bluuebunny/crossref_metadata_2025 huggingface dataset:
Advances in Biomimetic and Nanostructured Biohybrid Materials
Authors: Ruiz‐Hitzky Eduardo , Darder Margarita , Aranda Pilar , Ariga Katsuhiko
Published: July 2009

The rapid increase of interest in the field of biohybrid and biomimetic materials that exhibit improved structural and functional properties is attracting more and more researchers from life science, materials science, and nanoscience. Concomitant results offer valuable opportunities for applications that involve disciplines dealing with engineering, biotechnology, medicine and pharmacy, agriculture, nanotechnology, and others. In the current contribution we collect recent illustrative examples of assemblies between materials of biological origin and inorganic solids of different characteristics (texture, structure, and particle size). We introduce here a general overview on strategies for the preparation and conformation of biohybrids, the synergistic effects that determine the final properties of these materials, and their diverse applications, which cover areas as different as tissue engineering, drug delivery systems, biosensing devices, biocatalysis, green nanocomposites, etc.
Zinc‐Salen‐Catalyzed Asymmetric Alkynylation of Alkyl Acylsilanes
Authors: Li Feng‐Quan , Zhong Shi , Lu Gui , Chan Albert S. C.
Published: July 2009

Optically active tertiary propargylic alcohols are useful and versatile building blocks in organic synthesis, and their direct access by enantioselective addition of alkyne nucleophiles to ketones has achieved significant progress over the last ten years. In view of the potential applications of acylsilanes as useful synthetic equivalents of aldehydes, we described a general catalytic enantioselective addition of terminal alkynes to alkyl acylsilanes. After reaction optimization involving variation of solvent, temperature, catalyst ratio and various catalysts screen, the in situ generated Zn‐salen complex was chosen as catalyst. With hexane as solvent, the silylated tertiary propargylic alcohols were obtained in satisfactory yields and ees for both aliphatic and aromatic alkynes.
Regio‐ and Stereoselective Allylic Hydroxylation of D‐Limonene to (+)‐trans‐Carveol with Cellulosimicrobium cellulans EB‐8‐4
Authors: Wang Zunsheng , Lie Felicia , Lim Estella , Li Keyang , Li Zhi
Published: July 2009

Cellulosimicrobium cellulans EB‐8‐4 was discovered by screening of microorganisms as a powerful catalyst for the regio‐ and stereoselective allylic hydroxylation of D‐limonene to (+)‐trans‐carveol that is a useful and valuable fragrance and flavour compound. Cells of strain EB‐8‐4 were easily obtained, demonstrated more than 99% regio‐ and stereoselectivity, showed a specific hydroxylation activity of 4.0 U/g cdw (cell dry weight), and accepted 62 mM D‐limonene without inhibition. The hydroxylation was possibly catalyzed by an nicotinamide adenine dinucleotide (NADH)‐dependent oxygenase involved in the degradation of aromatic ring during cell growth. 13.4 mM of (+)‐trans‐carveol were obtained by biohydroxylation of D‐limonene with resting cells of C. cellulans EB‐8‐4, thus being 11 times higher than that obtained with the best biocatalyst known thus far. High conversion and high yield were obtained in the biohydroxylation of 11.6 mM of D‐limonene with the resting cells as catalyst in a closed shaking flask, giving 10 mM of (+)‐trans‐carveol, and 0.30 mM of carvone as the only by‐product. Thus, a unique biocatalyst for the regio‐ and stereoselective allylic hydroxylation of D‐limonene and an efficient synthesis of natural identical (+)‐trans‐carveol by biohydroxylation have been developed.
Conventional Tetrakis(triphenylphosphine)palladium‐Copper(I) Iodide‐Catalyzed Sonogashira Coupling of Free and BOC‐ Protected Propargylic Amines “On Water”
Authors: Soberats Bartomeu , Martínez Luis , Vega Manuel , Rotger Carmen , Costa Antoni
Published: July 2009

Alkynylation of aryl iodides with propargylic amines has been achieved by means of a Sonogashira coupling using “on water” methods. The use of less than 0.2 mol% of tetrakis(triphenylphosphine)palladium [Pd(PPh3)4] and 1.5 mol% copper(I) iodide [CuI] in the presence of diisopropylethylamine (DIPEA) allows the coupling to proceed at 95 °C yielding moderate to good yields of mono‐, bis‐, and tris‐aminoalkynylbenzene derivatives.
Aminations of Aryl Bromides in Water at Room Temperature
Authors: Lipshutz Bruce H. , Chung David W. , Rich Brian
Published: July 2009

Unsymmetrical di‐ and triarylamines can be formed under green chemistry conditions, taking advantage of micellar catalysis leading to palladium‐catalyzed aminations at ambient temperatures in water as the only medium.
Viscocapillary model of slide coating: Effect of operating parameters and range of validity
Authors: Tjiptowidjojo K. , Carvalho M. S.
Published: July 2009

Slide coating is one of the premetered high‐precision coating methods. The layer thickness is set by the flow rate and web speed. The uniformity of the layer, however, can be affected by other operating conditions. Modeling the flow in the coating bead is necessary in developing the range of operability conditions where the layer is adequately uniform. Lubrication and viscocapillary models have been used to describe the flow and some of the operability limits of different coating processes. However, the available models of slide coating were developed with adhoc hypotheses that compromise their accuracy. We present a critical review of the available viscocapillary models and proposed changes to improve its range of applicability. The accuracy of the model is tested by comparing its predictions to the solution of the full two‐dimensional Navier‐Stokes equation. The model is valid at low capillary and Reynolds number regime and at low gap‐to‐wet thickness ratio. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Multiperiod design and planning of multiproduct batch plants with mixed‐product campaigns
Authors: Corsano Gabriela , Aguirre Pío A. , Montagna Jorge M.
Published: July 2009

This work presents a multiperiod optimization model for multiproduct batch plants operating during several time periods with different characteristics because of seasonal and market fluctuations. This model simultaneously considers decisions about the design, operation, scheduling, and planning of the plant and the corresponding trade‐offs among them. Thus, decomposition mechanisms, which have been frequently used in previous approaches, are avoided through a formulation that takes into account the main elements of these problems. Besides, decisions are affected by different context conditions arisen by the multiperiod effect. Through a mixed integer nonlinear program, different alternatives of mixed production campaign are considered, handled by means of a novel set of scheduling constraints. This approach is posed for a fermentors network with high detail level in the description of the unit operations in a plant that produces yeast and ethanol. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Analysis of the effect of mixing vane geometry on the flow in an annular centrifugal contactor
Authors: Wardle Kent E. , Allen Todd R. , Anderson Mark H. , Swaney Ross E.
Published: July 2009

The annular centrifugal contactor is a compact mixer/centrifuge developed for solvent extraction processes for recycling used nuclear fuel. This research effort couples computational fluid dynamics (CFD) modeling with a variety of experimental observations to provide a valid detailed analysis of the flow within the centrifugal contactor. CFD modeling of the free surface flow in the annular mixing zone using the volume‐of‐fluid method combined with large eddy simulation of turbulence was found to have very good agreement with the experimental measurements. A detailed comparative analysis of the flow and mixing with different housing vane geometries (four straight vanes, eight straight vanes, and curved vanes) was performed. Two additional variations on the eight straight vane geometry were also simulated. This analysis determined that at the simulated moderate flow rate the four straight mixing vane geometry has greater mixing and fluid residence time as compared to the other mixing vane configurations. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Multivariable real‐time optimal control of a cooling and antisolvent semibatch crystallization process
Authors: Trifkovic Milana , Sheikhzadeh Mehdi , Rohani Sohrab
Published: July 2009

This article presents an experimental study of simultaneous optimization with respect to two variables (cooling rate and flow‐rate of antisolvent) in an offline and online (real‐time) manner on a semibatch crystallizer. The nucleation and growth kinetic parameters of paracetamol in an isopropanol‐water cooling, antisolvent batch crystallizer were estimated by nonlinear regression in terms of the moments of the crystal population density. Moments of crystal population were estimated from the measured chord length distribution, generated by the FBRM®, and the supersaturation was calculated from the measured concentration by attenuated total reflectance‐fourier transform infrared spectroscopy. The results of real‐time optimization showed a substantial improvement of the end of batch properties (the volume‐weighted mean size and yield). For the same objective function, the real‐time optimization method resulted in an increase in the volume‐weighted mean size by ∼100 μm and 15% of theoretical yield compared with the best result obtained in an offline optimization manner. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Design of mixed conducting ceramic membranes/reactors for the partial oxidation of methane to syngas
Authors: Tan Xiaoyao , Li K.
Published: July 2009

The performance of mixed conducting ceramic membrane reactors for the partial oxidation of methane (POM) to syngas has been analyzed through a two‐dimensional mathematical model, in which the material balance, the heat balance and the momentum balance for both the shell and the tube phase are taken into account. The modeling results indicate that the membrane reactors have many advantages over the conventional fixed bed reactors such as the higher CO selectivity and yield, the lower heating point and the lower pressure drop as well. When the methane feed is converted completely into product in the membrane reactors, temperature flying can take place, which may be restrained by increasing the feed flow rate or by lowering the operation temperature. The reaction capacity of the membrane reactor is mainly determined by the oxygen permeation rate rather than by the POM reaction rate on the catalyst. In order to improve the membrane reactor performance, reduction of mass transfer resistance in the catalyst bed is necessary. Using the smaller membrane tubes is an effective way to achieve a higher reaction capacity, but the pressure drop is a severe problem to be faced. The methane feed velocity for the operation of mixed conducting membrane reactors should be carefully regulated so as to obtain the maximum syngas yield, which can be estimated from their oxygen permeability. The mathematical model and the kinetic parameters have been validated by comparing modeling results with the experimental data for the La0.6Sr0.4Co0.2Fe0.8O3‐α (LSCF) membrane reactor. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Relationships between asthma and work exposures among non‐domestic cleaners in Ontario
Authors: Obadia Maya , Liss Gary M. , Lou Wendy , Purdham James , Tarlo Susan M.
Published: July 2009

Background

Cleaners have been reported to have increased risk for work‐related asthma symptoms but few studies have studied non‐domestic cleaners. In this study, we compared work‐related asthma symptoms among cleaners and other building workers and determined associations with tasks.

Methods

School and racetrack workers in Ontario, Canada, completed a questionnaire to identify the prevalence of cleaning tasks, physician‐diagnosed asthma, new‐onset asthma, respiratory symptoms, and work‐related asthma symptoms.

Results

Cleaners and controls had a similar prevalence of most asthma outcomes although female cleaners reported significantly more respiratory symptoms; odds ratio (OR), 2.59 confidence intervals (CI) 1.6–4.3, and work‐related asthma symptoms, OR 3.90 (CI 2.1–7.4) compared with female controls with adjustment for age and smoking history. Male cleaners showed a non‐significant trend to more physician‐diagnosed asthma, adjusted OR 2.10 (CI 0.9–4.8) and work‐related asthma symptoms, adjusted OR 1.53 (CI 0.8–3.0). The work‐related asthma symptoms among men were significantly associated with waxing floors, OR 2.19 (CI 1.0–4.4); wax‐stripping floors, OR 2.54 (1.2–5.2); spot‐cleaning carpets, OR 2.20 (1.3–3.8); and cleaning tiles, OR 4.46 (1.0–19.3) and grout, OR 2.12 (1.1–4.0).

Conclusions

Female cleaners have more asthma symptoms worse at work than controls. Work‐related asthma symptoms among male cleaners were associated with a number of specific cleaning tasks. Findings suggest the need for school cleaners to have reduced exposure to cleaning chemicals and need for protective strategies during performance of tasks expected to exacerbate asthma, such as wax stripping. Am. J. Ind. Med. 52:716–723, 2009. © 2009 Wiley‐Liss, Inc.
Expanding the phenotypic spectrum of acro‐cardio‐facial syndrome (ACFS): Exclusion of P63 mutation
Authors: Tanpaiboon Pranoot , Sittiwangkul Rekwan , Dejkhamron Prapai , Srikummool Metawee , Sripathomsawat Warissara , Kantaputra Piranit
Published: July 2009

Acro‐cardio‐facial syndrome (ACFS) is a rare autosomal recessive congenital malformation syndrome; consistent features include ectrodactyly, cleft lip/palate with minor facial anomalies, genital abnormalities, mental retardation, and growth retardation. Five cases have been reported. We report on a new patient with ACFS syndrome. In addition to the characteristic features of ACFS, the reported patient also has mild scoliosis, hemivertebrae and subclinical hyperthyroidism. These additional features may expand the phenotypic spectrum of the syndrome. © 2009 Wiley‐Liss, Inc.
A 1q42 deletion involving DISC1, DISC2, and TSNAX in an autism spectrum disorder
Authors: Williams Jaime M. , Beck Tyler F. , Pearson David M. , Proud Monica B. , Cheung Sau Wai , Scott Daryl A.
Published: July 2009

Individuals with autism spectrum disorders have impairments in social, communicative, and behavior development that are often accompanied by abnormalities in cognitive functioning, learning, attention, and sensory processing. In this report, we describe a 3‐year‐old male child with an autism spectrum disorder who carries a 2 Mb deletion of chromosome 1q42. Array comparative genome hybridization revealed that this deletion involves at least three genes—DISC1, DISC2, and TSNAX—which have been found to be associated with neuropsychiatric disorders and are likely to play key roles in normal CNS development. Further studies revealed that the deletion was inherited from his unaffected mother. This suggests that other genetic and/or environmental factors, some of which may be sex specific, may modify the phenotypic effects of this deletion. While this case provides evidence for the potential role of DISC1, DISC2, and TSNAX in the development of autism spectrum disorders, it is equally clear that caution must be taken when providing families with prognostic information and genetic counseling regarding such deletions. © 2009 Wiley‐Liss, Inc.
Investigation of factors associated with paternal nondisjunction of chromosome 21
Authors: Oliver Tiffany Renee , Bhise Archit , Feingold Eleanor , Tinker Stuart , Masse Nirupama , Sherman Stephanie L.
Published: July 2009

Previous studies on relatively small samples of individuals with trisomy 21 caused by paternally derived errors have shown that: (1) advanced paternal age is not a risk factor for chromosome 21 nondisjunction (NDJ), (2) absence of recombination, but not the location of recombination is associated with paternal NDJ and (3) there is an excess of males among live‐births with paternally derived trisomy 21. An excess of males is also observed among all individuals with trisomy 21. Using 128 families that had a child with trisomy 21 due to a paternally derived error, we examined: paternal age, recombination and the male/female sex ratio. We genotyped STRs along 21q to identify the origin of the error and the location of recombination on the paternal chromosome. Results showed that 32% of paternal meiotic errors occurred in meiosis I (MI) and 68% in meiosis II (MII). We confirmed the lack of a paternal age association with either type of error (mean paternal age for controls, MI, and MII errors: 31.3 ± 6.6, 32.2 ± 6.3, 30.6 ± 6.5, respectively). However, contrary to previous findings, we did not find altered patterns of recombination among paternal MI or MII errors. We found an increased male/female sex ratio among paternal (1.28, 95% CI: 0.68–1.91) and maternal (1.16, 95% CI: 1.02–1.33) meiotic errors. While the sex ratio among individuals with paternal errors was not statistically significant, these findings suggest that selection against female fetuses with trisomy 21 may contribute to the excess of males observed among all individuals with trisomy 21. © 2009 Wiley‐Liss, Inc.
Nicolaides–Baraitser syndrome: Delineation of the phenotype
Authors: Sousa Sérgio B. , Abdul‐Rahman Omar A. , Bottani Armand , Cormier‐Daire Valérie , Fryer Alan , Gillessen‐Kaesbach Gabriele , Horn Denise , Josifova Dragana , Kuechler Alma , Lees Melissa , MacDermot Kay , Magee Alex , Morice‐Picard Fanny , Rosser Elizabeth , Sarkar Ajoy , Shannon Nora , Stolte‐Dijkstra Irene , Verloes Alain , Wakeling Emma , Wilson Louise , Hennekam Raoul C.M.
Published: July 2009

Nicolaides–Baraitser syndrome (NBS) is an infrequently described condition, thus far reported in five cases. In order to delineate the phenotype and its natural history in more detail, we gathered data on 18 hitherto unreported patients through a multi‐center collaborative study, and follow‐up data of the earlier reported patients. A detailed comparison of the 23 patients is provided. NBS is a distinct and recognizable entity, and probably has been underdiagnosed until now. Main clinical features are severe mental retardation with absent or limited speech, seizures, short stature, sparse hair, typical facial characteristics, brachydactyly, prominent finger joints and broad distal phalanges. Some of the features are progressive with time. The main differential diagnosis is Coffin–Siris syndrome. There is no important gender difference in occurrence and frequency of the syndrome, and all cases have been sporadic thus far. Microarray analysis performed in 14 of the patients gave normal results. Except for the progressive nature there are no clues to the cause. © 2009 Wiley‐Liss, Inc.
Clinical variability of asphyxiating thoracic dystrophy (Jeune) syndrome: Evaluation and classification of 13 patients
Authors: Tüysüz Beyhan , Barış Safa , Aksoy Figen , Madazlı Rıza , Üngür Savaş , Sever Lale
Published: July 2009

Asphyxiating thoracic dystrophy‐Jeune syndrome (JS) is a rare autosomal recessive disease characterized by small thorax and short limb dwarfism. Besides the clinical variability, prognosis also differs greatly among patients. Pulmonary involvement is predominant in some cases whereas renal involvement is much more evident in others. We aimed to investigate the clinical variability and prognosis in 13 patients with JS from 11 families. Two of them, who had been diagnosed in the prenatal period were assessed by autopsy findings. All patients had a bell‐shaped or long narrow short thorax and brachydactyly at varying degrees from mild to severe. Short stature was common feature emerging in the postnatal period. One patient had atlantoaxial instability and spinal cord compression which have not been reported in JS before. In the postnatal follow up of 11 patients, respiratory distress was observed in eight patients and proved lethal in six, one patient died of chronic renal failure, and the remaining four patients were still alive at the end of the study. Patients were classified into three groups consisting of severe pulmonary involvement, renal involvement, and mild form in terms of prognosis. Patients with severe pulmonary involvement had bell‐shaped thorax and mild brachydactyly, the one patient with renal involvement had long narrow thorax and severe brachydactyly, and patients with mild involvement presented with polydactyly and moderate to severe brachydactyly. It is important to establish a correct diagnosis both in severe and mild forms since JS might recur within the same family. © 2009 Wiley‐Liss, Inc.
Water as green oxidant: a highly selective conversion of organosilanes to silanols with water
Authors: Chauhan Bhanu P. S. , Sarkar Alok , Chauhan Moni , Roka Abhishek
Published: July 2009

Selective hydrolytic oxidation of organohydrosilanes was achieved with water in the presence of Pt‐nanoparticle catalyst. The selectivity of the process was established by NMR analysis. In addition, various Pt‐based catalysts were screened to compare the activity and selectivity with Pt‐nanoparticles catalysis. The method was equally applicable to hydrosilanes bearing unsaturated functional groups, which led to corresponding silanols under mild reaction conditions without formation of any side products. Pt‐nanoparticle catalysis was studied in details using UV–vis, TEM and mercury poisoning experiments during the transformation. Copyright © 2009 John Wiley & Sons, Ltd.
Betti base‐derived tetradentate ligand: synthesis and application in copper‐catalyzed N‐arylation of imidazoles
Authors: Weng Bojie , Li Jing‐Hua
Published: July 2009

Betti base‐derived tetradentate ligand 2 has been successfully designed and synthesized through the condensation of Betti base with glyoxal. Its application in N‐arylation of imidazoles has been investigated which opens a new field for application of Betti base derivatives in organic transformation. Copyright © 2009 John Wiley & Sons, Ltd.
Semicontinuous copolymerization of 80/20 wt % [2‐(acryloyloxy)ethyl]trimethyl ammonium chloride/acrylamide in an inverse microemulsion at high comonomer concentrations
Authors: Ochoa‐Gómez José R. , Escudero‐Sanz Francisco J. , Sasia Pedro M. , Río Francisca , Nieto‐Mestre Javier , Torrecilla Jesús , Katime Issa A.
Published: July 2009

The semicontinuous inverse microemulsion copolymerization of 80/20 wt % [2‐(acryloyloxy)ethyl]trimethylammonium chloride/acrylamide in an isoparaffin solvent at high comonomer concentrations (30–42 wt %) was studied with a mixture of nonionic surfactants (Crill 43 and Softanol 90) as the emulsifier and sodium metabisulfite as the initiator. The influence of the total comonomer concentration (TCC), emulsifier concentration (EC), hydrophilic–lipophilic balance (HLB), isopropyl alcohol (chain‐transfer agent) concentration (IPC), and crosslinking agent concentration (CAC) on the weight‐average molar mass (Mw), absolute viscosity (BV), and viscometric structuring index (VSI) of the obtained copolymers was analyzed. Mw and BV increased with TCC and HLB and decreased with EC. At the higher TCC, Mw decreased with IPC; meanwhile, at the lower TCC, Mw increased with IPC above 0.5 wt %. VSI increased with TCC, HLB, and IPC and decreased with EC. VSI increased dramatically with CAC, whereas BV showed a peak at the CAC of 10 ppm. In the absence of both chain‐transfer and crosslinking agents, Mw increased linearly with VSI, and this suggests that linear copolymers of very high Mw values cannot be obtained by inverse microemulsion copolymerization, at least for high TCCs. The results are explained in terms of both the collapsed state of the copolymer chains inside the latex particles and changes in the interface structure and composition. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
On the toughness of photopolymerizable (meth)acrylate networks for biomedical applications
Authors: Smith Kathryn E. , Temenoff Johnna S. , Gall Ken
Published: July 2009

Photopolymerizable networks are being explored for a variety of biomedical applications because they can be formed in situ, rendering them useful in minimally invasive procedures. The purpose of this study was to establish fundamental relationships between toughness, network chemical structure, and testing temperature of photopolymerizable (meth)acrylate networks deformed in air and under hydrated conditions. Networks were formed by combining at least one monofunctional (meth)acrylate with a difunctional methacrylate, and weight ratios were adjusted to vary the degree of crosslinking, elastic modulus, and glass transition temperature (Tg). Stress–strain behavior and toughness were determined by performing tensile strain to failure tests at temperatures spanning the glassy and rubbery regimes of each network both in air and phosphate‐buffered saline. In air, all of the networks demonstrated a peak in toughness below the network's Tg. At an “equivalent” test temperature relative to Tg, crosslinking concentration and monomer chemistry influenced the toughness of each network. Apparent toughness is significantly altered in an aqueous environment, an effect driven by water absorption into the network causing the Tg to decrease. The results from this study provide the fundamental knowledge required to guide the development of tougher photopolymerizable networks for mechanically strenuous biomedical applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Alternating phenylenevinylene copolymers with dithienbenzothiadiazole moieties: Synthesis, photophysical, and photovoltaic properties
Authors: Mikroyannidis John A. , Stylianakis Minas M. , Dong Qingfeng , Pei Jianing , Tian Wenjing
Published: July 2009

Two new soluble alternating phenylenevinylene copolymers S and L which contained dithienbenzothiadiazole moieties were synthesized by Heck coupling. The repeating unit of L was longer than that of S and contained two additional phenylene rings and two cyano‐vinylene bonds. Both copolymers were stable up to about 350°C and afforded char yield of 52–66% at 800°C in N2. Their absorption spectra were broad and extended up to about 600 nm with a longer wavelength maximum at 447–502 nm and optical band gap of ∼ 2.0 eV. These copolymers emitted yellow light in solution with PL maximum at 551–580 nm and orange‐red light in thin film with PL maximum at 588–661 nm. The emission maximum of L was considerably red‐shifted relative to S. Photovoltaic cells based on S (or L) as donor and [6,6]‐phenyl C61‐butyric acid methyl ester as acceptor were investigated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
The effect of plasticizer and cellulose nanowhisker content on the dispersion and properties of cellulose acetate butyrate nanocomposites
Authors: Etang Ayuk Jackson , Mathew Aji P. , Oksman Kristiina
Published: July 2009

We studied the effects of plasticizer and cellulose nanowhisker content on the dispersion and properties of cellulose acetate butyrate (CAB)‐based bionanocomposites. The cellulose nanowhiskers in an aqueous medium were solvent‐exchanged to nonaqueous polar solvent (acetone) and used for nanocomposite processing by solution casting. The plasticized and unplasticized nanocomposites with 5 and 10 wt % cellulose nanowhisker content were prepared. Atomic force microscopy indicated nanoscale dispersion of whiskers in the CAB matrix. The dynamic mechanical analysis showed an increase in storage modulus with addition of cellulose nanowhiskers, especially above the glassy‐rubbery transition region. Thermogravimetric analysis showed an improvement in thermal stability with increased whisker content for both unplasticized and plasticized nanocomposites. The plasticized nanocomposites showed better transparency than the unplasticized composites, indicating a better dispersion of cellulose nanowhiskers in CAB, in the presence of a plasticizer. The dynamic mechanical properties and thermal stability increased, whereas transparency decreased with increased CNW content. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Toughened cycloaliphatic epoxy resin for demanding thermal applications and surface coatings
Authors: Tripathi Garima , Srivastava Deepak
Published: July 2009

An epoxy resin based on nonglycidyl ether and varying content of carboxyl‐terminated (poly)butadiene acrylonitrile copolymer was cured using an aromatic amine hardener. The ultimate aim of the study was to modify the brittle epoxy matrix by the liquid rubber to improve toughness characteristics. Fourier transform infrared spectroscopic analysis of the modified was performed to understand the structural transformations taking place during the uncured and cured stage of the modified systems. The decreasing trend in exothermal heat of reaction with increasing rubber content in the epoxy resin can be explained by the fact that the increase of carboxyl‐terminated butadiene acrylonitrile copolymer (CTBN) modifier might induce a high reactivity of the end groups with the epoxide ring and resulting shorter curing times and, hence, the faster curing process than the unmodified resin. Tensile strength, impact strength, and elongation‐at‐break behaviors of neat as well as modified networks have been studied to observe the effect of rubber modification. Blends sample exhibits better properties as compared to pure epoxy resin in terms of increase in impact strength and elongation‐at‐break of the casting and gloss, scratch hardness, adhesion, and flexibility of the film. The improvement in these properties indicate that the rubber‐modified resin would be more durable than the epoxy based on di glycidyl ether of bis‐phenol‐A and other epoxies. The films of coating based on epoxy with 15 wt % CTBN offered the maximum resistance toward different concentrations of acids, alkalies, and solvents as compared to the cured films of other blend samples. The thermal stability of the cycloaliphatic‐based epoxy resin was increased with the addition of 15 wt % CTBN in epoxy matrix. Cycloaliphatic‐based epoxy network modified with CTBN displayed two phase separated morphology with dispersed rubber globules in the matrix resin, i.e., they revealed the presence of two phase morphological features. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
A novel polymeric biomaterial based on carboxymethylstarch and its application in controlled drug release
Authors: Sen Gautam , Pal Sagar
Published: July 2009

This study reports investigation of the sustained release behavior of a model drug (acetylsalicylic acid) from carboxymethylstarch (CMS) based matrix. CMS was prepared by incorporation of carboxymethyl groups in the starch moiety; by reacting starch with sodium salt of monochloro acetic acid in presence of sodium hydroxide. The in vitro drug release study was performed by United States Pharmacopeia rotating paddle method, at various pH. The rate of drug release from the above matrix was found to increase with increase in pH. Further, the release behavior of the drug from the CMS based matrix was found to be non‐Fickian, n value being between 0.80 and 0.85, suggesting that the release was controlled by a combination of tablet erosion and diffusion of the drug from the swollen matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Mechanical and morphological properties of cellular NR/SBR vulcanizates under thermal and weathering ageing
Authors: Wimolmala Ekachai , Khongnual Kritsara , Sombatsompop Narongrit
Published: July 2009

The effects of addition of two chemical blowing agents in cellular rubber blend of natural rubber (NR) and styrene‐butadiene rubber (SBR) at a fixed blend ratio of 1 : 1 on cure characteristics, and mechanical and morphological properties were invesigated. The chemical blowing agents used in this work were Oxybis (benzene sulfonyl) hydrazide (OBSH) and Azo dicarbonamide (ADC). Three different fillers, fly ash (FA) particles, precipitated silica, carbon black (CB) at their optimum concentrations of 40 phr were used, the FA and silica particles being chemically treated by bis‐(3‐triethoxysilylpropyl) tetrasulphide. The results suggested that the overall cure time decreased with OBSH and ADC contents. The OBSH was more effective in cure‐acceleration of the NR/SBR blend than the ADC. The NR/SBR vulcanized foams produced by OBSH and ADC agents had closed‐cell structures. The specific density and mechanical properties of the blend tended to decrease with increasing blowing agent content. The CB gave NR/SBR foams with smaller cell size, better cell dispersion, and higher mechanical properties than the precipitated silica and FA particles. The heat ageing and weathering resulted in an increase in tensile modulus and hardness, but lowered the tensile strength, ultimate elongation and tear strength. The elastic recovery for cellular NR/SBR vulcanizates with FA was superior to that with CB and silica, the elastic recovery of the blends decreasing with blowing agent content. Resilience property was improved by the presence of gas phases. The optimum concentration of OBSH and ADC to be used for NR/SBR vulcanizates was 4 phr. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Physical properties of PLGA films during polymer degradation
Authors: Houchin M. L. , Topp E. M.
Published: July 2009

The rates of change of polymer properties (glass transition temperature, weight fraction sorbed water, and polymer molecular weight) were determined in poly (DL‐lactide‐co‐glycolide) films under accelerated storage conditions. Films were stored at 70°C and 95%, 75%, 60%, 45%, or 28% relative humidity. Weight fraction sorbed water was determined by thermogravimetric analysis, the glass transition temperature (Tgmix) of the polymer/water mixture by modulated temperature differential scanning calorimetry, and PLGA number‐average molecular weight (Mn) by size exclusion chromatography (SEC). Rates of moisture increase and Tgmix decrease were related to the decrease in PLGA Mn through a modification of the Gordon‐Taylor equation. Understanding the relative rates of polymer physical and chemical degradation will allow for improved design of PLGA formulations that control rates of drug delivery and preserve drug stability. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Effect of the processing techniques on the properties of ecocomposites based on vegetable oil‐derived Mater‐Bi® and wood flour
Authors: Scaffaro R. , Morreale M. , Re G. Lo , La Mantia F.P.
Published: July 2009

Polymer composites based on biodegradable polymers and natural‐organic fillers are becoming more and more important because of their interesting properties in terms of environmental impact, manufacturing cost, and esthetic features. In particular, the use of biodegradable polymer matrices allows obtaining a full biodegradability. One of the most interesting biodegradable polymer families is the Mater‐Bi® one. In this work, we investigated the processability, the influence of different processing techniques, and the influence of the filler particle size on the properties of Mater‐Bi/wood flour composites. Injection molding caused a partial degradation of the macromolecular chains, whereas single‐screw extrusion followed by calendering and twin‐screw extrusion provoked an increase of the elastic modulus and of the viscosity. The use of wood flour led to a significant increase of the rigidity, whereas a reduction of the ductility was observed. Because of the very similar aspect ratios of the two different filler size classes, no dramatic differences in the properties were found. These results are useful in order predicting and setting up the optimum preparation and processing strategy for the production of fully biodegradable polymer composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Transparent conducting films based on nanofibrous polymeric membranes and single‐walled carbon nanotubes
Authors: Kim Yeseul , Kim Hun‐Sik , Bak Hyeonseong , Yun Young Soo , Cho Se Youn , Jin Hyoung‐Joon
Published: July 2009

Transparent and electrically conducting films were fabricated using a novel and simple method in which single‐walled carbon nanotubes (SWCNTs) adsorbed onto bacterial cellulose membranes were embedded into a transparent polymer resin. The bacterial cellulose membranes consisting of numerous nanofibrils were found to play important roles in this process. The bacterial cellulose membranes impart optical transparency to the nanocomposites due to the size of the materials during the synthesis of the nanocomposite using a transparent polymer resin. The membranes play a secondary role as a template for depositing uniformly dispersed SWCNTs. This results in not only electrically conducting pathways but also prevents interference from the transmittance of optically transparent nanocomposites. Transparent conducting films with a wide range of transmittances and surface resistances could be obtained by controlling the immersion time and SWCNT concentration in the SWCNT dispersions. A transparent conducting film with a transmittance and surface resistance of 77.1% at 550 nm and 2.8 kΩ/sq, respectively, was fabricated from a 0.01 wt %. SWCNT dispersion for an immersion time of 3 h. In addition, the transparent conducting films were quite flexible and maintained their properties even after crumpling. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Application of corona discharge on desizing of polyvinyl alcohol on cotton fabrics
Authors: Ma Pibo , Wang Xin , Xu Weilin , Cao Genyang
Published: July 2009

In this study, corona discharge was applied to optimize the desizing of polyvinyl alcohol (PVA) on cotton fabric. The weight of sized fabric decreased slightly when the PVA sized fabric was treated by corona discharge. Percent desizing rate (PDR) of PVA sized fabric increased evidently after the fabric was subjected to corona discharge treatment, PDR increased with the enhancement of corona discharge treatment by increase of applied voltage and treating time. Water dissolution time and water‐contact angle decreased at the same time. SEM and AFM photos show the surface of PVA film was modified into uneven morphology with many ridges pores and cracks. ATR‐FTIR analysis shows that the content of CO, COOH, and CO bonds was increased after the PVA film was treated by corona discharge. Corona discharge can be applied to optimize the desizing of PVA on fabric by saving treating time and water or decrease the usage of the detergent of hydrogen peroxide; it provides a green process and energy saving method for textile finishing. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Role of specific interactions on fiber formation in the electrospinning of poly(vinyl phenol)/poly(vinyl pyrrolidone) blend solutions
Authors: Buruaga L. , Muñoz M. E. , Irusta L. , González A. , Iruin J. J.
Published: July 2009

The minimum concentration (Ci) required for electrospinning polymeric fibers from solutions of mixtures of poly(vinyl phenol) and poly(vinyl pyrrolidone) has been experimentally determined for different blend compositions. This minimum concentration Ci has its lowest value when the polymers are mixed in a 1/1 molar ratio. This article shows different results that seem to indicate that the strong hydrogen bonding interactions between the two polymers and the corresponding higher apparent molecular weight cause the reduction of the Ci value. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Mass transfer study of chlorine dioxide gas through polymeric packaging materials
Authors: Netramai Siriyupa , Rubino Maria , Auras Rafael , Annous Bassam A.
Published: July 2009

The mass transfer profile (permeability, diffusion, and solubility coefficients) of chlorine dioxide (ClO2), a strong oxidizing agent that is used in food and pharmaceutical packaging, was determined through various common polymeric packaging materials. A continuous system for measuring permeation of ClO2, using an electrochemical detector, was developed. It was observed that biaxially‐oriented poly(propylene), poly(ethylene terephthalate), poly(lactic acid), nylon, and a multilayer structure of ethylene vinyl acetate and ethylene vinyl alcohol were better barriers for gaseous ClO2, as compared to polyethylene, poly(vinyl chloride), and polystyrene. The activation energies of permeation for ClO2 through poly(ethylene terephthalate) and poly(lactic acid) were determined to be 51.05 ± 4.35 and 129.03 ± 2.82 kJ/mol, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, , 2009
Preparation of aldehyde‐, amino‐, and hydrazide‐functionalized polymer particles for direct immobilization of the sugars
Authors: Sun Z. C. , Wei Z. , Wei K. M.
Published: July 2009

The reaction of poly(vinyl alcohol) with glutaraldehyde (GA) at different molar ratio was systematically studied. By this reaction, white particles functionalized with aldehyde groups were obtained and their diameters were found to be between 50 and 150 nm. The amount of free CHO groups on the surface of the particles reached more than 1.6 mmol/g by adjusting the ratio of n(GA)/n(OH). The free CHO groups were then converted into alkyl amino, aromatic amino, and hydrazide groups by coupling with hexamethylene diamine, m‐phenylene diamine, and adipic dihydrazide, respectively, and the length of the spacer was also prolonged. Finally, a series of sugar‐particle conjugates were prepared by directly coating the functionalized particles with maltose, D‐(+)‐glucosamine, and heparin. The anticoagulant experiments show that the heparin immobilized on the aldehyde‐ and hydrazide‐functionalized particles is still biologically active. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Effects of prior aging at 288°C in argon environment on time‐dependent deformation behavior of a thermoset polymer at elevated temperature, part 1: Experiments
Authors: McClung Amber J. W. , Ruggles‐Wrenn Marina B.
Published: July 2009

The inelastic deformation behavior of PMR‐15 neat resin, a high‐temperature thermoset polymer, aged at 288°C in argon environment for up to 2000 h was investigated. The experimental program was designed to explore the inﬂuence of prior isothermal aging on monotonic loading and unloading at various strain rates. In addition, the relaxation response and the creep behavior of specimens subjected to prior aging of various durations were evaluated. All tests were performed at 288°C. The time‐dependent mechanical behavior of the PMR‐15 polymer is strongly influenced by prior isothermal aging. The elastic modulus increased and the departure from quasi‐linear behavior was delayed with prior aging time. Stress levels in the region of inelastic flow increased with prior aging time. Furthermore, prior aging significantly decreased the polymer's capacity for inelastic straining, including the material's capacity to accumulate creep strain. Conversely, the relaxation response was not affected by the prior aging. © 2009 Wiley Periodicals, Inc.† J Appl Polym Sci, 2009
Thermal analysis and ionic conductivity of ionic liquid containing composites with different crosslinkers
Authors: Sterner Elizabeth S. , Rosol Zachary P. , Gross Erin M. , Gross Stephen M.
Published: July 2009

Conductive polymer composites were synthesized by the polymerization of methylmethacrylate in the presence of ionic liquid solvents. These composites were characterized by attenuated total reflectance infrared spectroscopy, differential scanning calorimetry, and dynamic mechanical analysis. AC impedance measurements were performed on these composites as a function of ionic liquid type, ionic liquid concentration, crosslinker density, and molecular weight between crosslinks at various temperatures. 1‐Butyl‐3‐methylimidazolium thiocyanate produced composites with a greater conductivity than 1‐ethyl‐3‐methylimidazolium trifluoromethanesulfonimide, despite having a higher viscosity. The viscosity of the virgin ionic liquid could not be used to predict the order of ionic conductivity for composites made from these ionic liquids. The effect of crosslink density within the range of 0–0.6 mmol crosslinking agent per gram of monomer was studied. Composites with 25% ionic liquid (w/w) appeared to have an optimum crosslink density for maximum ionic conductivity. In the range of crosslink densities studied, composites with greater ionic liquid concentration exhibited no significant effect of crosslink density on ionic conductivity. This could be due to the fact that the difference in crosslink density did not effectively change the Tg of these composites. The composite with the lowest theoretical molecular weight between crosslinks had the lowest ionic conductivity. This could be due to restriction of ion movement at this molecular weight between crosslinks. The composite with the highest molecular weight between crosslinks had comparable ionic conductivity to an uncrosslinked composite. This study showed that these materials have ionic conductivities practical for advanced energy applications over a wide range of morphologies with dimensional stability. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Optimization of adhesive joints of low density polyethylene (LDPE) composite laminates with polyolefin foam using corona discharge plasma
Authors: Pascual Monica , Calvo Oscar , Sanchez‐Nácher Lourdes , Bonet Maria Angeles , Garcia‐Sanoguera David , Balart Rafael
Published: July 2009

In this work, surface modification of low density polyethylene (LDPE) film has been carried out to optimize adhesive joints with polyolefin foam for uses in technological applications. LDPE films were modified in a continuous way using corona discharge plasma with different powers, ranging from 200 to 600 W and several film advance rates in the 5–20 m min−1 range. Changes in surface wettability have been studied with contact angle measurements and subsequent solid surface energy calculation. A polyurethane adhesive was used to join the LDPE film to a polyethylene foam. Mechanical performance of the adhesive joints has been determined by T‐peel tests and also the aging effects of several hydrothermal conditions have been studied to evaluate the usefulness of these laminate composites in technological applications. Results show that corona discharge powers between 400 and 600 W are suitable in terms of wettability improvement; on other hand, a slight decrease in surface wettability as the film advance rate increases is detected but the overall changes as a consequence of the film advance rate in the 5–20 m min−1 range are small if compared to changes derived from working powers in the 200–600 W range. Adhesive joints offer excellent mechanical performance and good durability in hydrothermal conditions thus being appropriate for technical applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Recycled multilayer cartons as cellulose source in HDPE‐based composites: Compatibilization and structure‐properties relationships
Authors: Avella Maurizio , Avolio Roberto , Bonadies Irene , Carfagna Cosimo , Errico Maria Emanuela , Gentile Gennaro
Published: July 2009

In this article, an alternative mechanical recycling of multilayer carton scraps (MC), consisting in the use of MC without the physical separation of its different fractions (cellulose fibers and low‐density polyethylene, 80/20 wt/wt), is proposed. In particular, MC was considered as a source of cellulose fibers in the obtainment of high‐density polyethylene (HDPE)‐based composites. Composites containing up to 60 wt % of milled MC were prepared by reactive processing, i.e., by adding different amount (5 and 10 wt %) of a linear low‐density polyethylene grafted with maleic anhydride (coupling agent, maleated linear low‐density polyethylene) during HDPE/MC mixing. Then, structure/properties relationships were deeply investigated as a function of MC and coupling agent content. The coupling agent was able to induce a complete polymeric covering of cellulose fraction as well as a strong HDPE/cellulose interfacial adhesion. As a consequence, a significant improvement of mechanical properties at low and high deformation rates as well as a very interesting response of composites to water vapor permeability was obtained. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009