bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ternary Thermosetting Blends of Epoxy Resin, Poly(ethylene oxide) and Poly(ε‐caprolactone)
Authors: Yin Minghua , Zheng Sixun 
Published: April 2005

AbstractSummary:The ternary thermosetting blends composed of epoxy resin, poly(ethylene oxide) (PEO) and poly(ε‐caprolactone) (PCL) were prepared via in situ polymerization of epoxy monomers in the presence of the two crystalline polymers, PEO and PCL. DSC results showed that the binary blends of epoxy with PEO (and/or PCL) are fully miscible in the entire composition in the amorphous state. FTIR indicates that there were interchain specific interactions between the crosslinked epoxy and the linear polymers in the binary blends and the hydrogen bonding interactions between epoxy and PCL are much weaker than those between epoxy and PEO. The difference in the strength of interchain specific interactions gives rise to the competitive hydrogen bonding interactions in the ternary blends of epoxy, PEO and PCL, which were evidenced by the results of FTIR. The results of optical microscopy and DSC showed that in the ternary blends PCL component separated out with inclusion of PEO. The formation of the specific phase structures is ascribed to the competitive interchain specific interactions among the crosslinked epoxy, PEO and PCL.Phase boundary diagram of epoxy, PEO and PCL ternary blends.imagePhase boundary diagram of epoxy, PEO and PCL ternary blends.
Contributions to Forming and Analytical Investigations of Solutions of Cellulose and Cellulose Derivatives – A Research and Development Topic of the TITK eV
Authors: Kosan Birgit , Michels Christoph , Meister Frank 
Published: April 2005

AbstractModification, forming and analytical characterisation of cellulose and cellulose solutions represents one of the most important research topics of the Thuringian Institute for Textiles and Plastics Research (TITK). The presentation provides information on the current capabilities of the institute and on the analytical methods developed in these fields.
Carboxymethyl Ethers of Cellulose and Starch – A Review
Authors: Heinze Thomas , Koschella Andreas 
Published: April 2005

AbstractThis review article deals with the technically important carboxymethyl ethers of cellulose and starch. Recent developments of synthesis, characterization, and application are presented considering adequately own research work in this field. In particular, the structure characterization by means of chromatographic (HPLC) and NMR‐spectroscopic techniques as well as commercially important synthesis paths and alternative methods are described.
Carbamoylation Applied for Structure Determination of Cellulose Derivatives
Authors: Liebert Tim , Pfeiffer Katy , Heinze Thomas 
Published: April 2005

AbstractCarbamoylation of cellulose esters (CE) and investigation of the mixed derivatives obtained with NMR spectroscopy represents a useful analytical tool for the determination of the degree of substitution (DS) and analysis of the distribution of substituents on the level of the anhydroglucose unit (AGU). Especially the carbethoxymethylcarbamoylation and the ethylcarbamoylation of CE combined with 1H NMR spectroscopy are efficient and inexpensive ways to gain information on the over‐all DS and partial DS values in position 2, 3, and 6 of the AGU. Complete subsequent phenylcarbamoylation can be achieved even for CE with bulky substituents, e.g., adamantanecarboxylic acid esters. In addition to NMR experiments the carbamoylated CE were studied by HPLC after complete chain degradation. Carbethoxymethylcarbamoylation has turned out to be the most useful tool for this path. Chromatograms comparable to carboxymethylated cellulose (CMC) were obtained, which can be exploited to calculate the mole fractions of the basic building units (un‐, mono‐, di‐ and tri‐substituted glucoses) of the polymer. Comparison with statistic calculations gave a first hint on the distribution of substituents along the polymer chain. For a commercial cellulose diacetate a statistic pattern of substitution was determined.
Polymer‐Analogous Preparation of Cellulose Tricarbanilates: Mechanisms of Degradation in Dimethylsulfoxide
Authors: Fischer Martin , Fischer Klaus 
Published: April 2005

AbstractTwo cellulose samples were subject to treatment with phenylisocyanate (PhNCO), both in pyridine and in dimethylsulfoxide (DMSO). In each case, DMSO degraded cellulose in an extent depending on the derivatized cellulose. The formation of dimethylsulfonium ions was recognized as the cause leading to an oxidation of hydroxyl groups. This Pfitzner‐Moffatt type oxidation is dependent on carboxyl groups and therefore occurs most probably in their neighbourhood. It was deduced that formation of oxidised sections along the cellulose chains occurs containing either carbonyl and carboxyl groups in the same anhydroglucose unit (AGU) or singly oxidised AGUs in direct neighbourhood to each other. This leads to much facilitated eliminative degradation.
Structural Changes and Activation of Cellulose by Caustic Soda Solution with Urea
Authors: Kunze Jürgen , Fink Hans‐Peter 
Published: April 2005

AbstractInvestigations on the activation of cellulose by mixed solutions of caustic soda and urea are reported. The structural effects of those solutions on various dissolving pulps are studied by 13C‐CP/MAS‐NMR spectroscopy. In a series of steeping lyes, the concentration of NaOH was varied in a range from 0% to 8% and the urea‐concentration in a range from 15% to 40% at ambient temperature and −25 °C.Using solely the single NaOH or urea solutions in the concentration ranges given above, no or only minor structural changes were found. In contrast to that, the cellulose I structure was partially or completely destroyed by using the bicomponent solution with urea added to caustic soda. The structural effect of the bicomponent solutions is comparable with the effect of solely caustic soda solutions of approx. 10% to 18% NaOH. However, the 13C‐CP/MAS‐NMR‐spectra from the bicomponent pretreated samples indicate a structure different from the usual ordered structures of sodium cellulose I or II, namely a special urea‐NaOH‐cellulose complex. The results show that for cellulose activation the NaOH concentration of the caustic soda can be remarkably reduced by adding urea. The improved activating effect of an optimized caustic soda solution with added urea was proved to be useful for the synthesis of cellulose carbamate.
Analytical Investigations of Bacterial Cellulose
Authors: Udhardt Ulrike , Hesse Stephanie , Klemm Dieter 
Published: April 2005

AbstractThe cultivation of the bacterium Acetobacter xylinus AX 5 was carried out in the common Hestrin‐Schramm medium containing D‐glucose as C‐source and citric acid as buffer component. HPLC studies proved to be convenient methods to investigate the stability and interactions of these constituents in the starting culture liquid. Within the initial sterilization step and limited by the citric acid, up to 6% of the D‐glucose was partially isomerized to D‐fructose and degraded to dark‐yellow products. In static culture, A. xylinus AX 5 produces cellulose extracellularly on the surface of this medium. Solid‐state NMR spectroscopy represents a suitable analytical method to characterize the supramolecular structure of the bacterial cellulose in never‐dried, air‐dried, and freeze‐dried states. It could be demonstrated that the drying process reduces the degree of crystallinity in the range of about 12% without changes in the Iα/β ratio of these cellulose modifications.
Isolation and Identification of Residual Chromophores in Cellulosic Materials
Authors: Rosenau Thomas , Potthast Antje , Hofinger Andreas , Kosma Paul 
Published: April 2005

AbstractA general procedure was developed for the isolation of residual chromophores in or on cellulosic material, which were hitherto inaccessible to structure elucidation due to their extremely low content in the ppb concentration scale. It is applicable to cellulosic pulp, cellulosic fibers (viscose, Lyocell) and cellulose derivatives (acetate, carbonyl‐labeled cellulose) as well. The chromophore identification comprises treatment of the cellulosic material with boron trifluoride – acetic acid complex (BF3*2HOAc) containing sulfite, chromatographic separation of the resulting chromophore‐containing mixture, and structure determination of the main constituents by NMR / MS and comparison to authentic samples. Both adsorbed and covalently bound aromatic and quinoid compounds are selectively released by the treatment. Covalent ester, ether and secondary alkyl links between chromophore and cellulose are broken.Two cellulosic example substrates have been analyzed for their chromophore content: Lyocell fibers and non‐bleached viscose fibers, and up to eleven chromophores per sample have been identified.
The correlativity of positive temperature coefficient effects in conductive silicone rubber
Authors: Zhang Jie , Zhang Shengyou , Feng Shengyu , Jiang Zhigang 
Published: April 2005

AbstractA thorough study on the positive temperature coefficient (PTC) effects of conductive silicone rubber was made. Various conductive silicone rubbers with apparent differences in PTC anomalies (defined as the ratio of peak resistivity to room temperature resistivity) were chosen. The correlation between the size of the PTC anomaly and both the thermal expansion coefficient of conductive silicone rubber and the interaction between silicone rubber and carbon black (CB) were found. The effects of cross‐linking on the temperature effect of resistivity of conductive silicone rubber were also studied. The results testify the important role of the interaction between silicone rubber and CBs in the temperature effect of resistivity of conductive silicone rubber. Copyright © 2005 Society of Chemical Industry
Polyamide/silver antimicrobials: effect of crystallinity on the silver ion release
Authors: Kumar Radhesh , Münstedt Helmut 
Published: April 2005

AbstractPolyamide/silver (PA/Ag) composite materials are regarded as potential antimicrobials by virtue of their efficacy to release the Ag+ ions in an aqueous medium. The effects of the matrix crystallinity on the Ag+ ion release characteristics of PA/Ag composites are discussed. It is found that matrix crystallinity is very decisive for the silver ion releasing properties and hence the antimicrobial efficacy of silver‐based antimicrobial polyamides. The crystallinities of the composites were evaluated using differential scanning calorimetry. The silver ion release characteristics of these composites were measured by anode stripping voltammetry. Silver ion release was higher in systems possessing lower degrees of crystallinity. Water‐diffusion characteristics of the composites control the silver ion release. The effect of crystallinity on silver ion release rate depends on the time of soaking of the specimens in water. Copyright © 2005 Society of Chemical Industry
Preparation of ultrafine fibrous zein membranes via electrospinning
Authors: Miyoshi Takanori , Toyohara Kiyotsuna , Minematsu Hiroyoshi 
Published: April 2005

AbstractZein is a protein in corn gluten meal. It has been investigated for use as a structural material because it is renewable and biodegradable. Potential applications of zein include use in coating, film and fiber. In this paper, ultrafine fibrous zein membranes were produced by electrospinning of an 80 wt% ethanol aqueous solution. The morphology of fibers was affected by parameters such as polymer concentration and electric field. As the concentration of the solution increased, wrinkled beads became fewer and fibers became thicker. Fibers were mainly generated above a polymer concentration of 21 wt% with an electric field of 15 kV. However, with a 30 kV field fibers were already generated above 18 wt%. Copyright © 2005 Society of Chemical Industry
On activated seed swelling technique
Authors: Zohrehvand Shiva 
Published: April 2005

AbstractThe activated seed swelling technique is one of the promising methods in synthesis of micron‐sized monodispersed polymer particles. However, there are some parameters (eg the interference of acetone residue on particle swelling) that make this method difficult to carry out and even lead to a broad particle‐size distribution. Here, these parameters are studied and how to control them is discussed. The polydisperse seed swelling appeared at lower concentration of acetone and with incomplete evaporation of acetone from the system. The monodisperse swelling and larger particle sizes were achieved at higher concentration of acetone and longer evaporation time using a vacuum pump. These results suggest that the particle size and particle‐size distribution in the activated seed swelling technique can be controlled by the carrier (acetone) and the hydrophobe concentration in aqueous medium before and after the swelling process. Copyright © 2005 Society of Chemical Industry
The effect of compatibilization on the dynamic properties of polypropylene/nylon‐6 blends studied by broad band dielectric spectroscopy
Authors: Laredo E. , Grimau M. , Bello A. , Sánchez F. , Gómez M. A. , Marco C. , Campoy I. , Arribas J. M. 
Published: April 2005

AbstractPolypropylene (PP) and polyamide‐6 (Ny‐6) blends with a 70/30 composition have been studied by broadband dielectric spectroscopy. The unmodified blends are immiscible, and 10% of PP functionalized with maleic anhydride was added as a compatibilizer. The influence of the compatibilizer on the water sorption and on the molecular dynamics of the Ny‐6 phase is followed by the changes induced in the dielectric loss spectra of these blends in both wet and dry states. The shortest range motions are unaffected by the compatibilizer in the dry state, but a higher water sorption is observed in the unmodified blend. Higher activation energies are found for the β relaxation in the dry blends than for the Ny‐6 homopolymer, showing the existence of constraints on these longer scale motions. During increasing temperature experiments, two segmental modes are recorded, the lower temperature mode corresponding to the plasticized material; as the temperature is raised, a second cooperative mode is found, originating in the dry Ny‐6 amorphous phase, rigidized by the loss of moisture. The comparison of the dielectric strengths of the modes shows that the unmodified blend absorbs more water than the compatibilized blend. The segmental dynamics are unaffected by compatibilization. At high temperatures, the high temperature tail of the segmental mode is much higher in the absence of the compatibilizer. The contribution of a peak due to interfacial polarization is lowered by the presence of the compatibilizer, which makes the interface more diffuse and the trapping of free carriers less effective. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1408–1420, 2005
Morphological change of poly (ε‐caprolactone) with a wide range of molecular weight via formation of inclusion complex with α‐cyclodextrin
Authors: Shin Kyung‐Moo , Dong Tungalag , He Yong , Inoue Yoshio 
Published: April 2005

AbstractThe effect of molecular weight of poly(ε‐caprolactone) (PCL) on the formation and stability of inclusion complexes (ICs) between α‐cyclodextrin (α‐CD) and PCL was investigated by FTIR, WAXD, and DSC measurements. ICs between α‐CD and PCLs with a wide range of number‐average molecular weight, Mn = 1.21 × 104 – 1.79 × 105, were prepared by mixing the aqueous solution of CD and acetone solution of PCL followed by stirring at 60 °C for 1h and at the room temperature for 1 day. FTIR, WAXD, and DSC measurement showed the PCL chains were included into the α‐CD cavity, and the crystallization of PCL was suppressed in the α‐CD cavity. Stoichiometry and yield of each IC varied with the molecular weight of guest PCL, and the effect of IC formation on the crystallization behaviour of guest polymer decreased with the increase of molecular weight of guest polymer. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1433–1440, 2005
A Method to Evaluate the Tensile Strength and Stress–Strain Relationship of Carbon Nanofibers, Carbon Nanotubes, and C‐Chains
Authors: Márquez‐Lucero Alfredo , Gomez Jorge A. , Caudillo Román , Miki‐Yoshida Mario , José‐Yacaman Miguel 
Published: April 2005

AbstractA method is introduced to assess the tensile strength of carbon nanofibers, carbon nanotubes (CNTs), and linear chains of carbon atoms (C‐chains) obtained from thin amorphous carbon films by electron irradiation. Transmission electron microscopy images show that the nanofibers undergo a radiation‐induced necking process, characterized by CNT formation and often followed by the formation of a C‐chain. Simulations of the necking process are carried out to determine the tensile stress supported by the nanofiber and CNT neck.
Phase Separation Micromolding: A New Generic Approach for Microstructuring Various Materials
Authors: Vogelaar Laura , Lammertink Rob G. H. , Barsema Jonathan N. , Nijdam Wietze , Bolhuis‐Versteeg Lydia A. M. , van Rijn Cees J. M. , Wessling Matthias 
Published: April 2005

AbstractPhase separation micromolding (PSμM) is a versatile microfabrication technique that can be used to structure a very broad range of polymers, including block copolymers and biodegradable and conductive polymers without the need for clean‐room facilities. By incorporating a subsequent process step, carbon, ceramic, and metallic microstructures can also be fabricated from a polymeric or hybrid precursor. The replication process is straightforward and cost‐effective. It relies on phase separation of a polymer solution while in contact with a structured mold. Intrinsic shrinkage during the phase separation facilitates the release of the replica from the mold, which increases the reliability of the process even at small feature sizes, thin polymer films, or high aspect ratios. Under suitable circumstances perforation of the polymer film can be obtained, resulting in completely open “through” microstructures. Furthermore, porosity can be introduced in a microstructure, which may result in unknown functionalities.
Public Response to Chest Pain in Jordan
Authors: AL-Safi Saafan A. , Alkofahi Ahmad S. , El-Eid Hala S. 
Published: April 2005

Background: Chest pain is one of the main and most frequent manifestations of myocardial infarction (MI). Increased level of public awareness on the optimal response to chest pain due to MI attacks is crucial for minimizing its complications and mortality rate. Aims: The first aim of this investigation was to assess the level of public awareness on their response to acute chest pain. The second aim was to obtain information about self-reported risk factors for coronary heart disease and acute myocardial infarction. Settings and design: This survey was conducted in various regions of Jordan during the period of July–September 2004. A total of 4194 adults (out of 4500), 2086 males (49.7%) and 2108 females (50.3%) resident in Jordan were included in the sample. The response rate was 92.3%. Methods: Each individual of the sample who agreed voluntarily to participate in the investigation was asked to report in a questionnaire his/her possible risk factors for MI. Moreover, each person of the sample was asked “What do you do when you suffer from a severe and crushing chest pain that persists for longer than 15 min and radiates to jaws, neck or left shoulder, with sweating and paleness of the face?” The person was asked to choose one option out of 11. Statistical analysis: The frequency and percentage were determined for each investigated parameter. Results and conclusion: The highest percentage of respondents had good response by selecting the option “I go to a doctor” while the lowest percentage of respondents showed poor response by choosing the option “I use an antacid”. The remainder of responses was distributed among other options. Excellent awareness was reported by 47% of the sample. Differences in the type of responses were detected when the results were analyzed according to gender, type of job, level of education and ethnicity. Approximately half of the interviewed individuals of the sample had 2–4 clustering risk factors for developing acute MI attacks. Individuals in more than half of the sample had family history of hypertension and diabetes mellitus. It is concluded that although the type of response to chest pain in Jordan is good–excellent, more improvement is recommended since the risk to MI is relatively high. Community education campaigns may participate in increasing public health education on the optimal response to chest pain of myocardial origin.
Does Smoking Affect Blood Pressure and Heart Rate?
Authors: Al-Safi Saafan A. 
Published: April 2005

Background: Smoking is a risk factor for cardiovascular, coronary artery and thromboembolic disorders. There is overwhelming evidence supporting the association of cigarette smoking and the development of cardiovascular and thromboembolic events particularly in high risk populations. Aim: The aim of this investigation was to explore the correlation of smoking habit with blood pressure and heart rate values through a randomized cross-sectional epidemiological study in Jordan. Settings and design: This study was performed during the period of February–June 2004. The sample of this investigation included healthy adult males and females from various regions of Jordan. Most of the selected sample included Jordanian university students. Patients with hypertension or cardiovascular disorders were excluded. Methods: Selected individuals of the sample were interviewed by well-trained senior pharmacy students. They were asked initially if they have hypertension or other cardiovascular disorders and if the answer was negative, further questions were asked followed by measurement of the blood pressure and heart rate. Demographic data such as age, sex, nationality, place of residence, occupation and level of education were also recorded. Smokers (for ≥ 6 months) were asked to report how many cigarettes per day they smoke. For each individual of the sample, the systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate were measured three times with 10–15 min intervals in the sitting position and at the resting state. The arterial blood pressure (ABP) was calculated from the measured SBP and DBP. The mean values were distributed according to sex and smoking habit. Statistical analysis: The student unpaired t-test was used for statistical analysis. Results were considered statistically significant when the p value was less than 0.05. Results and conclusion: A total of 14,310 adult males (7400) and females (6910) were selected in various regions of Jordan. The frequencies of smokers and non-smokers in the sample were 3832 (26.8%) and 10478 (73.2%), respectively. Smoker males and females had significantly higher SBP, DBP, ABP values than non-smokers. However, smoking had statistically non-significant effects on heart rate in females while heart rate values were significantly higher in male smokers than in non-smokers. Smoker or non-smoker adults with a positive family history of hypertension had significantly higher blood pressure and heart rate values than those with a negative family history of hypertension. In conclusion, smokers have higher blood pressure than non-smokers.