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  • 1
    Electronic Resource
    Electronic Resource
    Probing the surface chemical structure of some novel poly(ortho esters) prepared with N-methyl and N-phenyl ethanolamine by time-of-flight secondary ion mass spectrometry (ToF-SIMS) (1992)
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 3 (1992), S. 293-301 
    Details
    ISSN: 1042-7147
    Keywords: Poly(ortho esters) ; Biodegradable polymer ; Surface chemical analysis ; Time-of-flight secondary ion mass spectrometry (ToF-SIMS) ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The surface chemical structures of a series of novel poly(ortho ester) homopolymer and copolymer films prepared using N-methyl- and N-phenyl-ethanolamine (MDE and PDE) have been investigated using time-of-flight secondary ion mass spectrometry (ToF-SIMS). Systematic fragmentation patterns were observed within the ToF-SIMS spectra up to m/z = 1600, which were readily interpreted in terms of the polymer structures. Cations were detected which could be assigned to structures arising from the diols, the ortho ester species and diads, triads etc. of the monomer, from both the homopolymer and the random portion of the copolymer chains. The analysis of the proposed ion structures suggested two major mechanisms of fragmentation based on the cleavage of the ortho ester bonds involving either the exocyclic or the endocyclic alkoxy group. The Tof-SIMS peak area ratios for ions diagnostic of the diols and the ortho ester species reflected the bulk copolymer composition in a semi-quantitative fashion. The observation of such relationships for high mass cations (up to m/z = 500) is particularly noteworthy and has not been reported previously. These studies allow a dramatic insight into the surface chemical structure of these poly(ortho esters), information which has formed the foundation of current investigations on the mechanisms of the acid-catalysed surface degradation of these polymers.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pat.1992.220030603
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  • 2
    Electronic Resource
    Electronic Resource
    The analysis of the surface chemical structure of biomedical aliphatic polyanhydrides using XPS and ToF-SIMS (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 1597-1605 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The surface chemical structure of a range of aliphatic polyanhydride films has been examined using XPS and ToF-SIMS. The XPS data confirms the purity of the surface, and the experimental surface elemental ratios are in good general agreement with the known stoichiometry of the polyanhydrides. The ToF-SIMS spectra of the polyanhydrides are shown to be significantly different. The SIMS data conforms to a systematic fragmentation, in both negative- and positive-ion SSIMS spectra, occurring throughout the entire series of polyanhydrides examined. Radical cations are observed in the positive-ion spectra. These results are discussed in terms of the general fragmentation patterns observed in the SIMS analysis of polymers. The combined use of ToF-SIMS and XPS is shown, to provide a detailed insight into the interfacial chemical structure of these polyanhydrides.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070420613
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  • 3
    Electronic Resource
    Electronic Resource
    Poly(ethylene terephthalate) melt spinning via controlled threadline dynamics (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 46 (1992), S. 531-552 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Fiber melt spinning of poly(ethylene terephthalate) (PET) was studied via modification of threadline dynamics. Several techniques were implemented in the high-speed spinning process for the judicious control of threadline dynamics. This included a thermal conditioning zone (TCZ) for controlling the threadline temperature profile and a dydraulic drag bath (HDB) for controlling the threadline spinning stress. Through controlled threadline dynamics, key factors affecting the structure development - namely, temperature, tensile stress, and crystallization time - were manipulated to favor formation of a highly oriented and transversely uniform structure in the spun fibers. This carries the implication that optimum or near-optimum processing conditions are being applied during the structure development period. More specifically, tensile stress in the threadline, independent of temperature, is substantially increased to many orders higher than that ordinarily attained in the normal high-speed spinning process. Concurrently, the temperature crucial to the structure development is being independently optimized and its duration extended to attain a highly oriented structural order. Properties of the spun fibers were found to be correlated with the threadline parameters including cooling profile, tension profile, and strain rate. PET fibers spun via the one-step process with the introduction of the TCZ and HDB possess superior mechanical performance. Structural characterization suggests that the spun fibers have a high amorphous orientation factor and a uniform radial structure distribution. Further on-line studies indicate that structure development in the threadline is completely different from that of the traditional high-speed spinning process. The attenuation profile of the threadline is observed to be dependent of TCZ temperature, residence time in the HDB, temperature of the HDB, and take-up speed. It is believed that for the melt spinning process with the TCZ and the HDB, the threadline dynamics is changed from one controlled by inertia and air drag forces to one controlled by the imposed hydraulic drag.
    Additional Material: 26 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070460320
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of water content on the properties of starch/poly(ethylene-vinyl alcohol) blends (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 52 (1994), S. 353-363 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The physical properties of unmodified starch, poly(ethylene vinyl alcohol), glycerol, and water mixtures are reported. Thermal and melt-flow properties of the preprocessed, physically mixed materials were determined along with the tensile properties and morphology of injection-molded microtensile samples. Melt-flow properties were measured by a capillary rheometer, and the water content was varied from 4 to 18%. The morphology, rheology, and tensile properties are all highly related to the percentage of water present. A transition in the tensile properties and morphology of the blends was observed at approximately 11% moisture content. © 1994 John Wiley & Sons, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070520301
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of spinning conditions on morphology and properties of polyethylene terephthalate fibers spun at high speeds (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 44 (1992), S. 447-458 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Fiber spinning of polyethylene terephthalate (PET) was studied at take-up speeds ranging from 2000 m/min to 7000 m/min under various spinning conditions. Effects of changes in process variables on the molecular orientation, crystallinity, and properties of as-spun PET fibers are reported. Conventional cross-flow quench in high-speed spinning yields fibers with undesirable crimp and asymmetric structure with respect to the fiber axis. Radial-flow quench eliminates these problems. Changes in other spinning conditions, such as extrusion temperature, throughput or take-up denier, and molecular weight, may also affect the development of PET fiber structure in the high-speed threadline.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070440310
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  • 6
    Electronic Resource
    Electronic Resource
    Ectopic induction of cartilage and bone by water-soluble proteins from bovine bone using a polyanhydride delivery vehicle (1990)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 24 (1990), S. 901-911 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Controlled release delivery vehicles for water-soluble osteogenic proteins from demineralized bovine bone matrix were constructed using polyanhydride polymers. The water-soluble proteins were isolated from a 4 M guanidine hydrochloride extract of bone matrix. The water-soluble proteins possessed Chondrogenic Stimulating Activity (CSA) when tested in stage 24 chick limb bud cell cultures, but were incapable of inducing cartilage or bone in vivo when implanted intramuscularly into mice by themselves. The polyanhydride polymers alone were also incapable of inducting ectopic cartilage or bone. However, when the water-soluble proteins were incorporated into the polymeric delivery vehicle, the combination was capable of inducing cartilage and bone up to 50% of the time. These results demonstrate that it is possible to use polyanhydride polymers as controlled-release delivery vehicles for soluble bioactive factors that interact with a local cell population.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820240708
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  • 7
    Electronic Resource
    Electronic Resource
    Characteristics and design procedure of hyperbolic dies (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 30 (1992), S. 557-561 
    Details
    ISSN: 0887-6266
    Keywords: extrusion from hyperbolic dies, characteristics and design procedures in ; strain rate in extrusion procedures, hyperbolic die design and ; filament production with constant extensional strain rate with hyperbolic dies ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Nozzle profiles capable of generating constant extensional strain rates are termed hyperbolic dies. When used in polymer extrusion, they exhibit greater potential in inducing and retaining polymer molecular orientation than conventional capillary dies. Most mathematical expressions found in the literature involve several processing variables in describing and designing such nozzle profiles. This report reveals that a hyperbolic die profile, although rather complicated, can be expressed with equations in terms of two ordinary geometrical parameters - the exit diameter and the hyperbolic length. This finding greatly simplifies the design procedure of hyperbolic dies. The extensional strain rate of a hyperbolic die can be related to the length-to-diameter ratio for any given exit diameter. Examples of various types of die profiles are presented and their constant extensional strain-rate characteristics are discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1992.090300606
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  • 8
    Electronic Resource
    Electronic Resource
    Surface enrichment in CuOx/ZnO samples at low Cu contents (1990)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 15 (1990), S. 614-616 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A recent report (G. Moretti et al., Surf. Interface Anal. 14, 325 (1989)) in this journal has used XPS to show unequivocally that surface enrichment of calcined CuOx/ZnO co-precipitates does not occur substantially; here, similar evidence for samples of low Cu content suggests that surface enrichment by copper does occur. This is an important finding for model precursors of methanol synthesis catalysts.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740151008
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  • 9
    Electronic Resource
    Electronic Resource
    Characterization of a range of alkyl-bonded silica HPLC stationary phases: XPS and ToF-SIMS studies (1994)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 21 (1994), S. 263-273 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A series of alkyl-bonded silica HPLC stationary phases with a mean particle diameter of 5 μm has been prepared using a variety of dimethylalkylsilyl chlorides (i.e. monofunctional bonding agents) with alkyl chain lengths varying from C1 to C18, including phenyl and cyanopropyl groups. The stationary phases have been characterized using XPS and time-of-flight (ToF)-SIMS. Elemental analyses by XPS have identified trace quantities of iron, sodium and chlorine at the silica/dimethylalkylsilyl chain interface, and aluminium was detected by ToF-SIMS. A comparison of percentage carbon obtained by XPS with bulk carbon-loading analyses suggests that the alkyl chains are bonded to the surface of the porous silica particles. Molecular ions characteristic of the dimethylalkylsilyl groups were identified in the ToF-SIMS data together with ions attributable to these alkylsilyl groups attached to fragments of silica, the latter indicating covalent bonding to the silica surface. In addition, a series of low-mass signals corresponding to alkyl chain fragments and silyl/silica-based ions was observed. The value of high-resolution ToF-SIMS data for ion assignments is well demonstrated. The relative ion intensities of several of these low-mass ions were studied as a function of changing alkyl chain length. In general, as the alkyl chain length increased, the abundance of the silicon-containing fragments decreased, whilst the abundance of the alkyl-based fragments increased, within the ToF-SIMS spectra.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740210502
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  • 10
    Electronic Resource
    Electronic Resource
    Oxide formation on Fe and Ti thin films and on Fe thin films modified with ultrathin layers of Ti (1991)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 17 (1991), S. 48-56 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Reactions of O2 and H2O to from thin oxides on Fe, Ti and Ti-modified Fe thin films have been studied by XPS, following O2 and H2O exposure in the range 0-600 L, to form oxides with thicknesses of 〈 40 Å. XPS Iineshape analysis is used, utilizing a special combination of reflection electron energy-loss spectroscopy (REELS) and nonlinear least-squares fitting routines to model the intrinsic and extrinsic energy losses that accompany potoemission for the Ti and Fe 2p lines. During the formation of the thinnest oxides, this approach yields a unique picture of the composition of the oxide, while for the thicker layers, there is little significant difference between this fitting approach and (1) fitting approaches using an integral background approach or (2) direct deconvolution methods using the REELS data. Both Fe and Ti are quite reactive to O2, yielding a surface oxide that is apparently an FeO-dominated FeO/Fe3O4 bilayer on Fe surface oxide that is predominantly TiO2 on the Ti surface. Pure Fe and Ti surfaces are unreactive to H2O. Predosing of thewse surfaces with low levels of O2 (5 L) does not increase the reactivity appreciably toward H2O. Ti dispersed on the Fe surface as an adatom layer, with an equivalent thickness of 3 Å, greatly suppresses the reactivity of Fe toward O2, while the Ti is oxidized primarily to TiO2, In contrast to the pure Ti layers, these Ti adatom layers are quite reactive toward H2O, yielding oxides (no evidence for hydroxide) in a uniform distribution of oxidation states (Ti+2, Ti+3 and Ti+4).
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740170112
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