bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis, characterization, and properties of photosensitive silicon‐containing copolyimides
Authors: Lee Yu‐Der , Lu Chi‐Chi , Lee Hurng‐Rern 
Published: April 2003

AbstractCopolyimides with siloxane moieties in the main chain were synthesized by solution polycondensation of 1,3‐bis(3‐aminopropyl) tetramethyldisiloxane (APMS), oxydianiline (ODA) with 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BTDA) in N‐methyl‐2‐pyrrolidone (NMP). The adhesion properties between copolyimides and silicon wafer were improved significantly with incorporation of siloxane moiety into polymer chain.Photosensitive copolyimide precursor was obtained by further reaction of silicon‐containing copolyamic acid with 2‐isocyanatoethyl methacrylate (IEM). The insoluble fraction of photosensitive copolyimide precursor reached 90% after 10 min of irradiation with UV light. In comparison, the thermal imidization of irradiated photosensitive copolyimide precursor was more difficult than that of silicon‐containing copolyamic acid. A longer heating time or higher imidization temperature was required.
Durable and hydrophobic surface modification by plasma polymers deposited from acetylene/hexafluoroacetone ethylene/hexafluoroacetone, and ethane/hexafluoroacetone mixtures
Authors: Inagaki N. , Tasaka S. , Takami Y. 
Published: April 2003

AbstractPlasma polymerization of mixtures of ethane/hexafluoroacetone (HFA), ethylene/HFA, and acetylene/HFA deposit hydrophobic and thin films. The IR and XPS measurements of the deposited films show that fluorination with HFA occur to yield hydrophobic plasma films which possess CF3, CF2, and CF moieties. The advancing contact angle of water on the surface of the deposited films increases with increasing the HFA concentration, especially plasma polymer films prepared from the acetylene/HFA mixture (87.5 mol % HFA) show an advancing contact angle of 126 degrees. Such high hydrophobicity of the plasma polymer surface is attributed to high concentration of fluorinated carbons, especially CF3 side groups. The CF3 concentration in the plasma polymers reach about 30 mol % of the total carbon units. These surfaces show no change in advancing contact angle even when stored in a moist atmosphere of 60% RH at 20°C for at least 2 weeks.
Electroconducting polyaniline composite films prepared by chemical oxidative polymerization at gas/liquid interface
Authors: Morita Mitsuyuki , Hashida Isao 
Published: April 2003

AbstractElectroconducting polyaniline composite films have been prepared by chemical oxidative polymerization at gas/liquid interface between heated aniline vapor and aqueous liquid membrane containing a water‐soluble matrix polymer and an oxidizing agent (and proton acid). The formed composite films are green, semitransparent and uniform. Conductivity, transmittance, and visible and IR spectra are investigated with the films prepared under various preparative conditions: aniline vapor exposure time, atmospheric and aniline temperatures, chemical species and concentration of the oxidizing agent, and concentration ratio of the proton acid to the oxidizing agent. The conducting composite films are formed with the liquid membrane containing above 680 mV of oxidation potential and some proton donor. The film conductivity is determined by the absolute amount of the radical cation structure component of polyaniline and the composition ratio of the radical cation component to the quinonediimine component of polyaniline, which is due to the oxidation potential and protonation effect of the liquid membrane. The excess proton acid coexisting with the oxidizing agent contributes to the film transmittance by uniform distribution of polyaniline in the composite film, aside from its contribution to conductivity by increase of the radical cation component at suitable concentration of the oxidizing agent.
High‐pressure FTIR studies of gas–polymer interactions
Authors: Fried J. R. , Li W. 
Published: April 2003

AbstractFTIR spectra of cellulose acetate (CA) and poly(methyl methacrylate) (PMMA) at 35°C have been obtained as a function of carbon dioxide pressure at pressures up to 55 atm in a specially designed FTIR cell. Results indicate that the carbonyl stretching vibrations for CA (1752 cm−1) and PMMA (1731 cm−1) shift to slightly higher wave numbers with increasing pressure. The small shifts suggest dipole–dipole interactions between CO2 and the carbonyl group. In both cases, the shift appears to be linear with pressure. This linearity is interpreted in the framework of the dualmode theory to suggest that gas–polymer interactions occur in the Henry's law dissolution mode.
Environmental effects on latex paint coatings. II. CP/MAS 13C‐NMR and XPS investigations of structural changes in the base polymer
Authors: Sankar S. S. , Patil D. , Schadt R. , Fornes R. E. , Gilbert R. D. 
Published: April 2003

AbstractFilms of a base polymer, primarily a terpolymer of n‐butyl acrylate, vinyl acetate, and vinyl chloride, that is used in latex paint, have been exposed to various combinations of UV/air, UV/SO2, and UV/SO2/H2O. Reported here are results of elemental analyses, XPS and 13C magic angle spinning NMR of the exposed samples. When samples are exposed to UV/SO2 or UV/SO2/H2O, there is clear evidence of the incorporation of sulfur into the polymer, and there is significant loss of the acetate group in the copolymer. There is also evidence of the formation of unsaturated carbon–carbon bonds which is due to loss of the acetate groups and some dehydrohalogenation. During the time scale of exposures, changes in the composition and structure of samples exposed to UV/air were not detected by the techniques considered here although some chain scission and crosslinking undoubtedly occur. The results suggest a synergistic interaction between SO2 and UV leading to rapid degradation of the polymer, and that the presence of atmospheric SO2 pollutants can have an adverse effect on the lifetime of latex coating materials.
Cure kinetics of an epoxy‐novolac molding compound
Authors: Hsieh T. H. , Su A. C. 
Published: April 2003

AbstractThe cure reaction of an epoxy‐novolac molding compound was studied by means of differential scanning calorimetry using the dynamic (i.e., temperature scanning) approach. Based on a modified version of Friedman's method, a procedure aiming at the phenomenological description of cure kinetics was developed. This method was found capable of following satisfactorily the thermokinetics of the molding compound. Our results indicate that the cure reaction is autocatalytic in nature and does not follow simple nth‐order kinetics.
Basic functionalization of molten linear low‐density polyethylene with 2‐(dimethylamino)ethyl methacrylate in an intermeshing corotating twin‐screw extruder
Authors: Song Zhiquiang , Baker Warren E. 
Published: April 2003

AbstractFunctionalization of molten linear low‐density polyethylene (LLDPE) with 2‐(dimethylamino)ethyl methacrylate (DMAEMA) was studied in an intermeshing co‐rotating twin‐screw extruder using a peroxide initiator. The influence of monomer concentration, initiator concentration, reaction temperature, the screw speed, and the mean reaction residence time on the grafting reaction was investigated in order to determine the reaction conditions necessary to obtain a controlled degree of grafting, DG, while minimizing homopolymerization and crosslinking. Relatively high grafting levels can be obtained without excessive polyethylene crosslinking by using high monomer concentrations, wm, with low initiator concentrations, wI. DG increased with increasing monomer concentration when wm exceeded a certain value. Processing temperatures between 130 and 160°C are optimal to achieve high grafting efficiency, GE. Too high a processing temperature resulted in both low DG and GE. An optimal reaction residence time of about 5 min was found for wm = 23 wt % and wI = 0.56 wt % to obtain relatively high DG and GE. The melt flow index of the reaction product, MFI, increased with increasing wm at constant wI. This suggests that the DMAEMA monomer has the ability to suppress crosslinking of the LLDPE chains. The ability of the DMAEMA monomer to compete for initiator and polymer radicals and reduce LLDPE crosslinking was further demonstrated by the study of sequential addition of monomer and initiator along the extruder. The competition among the three reactions (i.e., the desired grafting, homopolymerization, and crosslinking) is discussed.
Acoustic and viscometric studies of solutions of polystyrene and high‐impact polystyrene in benzene, toluene, and tetrahydrofuran
Authors: Al‐Jarrah Mustafa M. F. , Al‐Dujaili Amar H. , Hassun Subhi K. 
Published: April 2003

AbstractUltrasonic measurements of Polystyrene (PS) and high‐impact polystyrene (HIPS) solutions in benzene, toluene, and tetrahydrofuran are reported at 2‐MHz frequency. Effect of solvent and the rubbery phase of HIPS on the ultrasonic measurements are discussed. Observed relaxation times demonstrate the interaction of polymer–polymer macromolecules and polymer–solvent molecules. Results show a linear increase of velocity, density, viscosity, absorption coefficient, relaxation time, and relaxation amplitude values with increase of PS and HIPS concentrations. In contrast as a result of interaction between polymer molecules and solvent molecules compressibility decreased with increasing polymer concentration.
Blends of polyamide 6 with bisphenol‐A polycarbonate. II. Morphology–mechanical properties relationships
Authors: Gattiglia E. , Turturro A. , Pedemonte E. , Dondero G. 
Published: April 2003

AbstractThe relationships between morphology and mechanical properties in polyamide 6/bisphenol‐A polycarbonate blends have been investigated by means of Scanning Electron Microscopy and tensile tests. The immiscibility of the two polymers gives rise to biphasic blends in which the polycarbonate constitutes the matrix when its concentration is higher than 35 wt %. The morphology of the blends is controlled by the thermal and rheological characteristics, as well as by the mixing conditions. In general, the adhesion at the interface between the phases is absent. Moreover, polycarbonate‐rich blends can be considered as polycarbonate matrix with holes. As a consequence, the blends are mechanically much weaker than the pure components both in terms of Young's modulus and strength, at break. Blends very rich in polyamide, more than 90% by weight, behave differently, probably because of chemical, interchain interactions. This is reflected positively in the impact behavior, which was improved in this composition range.
Effective immobilization of protein linked with polyethylene glycol on silica via hydrogels using silica sol
Authors: Yoshinaga Kohji , Kito Taketoshi , Yamaye Makoto 
Published: April 2003

AbstractAn effective attachment of activated polyethylene glycol (PEG), which has dichloro‐s‐triazinyl functional groups, to silica and protein immobilization with the resulting PEG/SiO2 composite were studied. The reaction of methanol—silica sol with the PEG—silyl reagent resulted in an efficient PEG attachment to SiO2 as compared with the usual two‐step PEG modification of silica gel and glass surface. The activated PEG/SiO2 was able to immobilize over 600 mg of bovine serum albumin per unit gram of the PEG composite through hydrogel formation. The application of the present binding method of PEG‐linked protein on SiO2 was also discussed.
Viscoelastic behavior of concentrated oil solutions of sulfonated polymers. V. Effect of metal stearate plasticizers
Authors: Agarwal P. K. , Peiffer D. G. , Garner R. T. , Lundberg R. D. 
Published: April 2003

AbstractLinear viscoelastic studies of concentrated blend solutions of metal neutralized sulfonated elastomers and low molecular weight metal stearate plasticizers are presented. The data of the magnesium and zinc salts of sulfonated EPDM polymer solutions in 100 N oil solvent as a function of magnesium and zinc stearate polar plasticizers show that addition of the latter species into the ionomeric elastomer solutions enhances their low temperature relaxation spectrum. The changes in properties are directly related to the enhancement of ionic interactions and filler effects of the plasticizers. At high temperatures, the zinc stearate molecules behave more as a conventional plasticizer. For ionomeric associating polymers, the phenomenon appears to be quite general in nature. The enhancement in properties is found to be a function of the counterion structure on the ionomer and stearate. In the case of these solution blends, the studies confirm that an ion‐exchange process can occur, especially at high temperatures, resulting in the counterion on the stearate moieties “exchanging” ionic sites on the ionomer. Apparently, this process proceeds quite slowly at low temperatures. However, it is clear from these measurements that the incorporation of metal stearates into the ionomeric solution changes the network structure at both low and high temperatures.
Grafting onto preformed polyester network using thermolabile azo groups
Authors: Erciyes A. Tuncer , Avci Ilknur , Yagci Yusuf 
Published: April 2003

AbstractPolycondensation of 4,4‐azo‐bis(cyanopentanoyl chloride) and o‐phthalyl chloride between polyethylene glycol with addition of glycerine leads to polyester networks containing thermolabile azo groups. The networks have been characterized in terms of their swelling in benzene, chlorobenzene, and methacrylonitrile. Grafting of methacrylonitrile onto these preformed networks was then achieved by thermal decomposition of NN groups in the presence of methacrylonitrile.
Physical and chemical aspects of glow discharge reaction on synthetic fibers
Authors: Mitchenko Yu. I. , Fenin V. A. , Chegolya A. S. 
Published: April 2003

AbstractPolyethylene terephthalate (PET), polypropylene (PP), polyamide fibres, and films have been discharge treated. The resulting surface modifications analysed via ESR, IR, UV contact angle measurements. Discharge treatment introduces radicals and OH groups into the surface. But it does not correlate with wetability. Discharge treatment also produces the changes in conformation of macromolecules and roughness. This process is largely responsible for the wetability.
New epoxy compounds derived from substituted maleamic acids
Authors: Mikroyannidis John A. 
Published: April 2003

AbstractEight new epoxy compounds bearing maleamic acid moieties were prepared starting from 4‐(2,3‐epoxypropoxy)benzaldehyde (EPB) or 2,3‐epoxypropylglyoxylate monohydrate (EPG). The monomaleamic acid derived from an aromatic diamine (1,4‐phenylenediamine, 4‐aminophenyl ether, 4,4′‐diaminodiphenylmethane or 4,4′‐diaminodiphenylsulfone) reacted with EPB or EPG to afford the epoxy compounds. They were characterized by IR and 1H‐NMR spectroscopy. Their DTA traces showed that thermal polymerization started at 187–211°C. Network systems were obtained by crosslinking from the reaction of epoxy group with the maleamic carboxyl and through the olefinic bond. The TGA thermograms of crosslinked polymers showed that they were stable up to 275–295°C in N2 or air and afforded anaerobic char yield of 47–65% at 800°C. In addition, isothermal gravimetric analysis (IGA) was used to evaluate the thermo‐oxidative stability of a typical cured resin.
The four tiers of structure in integrally skinned phase inversion membranes and their relevance to the various separation regimes
Authors: Kesting R. E. 
Published: April 2003

AbstractThere are four superimposed tiers of structure in integrally skinned phase inversion membranes: macromolecules (functionally submacromolecules, that is, displacements between chain segments); nodules–approximately 200 Å in diameter spherical macromolecular aggregates, each of which contains several tens of macromolecules (nodule interiors are denser than interstitial regimes, therefore, chain segment displacements within and between nodules differ and hence constitute a bimodal pore size distribution which may account for the dual mode sorption and permeation of gases; transport of water in reverse osmosis occurs primarily through the less dense interstitial domains); nodule aggregates—400–1000 Å in diameter spherical clumps of nodules (the skins of reverse osmosis and gas separation membranes consist of a single layer of coalesced nodule aggregates; ultrafiltration pores are the spaces between incompletely coalesced nodule aggregates, and residual ultrafiltration pores are the defect pores found in reverse osmosis membrances); supernodular aggregates–aggregates of nodule aggregates which constitute the walls of the 0.1–2 μm in diameter open cells in the membrance substructure (microfiltration pores are the surface extensions of openings between adjacent cell walls).
Protease immobilization onto copoly(ethylene/acrylic acid) fiber
Authors: Emi Shingo , Murase Yasuhiro , Hayashi Toshio , Nakajima Akio 
Published: April 2003

AbstractWater‐insoluble proteases were prepared by immobilizing papain and chymotrypsin onto the surface of the copoly(ethylene/acrylic acid) fiber. The effect of the surface area of the copolymer fiber on the amount of the immobilized protease was investigated. The mode of the immobilization between protease and copolymer such as a covalent fixation or an ionic interaction on the enzymatic activity and the stability of the immobilized protease was also investigated. The stability of the immobilized protease was also investigated. The stability of the immobilized protease in this study meant thermal stability, durability for repeated use, stability in urea, and durability for repeated washing. The activity of covalently immobilized proteases was found to be still higher toward small ester substrates, but rather low toward casein, a high molecular weight substrate. The covalently immobilized proteases onto the copolymer fiber gave an almost constant specific activity, suggesting less structural deformation of the protease molecule than the conventional immobilized enzyme system in the lower surface concentration. The thermal stability of the immobilized proteases was higher than that of the respective ionic interaction or native proteases. The initial enzymatic activity of the covalently immobilized proteases was maintained almost unchanged without any elimination and inactivation of proteases when the batch enzyme reaction was performed repeatedly, indicating excellent durability.
General procedures to determine the composition of commercial, two‐part polysulfide aircraft sealants
Authors: Ennis Brian C. , Hanhela Peter J. , Huang Robert H. E. , Long Geoffrey J. , Paul D. Brenton 
Published: April 2003

AbstractInterpretation of the chemical processes which polysulfide sealants undergo either on storage or when the cured material is subjected to environmental influences requires detailed knowledge of formulations. Procedures have been developed to isolate and identify a range of additives in two‐part commercial aircraft sealants of both the dichromate and manganese dioxide cure types. Solvents, curing agent dispersants, and cure rate modifiers were separated chemically and thermal analysis was demonstrated to provide a ready means to estimate carbon in fillers. The phenolic resin adhesion enhancers were conveniently determined using 13C‐NMR spectroscopy and could also be identified using size exclusion chromatography. It was shown that virtually no interaction occurred between polysulfide liquid polymers and phenolic resins following aging at 70°C for 7 days. The most appropriate methods for determining curative levels were established and new means of assessing thiol content of the polysulfides by both 13C‐NMR and PMR spectroscopy are described. The significance of aspects of the sealant formulations is discussed.
Interpenetrating polymer networks of cellulose nitrate and castor oil based polyurethanes—development and characterization
Authors: Natchimuthu N. , Rajalingam P. , Radhakrishnan Ganga , Francis D. Joseph 
Published: April 2003

AbstractSemi‐interpenetrating polymer networks of cellulose nitrate and castor oil based polyurethanes have been prepared by using excess diisocyanate for the crosslinking process. Semi‐IPNs with 30% cellulose nitrate showed some degree of miscibility. Enhanced miscibility was observed by the partial replacement of cellulose nitrate with poly(vinyl chloride‐co‐vinyl acetate). The ternary IPNs of poly(vinyl chloride‐co‐vinyl acetate), cellulose nitrate, and polyurethanes showed increased tensile strength and decreased flammability than those based on cellulose nitrate and polyurethanes alone.
Photodegradation of ethylene–propylene copolymer and ethylene–propylene–ethylidenenorbornene terpolymer
Authors: Maecker Norbert L. , Priddy Duane B. 
Published: April 2003

AbstractSignificant progress has been made in recent years regarding the photooxidation of olefin copolymers, but questions still remain. This paper reviews the progress and probes the photooxidative chemistry of ethylene–propylene (EP) and ethylene/propylene/diene monomer (EPDM) copolymers. Both stabilized and unstabilized polymer plaques were irradiated in a xenon are and the surface chemistry followed using infra‐red spectroscopy. Model compounds were used to help elucidate the chemistry caused by unique structural features present in the copolymers. Volatile products evolved during photooxidation were determined giving valuable insight into the degradation chemistry.
Cooperation between chemical and physical networks in crosslinked and plasticized PVC
Authors: Hjertberg Thomas , Dahl Roger 
Published: April 2003

AbstractThe effect of crosslinking of plasticized PVC on the mechanical properties has been investigated. Crosslinking was performed by using a dithioltriazine, and penetration as a function of temperature was used to follow the changes in mechanical properties. Changes in the melting behavior were detected by differential scanning calorimetry. Even rather low levels of gel content gave a substantial reduction in penetration in the interval 60–110°C, while a more complete reaction prevented major penetration up to at least 200°C. The penetration curve of heavily crosslinked materials showed several plateaus and the transitions could be related to melting of different crystallites formed by annealing at different temperatures. The physical network formed by the crystallites constitutes an important complement to the chemical network in plasticized PVC crosslinked by dithioltriazine. Both the amount and the melting temperature of the crystallites increased after annealing. The introduction of the chemical network further improved the heat resistance of the crystallites. The presence of the two networks will therefore show a synergistic effect with respect to the mechanical properties at increased temperatures.
Mechanical relaxations of nylon–polyurea block copolymers
Authors: Gardlund Zack G. 
Published: April 2003

AbstractDynamic mechanical analysis from −150 to +150°C has been carried out on seven block copolymers that were prepared by the in situ anionic polymerization of caprolactam in the presence of a preformed polyurea. The various relaxations have been identified and activation energies calculated. Some polymer–polymer miscibility of the polyurea and amorphous nylon copolymer segments is indicated by the compositional dependence of the α relaxation.
Studies on the mechanism of draw resonance in melt spinning
Authors: Jinan Cao 
Published: April 2003

AbstractThe physical mechanism of draw resonance of polymer fluids in melt spinning has been studied. It is proposed, according to the cross‐sectional area dependence of the local draw ratio of the filament along the spinline, that filament drawing can be divided into three modes which are given in the main text. In particular, it is found that the nonuniformizing draw mode is the necessary condition of draw resonance. The mechanism is certified through the analytical solution of isothermal melt spinning under uniform spinning stress and the critical draw ratio of isothermal and uniform tension melt spinning. The mechanism was employed to analyze the promotive and suppressive factors of draw resonance in a real spinning system and the development of filament unevenness along the spinline.