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1

Digitale Medien

Purification of thermotropic liquid-crystalline siloxane oligomer with supercritical carbon dioxide (1989)

Krishnamurthy, Sushil ; Chen, Shaw H.

New York : Wiley-Blackwell

Die Makromolekulare Chemie 190 (1989), S. 1407-1412

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ISSN: 0025-116X

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Physik

Notizen: The effects of the purification of thermotropic liquid-crystalline siloxane oligomer with supercritical carbon dioxide were investigated. It was found that low-molar-mass contaminants, presumably the two alkene precursors, can be effectively removed at 80°C and carbon dioxide pressures up to 31,0 MPa. In support of this observation is the fact that glass transition temperature goes up as a result of purification. In addition, the selective reflection wavelength was found to increase at increasing purity level, as achieved by extraction at increasing carbon dioxide pressure.

Zusätzliches Material: 3 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/macp.1989.021900620

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2

Digitale Medien

Investigation of the thermal degradation of alkyl isocyanate polymers by direct pyrolysis mass spectrometry (1989)

Durairaj, B. ; Dimock, A. W. ; Samulski, E. T. ; [weitere]

Bognor Regis [u.a.] : Wiley-Blackwell

Journal of Polymer Science Part A: Polymer Chemistry 27 (1989), S. 3211-3225

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ISSN: 0887-624X

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: Thermal degradation mechanisms of alkyl isocyanate homo- and copolymers were studied using TGA and DP-MS. Both analyses showed that these polymers begin decomposing at around 190°C under inert or vacuum conditions. DP-MS analysis showed the formation of trace quantities of monomer from poly(butyl isocyanate) only and none from higher homologs. All polymers studied produced trimers as their principal decomposition product, implying that intramolecular cyclization is the dominant mechanism of decomposition.

Zusätzliches Material: 6 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/pola.1989.080271003

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3

Digitale Medien

Epoxy resins for deep UV lithography (1989)

Stewart, K. J. ; Hatzakis, M. ; Shaw, J. M.

Stamford, Conn. [u.a.] : Wiley-Blackwell

Polymer Engineering and Science 29 (1989), S. 907-910

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ISSN: 0032-3888

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: A negative resist based upon photo-acid initiated cationic polymerization of an epoxy resin (1, 2) was reported in the early eighties with the advent of onium salts (3-5). An efficient acid generating onium salt, triphenylsulfonium hexafluoroantimonate (6), absorbs light in the deep UV producing acid upon direct photolysis in this region of the spectrum. The resin component of such a negative resist system must be optically transparent over the exposure wavelengths to obtain vertical image profiles. Another difficulty often encountered with crosslinking negative resists is swelling of the crosslinked matrix during development with organic solvents. This swelling manifests itself in distorted images and/or complete adhesion loss, especially when submicron features are involved. Our goal has been to address these problems and develop an organic developable deep UV resist capable of providing submicron images. Optically transparent commercial resins, styrene-allyl alcohol copolymers, have been converted to glycidyl ethers, thereby providing cationically polymerizable functionalities. Careful choice of the resin was made to obtain reactive ion etch resistance, thermal stability, good adhesion, and coating properties. The synthetic procedure and characterization of the epoxy resin will be presented. The effect of the molecular weight distribution upon swelling during development and general solubility properties also will be discussed. Resist formulations exhibited sensitivities of 19 to 30 mJ/cm2 on a Perkin Elmer 500 in the deep UV (UV2) mode. The electron beam sensitivity is 3 to 5 μC/cm2 at 20 KeV. Submicron images have been generated in both optical and electron beam lithography.

Zusätzliches Material: 5 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/pen.760291405

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4

Digitale Medien

Effects of fiber orientation on the stress distribution in model composites (1989)

Fan, Cun F. ; Hsu, Shaw L.

Bognor Regis [u.a.] : Wiley-Blackwell

Journal of Polymer Science Part B: Polymer Physics 27 (1989), S. 2605-2619

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ISSN: 0887-6266

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Physik

Notizen: A Raman-mechanical technique was used to study the relationship between stress distribution and fiber orientation in model composites. Our experimental data generally were consistent with most simplistic mechanical models. A more complete analysis, using the Eshelby equivalent inclusion method, fitted our experimental data exceptionally well. For large applied strains, compressive failure occurred for fibers which were oriented at high angles relative to the draw direction. This occurred because of the lateral shrinkage associated with the matrix when the sample was stretched. The effect of fiber end geometry on the stress distribution for these misaligned fibers was the same as observed earlier. Tapered-end fibers generally carried loads more efficiently in composites than blunt-end fibers.

Zusätzliches Material: 14 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/polb.1989.090271304

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5

Digitale Medien

Mechanical behavior of polyblended polystyrene and ethylene-propylene-diene rubber by cationic reactions in the melt (1989)

Shaw, S. ; Singh, R. P.

New York, NY [u.a.] : Wiley-Blackwell

Journal of Applied Polymer Science 38 (1989), S. 1677-1683

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ISSN: 0021-8995

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: Attempts have been made to obtain high impact polystyrene by Lewis-acid-initiated degradation process in the melt reactions of PS and EPDM. It is found that impact strength improves whereas tensile strength decreases. This can be interpreted by the increased solubility of the coupled rubber molecules in the continuous phase.

Zusätzliches Material: 5 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/app.1989.070380908

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6

Digitale Medien

Parthenogenetic activation of unfertilized mouse oocytes by exposure to 1,2-propanediol is influenced by temperature, oocyte age, and cumulus removal (1989)

Shaw, J. M. ; Trounson, A. O.

New York, NY : Wiley-Blackwell

Gamete Research 24 (1989), S. 269-279

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ISSN: 0148-7280

Schlagwort(e): propanediol ; dimethylsulfoxide ; ethanol ; hyaluronidase ; Life and Medical Sciences ; Cell & Developmental Biology

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Biologie

Notizen: Cumulus-intact and -denuded unfertilized oocytes from two mouse strains were exposed to 1.5 m ethanol (EtOH) or two cryoproteclant solutions, 1.5 M propanediol (PROH) or 1.5 M dimethylsulfoxide (DMSO), for 4.5 min at 27°C, and the proportion of activating or degenerating oocytes studied. Exposure to DMSO did not significantly increase activation above that of oocytes not exposed to DMSO. Treatment of oocytes in PROH resulted in the activation of up to 87% of viable oocytes. This was significantly higher (P 〈01) than in control oocytes and comparable to the rate of activation after treatment with EtOH (59-96% activation). In solutions at 1°C, 47% of control oocytes were activated, which was not significantly different from the rate of activation in EtOH (36%) or PROH (50%) at 1°C. Following treatment with PROH, up to 87% of oocytes degenerated within a period of 6 h in vitro. The age of the oocytes (h post hCG) and the time of cumulus removal with the enzyme hyaluronidase, relative to the time of exposure to the chemicals, influenced the level of degeneration in most groups. Significantly fewer oocytes degenerated when cumulus cells were removed before treatment (0-31%) than when the cumulus was left intact throughout the treatment and 6 h culture period (10-87%). Exposure to PROH at 1°C reduced oocyte degeneration to 5%. We conclude that PROH causes significantly greater losses of oocytes as a result of parthenogenetic activation and degeneration than of exposure to DMSO.

Zusätzliches Material: 5 Tab.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/mrd.1120240304

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7

Digitale Medien

Phosphorus-nitrogen compounds. Part 59.For Part 58, see Ref. 1. Aromatic carbon-13 NMR spectra of phenyl-substituted cyclotriphosphazatrienes. Second-order effects with phosphorus-31 nuclei (1989)

Deutsch, W. Francis ; Parkes, Harold G. ; Shaw, Robert A.

Chichester : Wiley-Blackwell

Organic Magnetic Resonance 27 (1989), S. 207-213

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ISSN: 0749-1581

Schlagwort(e): Phosphorus-nitrogen compounds ; Aromatic 13C NMR spectra ; Second-order effects ; Phenyl-substituted cyclotriphosphazatrienes ; Chemistry ; Analytical Chemistry and Spectroscopy

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: The 13C NMR spectra were obtained for the geminal series N3P3Cl6-nPhn (n = 2, 4, 6) and for the mono spiro series N3P3Ph2[X(CH2)n Y]Cl2 (X = Y = O, n = 2, 3, 4; X = Y = NH, n = 2, 3, 4; X = Y = NMe, n = 2, 3; X = O, Y = NH, n = 3, 4; X = NH, Y = NMe, n = 2, 3; X = O, Y = NMe, n = 2). Multiplet structures were observed in the 13C NMR spectra of N3P3Ph2[HN(CH2)3NH]Cl2 at 0°C. The complexity of these resonances could be altered by a change in temperature. These observations have been rationalized in terms of second-order interactions with remote phosphorus nuclei, which can be systematically altered with temperature. Inductive and resonance substituent coefficients have been calculated using the dual substituent parameter method from the relative shelding of the meta (C-3) and para (C-4) nuclei in the phenyl ring.

Zusätzliches Material: 5 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/mrc.1260270302

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8

Digitale Medien

Elemental resonance ionization mass spectrometry: A review (1989)

Smith, D. H. ; Young, J. P. ; Shaw, R. W.

New York, NY [u.a.] : Wiley-Blackwell

Mass Spectrometry Reviews 8 (1989), S. 345-378

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ISSN: 0277-7037

Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Physik

Zusätzliches Material: 10 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/mas.1280080503

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9

Digitale Medien

Gelation and interaction in plasticizer/PVC solutions (1989)

Boo, Hwee-Khim ; Shaw, M. T.

Brookfield, Conn. : Wiley-Blackwell

Journal of Vinyl and Additive Technology 11 (1989), S. 176-179

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ISSN: 0193-7197

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Maschinenbau , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: Gelation of PVC solutions is generally agreed to result from network formation. The proposed network linkages include crystallites, hydrogen-bonds, and entanglements brought about by spinodal decomposition. The objective of this work is to relate the phase behavior or compatibility of PVC/plasticizer solutions to their gelation behavior. The thermoreversible sol-gel transition of plasticized PVC was studied using a simultaneous light scattering and dynamic viscoelastic analysis technique, in parallel with a thermal optical analysis (TOA). PVC solutions of 1% to 15% in different types of phthalate and sebecate plasticizers were used. Preliminary results suggest phase separation in the less compatible plasticizer during gelation process while more compatible plasticizer/PVC solutions gel without phase separation. This suggests that the gelation process can be relatively independent of the liquid-liquid phase equilibria in the system.

Zusätzliches Material: 7 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/vnl.730110407

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