bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biodegradable materials — Present situation and future perspectives
Authors: Bastioli Catia 
Published: March 2011

AbstractBiodegradable polymers constitute a loosely defined family of polymers that are designed to degrade through the action of living organisms. They offer a possible alternative to traditional nonbiodegradable polymers if recycling is impractical or not economical. The main driving force behind this technology is the solid waste problem, particularly with regard to the decreasing availability of landfills, the litter problem and the pollution of marine environment by non‐biodegradable plastics. Technologies like composting used for the disposal of food and yard waste are the most suitable for the disposal of biodegradable materials.European Standardisation Committee (CEN), Organic Reclamation and Composting Association (ORCA) and German Institute for Standardisation (DIN) have already defined, at a draft level, the basic requirements for a product to be declared compostable. They are based on: complete biodegradability of the product in a time period compatible with composting, measured through respirometric tests (ASTM D5338‐9, ISO/CD14855, etc); disintegration of the material during the fermentation phase; no negative effects on compost quality; checking of laboratory‐scale results on pilot/full‐scale composting plants. These requirements set forth a common base for a universal marking system to readily identify products to be composted.Thermoplastic starch‐based polymers and aliphatic polyesters are the two classes of biodegradable materials with the greatest near‐term potential. This paper reviews a great variety of properties, structures and biodegradation behaviour of thermoplastic starch in combination with poly(vinyl alcohol) or some aliphatic polyesters like poly(hydroxybutyrate‐co‐hydroxyvalerate), poly(lactic acid), poly(ϵ‐caprolactone) and poly(butanediyl succinate).
Conversion of polymers and biomass to chemical intermediates with supercritical water
Authors: Arai Kunio 
Published: March 2011

AbstractRecent results are described on conversion of polymers and biomass to chemical intermediates and monomers by using subcritical and supercritical water as the reaction solvent. Reactions of cellulose in supercritical water are rapid (<50 ms) and proceed to 100% conversion with no char formation. They show a remarkable increase in hydrolysis products and lower pyrolysis products when compared with reactions in subcritical water. Further, there is a jump in the reaction rate of cellulose at the critical temperature of water. If the methods used for cellulose are applied to synthetic polymers, such as PET, nylon or others, high liquid yields can be achieved although the reactions require about 10 min for complete conversion. The reason is the heterogeneous nature of the reaction system. For polyethylene, higher yields of short‐chain hydrocarbons, higher alkene/alkane ratios and higher conversions were obtained in supercritical water than those obtained by pyrolysis.
Degradability of biodegradable plastic under controlled composting conditions
Authors: Nakasaki Kiyohiko 
Published: March 2011

AbstractBiodegradability of poly(ß‐propiolactone) (PPL), one of biodegradable plastics, was tested in a bench‐scale composting reactor under controlled conditions, with uniform temperature, moisture content, and aerobiosis maintained. The composting raw mixture was prepared by mixing commercial dog food instead of real organic waste, saw dust as a bulking agent, commercial inoculum sold for acceleration of composting, and PPL in the ratio of 10:9:1:10 on dry weight basis. The degree and rate of PPL degradation were determined by comparing the difference in the CO2 evolution for composting with and without addition of PPL. The influence of temperature on the degradability of PPL was investigated at 40, 50, and 60 °C and the optimum temperature was found to be around 40‐50°C where ca. 40 wt.‐% of PPL was decomposed in 8 days. The effect of inoculum on the degradability of PPL during 50 °C composting was then examined, a considerable difference (100%) being observed in the biodegradability using two different inocula.
Ecological and economical aspects of polymer recycling
Authors: Brandrup Johannes 
Published: March 2011

AbstractRecycling is considered to play an essential role in developing a sustainable economy. A restrictive environmental legislation has forced German economy into extensive recycling activities. Meanwhile, German society and German industry have more than six years of practical experience with recycling of postconsumer plastic waste from household packaging due to this legislative situation. It is time to critically evaluate the situation. This paper summarizes the development in Germany and tries to show ecological impacts based on a life‐cycle analysis and correlates these data with economical consequences.
Chlorinated products of plastic pyrolysis
Authors: Blazsó Marianne 
Published: March 2011

AbstractThe formation of various chlorinated products in pyrolysis of polymers and plastics additives was studied. Formation of chlorobenzenes (in addition to the monomers) from poly(chlorostyrene) and poly(vinylbenzyl chloride) was observed. Hydrogen chloride is only produced from these polymers at above 600 °C when the chlorine atoms are cleaved off and abstract hydrogen. A similar process takes place in aromatic chlorine‐containing dyes, in which the strong aromatic molecular structure prevents the thermal cleavage of chloroaromatic volatile products. We have observed that cupric and ferric chlorides chlorinate phenolic thermal decomposition products of plastic materials which originate either from the polymer or from the stabilizer. The highest yields of chlorophenols are obtained in pyrolysis at around 700 °C.
Rubber recycling
Authors: Schnecko H. 
Published: March 2011

AbstractThe report summarizes the present situation on elastomer recycling with emphasis on tires. In the introduction it outlines the differences to other polymers and gives a global breakdown of present scrap tire volumes. It then specifies the various areas and possibilities of recycling, viz, reduction, reuse (retreading), rubber crumb manufacture and use, reclaim, recover, i.e. pyrolysis, hydrogenation and conversion to energy. Finally, landfills and biodegradation are touched on.
Study of cooperative effects of silanols on modified silica by dielectric relaxation method
Authors: Alekseev A. N. , Zaitsev V. N. , Alekseev S. A. , Pecheny A. B. 
Published: March 2011

AbstractTwo types of chemically modified silica gels with covalently bonded hydrophobic (alkyl, SiO2‐C8) and hydrophilic (aminoalkyl, SiO2‐NH2) groups were studied by dielectric relaxation method. For SiO2‐C8 two relaxation maxima were detected at 140 and 238K. From comparison with bulk silica the lower temperature maximum was assigned to cooperative re‐orientation of residual silanols and higher one to melting of physically adsorbed water. Both maxima are much weaker for SiO2‐C8 then for bulk silica. In Arrhenius coordinates relaxation at 238K exhibits similar behavior as OH groups in polyvinyl alcohol and so it was assigned to mobility of orientation defects in mono‐dimensional chain of physically adsorbed water. For SiO2‐NH2 no low temperature relaxation effect was observed. Intensive relaxation was measured at 248 K only. Strong interaction between supramolecules of silanol groups, bonded aminogroups and adsorbed water was assumed.
Observation and simulation of PbS nonocrystal formation at the initial steps
Authors: Gurin Valerij S. 
Published: March 2011

AbstractUltrafine lead sulfide clusters are produced by the reaction of long‐chain thiols with lead ions in non‐aqueous medium, and according to X‐ray diffraction (XRD) data reveal the different steps of he bulk‐like rocksalt lattice growth. XRD pattern is simulated by the Debye formula for four model clusters (27, 75, 125, 729 atoms) and the correspondence of model and experimental clusters is shown that allows to estimate their size. Ab initio MOLCAO calculations result in energetical parameters and charge distribution for the clusters with 27 atoms. The value of energy gap indicates the true tendency of variation for the clusters of different size but left yet higher than maxima in the optical absorption at the fixed steps.
Formation of langmuir‐blodgett films containing two‐dimensional monoatomic arrays of rare‐earth cations
Authors: Khomutov Gennady B. 
Published: March 2011

AbstractThe work is focused on the preparation and characterisation of rare‐earth containing stearic acid Langmuir‐Blodgett (LB) films. Stearic acid monolayer behavior on the rare‐earth containing aqueous subphase have been analyzed by thermodynamic measurements. The compression isotherm shape changed substantially under varying the anion type at the constant rare‐earth cation content in aqueous subphase. The structure of formed multilayer rare‐earth containing LB films was studied using small angle X‐rays diffraction. The considerable structural defects in multilayer films were found when rare‐earth chloride solution was exploited as aqueous subphase, caused presumably by electrostatic interactions at the monolayer surface under high binding of rare‐earth cations. The use of monodentate complexones like acetic acid was proposed to form bulk phase quasi‐neutral rare‐earth complexes. The electroneutral ligand exchange reactions of such complexes with stearic acid monolayer allowed to neutralise monolayer surface under rare‐earth cations binding and to form condenced monolayer below the triple‐point temperature. The compression of such monolayer to the state of minimal compressibility and subsequent monolayer deposition resulted in the formation of high ordered LB films with high content of adsorbed multivalent rare‐earth cations arranged in two‐dimensional monoatomic arrays.
Stoichiometry effects in gaAs epitaxy for ballistic tunneling semiconductor devices
Authors: Nishizawa Jun‐Ichi , Kurabayashi Toru 
Published: March 2011

AbstractThe effect of stoichiometry on various features of III‐V compounds are investigated. It is shown experimentally that the optimum vapor pressure of V elements minimizes the deviation from the stoichiometric composition. Vapor pressure control technology is applied not only to the liquid phase epitaxy and bulk crystal growth but also to the surface reaction in molecular layer epitaxy.The surface reaction and kinetic phenomena of GaAs mono‐molecular layer growth by using chemical adsorption of Ga(CH3)3 (trimethyl gallium: TMG) and arsine (AsH3) was investigated. The growth feature was strongly influenced by the surface stoichiometry of arsenic during growth. For example, the diffusion of the doped impurity is affected by the AsH3 amount of supply, the diffusion was prevented by controlling the stoichiometry. The control of stoichiometry was examined systematically and was applied for the device fabrication such as ballistic transistor.
Thiol‐stabilized CdSe and CdTe nanocrystals in the size quantization regime: Synthesis, optical and structural properties
Authors: Rogach Andrey L. , Eychmüller Alexander , Kornowski Andreas , Weller Horst 
Published: March 2011

AbstractWe report on the recently developed method for the synthesis, optical, and structural properties of CdSe and CdTe nanocrystals. They were formed in aqueous solutions at moderate temperatures by a wet chemical route in the presence of thiol molecules as effective stabilizing agents. The size‐selective precipitation technique was applied for the post‐preparative nanoparticle fractionation into a series of CdSe and CdTe nanocrystals with extremely narrow size distributions exhibiting mean cluster sizes in the range of 2 to 4 nm. The nature of stabilizing agent (mercaptoalcohols and mercaptoacids) had an important influence on the particle size and determines largely the photoluminescence properties. The nanocrystals were characterized by means of UV‐vis absorption and photoluminescence spectroscopy, X‐ray diffraction, and high resolution transmission electron microscopy (HRTEM).
Evaluation of bonded layer disorder from thermodynamic behavior of methylaminopropyl groups immobilized on sio2
Authors: Zaitsev V. N. , Oleynik V. D. , Budarin V. L. 
Published: March 2011

AbstractThermodynamic characteristics of reaction between proton and methylaminopropyl groups that are covalently bonded to silica gel surface were calculated. First evidence of short‐distance interaction between neighboring bonded amines was obtained. Addition of the first proton does not destroy such interaction. Second proton promotes significant geometry changing.
Photochemical synthesis of colloidal metals
Authors: Loginov Anatol V. , Boitsova Tatiana B. , Gorbunova Valentina V. 
Published: March 2011

AbstractNew photochemical method for preparation of colloidal metal particles (Cu, Ag, Au) as a films on the quartz surface and colloidal dispersion in different matrixes has been devised. Possibilities to control the properties of photogenerated colloidal metal particles are discussed.
Synthesis and polymerization of the 16‐(methacryloyloxy)‐hexadecanoic acid and phospholipid in monolayers
Authors: Baryshnikova Elena A. , Sergeeva Tatjana I. , Novikova Olga S. , Zubov Vitaly P. , Zaitsev Sergei Yu. 
Published: March 2011

AbstractTwo surface‐active monomers with methacrylic group at the end of hydrophobic tail: 16‐(methacryloyloxy)hexadecanoic acid (16‐MAHDA) and bis[16‐(methacryloyloxy)hexadecanoil]‐phosphatidylcholine (16‐MAHDPC) have been synthesized and investigated. The monomers form stable monolayers at the liquid/gas interfaces with liquid‐expanded and liquid‐condensed states at low and high surface pressures, respectively. These monomers have been polymerized in the monolayers by low intensity UV‐irradiation (254 nm). Dependences of polymerization rate vs. surface pressure for both monomers have maxima (3.4. 10−4 s−1 for 16‐MAHDA and 5.5.10−4 s−1 for 16‐MAHDPC) at about 12 mN/m. The higher rate of 16‐MAHDPC polymerization as compared to 16‐MAHDA is due to the two polymerizable group in the molecule of lipid as compared to the only one in the molecule of acid. The collapse pressures increase after monomer polymerization that evidences an increase of the monolayer stability in the case of polymer as compared to monomer.
Research of properties of polyfunctional polymeric films
Authors: Ostrovidova G. U. , Makeev A. V. , Zamyslov E. V. , Richter A. , Terukov E. I. 
Published: March 2011

AbstractAt present the problem of creating materials for medical application, which possess surface thromboresistant and antiseptic properties is of the great importance. The method of creating hydrogel films, containing anticoagulants, biologically active and antiseptic substances on the surface of well‐known polymers of medical purity allows to give their surface special functions and properties and to retain the good mechanical properties [1,2]. In the majority of cases, the methods which are used for the creation of such films have a limitations which impede their wide application as they do not allow to obtain surface layers, possessing different medico‐biological and physic‐chemical properties.The aim of our research was the electroformation of biocompatible, polyfunctional poly(vinyl alcohol) (PVA) films with immobilizied anticoagulant, enzyme and antibiotic on the surface of a composite material on the base of polysiloxane of medical purity [3,4].
Driving dendrimers with light: Dendrimers with azobenzene central linkers
Authors: McGrath Dominic V. , Junge Denise M. 
Published: March 2011

AbstractSeveral new classes of azobenzene‐containing dendrimers have been prepared and characterized. Three central linker azobenzenes, p‐(pî‐hydroxyphenylazo)phenol (A), aniline p‐(p'‐chlorocarbonylphenylazo)benzoyl chloride (B), and p‐(pî‐aminophenylazo) (C) were reacted with the appropriate dendritic fragment ([Gn]Br for A and C; [Gn]OH for B) to yield dendrimers 1–3 of varying generational size. The photoresponsive characterization of these dendrimers illustrates the insensitivity of the photoresponsive behavior of the azobenzene with respect to the nature of the attached dendritic fragment.
Photosensitive chiral polyisocyanates
Authors: Mayer Sabine , Maxein Georg , Zentel Rudolf 
Published: March 2011

AbstractThe dynamic polyisocyanate helix amplifies changes in the conformation of its side groups. Thereby it acts like a fast responding switch for optical properties. Here we show how the photoisomerization of chiral azo side groups can be used to induce large changes of chirooptical properties. These changes can be detected by CD measurements or by ORD measurements far from the absorption region. Large changes of the optical rotation can be induced reversibly in a multicycle process.
All‐optical manipulation of azo‐dye molecules
Authors: Fiorini Céline , Prudhomme Nicolas , Etilé Anne‐Catherine , Lefin Philippe , Raimond Paul , Nunzi Jean‐Michel 
Published: March 2011

AbstractA challenging issue in the field of the design of devices for photonic applications is to achieve complete manipulation of the molecular order. Azo‐dye aromatic polymers have been shown to offer interesting prospects for material engineering using light matter interactions. Dual‐frequency irradiation using appropriate combinations of circular beams polarizations are demonstrated to enable full control of the molecular polar rotation. More recent results on photoinduced surface‐relief gratings have also opened the way of molecular translation control using optical fields. Understanding of the relevant parameters of molecular translation processes is a key issue for optimization of such an optomechanical effect: a simple model accounting qualitatively for the essential features of photoinduced surface‐relief gratings will be presented.
Thermally stable photoaligned p‐cyanoazobenzene moieties in polymer thin films
Authors: Ichimura Kunihiro , Kidowaki Masatoshi , Fujiwara Takenori 
Published: March 2011

AbstractPoly(4‐cyano‐4î‐methacryloyloxyazobenzene) displayed a slow E‐to‐Z photoisomerization rate and a low Z‐isomer content at a photostationary state in a film. Linearly polarized 436 nm light irradiation resulted in the gradual generation of dichroism due to the reorientation of the azobenzene chromophores. The photodichroism was enhanced markedly by heating the film and not deteriorated even at 240 °C. Discussion was made on the thermally enhanced photodichroism of the polymer with p‐cyanoazobenzene side chains in respect to its semi‐crystallinity.
Dynamics of photoinduced orientational order of azo‐dyes in polymer films
Authors: El Osman Ahmad , Dumont Michel 
Published: March 2011

AbstractDynamical and spectral behavior of photoassisted electrical poling and photoinduced anisotropy are studied in films of DR1‐doped PMMA, DR1‐PMMA copolymer and new DR1‐Polyimide copolymer. The orientational mobility of DR1 is characterized both in ordering processes (angularly selective trans‐cis photoisomerization) and in disordering relaxation processes. Mobility is increased by the photoisomerization and decreases slowly with time, after the end of optical pumping. The transient dichroism recorded simultaneously on six probe wavelengths shows a spectral inhomogeneity of the absorption band of DR1 and of the photoinduced anisotropy (particularly in polyimide films).
Polarized light‐induced anisotropy depending on polymer matrices studied by polarized ftir spectroscopy
Authors: Tawa Keiko , Kamada Kenji , Sakaguchi Toru , Ohta Koji 
Published: March 2011

AbstractPolarized‐light induced anisotropy of Disperse Orange 3 (DO3) depending on the polymer matrices was investigated by polarized FTIR spectroscopy. The dynamic behavior of the azo dyes doped in a series of methacrylate polymers was analyzed in terms of the orientation factors. Two factors, the free volume and the local polarity of matrices, are found to govern the dynamic behavior of DO3. It was found that induced anisotropy for trans and cis isomers varies depending on Tg of polymer matrix. Further, the thermal isomerization rate depend on the isomerization mode which is governed by the matrix polarity. The branched‐alkyl chains are considered to block the interaction between ester groups and DO3 and introduce the DO3 molecules into the less polar environment.
Modelling of molecular interactions and inclusion phenomena in substituted β‐cyclodextrin: From simple probes to proteins
Authors: Miertus S. , Chiellini E. , Chiellini F. , Kona J. , Tomasi J. , Solaro R. 
Published: March 2011

AbstractThe ability of β‐cyclodextrin (βCD) to form stable complexes with α‐interferon was investigated. By using simple molecular mechanics approach interaction energy profiles of simple probes passing the center of βCD ring cavity along the main molecular symmetry axis were evaluated first. A computational study of host‐guest inclusion complexes between βCD and L‐α‐aminoacids and some selected pentapeptides was also carried out and aimed at understanding the nature of the driving forces and mechanism, leading to their formation. Relative complexation energies for the complexes and the solvation Gibbs free energies for single L‐α‐aminoacids were calculated. Both the aminoacid residue inside the βCD cavity and neighbouring residues were found to contribute to the stabilization of βCD complexes with the side‐chain of aminoacids present on the surface of α‐interferon. The most appropriate number of host βCD molecules for the encapsulation in the first shell of one α‐interferon molecule resulted to be 25.
Crystal structure of poly(ethylene‐oxide) supramolecular assemblies
Authors: Damman Pascal , Paternostre Laurent , Moulin Jean‐François , Dosière Marcel 
Published: March 2011

AbstractThe formation of poly(ethylene oxide) (PEO) supramolecular complexes is discussed in terms of intermolecular interactions and molecular packing. On the basis of the different known crystal structures, several mechanisms are proposed. First, the PEO complexes can be formed by an Intercalation or Inclusion process, guest molecules diffusing into the PEO unit cell. On the other hand, molecular complexes based on hydrogen bonding cannot be obtained by such a way, their formation requires the complete removal of the initial PEO structure either by melting or dissolution. Finally the relations between the crystal lamellar morphology, the host‐guest interactions and the PEO chain mobility are discussed.
Water sorption and protonic conductivity in a filled/unfilled thermostable ionomer for proton exchange membrane fuel cell
Authors: Baradie B. , Poinsignon C. , Sanchez J. Y. , Piffard Y. 
Published: March 2011

AbstractA filled ionomeric membrane is achieved by dispersing several % in weight of the phosphatoantimonic acid H3Sb3P2O14, xH2O (H3), in a Sulfonated PolySulfone (SPS) solution1). Water up‐take of pristine and filled SPS of different cation exchange capacity (cec) was measured at 25°C and 80°C: It is higher for filled than unfilled membrane. Comparatively, protonic conductivity measurements performed on the same samples show a higher conductivity for the filled samples than for the unfilled. The conductivity value is higher than that expected from the overall calculated concentration in charge carriers: A conductivity value of 0.06 S.cm−1 is gained at 80°C under 100% Relative Humidity (HR) for a 1.4 meq.g−1 cec SPS filled with 8% in H3.
Development and characterization of PPO composite membranes for gas separation
Authors: Bove Lucia , Clarizia Gabriele , Golemme Giovanni , Drioli Enrico 
Published: March 2011

AbstractPoly(phenylene oxide) (PPO) composite membranes have been prepared on a polysulfone (PSf) ultrafiltration support, which was previously coated with highly permeable polydimethylsiloxane (PDMS). The PDMS gutter layer was used in order to: Plug the pores of the support; minimise the thickness of the separating PPO deposit; and reduce the tortuosity of the path of the gas molecules to the pores of the support.Composite membranes with high fluxes and good selectivities for gas separations have been obtained with an amorphous and cross‐linkable phenylene oxide co‐polymer.