bluuebunny/crossref_metadata_2025_split huggingface dataset:
New Poly(sodium carboxylate)s Based on Saccharides, 1. Synthesis and Characterization of Ionic Allyl Glycoside Polymers
Authors: Mahrholz Thorsten , Klein Joachim , Klein Thomas 
Published: February 2003

AbstractNew poly(sodium carboxylate)s, containing monosaccharide side groups with ether linkages to the main chain, are presented as substitutes for water‐soluble homo‐ and copolymers of acrylic acid. Neutral and ionic allyl glycoside monomers, namely allyl‐α‐D‐galactopyranoside and allyl‐β‐D‐glucofuranosidurono‐6,3‐lactone, were synthesized by Fischer glycosidation. These monomers were copolymerized with maleic anhydride and itaconic acid in aqueous and nonaqueous solution. The corresponding copolymers with different structures, degrees of functionalization, and charge densities were characterized by 13C NMR spectroscopy, molecular‐weight measurements, and intrinsic viscosity [η] determination. From these, the monomer reactivity ratios and Mark–Houwink relations were established (see Figure).
Copolymerization curves of maleic acid copolymers 6 and 10. M1: mole fraction of allyl monomer 2β and 5α in the feed; m1: mole fraction of allyl monomer in the copolymer. The dashed line shows the course of an ideal alternating copolymerization (excepted: M1 = 0 mol‐%, M1 = 100 mol‐%).magnified imageCopolymerization curves of maleic acid copolymers 6 and 10. M1: mole fraction of allyl monomer 2β and 5α in the feed; m1: mole fraction of allyl monomer in the copolymer. The dashed line shows the course of an ideal alternating copolymerization (excepted: M1 = 0 mol‐%, M1 = 100 mol‐%).
Impact of Molecular Weight on Miscibility and Interdiffusion between Poly(N‐vinyl pyrrolidone) and Poly(ethylene glycol)
Authors: Bairamov Danir F. , Chalykh Anatoly E. , Feldstein Mikhail M. , Siegel Ronald A. 
Published: February 2003

AbstractMiscibility and mutual diffusion between poly(N‐vinylpyrrolidone) (PVP) and short‐chain poly(ethylene glycol)s (PEGs) of different molecular weight were studied by optical wedge microinterferometry (WMI). The PVP Mn varied from 1 300 to 360 000 g · mol−1, whereas that of PEG ranged from 200 to 6 000 g · mol−1. Photographs of interference patterns measured at λ = 546 nm with an optical microscope were used to observe the PVP/PEG interface. PVP blends with short‐chain PEG fractions, ranging in molecular weight from 200 to 1 500 g · mol−1, were found to be fully miscible above the temperatures of PEG fusion, whereas an increase in the molecular weight of up to 3 000 g · mol−1 renders the two polymers completely immiscible. Successive photographs of interference patterns (the interferogram of the contact interface between PEG6000 (left) and PVP is shown in the Figure) were used to determine composition‐distance profiles and to calculate the composition‐dependent mutual diffusion coefficient in miscible PVP/PEG blends. It was shown that the effects of PVP molecular weight are in reasonable agreement with those observed for other compatible polymer systems. In contrast to PVP behavior, the effects of PEG molecular weight indicate appreciable contribution of hydrogen bonding of terminal hydroxyl groups in short PEG chains to the miscibility and diffusivity behavior in the PVP/PEG system. The difference in the effects of PEG and PVP chain lengths is ascribed to hydrogen bonding between PEG terminal hydroxyl groups with carbonyl side groups of repeat units in PVP macromolecules and ether oxygens in the PEG chains.
Interferogram of the contact interface between PEG 6000 (left) and PVP. Magnification: 60‐fold.magnified imageInterferogram of the contact interface between PEG 6000 (left) and PVP. Magnification: 60‐fold.
A Novel Impact Modifier for Nylon 6
Authors: Peng Jing , Qiao Jinliang , Zhang Shijun , Wei Genshuan 
Published: February 2003

AbstractA new carboxylated styrene‐butadiene rubber (CSBR) in ultrafine powder form was used to modify the properties of nylon 6. The nylon 6/CSBR blends possessed higher toughness than nylon 6/maleic anhydride‐grafted polyethylene‐octene elastomer (POE‐g‐MAH) system. TEM micrographs revealed the fine dispersion of CSBR particles with a diameter of 150 nm. The effective toughening of nylon 6 with CSBR was attributed to the good interface, fine dispersion, and shear yielding.
TEM photograph of undeformed Nylon 6/CSBR (80/20) blend (×40 000).magnified imageTEM photograph of undeformed Nylon 6/CSBR (80/20) blend (×40 000).
EVA Copolymer Based Nanocomposites
Authors: La Mantia F. P. , Lo Verso S. , Tzankova Dintcheva N. 
Published: February 2003

AbstractNanocomposites are a new class of polymer material with an ultrafine phase dispersion of the order of a few nanometers that shows very interesting properties often very different from those of conventional filled polymers. In this work the mechanical and optical properties of Poly[ethylene‐co‐(vinyl acetate)] (EVA copolymer) based nanocomposites have been investigated to evaluate its possible use in several applications. For example, films for covering greenhouses made by EVA copolymer are appealing because of their interesting optical properties and for the so‐called greenhouse effect. Mechanical properties, and the rigidity in particular, are, on the contrary, quite low. Nanocomposites should avoid this shortcoming if optical properties and processability are not unfavorably effected. EVA copolymer based nanocomposites have been prepared by compounding polymer matrix and two different functionalized silicates (0–10 wt.‐%) in molten state. X‐Ray diffractograms show that the in the adopted experimental conditions no exfoliation of the filler is obtained, but an intercalated morphology is observed. Rheological behavior both in shear and in non‐isothermal elongational flow is only slightly influenced by the presence of the filler. As for the mechanical properties, the elastic modulus strongly increases without any worsening of the elongation at break. The permeability in the UV region is not influenced by adding even relatively high contents of the silicates. The improved mechanical and optical properties and the unmodified processability suggest then the use of these new polymeric systems in many applications and in particular as films for covering greenhouses.
UV spectra of the EVA/Nanofil system.magnified imageUV spectra of the EVA/Nanofil system.
The Effects of Copper Oxides on the Curing Behaviors of Bismaleimide Triazine Prepreg
Authors: Hong Shinn‐Gwo , Yeh Chin‐Sen 
Published: February 2003

AbstractThe effect of copper oxides on the curing behaviors of the bismaleimide triazine (BT) prepreg is studied with infrared spectroscopy (IR), attenuated total reflection infrared spectroscopy (ATR), and X‐ray photoelectron spectroscopy (XPS). The result of IR analyses indicates that there is a concentration distribution present in the prepreg surface layer and the outer surface layer contains less cyanate, imide, and epoxide but more triazine groups than the inner layer. From ATR, it is concluded that the cuprous oxide attracts more cyanate ester resins but less bismaleimide resins from the prepreg to its surface than the cupric oxide. The copper surface affects the curing extent of the BT resin in contact and the cupric oxide has a more pronounced effect than the cuprous oxide, and this surface effect can extend to at least two microns deep into the BT prepreg from the contacted interface. The XPS results confirm that the BT/CuO interface contains more thermally stable and polar functional groups than the BT/Cu2O interface, and both two copper oxides attract only a small amount of brominated epoxy resin onto their surfaces. These results are attributed to the difference in preferential adsorptions and catalytic curing effects of two copper oxides on the BT prepreg in contact.
The intensity changes of IR bands obtained from BT prepreg during cure.magnified imageThe intensity changes of IR bands obtained from BT prepreg during cure.
Microcomposites of Poly(ε‐caprolactone) and Poly(methyl methacrylate) Prepared by Suspension Polymerization in the Presence of Poly(ε‐caprolactone) Macromonomer
Authors: Abraham Gustavo A. , Kesenci Kemal , Fambri Luca , Migliaresi Claudio , Gallardo Alberto , Román Julio San 
Published: February 2003

AbstractPoly(methyl methacrylate)‐poly(ε‐caprolactone) (PMMA/PCL) microparticles were synthesized by suspension polymerization of methyl methacrylate in the presence of PCL. The incorporation of a small amount of a macromonomer, methacryloyl‐terminated PCL (M‐PCL), into the reaction mixture, led to the formation of grafted systems, namely PMMA‐g‐PCL/PCL. The synthesis of the macromonomer and its characterization by nuclear magnetic spectroscopy (1H NMR) is described. The role of M‐PCL as an effective compatibilizing agent in the composite was investigated. PMMA/PCL and PMMA‐g‐PCL/PCL composites were fully characterized by 1H NMR, gel permeation chromatography (GPC) and thermal analysis, including thermogravimetric analysis (TGA), conventional differential scanning calorimetry (DSC), modulated DSC (MDSC) and dynamic mechanical thermal analysis (DMTA). Finally, the morphology of the prepared systems was investigated by scanning electron microscopy (SEM). The addition of compatibilizing agent led the formation of a more homogeneous microcomposite with improved mechanical properties.SEM picture of PMMA‐g‐PCL/PCL composite surface.magnified imageSEM picture of PMMA‐g‐PCL/PCL composite surface.
Dry Processes for Surface Modification of a Biopolymer: Chitosan
Authors: Matienzo Luis J. , Winnacker Sarah K. 
Published: February 2003

AbstractStandard dry surface modification reactions have been applied to partially deacetylated chitosan without affecting its bulk properties. Chitin, extracted from shells of Penaeus vannamei, yielded chitosan with a degree of acetylation of 70% and molecular weight of 250 000 D. The copolymer consists of (β‐(1‐4)‐2‐2‐acetamido‐D‐glucose) units linked to (β‐(1‐4)‐2‐amino‐D‐glucose) units. Since the main interest of this work was to study the surface properties of films on substrates, a method to cast this material onto Al‐coated silicon wafers had to be developed. X ray photoelectron spectroscopy (XPS) has been used to determine the surface composition of the unmodified films and to follow modification changes. The films were treated in either an oxygen plasma environment or under UV/ozone irradiation. Water advancing contact angle measurements and infrared spectroscopy (FTIR) were used to complement XPS measurements. The films appeared to orient on the silicon wafer surface in the type II chitin structure. The rates of oxidation are faster for the plasma process but they result in similar changes to those induced by UV/ozone treatment. Atomic force microscopy (AFM) clearly shows the advantage of the milder modification reaction without much change in surface morphology. The oxidation processes, as detected by XPS, proceed without much alteration of the amine nitrogen atoms but carbonyl containing moieties are formed as a function of treatment time. Specific reactions with a fluorosilane to measure the activity of hydroxyl groups indicate that at short treatment times, these groups are essentially inactive. The resulting surfaces can also serve as a potential way to induce silica‐like domains that can function as diffusion barriers. Irradiation of chitosan solutions shows that UV/ozone induces depolymerization. In both cases, i.e., plasma and UV/ozone reactions, the main active component to surface modification appears to be UV irradiation with a wavelength below 360 nm.AFM surface profile for oxygen plasma treated film in barrel etcher for 1 min.magnified imageAFM surface profile for oxygen plasma treated film in barrel etcher for 1 min.
Determination of Mechanical Properties of Thermoplastics Suitable for Micro Systems
Authors: Haberstroh Edmund , Brandt Marcel 
Published: February 2003

AbstractAircraft and aerospace industry as well as medical and automotive engineering continuously develop smaller and lighter system components. Therefore it is not only important to be able to produce micro parts but also to provide properties for dimensioning and design. This paper explains to what extent mechanical properties from the macro‐range are also valid for micro structures. Thereby the modulus of elasticity as well as stress and strain at the yield point are regarded as relevant properties for the part dimensioning. Systematic investigations with tensile bars of different size show that the geometry‐dependent property changes are obviously not specific for the material classes of amorphous or semi‐crystalline thermoplastics, respectively. That is why a single material testing of micro samples is necessary to determine valid properties for this range. On the other hand the determination known from the classic materials science of plastics that lower temperatures as well as higher loading rates lead to a stiffer material behaviour, is also appropriate for the micro range. The measurements prove that the influence of temperature is much higher than the one of deformation rate. The influence of the production conditions on the mechanical behaviour of test specimen made of semi‐crystalline thermoplastics is demonstrated by using a varied cooling process. The correlation between the resulting different morphological structures and the changes in the mechanical properties is pointed up on the basis of microscopic views.Micro tensile testing machine at the IKV.magnified imageMicro tensile testing machine at the IKV.
Micro‐ and Nanoscale Evaluation of Scratch Damage in Poly(propylene)s
Authors: Dasari A. , Rohrmann J. , Misra R. D. K. 
Published: February 2003

AbstractThe technique of atomic force microscopy (AFM) has been used to obtain comparative evaluation of scratch damage in polymeric materials (low‐ and high‐crystallinity poly(propylene)s and ethylene‐propylene diblock copolymers) and examine the surface deformation processes. A comparative assessment of scratch damage is made in terms of average surface height of the plastically deformed region, and the depth, thickness, and density of the scratch tracks. The resistance to scratch deformation under identical conditions of scratch test follows the sequence: high‐crystallinity poly(propylene)s > low‐crystallinity poly(propylene)s > ethylene‐propylene diblock copolymers. Additionally, short‐chain polymers are characterized by a greater resistance to mechanical deformation than their respective long‐chain polymers. The scratch tracks in low‐ and high‐crystallinity poly(propylene)s are zig‐zag in shape, while in ethylene‐propylene diblock copolymers they are parabolic with localized plastic flow involving voids. The AFM observations suggest that higher tensile modulus and higher yield stress are key factors responsible for superior resistance to mechanically induced deformation in high‐crystallinity poly(propylene)s.Low magnification SEM micrographs of the scratch deformed regions of long‐chain EP‐L (e) and short‐chain EP‐S (f).magnified imageLow magnification SEM micrographs of the scratch deformed regions of long‐chain EP‐L (e) and short‐chain EP‐S (f).
1,8‐Naphthalimides as Blue Emitting Fluorophores for Polymer Materials
Authors: Grabchev Ivo , Petkov Christo , Bojinov Vladimir 
Published: February 2003

AbstractThe copolymerization of 1,8‐naphthalimide derivatives (as fluorophore) with acrylonitrile has been investigated. The photophysical characteristics of monomeric and polymeric fluorophores in N,N‐dimethylformamide solution have been determined and discussed. During copolymerization, no changes in the chromophoric systems of the fluorophore occur. The influence of the studied monomeric 1,8‐naphthalimide fluorophores upon the structurally bleached polyacrylonitrile has been determined. Infrared absorption characteristics of the polymerizable 4‐alkoxy‐ and 4‐allyloxy‐N‐substituted‐1,8‐naphthalimides have been measured and discussed. The effect of the substituents upon the vibration frequencies of the carbonyl and allylic groups has been established.Blue fluorescent polyacrylonitrile copolymers with 1,8‐naphthalimides side‐group.magnified imageBlue fluorescent polyacrylonitrile copolymers with 1,8‐naphthalimides side‐group.
Controlled Swelling of Poly(hydroxyethyl methacrylate) Hydrogels by Photochemical Grafting of Hydrophobic Acrylates
Authors: Campan Rozenn , Cazaux Frédéric , Coqueret Xavier 
Published: February 2003

AbstractThe photochemically induced grafting polymerization of various alkyl acrylates onto cross‐linked poly(hydroxyethyl methacrylate) (PHEMA) was performed to reduce the hydrophilicity of the swellable network. Butyl, 2‐ethylhexyl and lauryl acrylate were used as monofunctional monomers for increasing the hydrophobic character, whereas hexanediol diacrylate was used as a multifunctional monomer with the additional feature of forming networks. The various steps of the grafting procedure were examined sequentially so as to optimize the overall hydrophobing effect. The grafting yield was shown to depend primarily of PHEMA swelling in the considered ethanol/monomer mixture. In spite of their high specific hydrophobic character, alkyl monoacrylates were shown to be less efficient because of lower grafting yield. Grafting initiation by hydrogen abstraction with benzophenone or by homolytic cleavage of a hydroxyalkyl‐phenone resulted in comparable grafting yields even with monofunctional monomers. The hardness measured for the water swollen rubbery materials correlated well to the equilibrium water content.Shore A hardness as a function of the swelling ratio in water at T = 22 °C for grafted and ungrafted PHEMA hydrogels (same samples as those described in Table 5).magnified imageShore A hardness as a function of the swelling ratio in water at T = 22 °C for grafted and ungrafted PHEMA hydrogels (same samples as those described in Table 5).
Thermal Imidization of the Precursor of a Liquid Crystalline Polyimide
Authors: Pramoda Kumari P. , Liu Songlin , Chung Tai‐Shung 
Published: February 2003

AbstractImidization of the precursor of a liquid crystalline polyimide was investigated using modulated differential scanning calorimetry (MDSC), Fourier transform infrared (FTIR) spectroscopy, X‐ray photoelectron spectroscopy (XPS), and thermogravimetric analyzer (TGA) coupled to FTIR (TG‐IR). The FTIR study revealed that the rate and degree of imidization are functions of curing temperature and time. Imidization proceeds in two stages under isothermal condition. The initial weight loss up to 250 °C as observed from TGA was due to thermal cyclization, i.e., imidization process. The XPS analysis shows that the poly(amic acid) has two nitrogen 1s species at 400.3 and 399.2 eV possibly due to the isomerism of the dianhydride carbonyl, while liquid crystalline polyimide shows only a single nitrogen 1s species at 400.8 eV due to imide species.PLM micrograph of PAA (at 280 °C) after imidization.magnified imagePLM micrograph of PAA (at 280 °C) after imidization.
Novel Poly(N‐isopropylacrylamide)‐graft‐poly(vinylidene fluoride) Copolymers for Temperature‐Sensitive Microfiltration Membranes
Authors: Ying Lei , Kang En T. , Neoh Koon G. , Kato Koichi , Iwata Hiroo 
Published: February 2003

AbstractIn the present work, we report on the synthesis and characterization of poly(vinylidene fluoride) (PVDF) with N‐isopropylacrylamide (NIPAAM) polymer side chains from molecular graft copolymerization in solution. The copolymer can be readily cast into temperature‐sensitive microfiltration (MF) membranes by the phase inversion technique. The copolymer approach to membrane fabrication allows a much better control of the physicochemical nature of the membrane pores through the variation in graft concentration, membrane casting temperature and concentration of the membrane casting solution.
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Dual‐Curing of Waterborne Urethane‐Acrylate Coatings by UV and Thermal Processing
Authors: Decker Christian , Masson Frédéric , Schwalm Reinhold 
Published: February 2003

AbstractA waterbased dual‐cure urethane‐acrylate oligomer has been synthesized by polycondensation of monomers bearing hydroxyl, isocyanate and acrylate groups. To obtain a stable aqueous dispersion, carboxylate groups were grafted on the oligomer chain and the isocyanate groups were protected by a blocking agent. After water release by a brief heating, the dry films were cured either by a short UV exposure in the presence of a photoinitiator to induce the polymerization of the acrylate double bonds, or by heating up to 150 °C to release the isocyanates and promote the polycondensation by reaction with the hydroxyl groups, but mainly by a combination of UV and thermal cure. Both processes have been followed quantitatively by infrared spectroscopy to evaluate the influence of the temperature on the reaction rate and on the cure extent. The newly developed waterbased dual‐cure coatings were found to be quite resistant to accelerated weathering because of their aliphatic structure and their high crosslink density. Their light stability was substantially improved by the addition of a hydroxyphenyltriazine UV absorber and a hindered amine radical scavenger.
Thermal curing of the dual‐cure waterborne PUA formulation at a temperature of 150 °C.magnified imageThermal curing of the dual‐cure waterborne PUA formulation at a temperature of 150 °C.
Near Infrared Reflection Spectroscopy: A Versatile Tool for Rapid Characterization of Olefin Copolymers and High‐Throughput Experiments
Authors: Tuchbreiter Arno , Kappler Bernd , Stockmann Roger , Mülhaupt Rolf , Honerkamp Josef 
Published: February 2003

AbstractNear infrared (NIR) spectroscopy was developed as a rapid analytical method for the determination of the composition of olefin copolymers obtained in high‐throughput screening. NIR spectra of ethene/propene and ethene/1‐hexene copolymers, also characterized by means of 13C NMR spectroscopy, were recorded and used to design multivariate calibration models. Different methods for the preprocessing of the spectra, including the linearization by non‐linear transformations, were compared. Optimal methods and error estimates were established using crossvalidation. This technique is of particular interest for the rapid on‐line analysis of high‐throughput experiments in the field of polymer and catalyst design employing methods from combinatorial chemistry.
Predicted versus true value of the propene incorporation and standard deviation for ethene/propene copolymers.magnified imagePredicted versus true value of the propene incorporation and standard deviation for ethene/propene copolymers.
Biocomposites Made from Short Abaca Fiber and Biodegradable Polyesters
Authors: Shibata Mitsuhiro , Ozawa Koichi , Teramoto Naozumi , Yosomiya Ryutoku , Takeishi Hiroyuku 
Published: February 2003

AbstractNatural fiber‐reinforced biodegradable polyester composites were prepared from biodegradable polyesters and surface‐untreated or ‐treated abaca fibers (length ca. 5 mm) by melt mixing and subsequent injection molding. Poly(butylene succinate)(PBS), polyestercarbonate (PEC)/poly(lactic acid)(PLA) blend, and PLA were used as biodegradable polyesters. Esterifications using acetic anhydride and butyric anhydride, alkali treatment, and cyanoethylation were performed as surface treatments on the fiber. The flexural moduli of all the fiber‐reinforced composites increased with fiber content. The effect of the surface treatment on the flexural modulus of the fiber‐reinforced composites was not so pronounced. The flexural strength of PBS composites increased with fiber content, and esterification of the fiber by butyric anhydride gave the best result. For the PEC/PLA composites, flexural strength increased slightly with increased fiber content (0–20 wt.‐%) in the case of using untreated fiber, while it increased considerably in the case of using the fiber esterified by butyric anhydride. For the PLA composite, flexural strength did not increase with the fiber reinforcement. The result of soil‐burial tests showed that the composites using untreated fiber have a higher weight loss than both the neat resin and the composites made using acetylated fiber.Flexural modulus of PBS composites as a function of fiber content.magnified imageFlexural modulus of PBS composites as a function of fiber content.