bluuebunny/crossref_metadata_2025_split huggingface dataset:
Liquid mulch based on poly(vinyl alcohol). PVA‐soil interaction
Authors: Chiellini Emo , Cinelli Patrizia , D'Antone Salvatore , Ilieva Vassilka I. , Magni Simone , Miele Sergio , Pampana Silvia 
Published: August 2003

AbstractThis study is meant to provide a contribution in recent developments of biodegradable polymeric materials applied in agricultural practices with particular reference to the mulching segment. Special attention has been devoted to material based on renewable resources or utilization of waste products from agro‐industrial activities, thus suggesting cost‐effective and environmentally sound solutions to specific social needs. In the present contribution PVA solubility at room temperature has been improved by premixing with chemical additives and proteic materials. Waste materials from ethanol production by corn fermentation and from wood industries have been used as, respectively starch‐based and lignocellulosic additives. The prepared formulations were applied on the soil by conventional spraying agricultural equipment. Time of permanence of the film formed on the soil was monitored as well as the effect on corn growth and yield production. Finally, in order to investigate the final fate of the PVA applied on the soil, a test was performed in lysimeters, with half of the lysimeters cropped with maize plants. PVA amount applied for the mulching test was in order of 5‐10 g PVA/1 m2; under those conditions it resulted completely absorbed and no presence of PVA was recorded in the leached solutions.
Synthesis and thermal properties of epoxy resins from ester‐carboxylic acid derivative of alcoholysis lignin
Authors: Hirose Shigeo , Hatakeyama Tatsuko , Hatakeyama Hyoe 
Published: August 2003

AbstractAlcoholysis lignin (AL) was dissolved in ethylene glycol and the obtained mixture was reacted with succinic anhydride to form a mixture of ester‐carboxylic acid derivatives (AL‐polyacid, ALPA). Ethylene glycol‐polyacid (EGPA) was also prepared from ethylene glycol. The obtained mixture of ester carboxylic acid derivatives was treated with ethylene glycol diglycidyl ether in the presence of catalytic amount of dimethylbenzylamine to form ester‐epoxy resins. The curing reaction was analyzed by Ozawa's method using differential scanning calorimetry. The activation energy of curing reaction in the initial step was found to be ca. 84 kJ mol−1. The molar ratios of epoxy groups to carboxylic acid groups ([EPOXY]/[AA] ratios) were varied from 0.8 to 1.3. The contents of ALPA in the mixture of ALPA and EGPA were also varied from 0 to 100%. Thermal properties of epoxy resins were studied by DSC and thermogravimetry. Glass transition temperatures of epoxy resins showed a maximum value of −11.5 °C when [EPOXY]/[AA] ratio was 1.1. Tg increased with increasing ALPA contents suggesting that lignin acts as a hard segment in epoxy resin networks. Thermal degradation temperatures of epoxy resins slightly decreased with increasing ALPA contents.
Mechanical and thermal properties of rigid polyurethane foams derived from sodium lignosulfonate mixed with diethylene‐, triethylene‐ and polyethylene glycols
Authors: Hatakeyama T. , Asano Y. , Hatakeyama H. 
Published: August 2003

AbstractSodium salt of lignosulfonic acid (LS), which was obtained as by‐product of cooking process in sulfite pulping, was solved in diethylene, triethylene or polyethylene glycol. Three series of polyurethane foams (LSPU) were synthesized by varying the LS content from 0 to 33 wt%. Apparent density (ρ) of LSPU foams ranged from 0.08 to 0.18 g cm−3 and was affected by both LS content and oxyethylene chain length. Glass transition temperatures increased with increasing amount of LS and with decreasing oxyethylene chain length. Thermal gravimetry analysis indicated that the LS component decomposes first and that the thermal stability increases with decreasing oxyethylene chain length. Compression strength and compression modulus increased linearly with increasing apparent density. It is concluded that LS is successfully utilized as a hard segment of rigid PU foams, whose thermal and mechanical properties can be tuned by changing the amount of LS and the length of soft oxyethylene chains.
New thermo‐molded biodegradable films based on sunflower protein isolate: aging and physical properties
Authors: Orliac Olivier , Silvestre Françoise 
Published: August 2003

AbstractSmooth black films are obtained. Films plasticized with glycerol have the least stress at break, but show the highest strain at break (glycerol 33%: 6.7 MPa, 150%). The ethylene glycol family shows an increase in stress at break when the aliphatic chain length increases, while strain at break decreases. Lastly, a rigidification phenomenon of films occurs with the two plasticizers 1,2‐propanediol and ethylene glycol, which can be attributed to a loss of plasticizer (followed by HPLC). The triethylene glycol produces the most resistant films, with a great elasticity (TEG 33%: 9.5 Mpa, 100%). Moreover, the films produced with this plasticizer keep their properties during time, as good as films produced with glycerol. The water vapor permeabilities of all those films are low (in the region of 10−12 g.m−1.s−1.Pa−1); even if contact angle measurements carried out with water show the hydrophilic character of the films surface. This last result is in agreement with the water uptake tests which show a loss of plasticizer and an absorption of water (in the region of 100% of the dry matter of film); without considering the plasticizer nature, and this in spite of a nearly total insolubility of the crosslinked proteic network.
Effect of filler shape on mechanical properties of rigid polyurethane composites containing plant particles
Authors: Funabashi Masahiro , Hirose Shigeo , Hatakeyama Tatsuko , Hatakeyama Hyoe 
Published: August 2003

AbstractThe effect of types of fillers on mechanical properties of rigid polyurethane composite samples was investigated. Polyurethane (PU) composites were prepared using a molasses polyol (MP, a mixture of molasses and polyethylene glycol, Mw=200) diphenylmethane diisocyanate (MDI) and fillers. The following plant particles, bamboo powder, roast bamboo powder, wood meal, coffee grounds, ground coffee bean parchment and cellulose powder, were used as fillers. The mixture of MP and fillers was reacted with MDI by adding an adequate amount of acetone as a solvent. The content of fillers was defined as the ratio of filler weight to total weight of polyol and fillers. The filler content was varied from 10 to 90 wt%. Polyurethane (PU) composites were prepared using fillers with MP. Lengths of major axis and minor axis for each particle regarded as an ellipse were measured using an optical microscope. Averages of diameter and aspect ratio were derived for each plant particle. The relationships between these average values and the mechanical properties, such as strength and elastic modulus, determined by the compression tests were investigated. The effect of filler content was estimated using the apparent volume ratio which is determined as the ratio of the apparent volume of fillers to the reciprocal values of the apparent density of samples. The master curves of the relationships between the specific values of mechanical properties and the apparent volume ratio were obtained. It was found that the compression strength and the elastic modulus for composite samples with different fillers showed maximum values at average aspect ratio around 3. It was also found that the apparent volume ratio, where the mechanical properties showed maximums, decreases with increasing aspect ratio. Using master curves, it is possible to evaluate the mechanical properties of plant particle filled polyurethane composites are described.
Polycaprolactone based biodegradable polyurethanes
Authors: Wang Shu Hui , Silva Luiziana F. , Kloss Juliana , Munaro Marilda , Pinto de Souza Gabriel , Wada M. Alice , Gomez J. Gregório C. , Zawadzki S. , Akcelrud L. 
Published: August 2003

AbstractTwo series of segmented polyurethanes were prepared with systematic variation in soft and hard segment length. The soft segment was constituted by polycaprolactone (PCL) blocks of molecular masses 530 or 2000 and the hard segment (HS) by urethane blocks, in a concentration that varied from 12% to 44% in weight of the whole polyurethane. Morphological analyses indicated that the amount of crystallinity of copolymers was strongly dependent on the PCL molar mass and hard segment content. The copolymers with longer PCL soft segments (Mn=2000) were semicrystalline, but those with shorter PCL segment (Mn=530) were unable to crystallize. The primary factor affectingthe biodegradability of copolymers as evaluated by Sturm tests was the extent of the phase separation, and that the segmental blending of the less biodegradable polyurethane (HS) blocks with PCL in the amorphous phase had a critical unfavorable consequence, which may be attributed to the size of the accessible area by microorganisms.
Properties and adsorptive capacity of amino acids modified chitosans for copper ion removal
Authors: Dehonor‐Gómez Mariamne , Hernández‐Esparza Margarita , Ruiz‐Treviño F. Alberto , Contreras‐Reyes Roberto 
Published: August 2003

AbstractThis work presents the results of the modification of lateral groups of chitosan (2‐amino‐2‐desoxy‐β‐D‐glucose) by the reaction with different amino acids (glycine, L‐lysine, ‐glutamic acid and L‐isoleucine) under acid catalysis. The Cu2+ adsorption capacity of pure chitosan and of the chemically modified chitosans were also evaluated. The modification reaction favored the amide formation of the C‐2 carbon of the glycoside ring under the adopted reaction conditions: reaction time and temperature and using sulfuric acid as a catalyst. The Cu2+ adsorption kinetics and equilibrium response using pure chitosan and the chemically modified chitosans as adsorbents showes that the adsorption capacity of equilibrium depended on the initial ion concentration. The response of each adsorbent gave good correlation with Langmuir's isotherm model. The following maximum adsorption capacity constants were obtained: 172.4 mg/g for chitosan and 69.9, 34.4, and 26.7 mg/g for modified chitosan with glycine, L‐glutamic acid, and L‐lysine, respectively. The adsorptive capacity seems to be dependent on the length and complexity of the added group.
Malolactonate polymers and copolymers for biomedical applications
Authors: Bizzarri Ranieri , Chiellini Federica , Ober Christopher K. , Saltzman W. Mark , Solaro Roberta , Chiellini Emo 
Published: August 2003

AbstractA new class of malolactonate polymers and copolymers with a wide range of lateral chain structures were synthesized by anionic ring opening polymerization of alkyl malolactonate monomers. The monomers were prepared in good yields according to established procedures. Final macromolecular and thermal characteristics were in agreement with the designed monomer structures. Molecular weights in the range 4‐20 kD were attained, as a result of chain transfer reactions. Representative polymeric compounds displayed stability up to 200 °C. Many of the obtained poly(alkyl malolactonate)s were able to sustain and promote with 3T3 murine fibroblasts adhesion and proliferation onto their surface.
Biodegradable starburst carbon chain polymer‐protein and lysine dendrite conjugates: adjustment of immune properties, DNA bonding and delivery
Authors: Vlasov Guennady P. 
Published: August 2003

AbstractIn the past decade, the development of gene therapy technology has focused on the design of new nonviral carriers for gene delivery. Proteins modified with polyethyleneimine[1] or polylysine[2] as well as dendrites[3] have shown to be perspective carriers for DNA targeted delivery. The usage of protein conjugates as carriers of biologically active compounds will depend on the adjustment of their immune properties. To investigate this we have prepared starburst carbon chain polymer/protein conjugates containing low molecular weight biologically active compounds, salsolinol and bradykinin, in the polymer moieties and studied their immune properties. We have shown that chemical structure of the polymer moiety determines the conjugate biodegradation as well as their immune properties. The starburst poly(N‐vinylimidazole) transferring poly(N‐vinylimidazole) and polylysine 3G lysine dendrite conjugates have been prepared. The study of their ability to bind DNA and to guarantee its targeted delivery have shown that they are perspective DNA carriers.
Surface patterning and biological evaluation of semi‐interpenetrated poly(HEMA)/poly(alkyl β‐malolactonate)s
Authors: Chiellini Federica , Bizzarri Ranieri , Ober Christopher K. , Schmaljiohann Dirk , Yu Tianyue , Saltzman W. Mark , Solaro Roberto , Chiellini Emo 
Published: August 2003

AbstractSemi‐interpenetrating hydrogel networks were prepared by radical polimerization of monomer HEMA, co‐monomer EGDMA as cross‐linking agent and in the presence of 1 wt % of poly(alkyl β‐malolactonate)s. Biological evaluation in terms of cell adhesion and proliferation of the prepared materials showed the ability of HEMA‐based hydrogels to sustain a good cell adhesion and proliferation. Moreover, a method based on soft‐lithography to obtained surface microstructured semi‐interpenetrating hydrogel networks was developed, thus allowing for further investigation of the influence of surface topography on cell behavior.
A simple method suitable to test the ultimate biodegradability of environmentally degradable polymers
Authors: Chiellini Emo , Corti Andrea 
Published: August 2003

AbstractA straightforward experimental set‐up derived from the Biometer Flask previously utilized for experiments of pesticides biodegradation, has been adopted for testing the ultimate biodegradability of natural, synthetic and semi‐synthetic polymeric materials on solid substrates such as soil and mature compost. The use of these whole substrates as incubation media in respirometric experiments, may negatively affect the accuracy of the test due to the large amount of carbon dioxide developed from the blanks, especially in the presence of specimen degrading at low or moderate rates. In the present test procedure soil and compost samples are diluted with perlite, a naturally occurring inert aluminum silicate widely utilized in horticultural applications, in order to ensure optimal conditions for the microbial growth while reducing the carbon dioxide emissions from the blanks. The results so far reported clearly indicate that the adopted procedure is extremely valuable and versatile for the appreciation of even subtle differences in the biodegradation rate of different polymeric materials, as well as for long‐term degradation experiments.
Strategies for detecting ecotoxicological effects of biodegradable polymers in agricultural applications
Authors: Fritz J. , Sandhofer M. , Stacher C. , Braun R. 
Published: August 2003

AbstractBiodegradable is the long awaited and highly accepted property for materials (polymers) used in agricultural applications. Methods for determining biodegradability and material disintegration are established and already in use for routine analysis. Methods for analysing ecotoxic effects caused by biodegradable materials are neither established nor in routine use. In the past, biotests have been developed and optimised solely for investigations of single chemicals. Such tests are applicable even if they are not validated for the detection of undesired ecotoxicological effects deriving from biodegradation of polymers in soil. Since the biodegradation process does have an influence on the physical, chemical and biological status of the soil matrix, both biotests and chemical analysis are required in many cases. Theory, background data from method development and some results are presented.
Degradation of the blends of natural and synthetic copolyesters in different natural environments
Authors: Rutkowska Maria , Krasowska Katarzyna , Heimowska Aleksandra , Kowalczuk Marek 
Published: August 2003

AbstractThe paper presents results of the biodegradation of the blends of natural and synthetic copolyesters in two different natural environments. Environmental degradation took place in compost with activated sludge at sewage farm and ‐ for comparison ‐ in the Baltic Sea in Gdynia Harbour. Degradation of these blends was monitored for 16 weeks in compost and for 6 weeks in sea water. The changes in macroscopic features of surface and the weight loss of the samples were measured during the performed experiment. The characteristic parameters of compost and sea water were also controlled during all incubation time and their influence on the rate of biodegradation is discussed. The results of this study revealed that the natural aliphatic copolyester i.e. 3‐hydroxybutyrate‐co‐3‐hydroxyvalerate (PHBV) and its blends with the synthetic aliphatic‐aromatic copolyester of 1,4‐butandiol with adipic and terephthalic acids degrade faster in compost than in sea water. The rate of the biodegradation process depends on the composition of blends and different abiotic parameters of compost and sea water.
Liquid‐liquid equilibria of binary polymer blends: molecular thermodynamic approach
Authors: Chang Bong Ho , Bae Young Chan 
Published: August 2003

AbstractWe extended and simplified the modified double‐lattice model to binary polymer blend systems. The model has two model parameters, Cβ and Cγ. Those are not adjustable parameters but universal functions. In comparison with Ryu et al.'s simulation data for symmetric polymer blend with various chain lengths (r1 = r2 = 8, 20, 50, 100), Cγ is determined. Our results show that Cβ is negligible for symmetric polymer blend systems. The proposed model describes very well phase behaviors of weakly interacting polymer blend systems.
Modelling segmental dynamics in miscible polymer blends
Authors: Leroy Eric , Alegría Angel , Colmenero Juan 
Published: August 2003

AbstractThe complex thermorheological behaviour observed in miscible polymer blends is modelled by combining two existing theoretical approaches: The Thermal Concentration Fluctuation model (A. Zetsche, E.W. Fischer, Acta Polymer. 1994, 45, 168) and the Effective Concentration model (T.P. Lodge, T.C.B. McLeish, Macromolecules 2000, 33, 5278), giving rise to a simple model with only one adjustable parameter. This model is then tested in the case of two model blends allowing to show its abilities and limitations to describe how the respective segmental dynamics of lowest or highest Tg component are affected by blending.
Crystallization and structure formation in polymer blends with strong intermodular interactions: blends of poly(ethylene oxide) and styrene‐hydroxystyrene copolymers
Authors: Cho Jaedong , Xu Ruijian , Yeh Fengji , Hsiao Benjamin S. , Runt James 
Published: August 2003

AbstractTime‐resolved synchrotron wide‐ and small‐angle X‐ray scattering experiments were used to investigate crystallization behavior and microstructure development of a nearly monodisperse poly(ethylene oxide) [PEO] (Mw = 53,500), and its melt‐miscible blends with two fractionated styrene ‐ hydroxystyrene random copolymers [SHS]. PEO crystallization rates decrease significantly in the presence of the melt‐miscible SHS copolymers. All low and high molecular weight SHS blends exhibit a crystallization process at relatively short times characterized by large Avrami exponents (n), followed by a dominant process with n near that of neat PEO. A model for the crystallization of these blends is proposed.
Shear influence on the phase behavior of systems containing a homopolymer A and a block copolymer AB
Authors: Madbouly Samy A. 
Published: August 2003

AbstractCloud point temperatures (Tcp) and crystallization temperatures (Tl/s) of the ternary system tetrahydronaphthalene/poly(ethylene oxide)/poly(dimethyl siloxane‐b‐ethylene oxide) have been measured at different constant shear rates using a rheo‐optical device and an advanced rheometer. The cloud points temperatures (UCST‐type phase diagram) are reduced by several degrees as the system flows; i.e. the shear can suppress the phase separation and enlarge the homogenous region. The crystallization kinetics of PEO in the ternary mixtures has been investigated isothermally and non‐isothermally at quiescent state and under shear. The shear could strongly enhance the crystallization i.e. the (Tl/s) shifts to higher temperatures and the induction time, t0 (the time needs for the onset of crystallization) substantially decreases with increasing shear rate during the non‐isothermal and isothermal crystallization processes, respectively. The isothermal crystallization kinetics at quiescent state and at different shear rates was analyzed on the bases of Avrami approach. The Avrami exponent which provides qualitative information about the nature of the nucleation and growth process, was found to be shear rate and temperature dependent. The Avrami exponent increased from ∼3 at the quiescent state to as large as 9 at &&ggr;dot; = 100 s−1.
Detection of co‐continuous structures in SAN/PA6 blends by different methods
Authors: Pötschke Petra , Paul Donald R. 
Published: August 2003

AbstractThis paper describes the 70/30 wt% composition of SAN/PA6 blends having different types of morphology, namely PA6 dispersed in SAN, a co‐continuous structures of PA6 and SAN, and a “mixed structure” which exhibits PA6 particles in SAN which themselves form the matrix for smaller SAN particles. These morphologies were achieved by using different processing conditions during extrusion blending in a twin screw extruder, especially variation in the screw speed and by injection molding. Morphological analysis using SEM and TEM, solubility experiments, DMA, and oscillatory rheometry are presented. These methods were shown to be able to distinguish between the different types of morphology. In addition, DSC was used to detect the PA6 crystallization behavior.
Interfacially induced additional damping peaks in dynamic mechanical spectra – micromechanical transitions in multipolymeric materials
Authors: Colombini Didier , Maurer Frans H.J. 
Published: August 2003

AbstractThe viscoelastic properties of several hypothetical multiphase polymeric materials were investigated in relation to their phase‐property dependencies and microstructures. Theoretical mechanical considerations based on the self‐consistent interlayer model were performed to point out that specific geometrical arrangements into phases of a set of properties of the pure constituents can lead to interfacially induced damping peaks in dynamic mechanical spectra (DMS). Such additional contributions in DMS were referred to micromechanical transitions to distinguish them from ordinary molecular transitions.
Blends of isotactic polypropylenes and a plastomer: crystallization and viscoelastic behavior
Authors: Cerrada Maria L. , Prieto Oscar , Pereña José M. , Benavente Rosario , Pérez Ernesto 
Published: August 2003

AbstractBlends covering the entire range of compositions of a metallocenic ethylene‐1‐octene, CEO, copolymer and two conventional isotactic polypropylenes, iPP, of different molecular weights have been prepared, analyzing the effect of composition and molecular weight on the crystallization (studied by DSC and X‐ray diffraction) and viscoelastic behavior (DMTA). It was found that those blends rich in the iPP component show a behavior practically coincident with the weighted addition of the two components. On the contrary, significant deviations were found for the blends where the CEO copolymer is the major component. These deviations are considerably more important in the case of the blends with the iPP of higher molecular weight. Moreover, both components are not miscible, exhibiting the glass transitions of the two neat components. The area under the loss tangent curves provides a preliminary information about how the toughness is enhanced using this type of impact modifier, though it provokes a significant reduction of stiffness.