bluuebunny/crossref_metadata_2025_split huggingface dataset:
A dynamic mechanical and thermal analysis of unplasticized and plasticized poly(vinyl alcohol)/methylcellulose blends
Authors: Park Jun‐Seo , Park Jang‐Woo , Ruckenstein Eli 
Published: August 2002

AbstractThe miscibility of poly(vinyl alcohol) (PVA)/methylcellulose (MC) blends was investigated over the entire composition range using the dynamic mechanical analyzer (DMA) and the differential scanning calorimeter (DSC). On the basis of the glass transition temperature, determined by DMA, one could conclude that the blends exhibited some miscibility below 80 wt % of MC and a good miscibility above 80 wt % of MC. The highest depressions of the melting and crystallization temperatures of the blends compared to those of PVA, determined via DSC analysis, were observed for MC contents greater than 80 wt %. The miscibility between PVA and MC can be attributed to the hydrogen bonds formed between the two components. The DMA studies showed that water is a good plasticizer for PVA and poly(ethylene glycol) 400 (PEG 400), a good plasticizer for MC. The inclusion of both water and PEG 400 in the blends revealed a synergistic plasticizing effect, which resulted in an increased miscibility between PVA and MC over a greater range of MC compositions (>60 wt %). The elongations of PVA, MC, and their blends were found to increase with the addition of PEG 400, but the tensile strengths to decrease. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1825–1834, 2001
Macromolecular modification of EPDM: Wettability, miscibility, and morphology study
Authors: Ginic‐Markovic Milena , Choudhury Namita Roy , Dimopoulos Maria , Matisons Janis , Kumudinie Chandima 
Published: August 2002

AbstractThe present investigation deals with studies on wettability, miscibility, and morphology of the macromolecularly modified EPDM. Two different maleated EPDM rubbers (grafted rubber) were chosen (0.5 and 1% maleation) for such modification and they were used in various proportions. Wettability of the rubber substrate, as observed from dynamic contact angle measurement, was improved using these grafted rubbers. Results of X‐ray photoelectron spectroscopy showed an increase in oxygen level with higher levels of grafted rubber in the blends. Morphology study by transmission electron microscopy showed a smaller domain size for the blend with higher maleic anhydride content in the grafted rubber. The viscosity versus blend ratio results showed a negative deviation behavior for blends with 1% grafted rubber, whereas a positive negative deviation behavior was observed in blends with 0.5% grafted EPDM. As the strength of interaction increased, the glass transition shifted to a higher temperature. All blends were heterogeneous, as indicated by different degrees of dispersion. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2647–2661, 2001
Polyetherimide‐modified bismaleimide resins. II. Effect of polyetherimide content
Authors: Jin Jianyong , Cui Jun , Tang Xiaolin , Li Shanjun , Wang Jinchen , Zhao Qushen , Hua Xiangyang , Cai Xianqing 
Published: August 2002

AbstractA novel polyetherimide was prepared and used to improve the toughness of bismaleimide resin composed of bis(4‐maleimidediphenyl) methane and O,O′‐diallyl bisphenol A. The morphologies of the modified resins change from spherical particles to an inverted phase structure, depending on the modifier's content based on the scanning electronic microscopy results. Dynamic mechanical analysis is also used to characterize morphologies of the modified resins. The phase‐separation process of the modified system is traced by time‐resolved light scattering. The change in the light‐scattering profile with curing time showed that the phase separation mechanism depended on the modifier concentration. Phase separation took place via the spinodal decomposition mechanism in the PEI 15‐phr‐ and 20‐phr‐modified system. The fracture energy (GIC) increased with PEI content in the modified system; in the PEI 15‐phr‐modified system, the GIC value was three times greater than that of the unmodified BMI resin. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 350–358, 2001
Polycondensation of bis(cyanoacetate) and a,10bdihydrobenzofuro[2,3‐b]benzofuran‐2,9‐dicarbaldehyde via knoevenagel reaction: Synthesis of donor–acceptor polymers containing shoulder‐to‐shoulder main chains
Authors: Namazi H. , Assadpour A. , Pourabbas B. , Entezami A. 
Published: August 2002

AbstractCompound 5a,10b‐dihydrobenzofuro[2,3‐b]benzofuran‐2,9‐dicarbaldehyde (II) was prepared by two‐step reactions from p‐cresol and glyoxal. The bis(cyanoacetate) monomers (III) were prepared in a high yield by reacting ethyl cyanoacetate with the appropriate diol in the presence of tetra‐n‐butyl titanate. The polymers from II and III were synthesized by Knoevenagel polycondensation that was first carried out in anhydrous THF and followed by a solid‐state polycondensation, and main‐chain polymers with good glass transition temperatures in high yield were obtained. The polymerization of II and III afforded polymers IV, which exhibited good solubility in most organic solvents. The structure of all the monomers and polymers were characterized by conventional spectroscopic methods. The synthesized polymers contain acceptor groups (cyanide and carbonyl) and a donor group (benzodihydrofuran) in their main chain. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 505–511, 2001
Surface modification of poly(styrene) by the attachment of an antimicrobial peptide
Authors: Appendini P. , Hotchkiss J. H. 
Published: August 2002

AbstractPolymers that directly inhibit the growth of microorganisms at their surface are potentially useful. To investigate the feasibility of such materials, poly(styrene) (PS) resin beads that had had poly(ethyleneglycol) (PEG) grafted onto the surface were further derivatized by covalently linking an antimicrobial peptide onto the surface. The antimicrobial peptide was composed of 8 lysine and 7 leucine (6K8L) residues. The resulting surface‐modified polystyrene (SMPS) was microcidal in a concentration and time‐dependent manner against several micro‐organisms includingE. coliO157 : H7,L. monocytogenes, S. aureus, P. fluorescens,andK. marxianuswhen suspended in phosphate buffer. The SMPS inhibited the growth of pathogenicE. coliO157 : H7 in trypticase soy broth. SMPS was bactericidal at pH 3.5 to 7, retained activity after heating to 200°C for 30 min, and could be extensively washed without loss of antimicrobial activity. Bioassays and HPLC analyses of buffer that had been preincubated with SMPS indicated that antimicrobial activity may have been due, at least in part, to the slow release of a peptide–PEG ligand from the PS to the buffer. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 609–616, 2001
Electroinduced copolymerization of acrylonitrile–polyethylene glycol compared with chemical copolymerization
Authors: Saraç A. Sezai̇ , Özkara Şerife , Di̇ler Z. İrem 
Published: August 2002

AbstractElectroinduced copolymerization of acrylonitrile (AN)–polyethylene glycol (PEG‐400) initiated by Ce(IV) was performed in aqueous solution and compared with chemical copolymerization, which allowed Ce(III) to be converted to Ce(IV) electrochemically during the polymerization. The polymer that was insoluble in water was formed in the cathodic compartment. The effect of Ce(IV), H2SO4, monomer, PEG‐400 concentration, temperature, time, and potential on the yield were studied and compared with similar effects under nonelectrolytic conditions. The role of Ce(IV) salt on the copolymerization was followed by spectrophotometric methods during the reaction period. Polymers were characterized by FTIR, UV‐visible spectrophotometry, and NMR. Intrinsic viscosities of polymers were determined. Possible polymerization mechanisms are suggested in the case of electrolytic and nonelectrolytic conditions. The electrolytic process has a demonstrable advantage over the nonelectrolytic method. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1410–1419, 2001
Proton uptake by poly(2‐vinylpyridine) coatings
Authors: Tantavichet Nisit , Pritzker Mark D. , Burns Charles M. 
Published: August 2002

AbstractA titration technique has been used to directly measure the proton uptake by ion‐exchange poly(2‐vinylpyridine) coatings as a function of solution pH. Contrary to the common assumption that each nitrogen in the pyridine ring is attached to an H+ when the polymer film is fully protonated, the use of the titration technique has shown that the portion of the pyridine sites actually protonated does not exceed 25% anywhere in the pH range where the coating is stable. The pKa value for the poly(2‐vinylpyridine) coating has also been estimated to be 4.5 from the titration curve. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1493–1497, 2001
Free radical polymerization of nitropropyl acrylates and methacrylates. I. Heat of polymerization
Authors: Lee Keundeuk , Kim Jinseuk , Lee Bumjae 
Published: August 2002

AbstractThe heat of polymerization ΔHp, of nitropropyl(meth)acrylate monomers has been studied by differential scanning calorimetry (DSC) in dynamic and isothermal modes. DSC showed that ΔHp of 2‐nitropropyl(meth)acrylate was surprisingly smaller than that of propyl(meth)acrylate but similar to that of 2,2‐dinitropropyl(meth)acrylate. According to molecular structure analysis by a PM3 Hamiltonian in a MOPAC program, the contributing main factor to the lowering of ΔHp of 2‐nitropropyl (meth)acrylate was found to be the hydrogen bond between the O(C) and the H atom attached at position C6. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2929–2935, 2001
Crystallization and melting behavior in syndiotactic polypropylene: Origin of multiple melting phenomenon
Authors: Supaphol Pitt 
Published: August 2002

AbstractThe melting behavior of syndiotactic polypropylene (s‐PP) after isothermal crystallization from the melt state was studied using differential scanning calorimetry (DSC) and wide‐angle X‐ray diffraction (WAXD) techniques. Three melting endotherms were observed for isothermal crystallization at high degrees of undercooling. The minor endotherm, located closed to the corresponding crystallization temperature, was postulated to be the melting of the secondary crystallites formed at the crystallization temperature. The low‐temperature melting peak was found to be the melting of the primary crystallites formed, and the high‐temperature melting peak was a result of the melting of the crystallites recrystallized during a heating scan. The triple‐melting behavior observed in subsequent melting endotherms of s‐PP was therefore described as contributions from melting of the secondary crystallites and their recrystallization, partial melting of the less stable fraction of the primary crystallites and their recrystallization, melting of the primary crystallites, and remelting of the recrystallized crystallites formed during the heating scan. In addition, determination of the equilibrium melting temperature for this s‐PP resin according to the linear and nonlinear Hoffman–Weeks extrapolations provided values of 143.1 and 185.6°C, respectively. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1083–1097, 2001
Absorption and desorption of liquid water by a superabsorbent polyelectrolyte: Role of polymer on the capacity for absorption of a ground
Authors: Bakass M. , Mokhlisse A. , Lallemant M. 
Published: August 2002

AbstractTo study the potentialities of a polyelectrolyte superabsorbent for the storage of water, we have studied a ground representative of the area of Haouz (area of Marrakesh, South of Morocco) in the presence of polymer. We sought the optimal proportions allowing the best retention of water by the mixture made up of the polymer and the ground and to prolong the storage period of water in the ground. We have also studied the effect of certain ions and the pH on the capacity for absorption of polymer. These ions can be naturally present in the ground or introduced by the means of manure and pesticides. The presence of polymer in the ground makes it possible to increase the capacity for absorption of the water by the ground, which can thus involve a saving in water while decreasing the frequency of irrigation and by reducing the water losses by the phenomena of evaporation and infiltration. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1541–1548, 2001
In situ and ex situ FTIR–ATR and Raman microscopic studies of organosilane hydrolysis and the effect of hydrolysis on silane diffusion through a polymeric film
Authors: Eaton Peter , Holmes Paul , Yarwood Jack 
Published: August 2002

AbstractWe report combined FTIR–ATR and Raman microscopic studies of the distribution and redistribution of three different silane adhesion promoters in thin (10–20 μm) PVC films deposited on a Si/SiO2/SiOH substrate (a “model” glass surface). It has been shown that the different functionalized silanes diffuse at different rates through the polymer (at 70°C) and therefore have different distributions at the polymer/glass interface. The differences in behavior have been rationalized in terms of their respective abilities to hydrolyze and condense, under the different humidity and temperature conditions used. As the level of humidity rises there is evidence that the diffusion rate (measured using a dual‐mode sorption model) decreases as a result of hydrolysis and condensation in the polymer films. The data are of importance as a direct measure of the relation between humidity levels and the adhesive action of a silane promoter at polymer/glass interfaces. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2016–2026, 2001
Structural organization and transport properties of iPP/LLDPE blends solidified at controlled cooling rates
Authors: Coccorullo Ivano , Gorrasi Giuliana , Pantani Roberto 
Published: August 2002

AbstractThe structural organization of blends of isotactic polypropylene (iPP) and linear low‐density polyethylene (LLDPE), with different compositions, was studied and correlated with the thermal history followed by the samples during solidification from the molten state. The materials were cooled at two extreme controlled rates: 0.1 and 500°C/s. The resulting structure was investigated both in the crystalline and the amorphous phases. In particular, attention was focused toward the analysis of the diffusion parameters of dichloromethane vapors, and the morphological organization of the amorphous phases was interpreted using models that consider them (in terms of resistance to diffusion) combined in series and in parallel. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2237–2244, 2001
Structural changes of bulk polyethylene by stress impact as studied by solid‐state NMR
Authors: Satoh Hidenori , Kuroki Shigeki , Ando Isao 
Published: August 2002

AbstractSolid‐state 13C‐ and 1H‐NMR spectra of bulk high‐density polyethylene samples, cylindrical in form, to which stress impacts were applied with a home‐made stress‐impact apparatus, were measured. The fraction of the noncrystalline component increases with an increase in the stress‐impact strength. In the crystalline region, the monoclinic crystalline component appear with the stress impact, in addition to the major orthorhombic crystalline component. Furthermore, dynamic characterization was carried out on the basis of the observed values of the relaxation parameters 1H T2 and TCH of the 1H and 13C nuclei. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2268–2272, 2001
Safety assessment of polymeric additives for food packaging: Hydrolysis of polymeric plasticizers by digestive fluids
Authors: Hamdani M. , Thil L. , Gans G. , Feigenbaum A. E. 
Published: August 2002

AbstractThe in vitro hydrolysis of poly(1,2‐propylene adipate) by digestive fluid liquids was studied to assess the safety of polymeric plasticizers that could migrate into food. A high extent of hydrolysis was obtained with freshly prepared intestinal fluid solutions. High performance size exclusion chromatography analysis indicated that the bulk plasticizer completely disappeared and that low molecular weight oligomers were formed within 4 h. Hydrolysis did not result in a significant conversion to the free monomers, like adipic acid, as was shown by gas‐phase chromatography. Measurements by NMR indicated that the cleavage selectively occurred at primary ester linkages. Fractionation of the hydrolysis products on silica gel gave six oligomeric fractions, which were recovered and analyzed. The absolute molecular weight of the plasticizers and the average molecular weight of the hydrolysis products were evaluated using proton NMR. Hydrolysis did not take place (<2%) under simulated gastric and saliva conditions. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 956–966, 2002
Comparative analysis of Prx1 and Prx2 expression in mice provides evidence for incomplete compensation
Authors: Chesterman Elizabeth S. , Kern Michael J. 
Published: August 2002

AbstractThe family of paired‐related homeobox genes to which Prx1 and Prx2 belong plays an integral role in limb and craniofacial development, as evidenced by both transgenic mice and in situ hybridization data. However, little is known about protein expression of these homeodomain transcription factors. Recent studies in our lab have established the pattern of Prx1 protein expression during normal mouse embryogenesis. Here we present a comparative analysis of Prx1 and Prx2 protein expression in the developing mouse using a novel anti‐Prx2 antibody reagent. Anat Rec 266:1–4, 2002. © 2002 Wiley‐Liss, Inc.
Using web‐based animations to teach histology
Authors: Brisbourne Marc A.S. , Chin Susan S.‐L. , Melnyk Erica , Begg David A. 
Published: August 2002

AbstractWe have been experimenting with the use of animations to teach histology as part of an interactive multimedia program we are developing to replace the traditional lecture/laboratory‐based histology course in our medical and dental curricula. This program, called HistoQuest, uses animations to illustrate basic histologic principles, explain dynamic processes, integrate histologic structure with physiological function, and assist students in forming mental models with which to organize and integrate new information into their learning. With this article, we first briefly discuss the theory of mental modeling, principles of visual presentation, and how mental modeling and visual presentation can be integrated to create effective animations. We then discuss the major Web‐based animation technologies that are currently available and their suitability for different visual styles and navigational structures. Finally, we describe the process we use to produce animations for our program. The approach described in this study can be used by other developers to create animations for delivery over the Internet for the teaching of histology. Anat Rec (New Anat) 269:11–19, 2002. © 2002 Wiley‐Liss, Inc.
Comparative studies on the expression patterns of three troponin T genes during mouse development
Authors: Wang Qin , Reiter Rebecca S. , Huang Qi‐Quan , Jin Jian‐Ping , Lin Jim Jung‐Ching 
Published: August 2002

AbstractIn vertebrates, three troponin T (TnT) genes, cardiac TnT (cTnT), skeletal muscle fast‐twitch TnT (fTnT), and slow‐twitch TnT (sTnT), have evolved for the regulation of striated muscle contraction. To understand the mechanism for muscle fiber‐specific expression of the TnT genes, we compared their expression patterns during mouse development. Our data revealed that the TnT expression in the developing embryo was not as restricted as that in the adult. In addition to a strong expression in the developing heart beginning at day 7.5 p.c (postcoitum), the cTnT transcript was detected at later stages in some skeletal muscles, where beginning at day 11.75 p.c. the fTnT and sTnT genes were also expressed. Only sTnT but not fTnT was found transiently in the developing heart. At day 13.5 p.c., expressions of all three genes were detected in the developing tongue and this co‐expression continued to day 16.5 p.c. with the fTnT isoform being predominant. At this stage, overlapping and distinct expression patterns of both sTnT and fTnT genes were also evident in many developing skeletal muscles. These data suggest that different muscles during development undergo a complex change in TnT isoforms resulting in different contractile properties. Unexpectedly, the cTnT transcript was persistently found in the developing bladder, where presumably smooth muscle is present. In transgenic mice, expression of a LacZ gene driven by a rat cTnT promoter (−497 to +192 bp) was very similar to that of the endogenous cTnT gene, suggesting that this promoter contained regulatory elements sufficient for the control of tissue‐specific cTnT expression during development. Anat Rec 263:72–84, 2001. © 2001 Wiley‐Liss, Inc.
Ground penetrating radar study of iron age tombs in Southeastern Kazakhstan
Authors: Pipan M. , Baradello L. , Forte E. , Finetti I. 
Published: August 2002

AbstractAn international archaeological and geophysical expedition was carried out to study Iron Age tombs of the Saka culture in southeastern Kazakhstan. Single‐fold and multifold ground‐penetrating radar (GPR) surveys, in two and two and a half dimensions, focused on the identification of burial chambers beneath the mound‐shaped Saka tumuli, named kourgans. Primary objectives of the geophysical study were the testing and optimization of GPR techniques for studying this type of tomb and the reconstruction of subsurface images of use for the design of archaeological excavations. Single‐fold GPR grids with line spacing ranging between 50 and 200 cm were obtained at each of the 13 sites selected. After identification of the sectors of major potential interest from data processing performed directly in the field and interpretation of the single‐fold grids, multifold profiles with average 1200 per cent fold were designed and performed. Processing of the data focused on velocity analyses, pre‐stack coherent noise attenuation by means of FK and KL filters, stacking and analysis of the instantaneous attributes of the complex radar trace. Multifold GPR data processing techniques achieved a substantial increment in the signal to noise ratio at most sites, allowed accurate depth conversions of the stacked profiles (average deviation of estimated target location from the actual target was less than 5% of total depth) and provided indications to identify the characteristic response from the target of interest through the joint interpretation of pre‐stack gathers, velocity analysis and amplitude versus offset analysis. Interpretation of stacked sections and three‐dimensional models obtained from the single‐fold/multifold grid allowed the identification of a burial chamber located at an estimated depth of 140–150 cm, which was excavated successfully by the archaeological team. Further reflectors with similar characteristics are shown from other sites, which will be excavated by the next archaeological expeditions to the area. Copyright © 2001 John Wiley & Sons, Ltd.