bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recycling of cheap packaging waste versus expensive engineering materials
Authors: Karlsson Sigbritt , Albertsson Ann‐Christine 
Published: March 2011

AbstractThe economical incitement is larger for recycling of expensive engineering materials than for packaging plastics. It should, however, be possible also for municipal waste industry to profit from recycling of packaging waste. At present, municipal waste plants already sell sorted plastics fractions on the order basis. The degree of mixing of these plastic fractions is the key question to be solved in order to obtain a high‐quality product. The value of recycled HDPE fraction is lowered if it contains impurities of other polymers, e.g. PP, PS or PET because such impurities cause embrittlement. An addition of an impact modifier to contaminated HDPE was analyzed with respect to changes in morphology and mechanical properties. Oxidative stability of the polymer matrix decreased as a result of recycling, indicating decomposition of heat stabilizers, as shown for polyamide 66. The relation between expensive/cheap recycled plastics is discussed based on their long‐term properties.
The origin and role of structural inhomogeneities and impurities in material recycling of plastics
Authors: Pospíšil Jan , Horák Zdenêk , Kruliš Zdenêk , Nešpůrek Stanislav 
Published: March 2011

AbstractCharacteristics of aged polymers intended for material recycling are emphasized. Specific material properties of aged recyclates, containing new functional groups formed during processing and first‐life application (structural polymer inhomogeneities) and metallic compounds, pigments or compounds generated from additives (non‐polymeric impurities), are considered from the point of view of their influence on the aging resistance in the second‐life applications. Chemical transformations of the polymer matrix together with consumption of stabilizers deteriorate material properties of collected waste plastics in reprocessing and subsequent outdoor applications.
Polymer recycling: Thermodynamics and economics
Authors: Stein Richard S. 
Published: March 2011

AbstractPolymer recycling must conform to thermodynamic laws and economic restrictions. The objective of polymer recycling is twofold: (1) the reduction of rubbish and the burden of waste polymers on the environment, and (2) the conservation of resources. The environmental burden should be considered as part of the cost for employing polymers. Polymer input to landfills can be reduced by source reduction, materials substitution, recycling, incineration, and/or degradation or reduction to low molecular weight compounds. While the value of separated polymers is considerably greater than that of commingled ones, the separation is often difficult and requires an energy investment for “demixing”. With present technology, this has not been justified for more than about 25% of the polymer waste feedstock. For the rest, energy recovery through incineration appears to be the thermodynamically and economically sensible route.
Purification and monolayer study of the thylacoid lipids of moss marchantia polymorpha
Authors: Zaitsev Sergei Yu. , Volchenkova Tatjana A. , Kalabina Nadezda A. , Schaefer Christian , Zubov Vitaly P. 
Published: March 2011

AbstractThe original lipid content of the thylakoid membranes of moss Marchantia polymorpha has been determined for the first time. In particular, the content of SQDG is almost 3 times higher than those for both of the other classes. The ratios for DGDG and MGDG are just a little bit lower than those for green algae, but almost 2 times less than those for plants. The distribution of unsaturated bonds has changed in C18 ‐residues of fatty acids. The total content of C18‐residues in thylacoid lipids have been almost the same but the content of C18:1, C18:2 and C18:3 are altered in the fractions of DGDG, PG and PE. The light stress produces only the quantitative, but no qualitative, changes of the thylakoid lipid composition. The properties of the thylakoid lipids and corresponding fatty acids in the monolayers at the liquid/gas interfaces have been studied. The changes in distribution of unsaturated bonds in C18 residues of fatty acids at light stress have been confirmed by Langmuir method.
A Raman confocal microspectroscopic study on azopolymer holographic diffraction gratings: Photo‐ and mass transport‐induced effects on the molecular orientation
Authors: Labarthet F. Lagugné , Buffeteau T. , Sourisseau C. 
Published: March 2011

AbstractUsing the confocal microspectrometric technique we have recorded various resonance enhanced polarized Raman spectra from the surface profile of a permanent holographic diffraction grating prepared by interfering two circularly contra‐rotating polarized laser beams on a thin amorphous copolymer film containing azobenzene moities (pDRIM‐co‐MMA). Different theoretical equations of the Raman scattering intensities, including a treatment taking account for the effect of the high numerical aperture objective, are thus derived. Calculations and simulations of these equations allow for the first time to extract the second <P2> and fourth <P4> coefficients of the chromophore orientation function in the various regions and to obtain the corresponding information entropy distribution functions. We then discuss both contributions of the photo‐ and mass transport‐ induced effects in the grating formation mechanisms and confirm the existence of a significant dye concentration gradient (δN/N = 5.1±1.1%) in between the top and bottom regions. All the results are consistent with the model of a viscoelastic flow of the polymer involving large pressure gradients and translational diffusion dynamics.
Water‐polysaccharides interactions during apples drying process
Authors: Barra G. , Di Matteo P. , Lamanna R. , Limone G. , Osséo L. Sesti , Vittoria V. 
Published: March 2011

AbstractIn this work the state of water in samples of a food (apple) during the drying process was analyzed.Low resolution NMR, differential scanning calorimetry (DSC) and sorption measurements were performed on differently dried samples.It was possible to correlate the NMR proton relaxation time to the water activity aw=P/P0, in order to have an independent method for measuring this parameter. The calorimetric curves showed the thermal transitions of different water populations and the sorption measurements on dry apple gave the fraction of water tightly bond to the structure, which resulted about 30%.
Effect of polymer‐plasticizer interactions on the oxygen permeability of starch‐sorbitol‐water films
Authors: Gaudin S. , Lourdin D. , Le Botlan D. , Ilari J. L. , Forssell P. , Colonna P. 
Published: March 2011

AbstractThis study evaluated the oxygen permeability (O.P.) of starch‐sorbitol‐water films produced by casting. With a sorbitol content <20%, O.P. (0.15 10−16 cm2/s.Pa for 8.8% sorbitol) was lower than for other polymers classically used as oxygen barriers. With a sorbitol content >20%, O.P. (1.6 10−16 cm2/s.Pa for 24.9% sorbitol) was higher than for starch films without a plasticizer. These results were correlated with molecular mobility as determined by time‐domain NMR. Low and high O.P. corresponded respectively to a decrease and an increase of molecular mobility relative to sorbitol content.
Micro‐ and macro‐phase behavior in protein‐polyelectrolyte complexes
Authors: Mattison Kevin W. , Wang Yingfan , Grymonpré Kris , Dubin Paul L. 
Published: March 2011

AbstractNegatively charged polyelectrolytes such as carboxymethylcellulose, pectin, and alginate are commonly present in food products. These polyelectrolytes serve a variety of functions such as controlling viscosity and stabilizing emulsions. Proteins are also present in many food formulations. Because of their high charge density, polyelectrolytes can be expected to interact with these proteins. Hence, an understanding of the parameters controlling protein‐polyelectrolyte interactions is useful.
Spatially resolved NMR in polymer science
Authors: Blümich Bernhard , Blümler Peter , Gasper Lothar , Guthausen Andreas , Göbbels Volker , Laukemper‐Ostendorf Simone , Unseld Klaus , Zimmer Gisela 
Published: March 2011

AbstractSelected applications of spatially resolved NMR are presented, which demonstrate the use of the method for investigating applied topics relevant to polymer and materials science. Examples are given for imaging of rigid, soft, and fluid matter. They include characterization and interpretation of electrical aging in poly(ethylene), cross‐link density at the interface of covulcanized elastomer sheets, and cross‐filtration in hollow‐fiber filter modules. A novel NMR detector, the NMR‐MOUSE, has been developed for process and quality control by relaxation measurements. Its use for non‐destructive determination of the glass‐transition temperature by room temperature measurements on elastomer samples is demonstrated.
Materials analysis using confocal Raman microscopy
Authors: Sammon Chris , Hajatdoost Sohail , Eaton Peter , Mura Carine , Yarwood Jack 
Published: March 2011

AbstractThe recent development of Raman microscopes with high optical throughput and very sensitive CCD cameras has led to Raman spectroscopy again competing effectively with FTIR methods for materials analysis. Modern Raman instruments, designed to operate confocally without serious alignment or energy trade‐off problems, allow depth profiling of optically transparent polymers and polymer matrices to be routinely obtained with a spatial resolution of 1–2 μm. The use of such an instrument is illustrated by describing recent work on polymeric material problems including,1 The distribution and redistribution of small molecules in polymeric matrices.2 The monitoring of adhesion primer diffusion at a polymer/silica interface.3 The determination of the extent of interdiffusion and interaction at a polymer/polymer interface.4 A comparison of confocal and micotoming approaches to polymer laminate analysis.The range of possible applications is increasing rapidly. It is clear that Raman microscopy will become a very important tool for future materials analysis, both in the polymer area and many other areas.
Perfectly branched and hyperbranched poly(ether amide)s
Authors: Huber Thomas , Voit Brigitte , Wolf Dieter 
Published: March 2011

AbstractPoly(ether amide) dendrimer segments based on 5‐(2‐aminoethoxy)‐isophthalic acid have been synthesized using the convergent approach and mild reaction conditions. The monodendrons were combined to dendrimers via different core molecules and the resulting properties of the molecules were compared to those of the monodendrons. The melt polycondensation of the AB2 monomers with analog structure resulted first in undefined polymer structures. However, by thermal polyaddition reaction of suitable functionalized oxazoline monomers, well defined hyperbranched poly(ether amide)s with phenol terminal groups could be synthesized.
A new photobase generator containing oxime‐urethane group and its application
Authors: Chae Kyu Ho , Jang Du‐Jeon 
Published: March 2011

AbstractPhotochemical base formation from oxime‐urethane derivatives was observed via pH changes, GC and HPLC analysis, and laser flash photolysis study. Photolysis of these derivatives results in the formation of amines which induce cross‐linking of poly(glycidyl methacrylate) (PGMA) upon heating. Photocross‐linking reaction of the copolymers, containing epoxy and oxime‐urethane groups, were studied by measuring the insoluble fraction of copolymer films under various reaction conditions. Thermal cross‐linking reaction of the copolymer was catalysed by the photogenerated pendant amines. The copolymer containing oxime‐urethane groups which photogenerate aromatic amines can be utilized as an image recording material.
Structure and dynamics of silk fibroin studied with 13C, 15N and 2H solid state NMR
Authors: Asakura Tetsuo , Demura Makoto 
Published: March 2011

Abstract[1‐13C]Gly, L‐[1‐13C]Ala, [15N]Gly, L‐[15N]Ala, [2,2‐2H2]Gly, L‐[3,3‐2H2]Ser and [3,3,3‐2H3]Ala labeled silk fibroin fibers from Bombyx mori and Samia cynthia ricini silkworms were prepared in order to analyze structure of backbone and dynamics of side chain. The torsion angles ϕ and Ψ were determined from the angular dependent 13C and 15N solid state NMR spectra for uniaxially oriented fiber samples. In addition, the characteristic side chain dynamics of Ser residue determined from solid state 2H NMR measurements was compared with those of Ala and Gly residues.
Hyperbranched aramids by direct polyamidation of two reactant systems: Synthesis and properties
Authors: Russo Saverio , Boulares Alya , Da Rin Andrea , Mariani Alberto , Cosulich Maria Elisabetta 
Published: March 2011

AbstractSome A2 + B3 and A3 + B3 reagent pairs have been used for the direct polyamidation reaction leading, besides the network formation, to hyperbranched aramid structures. Depending on the chosen experimental conditions, variable amounts of a sol fraction having close similarities with the hyperbranched aramid structures derived from the polyamidation of AB2 monomers, have indeed been obtained. Solubility of the sol fraction in various organic solvents, as well as its thermal properties and its capability of enzyme fixation, have been determined for the various systems under investigation. Future developments are envisaged.
The diffusion of alcohols and water in polyamide 11: A study by fourier‐transform near‐infrared spectroscopy
Authors: Wu Peiyi , Siesler Heinz W. 
Published: March 2011

AbstractThe diffusion of different deuterium‐labeled (OD) low‐molecular‐weight alcohols and D2O in polyamide 11 (PA11) has been investigated by monitoring the NH/ND‐exchange in the polymer by Fourier‐Transform near‐infrared (FTNIR) spectroscopy. The results demonstrate that the diffusion process of the different penetrants is strongly controlled by their molecular structure and geometry. To characterize this phenomenon quantitatively, the diffusion coefficients for the different deuteration agents have been determined for PA11. Furthermore, it could be shown that with this technique the less ordered regions of the polymer can be separated spectroscopically from the crystalline domains which are not accessible for the isotopically labeled diffusants.
Degradation of oligo(lactone) branches linked to poly(methacrylate) networks
Authors: Seidel Peter , Sandner Barbara , Gopp Udo , Schöch Martin , Steurich Simone , Santerre J. Paul 
Published: March 2011

AbstractPartially resorbable composite materials were developed for bone applications and were prepared by crosslinking copolymerization of oligo(lactone) macromonomers with selected comonomers in the presence of hydroxy apatite. The composites were incubated in aqueous solution of different pH and electrolyte content over a period up to 300 days. The percentage of the released hydroxycarboxylic acid from the oligo(lactone) branches was determined by the titration or by high performance liquid chromatography (HPLC). A catalytic influence of cholesterol esterase (CE) on the hydrolysis of the materials was observed. Determination of CE activity in the presence of the different composite materials showed that the half‐life time of CE was the lowest in the presence of the material undergoing the fastest degradation. After degradation the composite materials have preserved their coherence and have shown higher glass transition temperatures in the dried state than the materials before degradation.
Kinetics and mechanism of biodegradation of (co)polyglycolide sutures
Authors: Belenkaya Bronislava G. , Sakharova Valentina I. , Sinevich Eugene A. , Belousov Sergej I. , Kuptsov Albert H. , Chvalun Sergei N. 
Published: March 2011

AbstractBiodegradation in vivo of modified and unmodified PG (polyglycolide) and PGL (copolymer glycolide — L — lactide) monofilament sutures were studied using 1H‐ NMR, wide and small angle X‐ray scattering, differential scanning calorimetry (DSC), electron microscopy (EM), Fourier transform (FT) Raman spectroscopy methods. It was found that the process includes a steady‐state and accelerated stages of biodegradation. The suture biostability depends on polymer morphology changing widely over the suture draw ratio. The modification of polymer chain results in an increase in suture useful lifetime without significant changes of complete polymer degradation time. It was also established the important role of weak intermolecular hydrogen bonds such as CH–‐O=C in the suture stability.
New catalysis for fast bulk ring‐opening polymerization of lactide monomers
Authors: Degée Philippe , Dubois Philippe , Jérǒme Robert , Jacobsen Sven , Fritz Hans‐Gerhard 
Published: March 2011

AbstractThe ring‐opening polymerization of lactides has been studied in bulk using either 2‐ethylhexanoic acid tin(II) salt, Sn(Oct)2, or aluminum triisopropoxide, Al(OiPr)3, as the initiator over a wide range of temperature and monomer‐to‐initiator molar ratio. A high increase in the bulk polymerization rate has been observed when the initiator was added with an equimolar amount of a Lewis base, such as triphenylphosphine (P(φ)3) and 4‐picoline (C6H7N) added to Sn(Oct)2 and Al(OiPr)3, respectively. Melt stable polylactides of high molecular weight and reasonably narrow molecular weight distribution have been accordingly prepared. The use of the Sn(Oct)2.P(φ)3 equimolar combination has allowed for reaching an acceptable balance between propagation and depolymerization rates, so that the polymerization is fast enough to be performed through a continuous single‐stage process in a twin‐screw extruder. A global activation mechanism is proposed and discussed by comparison with both investigated initiation systems.
Degradation of polyethylene containing ferric salt and starch
Authors: Gao Jianping , Wang Shaomin , Yu Jiugao , Lin Tong , Wang Xiaodong 
Published: March 2011

AbstractThe degradation of polyethylene containing four different ferric salts was compared, using remaining percentage elongation at break as a parameter; and the degradation process was also evaluated with carbonyl index, or with the formation and concentration of hydroperoxide groups. Starch can act as a synergist during the photodegradation of ferric contained PE film. X‐ray photoelectroscopy analysis shows that part of ferric ions turned into ferrous ions during the degradation process because of the redox reaction of ferric ions with oxygen. When stabilizer was added, the changes from ferric ions to ferrous ions decreased. If the PE samples were exposed to high pressure mercury lamp in the atmosphere of nitrogen gas, the absorption peaks of carbonyl group was not found in IR spectra after several days exposure.
Conformational changes in proteins at interfaces: From solution to the interface, and back
Authors: Norde Willem , Giacomelli Carla E. 
Published: March 2011

AbstractAfter adsorption, polymer molecules, including proteins, undergo conformational relaxation. It involves a certain degree of spreading of the polymer molecule over the sorbent surface. Adsorption kinetics experiments reveal that the characteristic time of spreading is much longer for globular proteins than for highly flexible polymers. Based on differential scanning calorimetry it is concluded that the degree of spreading of protein molecules decreases with increasing rate of covering the surface with the protein. It is furthermore inferred that the relaxation does not proceed gradually but rather in steps. According to circular dichroism spectra the relaxed protein molecules still contain a large fraction of ordered structure. As a rule, protein molecules that, by homomolecular exchange, are released from the surface re‐adopt their original structure; however, an exception to this rule is reported.
Intra‐ and inter‐chain fluctuations in entangled polymer melts in bulk and confined to pore channels
Authors: Kimmich Rainer , Fatkullin Nail , Seitter Ralf‐Oliver , Fischer Elmar , Beginn Uwe , Möller Martin 
Published: March 2011

AbstractIt is known that topological restraints by “chain entanglements” severely affect chain dynamics in polymer melts. In this field‐cycling NMR relaxometry and fringe‐field NMR diffusometry study, melts of linear polymers in bulk and confined to pores in a solid matrix are compared. The diameter of the pore channels was 10 nm. It is shown that the dynamics of chains in bulk dramatically deviate from those observed under pore constraints. In the latter case, one of the most indicative signatures of the reptation model is verified 28 years after its prediction by de Gennes: The frequency and molecular mass dependencies of the spin‐lattice relaxation time obey the power law T! ∝ M0 v3/4 on a time scale shorter than the longest Rouse relaxation time τR. The mean squared segment displacement in the pores was also found to be compatible to the reptation law < r2>∝ M−1/2t1/2 predicted for τR < t < τd, where τd is the so‐called disengagement time. Contrary to these findings, bulk melts of entangled polymers show frequency and molecular mass dependencies significantly different from what one expects on the basis of the reptation model. The data can however be described with the aid of the renormalized Rouse theory.
Ion aggregation in polymer gels
Authors: Philippova Olga E. , Khokhlov Alexei R. 
Published: March 2011

AbstractThis brief review deals with our early experimental studies of ion aggregation in polymer gels proceeding via the condensation of counterions on the oppositely charged monomer units of the network with the formation of ion pairs and their clustering into multiplets. The two particular cases of the emergence of ion aggregates are considered: (a) for monovalent counterions in media of low polarity and (b) for multivalent counterions in water.
Load separation principle in determination of J‐R curve for ductile polymers: Suitability of different material deformation functions used in the normalization method
Authors: Bernal Celina , Rink Marta , Frontini Patricia 
Published: March 2011

AbstractThe load separation principle states that the load, P, can be represented as the multiplication of two independent functions: A crack geometry function, G(a), and a material deformation function, H(v). The principle constitutes the theoretical basis for the single‐specimen J‐integral experiment and the incremental calculation of J‐integral crack growth resistance (J‐R) curves. The normalization method is a new method, which assumes load separation and uses characteristic deformation properties of materials to relate load, displacement and crack length in a functional form. From the deformation material function or “material key curve”, J‐R curve can be developed from a single precracking experiment. This investigation deals with the applicability of the load separation criterion to evaluation of ductile fracture mechanics parameters in rubber‐modified polystyrene, polypropylene, rubber‐modified PMMA, ABS resin and high‐density polyethylene in the bending configuration. Different mathematical relationships for the deformation function (power law function, LMN function and combined power law straight line relationship) have been proposed and compared. The resulting J‐R curves are in good agreement with those obtained by the traditional multiple‐specimen technique. The results presented here imply that the use of a single load‐displacement method for evaluation of J‐integrals for ductile polymers is possible and hence also the normalization method can be used for evaluation of J‐R curves from a single‐test record.