bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and Characterization of Waterborne Polyurethane/Clay Nanocomposite – Effect on Adhesive Strength
Authors: Rahman Mohammad Mizanur , Yoo Hye‐Jin , Mi Chung Jung , Kim Han‐Do
Published: March 2007

Waterborne polyurethane (WBPU)/clay nanocomposites were synthesized using prepolymer process with different clay content (0–5 wt%) of organoclay cloisite 15A. The optimum dispersion temperature of clay in polyol was found to be 80 °C at 3 hours. The XRD confirmed the exfoliation dispersion of clay by polyol in WBPU/clay nanocomposite. IR and 1H‐NMR spectroscopy confirmed the unreacted condition of clay component. Particle size of the WBPU/clay nanocomposite dispersion was increased with increasing of clay concentration. Water swelling was decreased with increasing of clay up to the optimum content (2 wt %) and then leveled off. The thermal stability, mechanical property and adhesive strength were increased with increasing clay content up to 2 wt% to reach its maximum value.
Multiwalled Carbon Nanotube‐Reinforced Poly(vinyl chloride)
Authors: Jung Rira , Kim Hun‐Sik , Jin Hyoung‐Joon
Published: March 2007

Multiwalled carbon nanotube (MWCNT)‐reinforced poly(vinyl chloride) (PVC) was prepared via a simple adsorption method in an aqueous system. MWCNTs possessing negatively charged carboxyl groups at their tips and sidewalls introduced during the purification process were dispersed in water with the cationic surfactant, cetyltrimethylammonium bromide, using ultra‐sonication. Then, PVC microspheres, which have a negative charge in water at pH 7.0, were added to the aqueous MWCNTs dispersion. As a result, the MWCNTs were stably and strongly adsorbed on the surface of the PVC microspheres by electrostatic interaction. Furthermore, the dispersivity of the MWCNTs in the PVC remained high, even when we manufactured the MWCNT‐adsorbed PVC microspheres in the form of solution cast films. The PVC/MWCNTs nanocomposite exhibited a marked increase in its electrical conductivity, in spite of the relatively low MWCNT content (2.9 wt%). The composite films also showed an improvement in their mechanical properties, such as their tensile strength and Young's modulus.
Luminescent Polymer Latex Particles Prepared by Oxidative Polymerization in Emulsion Polymerization
Authors: Jung Yeon Jae , Lee Jung Min , Cheong In Woo , Kim Jung Hyun
Published: March 2007

It was demonstrated that core‐shell poly(styrene/thiophene) latex particles were successfully prepared by oxidative polymerization during emulsifier‐free emulsion polymerization. This method provided a new fabrication route of core‐shell type luminescent polymer particles with a thin shell layer. The core/shell structure of the resulting latex particles was proved by SEM analysis. It supported a strong evidence that each composition was isolated in independent domains, and which was corroborated by the TGA analysis. The resulting latex particles showed that luminescence efficiency in the solid state was better than that in the emulsion state due to the core‐shell morphology with a thin shell structure. This new strategy is universal for the synthesis of many other materials or composite particles with controlled morphology. Such core‐shell morphology controlled conjugated polymer composite particles may have potential practical applications in various electrical and electro‐optical devices, especially in polymer light emitting diodes (PLEDs).
Study on the Functionalization of Multi‐Walled Carbon Nanotube with Monoamine Terminated Poly(ethylene oxide)
Authors: An Jung Sook , Nam Byeong‐Uk , Tan Soon Huat , Hong Sung Chul
Published: March 2007

Through the introduction of carboxylic acid or thionyl chloride groups in multi‐walled carbon nanotubes (MWNT‐COOH or MWNT‐COCl) and amine group in poly(ethylene oxide) (PEO‐NH2), complexation of MWNT with PEO was successfully performed, yielding MWNT/PEO complex having approximately 40 wt.% of PEO. The MWNT/PEO complexes exhibited excellent dispersibility in solvents including water, ethanol and DMF. From SEM observation, the increases in the diameter of the nanotubes were observed. The presence of PEO on the nanotube surface was also confirmed through EDX and FT‐IR. The effects of different functionality on MWNTs (COOH vs. COCl) and different molecular weight of PEOs (1000 g/mol vs. 2000 g/mol) were not so prominent.
Ultrasonic Effects on PP/PS/Clay Nanocomposites during Continuous Melt Compounding Process
Authors: Kim Kyung Yl , Ju Dong Uk , Nam Gi Joon , Lee Jae Wook
Published: March 2007

Polymer blend/clay nanocomposites were prepared by ultrasonic‐assisted continuous extrusion process. This process was employed to enhance the compatibility between two polymers, and nano‐scale dispersion between the polymer blend and organically modified clay. Materials were linear polypropylene and polystyrene with 3 phr loading of organophilic montmorillonite clay. The effectiveness of the proposed ultrasonic‐assisted process on the polypropylene/polystyrene/clay nanocomposites was confirmed by rheological property measurements and structural analysis by scanning electron microscope and X‐ray diffraction. The sonication during extrusion was effective in improving the compatibility between polypropylene and polystyrene. Also, it led to enhanced breakup of the clay agglomerates. The observed clay was in the exfoliated state from the X‐ray diffraction analysis.
Electrospinning of Poly(ethylene oxide) with Bacterial Cellulose Whiskers
Authors: Park Won‐Il , Kang Minsung , Kim Hun‐Sik , Jin Hyoung‐Joon
Published: March 2007

In the present study, cellulose whiskers were incorporated into nanofibers of polyethylene oxide (PEO) by the electrospinning process to enhance the mechanical properties of the electrospun PEO fibers. Cellulose whiskers consisting of highly crystalline rod‐like particles with a high aspect ratio and specific area were obtained by the acid hydrolysis of bacterial cellulose microfibrils. From the transmission electron microscopy (TEM) images of the bacterial cellulose whiskers, their length was measured to be 420 ± 190 nm and their width 11 ± 4 nm. The height of the whiskers was measured to be 10 ± 2 nm by atomic force microscopy. The successful formation of electrospun fibers with a diameter of less than 1 µm and well‐embedded microfibrils was confirmed by scanning electron microscopy and TEM.
In‐situ Synthesis and Characterization of Polyamide 6/POSS Nanocomposites
Authors: Ramasundaram Subramaniya Pillai , Kim Kap Jin
Published: March 2007

The nanocomposites of polyamide 6 (PA6) and polyhedral oligomeric silsesquioxane (POSS) containing primary and secondary amino groups were synthesized through in‐situ polymerization. The chemical structure of the PA6/POSS nanocomposites was characterized with FT‐IR and 1H‐NMR spectroscopies. The solution viscosity results showed the increase in intrinsic viscosity with increasing POSS loadings. The random positioning of the POSS molecules in PA6 chain was confirmed by x‐ray diffraction studies. The gradual decrease in the melting point and crystallization temperature with increasing POSS content was observed by the differential scanning calorimetry. The thermogravimetric analysis results showed that the POSS incorporation does not enhance the thermal resistance of PA6/POSS nanocomposites.
The Synthesis of Random Brush for Nanostructure of Block Copolymer
Authors: Kim Bong Hoon , Koo Chong Min , Shin Dong Ok , Jeong Seong Jun , Kim Sang Ouk
Published: March 2007

Polymer brush has been synthesized via conventional free radical polymerization to use a surface active material on the silicon substrate. The synthesized polymer brushes were successfully grafted onto the silicon oxide substrate and the hydrophilic silicon oxide substrate has been changed into the more hydrophobic one. The synthesized poly(styrene‐ran‐methyl methacrylate) brush grafted silicon substrate could provide poly(styrene‐block‐methyl methacrylate) with neutral surface.
Preparation of Cationic Comb‐Type Copolymers Having High Density of PEG Graft Chains for Gene Carriers
Authors: Choi Sung Won , Yamayoshi Asako , Hirai Miwa , Yamano Takeshi , Takagi Motoki , Sato Ayumi , Kano Arihiro , Shimamoto Akira , Maruyama Atsushi
Published: March 2007

A series of poly(L‐lysine)‐graft‐polyethylene glycol (PLL‐g‐PEG) was prepared by a reductive amination reaction of PLL with aldehyde modified PEG using NaBH3CN as a reductant. The high coupling efficacy observed in the 80% acetonitrile aqueous solution led to the grafting polymers with abundant PEG chains (more than 90 wt % and 30 mol %). By the method, we can retain high cationic charge density of the polymer backbone, because the resulting secondary amino groups are still protonated. By controlling the primary structure of the copolymer, we can also regulate the ionic interaction with nucleic acids and other biological components for gene delivery purpose.
DNA Nanomachine Switching Improved by Cationic Comb‐Type Copolymer
Authors: Choi Sung Won , Makita Naoki , Kano Arihiro , Yamayoshi Asako , Akaike Toshihiro , Maruyama Atsushi
Published: March 2007

The unique folding and assembling properties of DNA have been elaborated to construct various nanomachines that can be reversibly switched between two or more distinct conformations. For the better applications and developments of DNA nanomachines, their responding kinetics, outputs, and sequence‐selectivity need to be improved. Furthermore, the DNA nanomachines currently have several limitations in the operation conditions such as temperature, salt condition, and DNA strand concentration. In this study, we evaluated the effect of a cationic copolymer on the responses of a DNA‐fueled nanomachine. We found that the copolymer increases quickness of the nanomachine under moderate conditions including physiologically relevant conditions even at very low strand concentrations (nM range).
A Novel Nano Structured Blend Membrane for Gas Separation
Authors: Ghalei Behnam , Semsarzadeh Mohamad‐Ali
Published: March 2007

This investigation involves the preparation and characterization of poly (urethane)/poly (vinyl acetate) (PU/PVAc) blend membranes. PU was synthesized by two step polymerization from toluene diisocyanate (TDI), poly (propylene glycol) (PPG) and 1, 4‐butanediol (BDO).Fourier transform infrared (FTIR) spectroscopy was used to verify the chemical structure of the resulting polymer. Blend membranes with a thickness of 100 µ were prepared from the solution of PU and PVAc in chloroform by a solution‐evaporation method. The amount of PVAc was varied among 10, 20 and 30 percent by weight of the membrane. Scanning Electron Microscopy (SEM) was used to investigate the morphology of the prepared membranes. The membrane containing 20% by weight of PVAc displayed a more homogenous dispersion of PVAc domains and was selected for gas permeation tests. For this purpose; oxygen (O2), nitrogen (N2), carbon dioxide (CO2) and methane (CH4) gases were used and the gas pressure was varied between 2, 4, 6, 8 and 10 bars. Comparison of the results with that of the pure PU membrane revealed that the blend membrane had a higher permeability to CO2 and a lower permeability to the other gases and therefore had a higher value of CO2/N2 and CO2/CH4 ideal selectivity.
Synthesis and Characterization of Diazonium Containing Block Copolymers via Controlled Ring Opening Metathesis Polymerization (ROMP) and the Subsequent Chemical Modification
Authors: Moon Bongjin , Kang Minhyuck
Published: March 2007

7‐Oxanorbornene‐5,6‐dicarboximide derivatives bearing either an alkyl‐ or a nitrophenyl group were prepared and these monomers were subjected to the controlled ring opening metathesis polymerization (ROMP). The resulting polymer, poly[N‐(n‐butyl)‐7‐oxanorbornene‐5,6‐carboximide‐b‐N‐(2‐(4‐nitrobenzoyl)ethyl)‐7‐ oxanorbornene‐5,6‐dicarboxiimide] P(BuONDI‐b‐NbONDI) (8), showed good molecular weight and narrow polydispersity control (PDI < 1.1). The alkene and the nitrophenyl groups in the block copolymer were selectively reduced using tosyl hydrazide and ammonium sulfide, respectively. The resulting aryl amines in the block polymer were then oxidized to the corresponding diazonium salts by treatment with nitrosyl tetrafluoroborate. The presence of the diazonium groups was verified by IR and cyclic voltammetry (CV), and also by several chemical reactions which are unique for diazonium salts.
Polymer‐Supported Chiral 1,2‐Diamines by Radical Copolymerization with Vinyl Monomer for Asymmetric Hydrogenation of Aromatic Ketones
Authors: Haraguchi Naoki , Chiba Masahiro , Takahashi Miyuki , Itsuno Shinichi
Published: March 2007

Novel polymer‐supported chiral 1,2‐diamines have successfully synthesized by radical copolymerization of N‐Boc protected enantiopure 1,2‐diamine bearing two vinylphenyl moieties ((S,S)‐5) with various achiral vinyl monomer including methyl methacrylate, 2‐hydroxyethyl methacrylate, butyl acrylate, and N‐isopropyl acrylamide, followed by deprotection of N‐Boc moiety. Hydrogenation of acetophenone in 2‐propanol/DMF mixed solvent was performed with use of polymeric catalyst system prepared from the polymer‐supported chiral 1,2‐diamine and RuCl2/(S)‐BINAP. The reaction proceeded smoothly to give 1‐phenylethanol in quantitative yield with high level of enantioselectivity. In addition, various other aromatic ketones could be asymmetrically hydrogenated by the polymeric catalyst system. Furthermore, the polymeric catalyst could be reused several times in hydrogenation of aromatic ketones without loss of the enantioselectivity.
Spontaneous Copolymerization of 1,3‐Dehydroadamantane
Authors: Ishizone Takashi , Matsuoka Shin‐ichi , Ogiwara Naoto , Uehara Yosuke , Kobayashi Shingo
Published: March 2007

Copolymerizations of 1,3‐dehydroadamantane, 1, and various vinyl monomers were carried out in THF at room temperature. On mixing of 1 with electron‐deficient vinyl monomers such as acrylonitrile and methyl acrylate in the absence of initiator, the copolymerization spontaneously proceeded to give alternating copolymers in 28–88% yields. By contrast, no reaction of 1 occurred at all, when isobutyl vinyl ether or styrene was mixed under the similar conditions. These results indicate the high electron density of a central σ‐bond in a strained [3.3.1]propellane derivative, 1. Alternating sequences of the resulting copolymers were characterized by NMR and MALDI‐TOF‐MS measurements. DSC and TGA measurements revealed the high thermal stability of the alternating copolymers containing bulky, stiff, and strain‐free adamantane skeletons.
Controlled Synthesis of Reactive Polymeric Architectures Using 5‐Norbornene‐2‐carboxylic Acid Pentafluorophenyl Ester
Authors: Vogel Nicolas , Théato Patrick
Published: March 2007

Exo‐5‐norbornene‐2‐carboxylic acid pentafluorophenyl ester was synthesized from 5‐norbornene‐2‐carboxylic acid and polymerized by ring‐opening metathesis polymerization. The obtained polymers were soluble polymeric active esters that could be used for the preparation of multifunctional polymers. The molecular weight of the polymers was controlled by variation of the monomer to initiator ratio. The precursor polymers reacted quantitatively with primary and secondary amines. Time resolved FT‐IR studies at different temperatures of the polymer analogous reactions were performed and rate constants were determined.
Controlled Polymerization of Glycidyl Methyl Ether Initiated by Onium Salt/Triisobutylaluminum and Investigation of the Polymer LCST
Authors: Labbé Amélie , Carlotti Stéphane , Deffieux Alain , Hirao Akira
Published: March 2007

New initiating systems developed for monomer activated anionic polymerization of propylene oxide, i.e. onium salt/triisobutylaluminum, were applied to the polymerization of glycidyl methyl ether. At low to medium temperature they yield fast polymerization and allow the synthesis of poly(glycidyl methyl ether) with high molar masses in a controlled way. Poly(glycidyl methyl ether) exhibits a critical solubility temperature (LCST) in water which is influenced by the polymer molar masses. Surprizingly Poly(glycidyl methyl ether)s show also some tendency to crystallize in water at low temperature, which perturb their solubility characteristics and behaviour in water.
Synthesis of Star Polymers Based on Xanthate‐Mediated Controlled Radical Polymerization of N‐Vinylcarbazole
Authors: Mori Hideharu , Ookuma Hiroshi , Endo Takeshi
Published: March 2007

Poly(N‐vinylcarbazole) [poly(NVC)] stars were synthesized by macromolecular design via interchange of xanthate (MADIX)/reversible addition‐fragmentation chain transfer (RAFT) polymerization. Four‐armed poly(NVC) stars with controlled molecular weights and low polydispersities were obtained using a tetrafunctional xanthate, in which the stabilizing groups are linked to the core. The controlled character of the polymerization was also confirmed by the linear increase in the molecular weight with the conversion. The comparison of the polymerization behaviors using the tetrafunctional xanthate and a monofunctional one suggested that the multifunctional core has a clear effect on the polymerization kinetics, but has no significant influence on the controlled character of the polymerization.
Anionic Polymerization of N‐Methacryloyl‐2‐methylaziridine and N‐Methacryloylazetidine
Authors: Suzuki Takashi , Kusakabe Jun‐ichi , Ishizone Takashi
Published: March 2007

Anionic polymerizations of N‐methacryloyl‐2‐methylaziridine (1) and N‐methacryloylazetidine (2) were carried out in THF with 1,1‐diphenyl‐3‐methylpentyllithium (DMPLi) and with diphenylmethylpotassium (Ph2CHK) in the presence of LiCl or Et2Zn. Poly(1) and poly(2) possessing predicted Mns based on the molar ratios between monomer to initiators and narrow molecular weight distributions (MWD, Mw/Mn < 1.1) were quantitatively obtained at −40 °C within 24 h. The stability of the propagating chain end of poly(1) was confirmed by the quantitative initiation efficiency in the postpolymerization. The radical polymerizations of 1 and 2 with AIBN gave the polymers in 77 and 40% yields, respectively. These are first examples demonstrating the positive polymerizability of N,N‐dialkylmethacrylamide derivatives, while N,N‐dimethylmethacrylamide showed the negative polymerizability under the radical and anionic polymerization conditions.
The Control of Surface Structure of Fluorocarbon End‐Capped Poly(L‐lactide)/Stereochemical Polylactide Blend Films
Authors: Yoon Seog‐Young , Lee Jin‐Kook , Chung Ildoo , Park Seong Soo
Published: March 2007

The propose of this study is to investigate stereocomplexation‐induced surface structure of enantiomeric PLA blends on the basis of complex formation between L‐ (LLA) and D‐lacide (DLA) unit sequences. In order to control the complexation, stereochmical PLAs with % D repeat unit contents of 100, 98, 95, 90, and 80 were synthesized from the mixtures of DLA and LLA using stannous octoate as catalyst. Fluorocarbon end‐capped PLLA (F‐PLLA) instead of PLLA was used as a surface probe material because of the surface segregation of fluorocarbon groups. Large changes in the melting temperature (Tm) behavior and the surface structure for (F‐PLLA/stereochmical PLA) blend films were observed by differential scanning calorimetry and electron spectroscopy for chemical analysis, respectively. (F‐PLLA/stereochmical PLA) blend films showed the increase in both Tm and heat of fusion from the stereocomplexes with the optical purity of stereochmical PLAs in the blend. Also, the surface composition of fluorocarbon groups in the blends was proportionally increased with decreasing the optical purity in the blend because the stereocomplex formation in (F‐PLLA/stereochmical PLA) blends prevents the surface segregation of fluorocarbon groups. These results indicate that surface structure of (F‐PLLA/stereochmical PLA) blends could be controlled by changing a degree of complexation.
Nonradiative Energy Transfer in Chromophore‐Tagged PS–PEO Diblock Copolymers
Authors: Cho Eun‐Bum , Kim Dukjoon
Published: March 2007

Nonradiative energy transfer fluorescence was used to investigate the micelle behavior of polystyrene‐b‐poly(ethylene oxide) diblock copoly‐ mers tagged with either donor naphthalene or acceptor pyrene in solutions and solid films. The effects of the variation in the solvency and micelle collision frequency caused by changing the total block copolymer concentration and the difference in the micelle concentration between polystyrene–poly(ethylene oxide) block copolymers labeled with two different chromophores on the chain release and exchange of micelles were observed. It was noted that the chain exchange of the polymer micelles is clearly observed when the concentration difference and the total micelle concentration are sufficiently large. In the case of the solid film, the NRET efficiency is increased as the molecular weight of the matrix polystyrene homopolymer added is increased.
Shape‐Stabilized Phase Change Materials: Frozen Gel fom Polypropylene and n‐Octadecane for Latent Heat Storage
Authors: Son Tae‐Won , Kim Tae‐Hun , Kim Bong‐Sick , Kim Byung‐Giu
Published: March 2007

We prepared polymer‐PCM gels such as prepared frozen gel from polypropylene and n‐octadecane for thermal storage and release materials, their basic properties and possible applications especially in latent heat storage. The preparation methods are used to melting method and absorption method respectively. The composition and properties of prepared frozen gels from polypropylene and n‐octadecane were observed by DSC, WAXD, FT‐IR spectra, ARES and Elemental analysis. We can prepare frozen gels in different temperature for latent heat storage materials as controlling composition of phase change material as well as using different incorporating phase change materials. These frozen gels can be used to latent heat storage materials for several applications.
The Effects of MWD on the Rheological Properties of Shear‐Induced Structural Formation for PVA Solutions in DMSO
Authors: Lee Eun Jeoung , Kim Byoung Chul
Published: March 2007

The effects of molecular weight distribution (MWD) on the rheological responses of shear‐induced structural formation in the general‐purpose polyvinyl alcohol (PVA) solutions dissolved in dimethyl sulfoxide (DMSO) were investigated. On the whole, time‐dependence of rheological properties was more influenced by the PVA solutions with broad MWD at the similar weight average molecular weight (Mw). The dynamic viscosity (η′) of PVA/DMSO solution with broad MWD was lower than that with narrow MWD at the similar Mw until the second time sweep (T2) of PVA/DMSO solution. After the time‐sweep experiment was repeated, the η′ of PVA/DMSO solution with narrow MWD was lower than that of PVA/DMSO solution with broad MWD at the similar Mw. The G′ until 5 min of relaxation of PVA/DMSO solution with broad MWD was lower than that of PVA/ DMSO solution with narrow MWD at the similar Mw. After the time‐sweep experiment was repeated, the G′ of PVA/DMSO solution with narrow MWD was lower than that of PVA/DMSO solution with broad MWD at the similar Mw. It could be interpreted as a consequence of the formation of three‐dimensional gel structure through the polar interactions by hydroxyl groups whose strength was dependent on shearing conditions and MWD.
Morphology and Physical Properties of Binary Blend Based on PVDF and Multi‐Walled Carbon Nanotube
Authors: Nam Young Wan , Kim Woo Nyon , Cho Yong Han , Chae Dong Wook , Kim Gwang Ho , Hong Seung Pyo , Hwang Seung Sang , Hong Soon Man
Published: March 2007

Semicrystalline Poly(vinylidene fluoride)(PVDF) was melt blended by multi‐ walled carbon nanotube (MWNT) at various contents (0.01 ∼ 5 wt%) using internal mixer. The relationships between morphology and physical properties based on PVDF and MWNT were investigated. As the MWNT content is increased, the apparent supercooling required for PVDF crystallization and the size of spherulites in PVDF decrease. In the WAXD profiles, the incorporation of MWNT produced a large shoulder at 2θ = 20.7° with increasing the MWNT content, corresponding to the polar β‐form crystal of PVDF. The experimental percolation threshold for the electrical conductivity in PVDF was estimated and clearly occured between 2 and 2.5 wt%. Similar tendency was also observed in thermal conductivity and permittivity.
Reactive Extrusion of Polypropylene and Nylon Blends from Commingled Plastic Wastes
Authors: Kim Gwang Ho , Hwang Seung Sang , Cho Bong Gyoo , Hong Soon Man
Published: March 2007

Reactive extrusion for recycled PP/nylon blends from commingled plastic wastes was investigated through thermal, morphological, mechanical and rheological studies. From SEM investigation, we found improved surface morphologies with homogeneous domains in the recycled 75/25 PP/nylon blends compatibilized with copolymers containing maleic anhydride (MA) as a reactive functional group; SEBS‐g‐MA, PP‐g‐MA, PE‐g‐MA. Especially, SEBS‐g‐MA thermoplastic elastomer which is highly reactive with amine terminal group of nylon, resulted in a large increase of impact strength above nearly 200%. This compatibilization effect resulted from the increase of interfacial adhesion and the reduction of domain size of dispersed phase in PP/nylon blend system. To confirm the existence of this network structure, we measured a dynamic rheological properties.
High Molecular Weight Poly(L‐lactide) and its Microsphere Synthesized in the Supercritical Dimethyl Ether
Authors: Yoon Cheol Soo , Park Hyun Deok , Kim Se Yoon , Kim Soo Hyun
Published: March 2007

The ring‐opening polymerization of L‐lactide initiated by stannous octoate was carried out in supercritical dimethylether(scDME) at various reaction conditions (time and temperature). The monomer conversion increased to ca. 90% on increasing the reaction time to 1hr. The molecular weight of the poly(L‐lactide)(PLLA) also increased to ca. 160,000 g · mol−1 over the same period. Increasing reaction temperature from 118 to 135 °C or reaction pressure from 280 to 520 bar resulted in increased monomer conversion and molecular weight. After the polymerization, PLLA microspheres were prepared in situ by using a continuous supercritical anti‐solvent process without residual organic solvent.
Rheological Properties of Starch‐Based Materials and Starch/Poly(lactic acid) Blends
Authors: Xie Fengwei , Xue Tao , Yu Long , Chen Ling , Li Xiaoxi , Zhang Ximei
Published: March 2007

The rheological properties of pure starch and blends of gelatinized starch/poly(lactic acid) (PLA) were studied using a rheometer incorporating a twin‐roll mixer and a single‐screw extruder. The mixer provides a useful and convenient tool to study the rheological properties and gelatinization processes of starch. The single‐screw extruder with a slit capillary die was used to measure shear stress and viscosity under different shear rates at different temperatures. Starch was shown to increase the shear viscosity of PLA. Methylenediphenyl diisocyanate (MDI) was used as a compatibilizer, and was distributed in different phases through controlled processing. The addition of MDI showed a stronger effect on rheological properties when it was distributed in the PLA phase prior to blending. Both the pure starch and blends showed a power law dependence of viscosity on shear rate.
Purification and Characterization of Poly(ethylene succinate) Hydrolase from the Mesophilic Fungus Aspergillus clavatus NKCM1003
Authors: Ishii Nariaki , Mitomo Hiroshi , Kasuya Ken‐ichi , Inoue Yoshio
Published: March 2007

A poly(ethylene succinate) (PESu) hydrolase was purified from the culture supernatant of the PESu‐degrading fungus Aspergillus clavatus NKCM 1003, which was cultivated on a mineral medium containing PESu as the sole carbon source. The enzyme had a molecular mass of 57,000 Da and an isoelectric point of 5.6, and it was stable in the rage pH5‐8; the optimum pH was 7.0. Its PESu hydrolytic activity remained constant below 40 °C after incubation for 30 min. Liquid chromatography electrospray mass spectrometry analysis of enzymatic hydrolysates revealed that the major products are ES, ESE, SES, and ESES(S; succinate unit, E; ethylene glycol unit). This enzyme degraded not only PESu but also poly(3‐hydroxybutyrate) (P(3HB)) and its copolymers. Further, it showed high binding affinity to P(3HB). It was concluded that PESu hydrolase belongs to the class of P(3HB) depolymerases.
Synthesis of Hybrid Polyacetylene Gels Using Octafunctional POSS Initiator
Authors: Kim Kyung‐Min , Lim Jung‐Hyurk , Jang Nae‐Youn , Kim Sung‐Ryong
Published: March 2007

Hybrid polyacetylene gels having polyhedral oligomeric silsesquioxanes (POSS) moieties were prepared by polymerization of 2‐ethynylpyridine using octafunctional POSS as an initiator with changing the feed ratio of POSS to 2‐ethynylpyridine. The resulting black polyacetylene gels were not soluble in any organic solvents such as THF, chloroform, methanol, DMF, and acetone. The polyacetylene gels with higher mole ratio of 2‐ethynylpyridine to POSS show higher thermal stability because of the tight polymer network caused by high degree of polymerization. It is proposed that the tether structure between polyacetylene matrix and POSS cages was crucial to the great improvement in thermal stabilities of hybrid polyacetylene gels with POSS.
Thermal and Mechanical Properties of Carbon Fiber Reinforced Epoxy Composites Modified with CTBN and Hydroxyl Terminated Polyester
Authors: Park Jong‐Sung , Park Sung‐Sil , Lee Soo
Published: March 2007

Carbon fiber reinforced epoxy composites toughened with carboxyl terminated acrylonitrile butadiene rubber (CTBN) and hydroxyl terminated polyester (HTP) were prepared by autoclave vacuum bag molding process. The influence of compositions and blending method with toughening agents on glass transition temperature (Tg) and impact energy of cured laminates was evaluated. To improve the blending capability, different pre‐treatment methods were adopted for CTBN and HTP. The toughness of the carbon fiber reinforced epoxy composite materials (C‐FRP) modified with HTP showed a maximum when the HTP contents was 3.1 wt%. In case of CTBN, the maximum was 5.7 wt%. In addition, the fracture surfaces of toughened epoxy resin were examined by scanning electron microscopy (SEM) and the morphology was also discussed in this study.
Preparation of Polypropylene Compatibilizer by Radiation Grafting and Its Effect on PP/Nylon 6 Blend
Authors: Jung Chan‐Hee , Choi Jae‐Hak , Lim Youn‐Mook , Jeun Joon‐Pyo , An Sung‐Jun , Kang Phil‐Hyun , Nho Young‐Chang
Published: March 2007

The polypropylene‐based compatibilizers, polypropylene‐g‐maleic anhydride (PP‐MAH), polypropylene‐g‐maleic anhydride/styrene (PP‐St/MAH), and polypropylene‐g‐acrylic acid (PP‐AA), were prepared by a high energy irradiation method. The compatibilizing effect of newly prepared graft copolymers on immiscible PP/Nylon6 blends has been studied by means of UTM, SEM and DSC techniques. The results indicate that PP‐MAH and PP‐ St/MAH are more effective compatibilizers for PP/Nylon6 blends than PP‐AA, and the compatibilizing effect on PP/Nylon6 blends depends on molecular structure of the compatibilizers and the composition of the blends.
Effects of High‐Intensity Ultrasound and Supercritical Nitrogen on PP‐MA Reactive Extrusion
Authors: Sohn Chang Hee , Shim Dong Chul , Lee Jae Wook
Published: March 2007

The reaction of polypropylene (PP) and maleic anhydride (MA) was successfully generated by imposition of ultrasonic energy during the mixing process of extrusion. The possibility of the various transformations by PP‐MA reaction became stronger under the sonicated supercritical fluid mixing. The properties of the compatibilizer and the nanocomposites as the final products in the presence of ultrasound and supercritical fluid nitrogen were properly obtained without the addition of any solvents or additives.
Improvement of Adhesion between Copper Layer and Polyimide Films Modified with Alkaline Potassium Permanganate and/or Alkali Surface Treatments
Authors: Lee Soo , Park Seong Sil , Lee Hong Kee
Published: March 2007

The adhesion strength of polyimide films were enhanced by treatment with alkali and/or alkaline potassium permanganate. No effect observered on the thermal decomposition as measured by TGA. The chemically modified PI film surface was then treated with a catalyst, coated with nickel by electroless plating, and a subsequent layer of electrolytically applied copper. Water contact angles on the treated PI surface were decreased. As surface roughness of treated PI films was increased, adhesion increased also. Even though the modified PI films had little decrease in their thermal properties, they demonstrated a maximum adhesion strength up to 837 gf/cm.
Rheological Investigation of the Effects of Introducing Diethylene Glycol on the Physical Properties of PVA Solutions and PVA Films
Authors: Chang Myung‐Hwan , Kim Byoung Chul
Published: March 2007

The effects of diethyl glycol (DEG) on the rheolgical properties of polyvinyl alcohol(PVA) solutions in dimethyl sulfoxide and on the physical properties of PVA films were investigated. DEG seemed to change the state of hydrogen bonding in the solutions and in the films. In the case of 6 wt% PVA solutions, incorporating DEG abruptly reduced shear viscosity if DEG content exceeded 30 wt% to PVA whereas a little decrease of them was observed in 12 wt% PVA solutions over the DEG content observed. Further, at the same DEG content 6 wt% PVA solutions showed a more notable increase of viscosity with time at a constant shear rate than 12 wt% solutions. Dynamic mechanical thermal analysis revealed that introducing DEG broadened the peak of tan δ curve and lowered the glass transition temperature of PVA. DEG imparted toughening effects to PVA film preferably in the range of 10 to 20 wt% to PVA.
Study on Nanocomposite Thermoplastic Elastomer Gels
Authors: Paglicawan Marissa A. , Balasubramanian Maridass , Kim Jin Kuk
Published: March 2007

The effect of several network‐forming nanoscale materials such as two different types of graphite and multiwalled carbon nanotube on the property development of thermoplastic elastomer (TPE) gels prepared from microphase‐ ordered poly(styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene) (SEBS) triblock copolymer dissolved in paraffin oil was studied. Dynamic rheological measurements of the resultant nanocomposite TPE (NCTPE) gels showed that at temperature between 30 °C to 40 °C below the gel point, the NCTPE gels have dynamic storage modulus greater than loss modulus (G′ and G″), thereby indicating that at ambient temperature a physical network is still present despite the addition of nanoparticles. In general, the nanoparticles lower the gelation temperature. The X‐ray diffraction of NCTPE gels showed that EG2 system exhibited intercalation, those with CNTs exhibited exfoliation and EG1 did not change at all.
Fabrication of Ordered Porous SWNT‐Polymer Nanocomposites by Emulsion Templating
Authors: Lee Sun Hwa , Ham Hyeong Taek , Park Ji Sun , Chung In Jae , Kim Sang Ouk
Published: March 2007

Porous polymer films were produced from water‐in‐oil emulsion. Aqueous droplets were dispersed in PMMA/benzene solution without any emulsifier. Simple dip‐coating of the emulsion on a substrate and air‐drying led to hexagonally ordered porous thin films. Porous single walled carbon nanotubes (SWNT)‐polymer composite films were prepared through the similar procedures also. The electrical conductivity of porous SWNT‐polymer composites increased with the content of SWNT.
Miscibility of TPU(PCL diol)/PCL Blend and Its Effect on PCL Crystallinity
Authors: Ajili Shadi Hassan , Ebrahimi Nadereh Golshan
Published: March 2007

Poly(ε‐caprolactone) (PCL) was melt blended with thermoplastic polyurethane based on polycaprolactone diol (TPU(PCL diol)). The amount of PCL was varied from 20% to 50% by weight. A single composition dependent glass transition temperature (from DSC) shows the miscibility of system. Also the negative value of polymer‐polymer interaction density, obtained from the analysis of the equilibrium melting point depression, confirms the blends' miscibility. Tc and Tm of the PCL component in the blend decrease significantly with an increase in the TPU content, in comparison with that of pure PCL. The position of the diffraction peak related to (110) planes of PCL in the blends using WAXS has been shifted to lower value. This means the b‐axis of orthorhombic unit cell of PCL is spread out in the blends. On the whole, increase of TPU content in the blend decreases crystallization ability of PCL compared to pure PCL.
Effects of Process Conditions on Surface Replication and Higher‐Order Structure Formation in Micromolding
Authors: Ito Hiroshi , Kazama Kunihiko , Kikutani Takeshi
Published: March 2007

Injection molding of thin‐wall parts with microscale surface grooves of polypropylene (PP) and cyclo‐olefin copolymer (COC) were performed for this study. Effects of cavity thickness and process conditions on processability, surface replication, and higher‐order structure of the molded products were evaluated. Surface replication and optical anisotropy of molded products were analyzed using a polariscope, a polarizing optical microscope, SEM, and a confocal laser scanning microscope. Optical anisotropy in the vicinity of the gate was higher than that at any other position; also, optical anisotropy increased with decreased cavity thickness. The replication property at the center area was more pronounced than those of the flow end and the gate vicinity. The distribution of the replication ratio inside the product decreased with increasing mold temperature. Results showed that the replication properties were correlated closely with skin‐shear layer thickness inside the products, and that the replication ratio was lower for greater thickness of the skin‐shear layer.
The Relationship between Rheological Properties and Spraying Behavior of Polymer Dispersions
Authors: Dijkstra Dirk J. , Kiyomoto Yasuhiro , Abe Katsuya , Tani Takaaki , Umemoto Satoshi
Published: March 2007

The influence of the rheological properties on the spraying behavior of an adhesive polyurethane dispersion modified with different thickeners was investigated. The differences in shear rheology for the three different kinds of thickeners were found not to be representative for the spraying behavior. The extended fan sheets and reduced overspray for the water‐soluble thickener correspond to a more pronounced elastic rheological behavior of the dispersion.
Polyurethane Modified Epoxy Adhesives for the Application to FCCL
Authors: Baek Jung‐ok , Park Sun‐joo , Gong Hui‐jin , Kim Wonho
Published: March 2007

The peel strength of blends of epoxy resin/curing agent (diamino diphenyl sulfone, DDS)/ polyurethane was measured using INSTRON 4485 under normal, chemical and thermal treated states. Glass transition temperature was measured by using differential scanning calorimetry (DSC, Pyris1) according to the contents of polyurethane. Adhesive strength was, approximately, 1.3N/mm and there was no significant effect on the peel strength by the chemical and heat cycle treatments. Glass transition temperature of the adhesive increased from 0 °C to 74.76 °C by increasing the contents of polyurethane. The dimensional stability of epoxy adhesives which contain 30wt% of polyurethane was improved about 98% compared to that of neat epoxy adhesives.
Co‐carcinogenic effect of cyclohexanol on the development of preneoplastic lesions in a rat hepatocarcinogenesis model
Authors: Márquez‐Rosado Lucrecia , Trejo‐Solís Cristina , del Pilar Cabrales‐Romero María , Arce‐Popoca Evelia , Sierra‐Santoyo Adolfo , Alemán‐Lazarini Leticia , Fatel‐Fazenda Samia , Carrasco‐Legleu Claudia E. , Villa‐Treviño Saúl
Published: March 2007

Cyclohexanol is a basic industrial chemical widely used because of its versatility as an industrial solvent. No studies have been conducted to evaluate the carcinogenic/co‐carcinogenic hazards associated with cyclohexanol exposure. In male Fisher 344 rats liver preneoplastic lesions were induced by N‐nitrosodiethylamine (150 mg/Kg) i.p., followed by the tumor promoter 2‐acetylaminofluorene (2‐AAF: 20 mg/kg) orally administered on three consecutive days before partial hepatectomy. The cyclohexanol administration in this hepatocarcinogenesis assay revealed that it has a strong tumor co‐promoter potential. There is clear evidence that oxidative stress and the CYP2E1 are components of carcinogenesis. Although no changes in the lipid peroxidation levels were observed between treated and untreated animals, a significant increase in CYP2E1 expression was observed when cyclohexanol was administered 24 h after the last 2‐AAF dose. On the other hand, levels of the proliferation markers PCNA and Ki‐67 were not increased after treatment with cyclohexanol, but a marked downregulation of the Bax proapoptotic protein was found exclusively in mitochondrial extracts of animals treated with cyclohexanol. This study represents the first report of the ability of cyclohexanol‐induced lesions, when administered simultaneously with 2‐AAF, to potentiate the development of preneoplastic liver. © 2007 Wiley‐Liss, Inc.
Gene transfer therapy for neurodegenerative disorders
Authors: Feigin Andrew , Eidelberg David
Published: March 2007

Recent advances in gene transfer technology have led to promising new therapies for neurodegenerative disorders. This article will review methods of gene transfer therapy and applications of these techniques to both genetic and sporadic neurodegenerative illnesses. The article will focus on Parkinson's disease, Huntington's disease, and Alzheimer's disease. Several promising gene therapy approaches to these diseases are being pursued both in animal models and in early human trials. Initial safety–tolerability results from these trials appear promising. It is therefore likely that the number of human trials of gene therapy for neurodegenerative disorders will increase over the coming years. © 2007 Movement Disorder Society
Analysis of Generalised Galerkin methods in the numerical solution of elliptic equations
Authors: Anderssen R. S. , Mitchell A. R.
Published: March 2007

The Petrov‐Galerkin projection method is outlined for the solution of the linear elliptic equation Lu = f with homogeneous boundary conditions. By choosing appropriate finite dimensional trial and test spaces, the methods of weighted residuals, collocation, and H1 Galerkin can be interpreted within the Petrov‐Galerkin projection method framework.

The important question of how best to choose the trial and test functions to suit a particular type of problem is then discussed. Objective criteria associated with the matrix which governs the Petrov‐Galerkin numerical process are proposed.
The construction of solutions to the heat equation backward in time
Authors: Colton D. , Wimp J. , Meister E.
Published: March 2007

Solutions to the backwards heat equation are approximated by solutions of a pseudo‐heat equation. Solutions to this modified equation are constructed by means of a fundamental solution and potential theory, and it is shown that the fundamental solution can be approximated by various expansions in special functions.
On the treatment of free boundary problems with the heat equation via optimal control
Authors: Baumeister J.
Published: March 2007

In this paper we consider a free boundary problem of general type for the heat equation in one space dimension. We formulate this problem as an optimal control problem and derive necessary conditions for a solution of it. In order to compute a solution of the control problem, we apply the projection‐gradient‐method. Simple numerical examples illustrate the results.
Periodic solutions of ẋ(t) = –f(x(t), x(t – 1))
Authors: Hadeler K. P.
Published: March 2007

The existence of periodic solutions of general first order nonlinear difference‐differential equations is shown using an appropriate cone of initial data and an asymptotic fixed point theorem.
Proteins interacting with the ascidian vitelline‐coat sperm receptor HrVC70 as revealed by yeast two‐hybrid screening
Authors: Harada Yoshito , Sawada Hitoshi
Published: March 2007

Ascidians are hermaphrodites releasing sperm and eggs nearly simultaneously, but many species are self sterile. We have previously reported that HrVC70 consisting of 12 EGF‐like repeats is a major component of the vitelline coat, functioning as a self/nonself‐recognizable sperm receptor during fertilization of the ascidian Halocynthia roretzi. Here, in order to identify the binding partner of HrVC70, we explored HrVC70‐interacting proteins by yeast two‐hybrid screening. HrVC70 is capable of interacting with HrVC70 precursor HrVC120 itself and also with three additional extracellular and/or transmembrane proteins, HrVLP‐1, ‐2, and HrTTSP‐1. Specific interaction of HrVC120, HrVLP‐1, ‐2, and HrTTSP‐1 with HrVC70 was confirmed by exchanging prey and bait, and also by a pulldown assay using the GST‐fusion proteins. HrVLP‐1 and ‐2 are proteins structurally related to HrVC120; both are expressed in the oocytes and may be novel components of the ascidian vitelline coat. HrTTSP‐1 appears to be a member of the serine protease family with type II transmembrane topology. HrTTSP‐1 is expressed in the testis and its gene product contains multiple conserved motifs known to be involved in protein–protein or protein–carbohydrate interactions. Close inspection revealed that the protease domain of HrTTSP‐1 is considerably divergent, in particular around the region of the catalytic center Ser residue. Possible roles of these proteins in ascidian fertilization are also discussed. Mol. Reprod. Dev. 74: 1178–1187, 2007. © 2007 Wiley‐Liss, Inc.
Active caspase‐3 and ultrastructural evidence of apoptosis in spontaneous and induced cell death in bovine in vitro produced pre‐implantation embryos
Authors: Gjørret Jakob O. , Fabian Dušan , Avery Birthe , Maddox‐Hyttel Poul
Published: March 2007

In this study we investigated chronological onset and involvement of active caspase‐3, apoptotic nuclear morphology, and TUNEL‐labeling, as well as ultrastructural evidence of apoptosis, in both spontaneous and induced cell death during pre‐implantation development of bovine in vitro produced embryos. Pre‐implantation embryos (2‐cell to Day 8 blastocysts) were cultured with either no supplementation (untreated) or with 10 µM staurosporine for 24 hr (treated). Embryos were subjected to immunohistochemical staining of active caspase‐3, TUNEL‐reaction for detection of DNA degradation and DAPI staining for detection of apoptotic nuclear morphology, and subjected to fluorescence microscopy. Additionally, treated and untreated blastocysts were fixed and processed for ultrastructural identification of apoptosis. Untreated embryos revealed no apoptotic features at 2‐ and 4‐cell stages. However, active caspase‐3 and apoptotic nuclear morphology were observed in an untreated 8‐cell stage, and TUNEL‐labeling was observed from the 16‐cell stage. Blastomeres concurrently displaying all apoptotic features were present in a few embryos at 16‐cell and morula stages and in all blastocysts. All three features were observed from the 8‐cell stage in treated embryos, and blastomeres with apoptotic features appeared more numerous in treated than in untreated embryos. Ultrastructural evidence of apoptosis occurred with a comparable distribution pattern as apoptotic features detected by fluorescence microscopy in both treated and untreated blastocysts. Activation of caspase‐3 is likely involved in both spontaneous and induced apoptosis in bovine pre‐implantation embryos, and immunohistochemical staining of active caspase‐3 may be used in combination with other markers to identify apoptosis in pre‐implantation embryos. Mol. Reprod. Dev. 74: 961–971, 2007. © 2007 Wiley‐Liss, Inc.