bluuebunny/crossref_metadata_2025_split huggingface dataset:
Targeting of an appropriate amylose type starch for specific product applications
Authors: Friedman Robert B. , Deboer Edward D. , Delgado Gregory A. , Furcsik Susan L. , Qvyjt Fernando , Tenbarge Frank L. 
Published: March 2011

AbstractSome varieties of maize are known to produce starches with different chemical and physical properties. These characteristics have been recognized over the years to provide different functional properties. Amylose, in particular, has been used to provide unique functionality in numerous applications where gel strength and rigidity, as well as film forming capability, have been desired qualities. In recent years, researchers have begun to recognize that amylose is not a single chemical substance, but rather a diverse group of glucans differing in molecular size, and branching characteristics. The main shared attribute of all “amylose” polymers is their common ability to bind iodine. This binding ability is still the basis for most routine amylose determination assays. We have shown that there are uniquely different amylose polymers, and our laboratory has reported on some of the differences in physical properties. This paper reports how these unique physical properties can be applied effectively to practical applications.
Branching ratios of starch via proton nuclear magnetic resonance and their use in determining amylose/amylopectin content: Evidence for three types of amylopectin
Authors: Dunn Larson B. , Krueger William J. 
Published: March 2011

AbstractThe branching (α‐1,4)/(α‐1,6) ratio of starch from a number of sources can be quickly and accurately determined by proton nuclear magnetic resonance (NMR). This NMR ratio, with standard ratios for isolated amylose and amylopectin, can then be used to determine the amylose/amylopectin content of starches. In the course of determining the amylose/amylopectin content of various starches, it was discovered that two different types of amylopectin standards were required to obtain results comparable to those obtained from iodine‐binding amylose determinations. These two types were a waxy amylopectin, with a high level of branching, and a potato amylopectin, with a lower level of branching. A third type of amylopectin, with a still lower level of branching, is apparently present in high amylose cornstarches, leading to the conclusion that starches with higher amylose contents generally contain amylopectin with a lower level of branching. The three amylopectin types are referred to as amylopectin I, II and III, with the higher numeral coinciding with higher branching (α‐1,4)/(α‐1,6) ratio, or less branching.
Latex film formation and dissolution: A fluorescence study
Authors: Pekcan Önder , Ugur Saziye 
Published: March 2011

AbstractA new technique based on steady state fluorescence (SSF) measurements is introduced for studying dissolution of polymer films. These films are formed from naphthalene (N) and pyrene (P) labeled poly(methyl methacrylate) (PMMA) latex particles, sterically stabilized by polyisobutylene (PIB). Annealing was performed above Tg at elevated temperatures for 30 min time intervals for film formation. Film formation from these latexes is monitored by the extent of energy transfer from N to P using SSF and by the transmitted photon intensity from these films using UV visible (UVV) methods. Desorption of P labeled PMMA chains was monitored in real‐time by the change of pyrene fluorescence intensity. Dissolution experiments were performed in various solvents with different solubility parameters, δ, at room temperature. Diffusion coefficients, D, in various solvents were measured and found to be around 10−10 cm2/s. Strong relationships between D and δ were observed. Diffusion activation energy was measured by performing dissolution experiments in toluene‐heptane mixtures at elevated temperatures and determined to be 24.4 kcal mol−1.
Synthesis and solution properties of rodlike polyelectrolytes
Authors: Wittemann Matthias , Kelch Steffen , Blaul Jürgen , Hickl Peter , Guilleaume Birgit , Brodowski Gisela , Horvath Andreas , Ballauff Matthias , Rehahn Matthias 
Published: March 2011

AbstractThe synthesis and the solution behavior of rigid, rodlike cationic polyelectrolytes having (i) poly(p‐phenylene) backbones and (ii) main chains composed of 4,4“‐bis(2,2′:6′,2”‐terpyridine)2′,5′‐dihexyl‐p‐terphenyl moieties and ruthenium(II) centers are presented. All these polymers are shown to have a homogeneous constitution and degrees of polymerization of up to Pn ≈ 70. Their solution properties were analyzed using viscosimetry, small‐angle X‐ray scattering (SAXS) and osmometry. Pronounced polyelectrolyte effects were found in salt‐free solutions using viscosimetry. Small‐angle X‐ray scattering demonstrated directly the strong correlation of the counterions and the macroions. The osmotic coefficients measured in salt‐free solution as function of polyelectrolyte concentration were found to be lower than predicted by the cell model.
Synthesis and properties of new aromatic polyimides — Polymeric materials for light‐emitting and liquid‐crystal displays
Authors: Ree Moonhor , Kim Sang Il , Pyo Seung Moon , Shin Tae Joo , Park Hong Ki , Jung Jin Chul 
Published: March 2011

AbstractNew aromatic diamines containing π‐conjugated heterocyclic rings were synthesized, which emit blue light in the photoluminescence. Using these new monomers, soluble poly(amic acid)s were prepared by the polycondensations with pyromellitamic dianhydride, and thermally converted to the polyimides in films which emit intense blue‐light. These polyimides are considered as potential candidate materials for fabricating optoelectronic devices which emit blue light. In addition, new poly(m‐phenylene 4,4′‐oxydiphthalimide)s containing various side chains were synthesized. For these polyimides, thermal properties were investigated with considering the chain flexibility of polymer backbone as well as the spacer and biphenyl mesogen end group in the side chains. In particular, these polyimides exhibited excellent performance in the rubbing process and the controlling of both the alignment and the pretilt of liquid‐crystal (LC) molecules in the LC cell. This might be attributed mainly to a strong interaction between the biphenyl mesogen end group in the side chains and the mesogen unit of LC molecules.
Fluorinated heteroaromatic polyethers for low dielectric constant / high temperature applications
Authors: Maier Gerhard , Haußmann Jörg , Dietlmeier Marcus , Banerjee Susanta 
Published: March 2011

AbstractSeveral series of poly(arylene ether)s with trifluoromethyl substituents were prepared and characterized. These materials are potential candidates for the use as low dielectric constant insulators (intermetal dielectrics, IMD, and interlayer dielectrics, ILD) on microchips. Thermal stability up to 450 °C and a dielectric constant below 3 preferably below 2.5) is required for this application. The thermal stability of the poly(arylene ether)s was increased from 320°C to more than 500 °C by optimization of the structure of the repeating unit. The dielectric constant of one of the most promising structures was determined to be 2.8. In addition, plasma polymerized thin films from hexafluorobenzene, tetrafluorobenzene, perfluorotoluene and perfluorodecaline were prepared and characterized with respect to solubility, dielectric constant, adhesion, and thermal stability.
Photocrosslinking of thin polymer films – materials for sensors and actuators
Authors: Kuckling Dirk , Adler Hans‐Jürgen , Arndt Karl‐Friedrich , Wolff Thomas , Hoffmann Jan , Fischer Wolf‐Joachim 
Published: March 2011

AbstractPolymers with temperature dependent degrees of swelling, especially polymers which exhibit lower critical solution temperature (LCST) behaviour in aqueous solutions, are of interest for applications in microsystems. For these applications it is necessary to form and pattern thin films in the μm‐range. This has been achieved through photocrosslinking of linear prepolymers. Copolymers based on N‐isopropylacrylamide (NIPAAm) were modified with a stilbazolium salt chromophore to yield photocrosslinkable temperature sensitive polymers. The chromophore reacts via a [2+2]‐cycloaddition under irradiation, this can be used to crosslink the polymer. The photocrosslinking properties were studied by UV irradiation of thin films and measuring the changes in UV absorption spectra. Through irradiation of thin films through a mask it was possible to obtain patterned networks in the μm‐range (20 μm space width and > 50 μm line width). The polymers exhibited LCST behaviour, which was measured using DSC. The resulting patterned networks had temperature dependent swelling properties in aqueous media.
Soluble polyimides containing alicyclic structures
Authors: Choi Kil‐Yeong , Yi Mi Hie 
Published: March 2011

AbstractA series of novel aromatic diamines containing kinked cycloalkane structures between two phenyl rings were synthesized by HCl‐catalyzed condensation reaction of excess aniline and corresponding cycloalkanone derivatives. The structures of the diamines were indentified by 1H NMR, 13C NMR, FT‐IR spectroscopy and elemental analysis. The polyimides were synthesized from the obtained diamines with various aromatic dianhydrides by one‐step polymerization in m‐cresol. The polymerization was conducted for 6∼8 h with refluxing, which was enough to obtain the polymers with high molecular weight. The inherent viscosities of the resulting polyimides were in the range of 0.37∼1.66 dl/g. All polymers were readily soluble in common organic solvents such as chloroform, tetrachloroethane, dimethylacetamide, etc. and the glass transition temperatures were observed at 290 to 372°C. UV‐visible spectra were obtained to measure the transparency of polymer films. Most of the polymers showed high transmission above 90 % in the wavelength of 450 ∼ 600 nm.
Preparation and photophysics of polyimide/silica organic/inorganic hybrid composites
Authors: Ha Chang‐Sik , Cho Won‐Jei 
Published: March 2011

AbstractIn this work, polyimide/silica hybrid composites were prepared by the sol‐gel reaction of tetraethoxysilane(TEOS) and the thermal imidization of poly(amic acid) from 3,3′,4,4′‐biphenyltetracarboxylic dianhydride(BPDA) and 4,4′‐oxydianiline(ODA), and their photophysical properties were investigated using a fluorescence spectroscopy. It was found that the intrinsic fluorescence of poly(4,4′‐oxydiphenylene‐3,3′4,4′‐biphenyltetracarboximide)(BPDA‐ODA) such as emission intensity and emission wavelength depends strongly on the changes in the molecular conformations during the sol‐gel reaction and the thermal imidization. In conclusion, we found that the fluorescence spectroscopy can provide an insight into how the intermolecular or intramolecular interaction of polyimide in the hybrid composite system is affected by the silica contents, depending on the sample states.
Photooxidative degradation of polyether‐based polymers
Authors: Gardette Jean‐Luc , Mailhot Bénédicte , Posada Fabrice , Rivaton Agnès , Wilhelm Catherine 
Published: March 2011

AbstractThe mechanisms of photooxidation of several polyether based polymers were compared in order to give general rules of orientation of the oxidative reactions. These polymers were a poly(ether‐ester) and two poly(ether‐urethane)s. The behavior of the polyether component as homopolymer was also studied. This study was extended to copolymers of fluorinated olefins and allyl or vinyl ethers, and the non fluorinated homologues. The elucidation of the photooxidation mechanisms was based on the identification of the photoproducts by analysis of both the solid polymeric matrix and the gaz phase formed on irradiation. It was shown that the photochemical sensitivity of the polyether component was responsible for the rapid oxidation of the copolymers. However, in the case of the fluorinated compounds, different behaviors were observed. It was shown that the presence of the fluorine atoms strongly influenced the orientation of the reaction and modified the oxidation kinetics. The reactivity of the methylene groups in α‐position of the oxygen atom of the ether groups were not found to be equivalent regarding oxidation and the secondary was more oxidizable than the tertiary one.
Chain transfer to polymer in emulsion polymerization
Authors: Ahmad Nasir M. , Heatley Frank , Britton David , Lovell Peter A. 
Published: March 2011

AbstractChain transfer to polymer in emulsion polymerizations of acrylate monomers and vinyl acetate has been studied using 13C NMR spectroscopy to elucidate the chemistry by which chain transfer occurs and to quantify the mol% branches resulting from the reaction. In emulsion polymerizations of n‐butyl acrylate, ethyl acrylate and methyl acrylate, chain transfer to polymer proceeds via abstraction of hydrogen atoms from backbone tertiary C‐H bonds and typically gives rise to 2‐4 mol% branches in the polymers obtained at complete conversion, the level of branching increasing with reaction temperature. For these acrylates, there is no evidence for a significant difference between the extent of chain transfer to polymer. In emulsion polymerizations of vinyl acetate, chain transfer to polymer proceeds mainly via H‐abstraction from methyl side‐groups, though there is a small contribution from abstraction at backbone tertiary C‐H bonds. The levels of branching that result are substantially lower than in acrylate emulsion polymerizations, typically being in the range 0.6‐0.8 mol% in the polymers obtained at complete conversion. The level of branching increases with temperature and as the degree of monomer starving (and hence instantaneous conversion) increases. Emulsion copolymerization of vinyl acetate with a small amount (5‐20 wt%) of n‐butyl acrylate gives rise to a significant increase in the level of branching (to values around 1.3‐1.6 mol%), which results predominantly from H‐abstraction of backbone tertiary C‐H bonds in n‐butyl acrylate repeat units by propagating radicals with vinyl acetate end units.
Biodegradability of scott‐gelead photodegradable polyethylene and polyethylene wax by microorganisms
Authors: Kawai F. , Shibata M. , Yokoyama S. , Maeda S. , Tada K. , Hayashi S. 
Published: March 2011

AbstractThis paper describes the biodegradability of photodegraded polyethylene (PE) and commercial PEwax and molecular size limits of PE for biodegradation. Photodegradation was accelerated by Scott‐Gelead System. Photofragmented PE and commercial PEwax were used as a sole carbon and energy source for soil microorganisms, respectively. Biodegradation by microbial consortia was confirmed by the increase of viable cell numbers and GPC analysis of PE added. Significant weigh decrease of PE samples added was also observed. Both photofragmented PE and PEwax were suggested to be biodegradable up to Mw 5,000 or more: Mw lower than 500 was degraded by more than 40%. Mw 500–2,000 was by more than 10%. Mw higher than 2,000 was only by a few %. Logarithms of biodegradation ratio (%) and Mw were correlated to show linearity and to suggest the biodegradability limit close to Mw 10,000.
Antioxidant control of polymer biodegradation
Authors: Scott Gerald 
Published: March 2011

AbstractHydrocarbon‐based synthetic polymers are versatile and cost‐effective materials in packaging and agriculture. Unstabilised polyolefins are known to biodegrade through peroxidation initiated by both abiotic and biotic and mechanisms. Both abiotic and biotic peroxidation can be accelerated and controlled by specially designed antioxidants and this has resulted in their commercial use in packaging, mulching films and baler twines. They are currently being evaluated in controlled release fertilisers.
Characterization of polymer soil burial degradation by thermal analysis and mechanical spectroscopy
Authors: Contat‐Rodrigo Laura , Ribes‐Greus Amparo 
Published: March 2011

AbstractPolypropylene (PP) and High density polyethylene (HDPE) / Polypropylene (PP) blend with different biodegradable additives (Granular starch/iron oxide mixture, Bioefect 72000 and Mater‐Bi AF05H) were selected for degradation experiments. All the samples, processed by injection as seedboxes, have been subjected to an outdoor soil burial test and removed at different periods of time between 0 and 21 months. Their chemical structure and morphology have been analysed. Studies of dynamic‐mechanical relaxation spectra of the samples before and after each exposure time have been carried out. The three characteristic relaxation zones α, β and γ, in order of decreasing temperature, have been obtained. It has been observed that due to the degradation process both, the HDPE/PP blend and the PP matrix, become more brittle than the undegraded ones regardless of the additive used. Degradation seems to start from the molecular chains of the amorphous phase or interfacial region. However the analysis of the mechanical behaviour manifested that the crystalline zone is also been affected by the exposure time.
Viscosity, sorption of water and biodegradation of starch/copolyamide blends
Authors: Suvorova Anna I. , Tujkova Irina S. , Trufanova Elena I. 
Published: March 2011

AbstractCompatibility of the components, shear viscosity, sorption properties in liquid and vapor water were determined for the mixture of ternary copolyamides (types 6/66/610 and 6/12/66) and amilose starch. This system was shown to be suitable for creation of biodegradable materials.
Dextran as antioxidant's activity carrier
Authors: Domnina Nina , Aref'ev Denis , Komarova Elena , Bilibin Alexander 
Published: March 2011

AbstractTwo series of conjugates of dextran and antioxidants from the class of sterically hindered phenols were prepared. The conjugates were characterized by the substitution degree of glycoside units, solubility in different solvents, intrinsic viscosity. The investigation of radical scavenging activity (RSA) of conjugates was carried out in their reactions with two free radicals — 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) and sodium salt of 2,2‐diphenyl‐1‐picrylhydrazyl sulfonic acid (DPPH‐salt). The usage of water soluble DPPH‐salt enabled to estimate the RSA of the conjugates in water. It was shown that the rate constants of interaction of the DPPH‐salt and the conjugates were 10–30 times higher than this value for low‐molecular analogue of phenoxan. High RSA of the conjugates in water can be explained by large solvation shell formed due to high content of hydroxy groups in dextran.
Biodegradable composite films based on waste gelatin
Authors: Kenawy El‐Refaie , Cinelli Patrizia , Corti Andrea , Miertus Stanislav , Chiellini Emo 
Published: March 2011

AbstractGelatin, a naturally occurring polymer, is currently used in various applications comprising manufacturing of pharmaceutical products, x‐ray and photographic films development and food processing. However, gelatin scraps generated in the different manufacturing processes may constitute a concern for the environment. Basically speaking, waste disposal deriving from plastics based on synthetic as well as semisynthetic polymeric materials, is becoming an increasingly difficult problem for their unfavorable volume‐to‐weight ratio and extremely wide variability of type, shape and composition of post consume plastic items that hinder the way to a general unique option for a simple and economically feasible management.As a partial solution to the global issue of plastic waste, in recent years much interest has been devoted to the formulation of environmentally degradable plastic items.Biodegradable mulching films were formulated from blends and composites based on waste gelatin and other natural waste such as sugarcane bagasse or synthetic materials such as PVA. Also, crosslinked films were produced using external or inherent crosslinker. The films were produced either by casting method or spraying on soil surface. The composites were submitted to biodegradation trials. The results showed that the films were biodegradable and the crosslinking could delay and predeterminate their biodegradation rate and extent.
Production of PHAs from agricultural waste material
Authors: Braunegg Gerhart , Genser Klaus , Bona Rodolfo , Haage Gudrun , Schellauf Florian , Winkler Elisabeth 
Published: March 2011

AbstractPolyhydroxyalkanoates (PHAs) are biodegradable substitutes to fossil fuel plastics that can be produced from renewable raw materials such as saccharides, alcohols and low‐molecular‐weight fatty acids. They are completely degradable to carbon dioxide and water through natural microbiological mineralization. Consequently, neither their production nor their use or degradation have a negative ecological impact. By keeping closed the cycle of production and re‐use, PHAs can enable at least part of the polymer‐producing industry to switch from ecologically harmful end‐of‐the‐pipe production methods towards sounder technologies. Up to now such polyesters have been produced biotechnologically from refined raw materials (e.g. glucose and sodium propionate), but they can as well be produced much cheaper from agricultural waste materials (e.g. molasses, maltose, glycerol phase from biodiesel production, whey), as long as these materials have a known composition and are available in appropriate quantities. Yield factors and specific rates for growth and PHA accumulation are shown for 3 strains of Alcaligenes latus for different agricultural waste carbon sources.
Characterisation and morphology of biodegradable chitosan / synthetic polymer blends
Authors: Mucha Maria , Piekielna Joanna , Wieczorek Anna 
Published: March 2011

AbstractChitosan has been used to form miscible, biodegradable blends with hydrophilic synthetic polymers as PVA and PEO. Characterisation of the blends by DSC, IR and microscopy analysis was made giving much attention to possible interactions of molecular polar group in the polymer chains. PVA/chitosan are found to be amorphous in the whole range of composition having one glass transition temperature. Molecular interactions in the pair of polymers are connected with amide group of chitosan and hydroxyl groups of PVA. PEO/chitosan blends stay amorphous up to 0.2 weight fraction of PEO. For a higher amount of PEO that polymer crystallises forming a spherulite crystalline structure. We correlate the overall kinetics of crystallisation and melting behaviour of solid, semicrystalline blends PEO/chitosan in the form of thin films for a set of PEO species of different blend composition with a morphological structure of the blends. Negative values of the Flory‐Huggins interaction parameter due to specific interactions by hydrogen bonding through ether group of PEO and hydroxyl group of chitosan were evaluated. Amide groups do not participate in the molecular interaction between PEO and chitosan molecules. Avrami equation was applied to describe kinetics of crystallisation of pure PEO and PEO/chitosan blends of various compositions.
Evaluation of the transport properties of Poly(3‐hydroxybutyrate) and its 3‐hydroxyvalerate copolymers for packaging applications
Authors: Miguel Oscar , Iruin Juan José 
Published: March 2011

AbstractPoly(3‐hydroxybutyrate) (PHB) and ist 3‐hydroxyvalerate containing copolymers form a family of fully biodegradable polyesters with many potential applications. In this work, the results obtained in our laboratory concerning carbon dioxide, water and organic solvent transport through PHB and three low 3‐hydroxyvalerate copolymers are reviewed. Comparison established between the former results and some data taken from the literature, have revealed that PHB and the above mentioned copolymers show transport properties similar to other common thermoplastics such as PVC and PET, particularly in the case of carbon dioxide and water. Consequently, PHB and copolymers can be catalogued as good barrier materials against these penetrants. On the other hand, these biopolymers show a low barrier character against organic compound permeation. All these features conform a good balance of physicochemical properties for these polyhydroxyalkanoates, which may take them suitable for several applications, including its use in biodegradable packaging materials.