl methacrylate (OFHMA), were prepared by emulsion polymerization. The effect of perfluoroalkyl methacrylate and sodium lauryl sulfate (SLS), which can act as a surfactant and a pore‐forming agent, on the equilibrium swelling ratio and mechanical properties of the present hydrogels was investigated. Results show that hydrophobic monomers made the swelling ratio of the gel decrease and the mechanical property of the gel increase; however, SLS exhibits a contrary result. In addition, the effect of perfluoroalkyl methacrylate on the drug release behavior was also investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4661–4667, 2006
Influence of branch content, comonomer type, and crosshead speed on the mechanical properties of metallocene linear low‐density polyethylenes
Authors: Islam Ashraful , Hussein Ibnelwaleed A.
Published: March 2006

The effects of branch content (BC) and comonomer type on the mechanical properties of metallocene linear low‐density polyethylene (m‐LLDPEs) were studied by means of a stress–strain experiment at room temperature. A total of 16 samples with different BCs and comonomer types were used. In addition, the effect of crosshead speed on the mechanical properties of m‐LLDPEs with different BCs was examined. The degree of crystallinity (Xt) of these copolymers was determined by differential scanning calorimetry. In addition, Ziegler–Natta linear low‐density polyethylenes (ZN‐LLDPEs) were also studied for comparison purposes. The increase in BC of m‐LLDPEs decreasedXtand the modulus. However, the ZN‐LLDPEs showed higher small‐strain properties but lower ultimate properties than the m‐LLDPEs with similar weight‐average molecular weights and BCs. In comparison with low‐BC resins, m‐LLDPEs with high BCs exhibited a stronger strain hardening during the stress–strain experiments. Strain hardening was modeled by a modified Avrami equation, and the order of the mechanically induced crystal growth was in the range of 1–2, which suggested athermal nucleation. The crosshead speed was varied in the range 10–500 mm/min. For low‐BC m‐LLDPEs, there existed a narrow crosshead speed window within which the maxima in modulus and ultimate properties were observed. The location of the maxima were independent of BC. The effect of the crosshead speed on the mechanical properties of the m‐LLDPEs was a strong function of BC. However, highly branched m‐LLDPE in this experiment showed a weak dependence on the crosshead speed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 5019–5033, 2006
Development of biodegradable composites with treated and compatibilized lignocellulosic fibers
Authors: Tserki V. , Matzinos P. , Zafeiropoulos N. E. , Panayiotou C.
Published: March 2006

The aliphatic polyester Bionolle 3020 was combined with lignocellulosic fibers, namely, flax, hemp, and wood, to produce biodegradable composite materials. The effect of two fiber surface treatments, acetylation and propionylation, and the addition of maleic anhydride (MA)‐grafted Bionolle 3001 as a compatibilizer on the fiber/matrix interfacial adhesion was studied. The compatibilizer was synthesized through a MA grafting reaction in the presence of dicumyl peroxide as an initiator. The composites' mechanical properties, water absorption, fracture morphology (scanning electron microscopy), and biodegradation were evaluated. Both the fiber treatments and the compatibilizer incorporation significantly improved the composites' tensile strength, whereas an important reduction in the water absorption was found with the addition of treated fibers. Moreover, fiber incorporation into the matrix increased its biodegradation rate. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4703–4710, 2006
Enhancement of hydrostatic pressure for water repellent treated fabrics
Authors: Huang Pei‐Yuan , Chao Yu‐Chou , Liao Yih‐Tyan
Published: March 2006

The aqueous dispersions based on perfluorinated acrylate and other comonomers were prepared by means of emulsion polymerization in the presence of stearyl trimethyl ammonium chloride (STAC) and 2,2′‐azobis(2‐amidinopropane) dihydrochloride (ABAP) as water‐soluble initiators. Several different types of resins and additives were added with the water‐repellent polymers. Hydrostatic pressure and water repellency of fabrics that were treated by fluorinated water repellents with different recipes were measured and compared. In addition, the nano clay and the blocked isocyanate crosslinking agent (Jintexguard FCN) do, indeed, substantially increase the hydrostatic pressure. Actually, increased hydrostatic pressure for the water repellent treated fabrics is our objective of this study. However, our recipes containing the fluorinated‐acrylate copolymer, nano clay, and Jintexguard FCN will successfully provide excellent hydrostatic pressure, excellent water repellency, and excellent soft hand. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4711–4715, 2006
Shearing of drag‐reducing polymers with ultrasonic methods in fuel‐oil pipelines: A feasibility study
Authors: Rabecki Frédéric , Henrist Marc , Wildéria Daniel , Cuenca Felix Gómez
Published: March 2006

The purpose of this study was to assess the feasibility and experimental conditions for the shearing of polymers (polyolefins) in fuel oil. These drag‐reducing agents are mixed with fuel oil to reduce the friction during transportation in pipelines and, hence, to save energy, but they must be destroyed after use to restore all the properties of the fuel. One attractive solution consists of the use of ultrasonic energy to carry out this destruction. Ultrasound produces microbubbles (cavitation) in liquids. These bubbles grow and finally collapse, releasing a large amount of energy as a shockwave that can break polymer chains. We studied the influence of parameters affecting cavitation on the shearing index (percentage of initial additive after sonication). We concluded that polymers A and B could be used indiscriminately. The ultrasonic energy could be injected at a frequency of 20 kHz (like in commercial equipment), and the mode of injection did not influence the yield. The results were similar in static and flowing fuels. The temperature did not exert a significant influence. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4723–4728, 2006
Thermoplastic vulcanizates based on epoxidized natural rubber/polypropylene blends: Effect of compatibilizers and reactive blending
Authors: Nakason C. , Wannavilai P. , Kaesaman A.
Published: March 2006

Epoxidized natural rubber (ENR) was prepared using the performic epoxidation method. TPVs based on ENR/PP blends were later prepared by melt‐mixing processes via dynamic vulcanization. The effects of blend ratios of ENR/PP, types of compatibilizers, and reactive blending were investigated. Phenolic modified polypropylene (Ph‐PP) and graft copolymer of maleic anhydride on polypropylene molecules (PP‐g‐MA) were prepared and used as blend compatibilizers and reactive blending components of ENR/Ph‐PP and ENR/PP‐g‐MA blends. It was found that the mixing torque, apparent shear stress and apparent shear viscosity increased with increasing levels of ENR. This is attributed to the higher viscosity of the pure ENR than that of the pure PP. Furthermore, there was a higher compatibilizing effect because of the chemical interaction between the polar groups in ENR and PP‐g‐MA or Ph‐PP. Mixing torque, shear flow properties (i.e., shear stress and shear viscosity) and mechanical properties (i.e., tensile strength, elongation at break, and hardness) of the TPVs prepared by reactive blending of ENR/Ph‐PP and ENR/PP‐g‐MA were lower than that of the samples without a compatibilizer. However, the TPVs prepared using Ph‐PP and PP‐g‐MA as compatibilizers exhibited higher values. We observed that the TPVs prepared from ENR/PP with Ph‐PP as a compatibilizer gave the highest rheological and mechanical properties, while the reactive blending of ENR/PP exhibited the lowest values. Trend of the properties corresponds to the morphology of the TPVs. That is, the TPV with Ph‐PP as a blend compatibilizer showed the smallest rubber particles dispersed in the PP matrix, while the reactive blending of ENR/PP‐g‐MA showed the largest particles. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4729–4740, 2006
Soybean oil based resin: A new tool for improved immobilization of α‐amylase
Authors: Kahraman M. Vezir , Kayaman‐Apohan Nilhan , Ogan Ays̨e , Güngör Atilla
Published: March 2006

Acrylated epoxidized soybean resin has been utilized to immobilize the α‐amylase via UV‐curing technique. Among the numerous methods that exist for enzyme immobilization, entrapment and covalent binding are the focus of this study. The properties of immobilized enzyme were investigated and compared with those of the free enzyme. Upon immobilization by the two methods, the catalytic properties of the enzyme were not considerably changed as compared with that of nonimmobilized form; only the pH profile was broadened for the immobilized enzyme. The free enzyme lost its activity completely in 20 days, where as storage and repeated usage capability experiments demonstrated higher stability for the immobilized form. Immobilized enzyme prepared by attachment method possesses relatively higher activity compared with the activity of those obtained by entrapment method. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4757–4761, 2006
Preparation and barrier property of poly(ethylene terephthalate)/clay nanocomposite using clay‐supported catalyst
Authors: Joon Choi Won , Kim Hee‐Joon , Han Yoon Kwan , Hyeong Kwon Oh , Ik Hwang Chang
Published: March 2006

Poly(ethylene terephthalate) (PET)/clay nanocomposite was prepared by the direct polymerization with clay‐supported catalyst. The reaction degree of catalyst against the cation exchange capacity of clay was 8 wt %. The intercalation of PET chains into the silicate layers was revealed by X‐ray diffraction studies. SEM morphology of the nanocomposite showed a good dispersion of clay‐supported catalyst, ranging from 30 to 100 nm. The intercalated and exfoliated clay‐supported catalyst in PET matrix was also observed by TEM. The improvement of O2 permeability for PET/clay‐supported catalyst composite films over the pure PET is approximately factors of 11.3–15.6. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4875–4879, 2006
Development of an epoxy system characterized by low water absorption and high thermomechanical performances
Authors: Blanco I. , Cicala G. , Costa M. , Recca A.
Published: March 2006

Water absorption and thermomechanical properties of epoxy systems based on multifunctional dicyclopentadiene epoxy novolac resin Tactix556 cured with 4,4′ diaminodiphenilsulfone (4,4′DDS) as curing agent has been studied. The base system was modified by the addition of a novel 40 : 60 PES : PEES (Polyethersulphone : Polyetheretheresulphone) amine‐ended copolymer to improve toughness properties. The effect of thermoplastic addition on water adsorption was studied by gravimetric experiments. The viscoelastic properties of the resulting blend were analyzed by means of dynamic mechanical thermal analysis. The formulated systems were compared with a system based on tetraglycidyl‐4,4′diaminodiphenylmethane resin (MY721) cured with 4,4′ diaminodiphenilsulfone. The use of Tactix556 resin showed that water uptake values were minimized while retaining high glass transition temperatures, and toughness values were found in the same range of standard toughened matrices used for aerospace composites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4880–4887, 2006
Effects of the pH, concentration, and solvents on the ultrasonic degradation of poly(vinyl alcohol)
Authors: Vijayalakshmi S. P. , Madras Giridhar
Published: March 2006

The ultrasonic degradation of poly(vinyl alcohol) was investigated at different pHs of the solvent, in different water/solvent binary mixtures, and at different polymer concentrations. The samples were analyzed with gel permeation chromatography. The degradation rate coefficients were determined with a continuous distribution model. A higher degradation rate was obtained at pH extremes, in better solvents, and at lower polymer concentrations. The results are explained and discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4888–4892, 2006
Synthesis, formulation, and characterization of siloxane‐modified epoxy‐based anticorrosive paints
Authors: Ahmad Sharif , Ashraf S. M. , Sharmin Eram , Mohomad Ash , Alam Manawwer
Published: March 2006

Diglycidyl ether of bisphenol A epoxy (E) was modified with hydroxyl‐terminated polydimethylsiloxane through a ring‐opening addition polymerization reaction. The structural elucidation of the siloxane‐modified epoxy resin (ES) was carried out with Fourier transform infrared, 1H‐NMR, and 13C‐NMR spectroscopy techniques. The physicochemical characterization of the synthesized resin (ES) was performed with standard methods. E and ES were subjected to paint formulation with the help of a rutile (TiO2) pigment. The formulated paint systems were cured at room temperature with 1,6‐diaminohexane (AH) and 1,3‐diaminopropane (AP), which were used as curatives. The E–AH, E–AP, ES–AH, and ES–AP paint systems were applied to mild steel strips. The physicomechanical and anticorrosive performance of the coated panels was evaluated with standard methods. The thermal analysis of these E–amine and ES–amine systems was carried out via thermogravimetric analysis. The effects of siloxane incorporation and amine curatives on the coating properties of the paint systems were also investigated. The ES–AP system exhibited good thermal and corrosion stability performance among all the E and ES paint systems. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4981–4991, 2006
Micromechanical properties of injection‐molded starch–wood particle composites
Authors: Ueberschaer A. , Cagiao M. E. , Bayer R K. , Henning S. , Calleja F. J. Baltá
Published: March 2006

The micromechanical properties of injection‐molded starch–wood particle composites were investigated as a function of particle content and humidity conditions. The composite materials were characterized by scanning electron microscopy and X‐ray diffraction methods. The microhardness of the composites was shown to increase notably with the concentration of the wood particles. In addition, creep behavior under the indenter and temperature dependence were evaluated in terms of the independent contribution of the starch matrix and the wood microparticles to the hardness value. The influence of drying time on the density and weight uptake of the injection‐molded composites was highlighted. The results revealed the role of the mechanism of water evaporation, showing that the dependence of water uptake and temperature was greater for the starch–wood composites than for the pure starch sample. Experiments performed during the drying process at 70°C indicated that the wood in the starch composites did not prevent water loss from the samples. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4893–4899, 2006
Wound dressings containing bFGF‐impregnated microspheres: Preparation, characterization, in vitro and in vivo studies
Authors: Huang Sha , Jin Yan , Deng Tianzheng , Wu Hong
Published: March 2006

The purpose of this study was to synthesize a novel wound dressing containing bFGF‐loaded microspheres for promoting healing and tissue regeneration. Gelatin was chosen as the underlying layer and was prepared in porous sponge. As the external layer, elastomeric polyurethane membranes were used. bFGF was loaded in microspheres to achieve prolonged release for higher efficiency. The microspheres were characterized for particle size, in vitro protein release, and bioactivity. The dressings were tested in in vivo experiments on skin defects created on pigs. At certain intervals, wound areas were measured and tissues from wound areas were biopsied for histological examinations. Average size of the microspheres was 14.36 ± 3.56 μm and the network sponges were characterized with an average pore size of 80–160 μm. Both the release efficiency and the protein bioactivity revealed that bFGF was released in a controlled manner and was biologically active, as assessed by its ability to induce the proliferation of fibroblasts. The rate of wound‐area decrease was much faster and the quality of the newly‐formed dermis was almost as good as the normal skin. The application of this novel bilayer wound dressing provided an optimum healing milieu for the proliferating cells and regenerating tissues. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4772–4781, 2006
Crystal structures and their effects on the properties of polyamide 12/clay and polyamide 6–polyamide 66/clay nanocomposites
Authors: Zhang Y. , Yang J. H. , Ellis T. S. , Shi J.
Published: March 2006

Both polyamide 12 (PA 12)/clay and polyamide 6–polyamide 66 copolymer (PA 6/6,6)/clay nanocomposites were prepared by melt intercalation. The incorporation of 4–5 wt % modified clay largely increased the strength, modulus, heat distortion temperature (HDT), and permeation resistance to methanol of the polyamides but decreased the notched impact strength. Incorporation of the clay decreased the melt viscosities of both the PA 12 and PA 6/6,6 nanocomposites. Incorporation of the clay increased the crystallinity of PA 6/6,6 but had little effect on that of PA 12, which explained why the clay obviously increased the glass‐transition temperature of PA 6/6,6 but hardly had any effect on that of PA 12. The dispersion and orientation of both the clay and the polyamide crystals were studied with transmission electron microscopy, scanning electronic microscopy, and X‐ray diffraction. The clay was exfoliated into single layers in the nanocomposites, and the exfoliated clay layers had a preferred orientation parallel to the melt flow direction. Lamellar crystals but not spherulites were initiated on the exfoliated clay surfaces, which were much more compact and orderly than spherulites, and had the same orientation with that of the clay layers. The increase in the mechanical properties, HDT, and permeation resistance was attributed to the orientated exfoliated clay layers and the lamellar crystals. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4782–4794, 2006
Structure and properties of polypropylene alloy in situ blends
Authors: Cui Nannan , Ke Yucai , Lu Zhanxia , Wu Chunhong , Hu Youliang
Published: March 2006

A series of polypropylene (PP) alloys containing different ethylene contents have been prepared by the in situ sequential polymerization technique, using Ziegler–Natta catalyst (MgCl2/TiCl4/BMF; BMF is 9,9‐bis(methoxymethyl)fluorine, as an internal donor) without any external donor. The structure and properties of PP alloys obtained have been investigated by nuclear magnetic resonance, Fourier transform infrared spectroscopy, dynamic mechanical analysis, differential scanning calorimetry, and scanning electron microscopy (SEM). The results have suggested that PP alloys are the complex mixtures containing PP, the copolymer with long sequence ethylene chain, ethylene‐propylene rubber (EPR), and block copolymer etc. In the alloys, PP, EPR, and the copolymer with long sequence ethylene chain are partially compatible. The investigation of the mechanical properties indicates that notched Izod impact strength of PP alloy greatly increases at 16°C/−20°C in comparison with that of pure PP. The noticeable plastic deformation is observed in SEM photograph. The increase in the toughness, the mechanical strength of PP alloy decreases to a certain extent. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4804–4810, 2006
Comparison of physical and mechanical properties of NR/carbon black/reclaimed rubber blends vulcanized by conventional thermal and microwave irradiation methods
Authors: Sombatsompop N. , Kumnuantip C.
Published: March 2006

This work experimentally monitored the physical and mechanical properties of natural rubber/carbon black/reclaimed rubber blends vulcanized by microwave (MW) irradiation and conventional thermal (CT) systems, and the curing mechanisms are addressed in conjunction with the vulcanizate properties. The microwave oven for rubber blend vulcanization was specially designed and constructed in this work. The results suggested that the tensile modulus and the hardness of the vulcanizates could be enhanced by increasing the reclaimed rubber (RR) content, whereas the tensile stress, elongation at break, and tear strength decreased with the RR loading. The mechanical properties of the vulcanizates from the CT method were higher than those from the MW method. The vulcanizates from the MW method had higher resistance to toluene penetration than those from the CT method. The differences in the properties of the vulcanizates from the CT and MW methods became smaller at higher RR contents. The sensitivity in property changes of the vulcanizates due to addition of the RR content was greater for the CT method than for the MW method. The differences in the results between these two curing systems could be explained in terms of the density and the types of crosslinks present in the vulcanizates. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 5039–5048, 2006
Blends of polypropylene with poly(cis‐butadiene) rubber. III. Study on the phase structure and morphology of incompatible blends of polypropylene with poly(cis‐butadiene) rubber
Authors: Ma Gui‐Qiu , Zhao Yun‐Hui , Yan Li‐Tang , Li Yun‐Yan , Sheng Jing
Published: March 2006

Scanning electron microscopy (SEM) was used to study the structure and morphology of partly compatible binary blends of polypropylene with poly(cis‐butadiene) rubber. The SEM images were transformed by digital image process software designed by our group, and binarized images were obtained. The size (mean diameters dp and characteristic lengths L) of phases was calculated using binarized images. Small‐angle light scattering was employed to study the structure and morphology of phases in the blends. The structural parameters, including correlation distance ac, average chord lengths l, and mean diameter DS to describe the structure and morphology of phases in binary blends, were calculated based on the corresponding theory. The variation of correlation distance ac, average chord length l, and mean diameter DS were the same as that of mean diameters dp and characteristic length L. At the same time, the distribution of sizes of the dispersed phase in binary blends was calculated with graph transition technique, which possessed log‐normal distribution characterization. The power spectrum images corresponding to small‐angle light scattering images were obtained by two‐dimensional fourier transformation of binary images. The correlation distances acf and average chord length lf have been calculated by intensity of power spectrum images and that was the same as ac and l. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4900–4909, 2006
Crystallite size and shape in Twaron fibers heat treated at different temperatures using WAXS
Authors: Jain Anjana , Abhishek S. , Sangappa  , Mahesh S. S. , Somashekar R.
Published: March 2006

We have determined the crystallite size of Twaron fibers heat treated at various temperatures by analyzing the wide angle X‐ray scattering (WAXS) data employing a profile analysis technique developed by us. This study indicates that the differential change of size with temperature is less than 1% of the mean value along both (110) and (200) directions. Hence, these fibers are thermally stable and thermal aging is negligible. We have also observed that the lattice strain variation with temperature is negligible. These studies demonstrate the thermal stability of fibers in terms of the changes in the microcrystalline parameters. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4910–2916, 2006
Analysis of the epoxy polymerization process with piperidine as the initiator
Authors: Aitken Edward A.
Published: March 2006

Measurements of the rate of heating from a polymerization reaction of a popular Epoxy compound, EPON 828, with piperidine as the initiator were made until no further heat output was detectable. The results were obtained using a microcalorimeter at a temperature of 27.5°C. Three experiments were run where the amine equivalents relative to the epoxy equivalents were 0.034, 0.100, and 0.170. At these ratios, the amine was insufficient to bond with all the epoxide rings. Each amine bond produces an oxide ion, which in turn reacts with other epoxide rings creating another oxide ion. This propagation reaction continues until all the epoxy groups are opened and bonded. The heat rate from the epoxy reaction started at a value proportional to the amine content but then it accelerated rapidly by over an order of magnitude and then decelerated after about 50% completion. The heat rate profiles were found to fit a combination of three mechanisms operating during the polymerization. The first stage is generation of an oxide ion by amine reaction and by a hydrogen ion exchange between the unreacted amine and a hydroxyl group present in the EPON 828 molecule. The second stage is the rapid acceleration in heat rate due to a build up of an ether bond from the reaction of the oxide ion with an epoxy group. The peak heating rate occurred when the epoxy rings and ether bonds were equal. The last stage is a classic diffusion process, which is the only mechanism left to allow reaction after the other mechanisms have dissipated. The paper generates rate equations and discusses specific issues arising from the heat rate database. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 5066–5086, 2006
Synthesis of Fe3O4/PMMA composite latex particles: Kinetic modeling
Authors: Wang Ping‐Chieh , Chiu Wen‐Yen , Young Tai‐Horng
Published: March 2006

In this work, a generalized mathematical model was developed to estimate the variation of particle concentration during the entire course of soapless emulsion polymerization of methyl methacrylate with ferrofluid. Two mechanisms for the nucleation and growth of particles throughout the polymerization reaction were discussed: Mechanism I – seeded polymerization; and Mechanism II – self‐nucleation polymerization. Here, the self‐nucleation included homogeneous nucleation and micelle nucleation. Coagulation between particles, which came from different nucleation mechanisms during the course of polymerization, was considered and included in this model. When appropriate parameters were selected, this model could be successfully used to interpret the variation of particle concentration during the entire reaction. Under different conditions, rate of polymerization, number of radicals in each particle, average molecular weight of polymers, and rate constant of termination were also calculated. All of them explained the experimental results quite well. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4925–4934, 2006
Superparamagnetic flexible substrates based on submicron electrospun Estane® fibers containing MnZnFeNi nanoparticles
Authors: Gupta Pankaj , Asmatulu Ramazan , Claus Rick , Wilkes Garth
Published: March 2006

Flexible, elastomeric, and superparamagnetic substrates were prepared by electrospinning a solution of elastomeric polyurethane containing ferrite nanoparticles (∼14 nm) of MnZnNi. The flexible mats were characterized in terms of fiber morphology and magnetic properties. Field emission scanning electron microscopy (FESEM) indicated that the diameter of these composite fibers was ∼300–500 nm. Furthermore, the back‐scattered electron FESEM images indicated agglomeration of the nanoparticles at higher wt % (ca. 17–26 wt %) loading in the electrospun fibers. The induced specific magnetic saturation and the relative permeability were found to increase linearly with increasing wt % loading of the ferrite nanoparticles on the submicron electrospun fibers. A specific magnetic saturation of 1.7–6.3 emu/g at ambient conditions indicated superparamagnetic behavior of these composite electrospun substrates. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4935–4942, 2006
BIMS/filler interactions. I. Effects of filler structure
Authors: Tse M. F.
Published: March 2006

Polymer/filler interactions have been found to affect the performance of tire tread, sidewall, innerliner, or carcass and other industrial rubber products that are all based on filled elastomers. Identification of types of various polymer/filler interactions and ranking of their impacts have been elusive. Isobutylene‐based polymers have relatively saturated structures and contain very low concentrations of functional group. Examples are BIMS (a brominated isobutylene/p‐methylstyrene copolymer) containing p‐bromomethylstyrene and p‐methylstyrene; bromobutyl rubber containing Br and olefin; chlorobutyl rubber containing Cl and olefin; and butyl rubber containing olefin. On the other hand, high diene rubbers, such as polybutadiene rubber, polyisoprene rubber, and styrene/butadiene rubber, have unsaturated backbones and high olefin contents. Hence, different types and extents of interaction with reinforcing fillers, such as carbon black (CB) or silica, are expected in these two classes of elastomer. This work employs bound rubber (solvent extraction), viscoelasticity, stress–strain measurements, and solid state NMR to identify, differentiate, and scale polymer/filler interactions in unvulcanized BIMS/CB, BIMS/silica, SBR/CB, and SBR/silica composites, where SBR denotes a styrene/butadiene rubber. Four different types of CB and one type of silica have been studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4943–4956, 2006
A nanofoaming process and dielectric properties of polymethylphenylsilsesquioxane‐based nanofoams
Authors: Hong Soo Man , Hwang Seung Sang
Published: March 2006

We prepared polymethylphenylsilsesquioxane (PMPSQ) as an inorganic, thermally stable, matrix and poly‐D,L‐lactide‐1,6‐hexanediol (PDLLA‐1,6‐hexanediol) as a porogen material. PMPSQ was initially designed to obtain synergistic effects from polyphenylsilsesquioxane and polymethylsilsesquioxane. The PDLLA‐1,6‐hexanediol was chosen as a porogen since it has a much lower thermal stability when compared with PMPSQ. The initial decomposition temperature of the PMPSQ (458°C) was higher than the terminal decomposition temperature of PDLLA‐1,6‐hexanediol by 148°C, resulting in a broad processing window for the nanofoaming process. The broad window was utilized not only for optimization of the foaming condition, but for preparation of the nanofoamed PMPSQ without disruption in the structural stability of the matrix. Furthermore, hydroxyl end groups on PMPSQ and PDLLA‐1,6‐hexanediol played a role in the uniform and well‐distributed phase separation behavior. PMPSQ and PDLLA‐1,6‐hexanediol were investigated by 1H NMR, GPC, and thermogravimetric analysis to characterize the properties of polymers and optimize the foaming condition. The inorganic/organic hybrids based on the PMPSQ and PDLLA‐1,6‐hexanediol were prepared and measured in terms of phase separation behavior and dielectric properties. In these hybrid systems, PMPSQ/PDLLA‐1,6‐hexanediol (85/15) exhibited the most uniform and the smallest nanofoam distribution in the continuous PMPSQ matrix. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4964–4971, 2006
Molecular characteristics of room‐temperature soluble fractions of low‐density polyethylene film resins
Authors: Yu Youlu , Tso Chung C. , DesLauriers Paul J.
Published: March 2006

The molecular characteristics of the room‐temperature soluble fractions (RT solubles) of three low‐density polyethylene film resins were characterized by size‐exclusion chromatography (SEC), SEC combined with FTIR (SEC–FTIR), and nuclear magnetic resonance spectroscopy (NMR). The high‐molecular‐weight components of the RT solubles were found to be highly branched components with uniform short‐chain branching (SCB) profiles. For the low‐molecular‐weight components, however, SCB content was a function of molecular weight (MW), increasing with an increase in MW. When the chain ends were considered as SCB equivalents, the distribution of the sum of SCB and chain ends across the molecular weight distribution was practically flat, suggesting that the driving force for polymer chains remaining in solution at RT was the length of the undisrupted methylene sequence in the backbone, or methylene run length, which was too short to form crystal lamellae with a melting temperature above RT, regardless of the molecular weight of the polymer. Moreover, the NMR results revealed that the polymer components of the RT solubles had “superrandom” SCB distributions, that is, the fraction of comonomer clusters in the polymer chains of the RT solubles was lower than that predicted by Bernoullian statistical analysis, indicating that the probability of adding a comonomer to a comonomer‐ended propagating chain was lower than that of adding a comonomer to an ethylene‐ended one, presumably because of an unfavorable steric effect. Furthermore, contrary to the common belief that RT solubles are mainly low‐molecular‐weight polymers, high‐molecular‐weight components were found in high concentrations in the RT solubles, with a cutoff MW as high as 1,000,000 g/mol. The proportion of RT solubles in the film resins was found to depend on the type of resin. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4992–5006, 2006
Optimization of the hot alkali treatment of polyester/cotton fabric with sodium hydrosulfite
Authors: Montazer M. , Sadighi A.
Published: March 2006

The treatment of cotton or polyester fabric in alkali media is a common modification process for producing a fabric with desirable qualities. Alkali treatment of polyester/cotton fabric could produce a fabric with better performance. In this research, polyester/cotton fabric was treated with NaOH at different temperatures and times. The results show that alkali treatment at the optimum temperature and time with NaOH could hydrolyze the polyester fiber surface and remove some of the impurities from the cotton fiber at the same time and may also improve some of the fabric properties, such as fabric regain, water drop absorbency, and fabric pilling. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100:5049–5055, 2006
Porous dye affinity beads for nickel adsorption from aqueous solutions: A kinetic study
Authors: Akgöl Sinan , Kuşvuran Erdal , Kara Ali , Şenel Serap , Denizli Adil
Published: March 2006

We investigated a new adsorbent system, Reactive Red 120 attached poly(2‐hydroxyethyl methacrylate ethylene dimethacrylate) [poly(HEMA–EDMA)] beads, for the removal of Ni2+ ions from aqueous solutions. Poly(HEMA–EDMA) beads were prepared by the modified suspension copolymerization of 2‐hydroxyethyl methacrylate and ethylene dimethacrylate. Reactive Red 120 molecules were covalently attached to the beads. The beads (150–250 μm), having a swelling ratio of 55% and carrying 25.5 μmol of Reactive Red 120/g of polymer, were used in the removal of Ni2+ ions. The adsorption rate and capacity of the Reactive Red 120 attached poly(HEMA–EDMA) beads for Ni2+ ions was investigated in aqueous media containing different amounts of Ni2+ ions (5–35 mg/L) and having different pH values (2.0–7.0). Very high adsorption rates were observed at the beginning, and adsorption equilibria were then gradually achieved in about 60 min. The maximum adsorption of Ni2+ ions onto the Reactive Red 120 attached poly(HEMA–EDMA) beads was 2.83 mg/g at pH 6.0. The nonspecific adsorption of Ni2+ ions onto poly(HEMA–EDMA) beads was negligible (0.1 mg/g). The desorption of Ni2+ ions was studied with 0.1M HNO3. High desorption ratios (>90%) were achieved. The intraparticle diffusion rate constants at various temperatures were calculated as k20°C = 0.565 mg/g min0.5, k30°C = 0.560 mg/g min0.5, and k40°C = 0.385 mg/g min0.5. Adsorption–desorption cycles showed the feasibility of repeated use of this novel adsorbent system. The equilibrium data fitted very well both Langmuir and Freundlich adsorption models. The pseudo‐first‐order kinetic model was used to describe the kinetic data. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100:5056–5065, 2006
Bayesian Inference for a Correlated 2 × 2 Table with a Structural Zero
Authors: Stamey James D. , Seaman John W. , Young Dean M.
Published: March 2006

We develop a new Bayesian approach to interval estimation for both the risk difference and the risk ratio for a 2 × 2 table with a structural zero using Markov chain Monte Carlo (MCMC) methods. We also derive a normal approximation for the risk difference and a gamma approximation for the risk ratio. We then compare the coverage and interval width of our new intervals to the score‐based intervals over various parameter and sample‐size configurations. Finally, we consider a Bayesian method for sample‐size determination. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Regression as a Method to Predict Copy Numbers in Comparative Genomic Hybridization Studies on Bacteria
Authors: Feten Guri , Almøy Trygve , Snipen Lars , Aakra Ågot , Aastveit Are H.
Published: March 2006

Comparative genomic hybridizations (CGH) using microarrays are performed with bacteria in order to determine the level of genomic similarity between various strains. The microarrays applied in CGH experiments are constructed on the basis of the genome sequence of one strain, which is used as a control, or reference, in each experiment. A strain being compared with the known strain is called the unknown strain. The ratios of fluorescent intensities obtained from the spots on the microarrays can be used to determine which genes are divergent in the unknown strain, as well as to predict the copy number of actual genes in the unknown strain. In this paper, we focus on the prediction of gene copy number based on data from CGH experiments.

We assumed a linear connection between the log2 of the copy number and the observed log2‐ratios, then predictors based on the factor analysis model and the linear random model were proposed in an attempt to identify the copy numbers. These predictors were compared to using the ratio of the intensities directly.

Simulations indicated that the proposed predictors improved the prediction of the copy number in most situations. The predictors were applied on CGH data obtained from experiments with Enterococcus faecalis strains in order to determine copy number of relevant genes in five different strains. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling the utilization of starch by activated sludge for simultaneous substrate storage and microbial growth
Authors: Karahan Özlem , van Loosdrecht Mark C. M. , Orhon Derin
Published: March 2006

This paper presents a mechanistic model incorporating microbial growth on external substrate with simultaneous formation of storage biopolymers (activated sludge model for growth and storage‐ASMGS) for the utilization of starch by activated sludge. Model description and calibration utilized experimental data of an SBR fed with particulate native potato starch (NPS) and soluble starch (SolS) selected as model substrates. The fate of starch was monitored in a cycle together with glycogen and oxygen uptake rate (OUR) profiles. In the experiments, glycogen formation was significantly lower than predicted by total conversion of starch to glycogen, justifying the need to account for primary growth on starch. The proposed model basically modified Activated Sludge Model No.3 (ASM3), to include adsorption of starch, its hydrolysis and simultaneous growth and glycogen formation using the hydrolysis products, which was mainly maltose. Model simulations indicated hydrolysis of the adsorbed starch as the rate limiting process. The proposed model calibrated well the fate of all major model components, namely, starch, glycogen, and OUR. Particulate NPS and SolS were hydrolyzed with similar rates; however, primary and secondary growth processes on SolS were more efficient, with higher yields, due to the more easily utilizable products of SolS, both in terms of extracellular hydrolysis and of stored poly‐glucose. Modeling with ASM3, assuming starch as either readily or slowly biodegradable, did not provide an equally acceptable fit for the glycogen and OUR curves; supporting the need to consider primary growth together with storage as defined in the proposed model. © 2006 Wiley Periodicals, Inc.
Chromate reduction by immobilized palladized sulfate‐reducing bacteria
Authors: Humphries A.C. , Mikheenko I.P. , Macaskie L.E.
Published: March 2006

Resting cells of Desulfovibrio vulgaris NCIMB 8303 and Desulfovibrio desulfuricans NCIMB 8307 were used for the hydrogenase‐mediated reduction of Pd(II) to Pd(0). The resulting hybrid palladium bionanocatalyst (Bio‐Pd(0)) was used in the reduction of Cr(VI) to the less environmentally problematic Cr(III) species. The reduction of Cr(VI) by free and agar‐immobilized Bio‐Pd(0) was evaluated. Investigations using catalyst suspensions showed that Cr(VI) reduction was similar (∼170 nmol Cr(VI)/h/mg Bio‐Pd(0)) when Bio‐Pd(0) was produced using D. vulgaris or D. desulfuricans. Continuous‐flow studies using D. vulgaris Bio‐Pd(0) with agar as the immobilization matrix investigated the effect of Bio‐Pd(0) loading, inlet Cr(VI) concentration, and flow rate on the efficiency of Cr(VI) reduction. Reduction of Cr(VI) was highest at a D. vulgaris Bio‐Pd(0) loading of 7.5 mg Bio‐Pd(0)/mL agar (3:1 dry cell wt: Pd(0)), an input [Cr(VI)] of 100 µM, and a flow rate of 1.75 mL/h (approx. 3.5 column volumes/h). A mathematical interpretation predicted the activity of the immobilized Bio‐Pd(0) for a given set of conditions within 5% of the value found by experiment. Considering the system as an ‘artificial enzyme’ analog and application of applied enzyme kinetics gave an apparent Km value (Km app) of 430 µM Cr(VI) and a determined value of flow‐through reactor activity which differed by 11% from that predicted mathematically. © 2006 Wiley Periodicals, Inc.
Kinetics and equilibria of lysozyme precipitation and crystallization in concentrated ammonium sulfate solutions
Authors: Cheng Yu‐Chia , Lobo Raul F. , Sandler Stanley I. , Lenhoff Abraham M.
Published: March 2006

The kinetics and thermodynamics of lysozyme precipitation in ammonium sulfate solutions at pH 4 and 8 and room temperature were studied. X‐ray powder diffraction (XRD) was used to characterize the structure of lysozyme precipitates. It was found that, if sufficient time was allowed, microcrystals developed following an induction period after initial lysozyme precipitation, even up to ionic strengths of 8 m and at acidic pH, where lysozyme is refractory to crystallization in ammonium sulfate. The full set of precipitation and crystallization data allowed construction of a phase diagram of lysozyme, showing the ammonium sulfate dependence. It suggests that precipitation may reflect a frustrated metastable liquid‐liquid phase separation, which would allow this process to be understood within the framework of the generic phase diagram for proteins. The results also demonstrate that XRD, more frequently used for characterizing inorganic and organic polycrystalline materials, is useful both in characterizing the presence of crystals in the dense phase and in verifying the crystal form of proteins. © 2006 Wiley Periodicals, Inc.
Kinetic modeling to optimize pentose fermentation in Zymomonas mobilis
Authors: Altintas Mehmet M. , Eddy Christina K. , Zhang Min , McMillan James D. , Kompala Dhinakar S.
Published: March 2006

Zymomonas mobilis engineered to express four heterologous enzymes required for xylose utilization ferments xylose along with glucose. A network of pentose phosphate (PP) pathway enzymatic reactions interacting with the native glycolytic Entner Doudoroff (ED) pathway has been hypothesized. We have investigated this putative reaction network by developing a kinetic model incorporating all of the enzymatic reactions of the PP and ED pathways, including those catalyzed by the heterologous enzymes. Starting with the experimental literature on in vitro characterization of each enzymatic reaction, we have developed a kinetic model to enable dynamic simulation of intracellular metabolite concentrations along the network of interacting PP and ED metabolic pathways. This kinetic model is useful for performing in silico simulations to predict how varying the different enzyme concentrations will affect intracellular metabolite concentrations and ethanol production rate during continuous fermentation of glucose and xylose mixtures. Among the five enzymes whose concentrations were varied as inputs to the model, ethanol production in the continuous fermentor was optimized when xylose isomerase (XI) was present at the highest level, followed by transaldolase (TAL). Predictions of the model that the interconnecting enzyme phosphoglucose isomerase (PGI) does not need to be overexpressed were recently confirmed through experimental investigations. Through such systematic analysis, we can develop efficient strategies for maximizing the fermentation of both glucose and xylose, while minimizing the expression of heterologous enzymes. © 2006 Wiley Periodicals, Inc.
Biohydrogen production in granular up‐flow anaerobic sludge blanket (UASB) reactors with mixed cultures under hyper‐thermophilic temperature (70°C)
Authors: Kotsopoulos Thomas A. , Zeng Raymond J. , Angelidaki Irini
Published: March 2006

Hyper‐thermophilic hydrogen production without methane was demonstrated for the first time in granular up‐flow anaerobic sludge blanket (UASB) system fed with glucose using mixed cultures. The maximum hydrogen yield in this study was 2.47 ± 0.15 mol H2/mol glucose. This high yield has never been previously reported in mixed culture systems and it was likely due to more favorable thermodynamic conditions at hyper‐thermophilic temperatures. Different start‐up strategies (bromoethanosulfonate (BES) addition and flow recycle) were evaluated. BES addition during start‐up prevented the establishment of methanogenic cultures in granules. Flow recycle was important to achieve higher hydrogen yield through enriching better hydrogen‐producing organisms and reduced the start‐up period as well. This study indicated UASB system was a promising system for hydrogen production. © 2006 Wiley Periodicals, Inc.