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  • 1
    Digitale Medien
    Digitale Medien
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 1071-1076 
    ISSN: 0887-624X
    Schlagwort(e): functional aromatic polyethers ; fluorescent polymers ; aromatic nucleophillic substitution polymerization ; thermal behavior ; electron spin resonance ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The poly(arylene ether)s were prepared by the nucleophillic aromatic substitution polymerization of phenolphthalin and its derivatives with activated aromatic difluorides. The polymers had glass transition temperatures ranging from 210 to 240°C. Though the monomers have no fluorescence, the resulting polymers fluoresced a light green color in solid and solution states. The maximum excitation and emission wavelengths are 420 nm and 470 nm, respectively. In the polymer solutions, the fluorescence intensity decreased gradually, but the intensity was recovered by heating the polymer at 220°C for a few minutes. The fluorescent polymer had a stable radical. A model compound having the same repeating unit of the polymer was also prepared. The fluorescence properties of this model were almost the same as those of the polymers. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 34 (1993), S. 314-322 
    ISSN: 1040-452X
    Schlagwort(e): Nuclear transplantation ; In vitro maturation ; In vitro fertilization ; Electrofusion ; Oocyte activation ; Coculture ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie
    Notizen: Single blastomeres from eight-cell stage bovine embryos matured and fertilized in vitro were electrically fused with enucleated oocytes matured in vitro. In experiment 1, The percentage of these reconstituted embryos developed to the two- to eight-cell stage 48 hr after electrofusion was increased when both the eight-cell embryos and the enucleated oocytes were derived from oocytes cultured with granulosa cells (14% vs. 38%). In experiment 2, the relationship between activation of oocytes and developmental ability of reconstituted embryos was examined. Although both ethanol and electrical stimulation efficiently induced parthenogenetic activation of oocytes matured in vitro for 26-28 hr (ethanol, 89%; electrical stimulation, 73%), the ratio of the second polarbody extrusion differed (80% vs. 22%). Ethanol-treated enucleated oocytes, however, were not significantly different from the early cleavage of the reconstituted embryos 48 hr after electrofusion (nontreated, 38%; treated, 43%). In experiment 3, reconstituted embryos at the two- to eight-cell stage 48 hr after the electrofusion were cocultured with granulosa cells for 6-7 days. Of 69 embryos, one developed to a morula and three developed to blastocysts. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Poly(vinyl chloride) (PVC) with a broad molecular weight distribution (BMD-PVC) was prepared by suspension polymerization in the presence of PVC with relatively lower molecular weight (LMW-PVC), which was prepared by suspension polymerization in the presence of 2-mercaptoethanol as a chain-transfer agent. It is elucidated using porosity measurement, scanning electron microscopy (SEM), and energy dispersion X-ray microscopy (EDXM) that the resultant BMD-PVC grains have an interesting internal structure at the level of primary particles. Discoloration time and fusion time of the BMD-PVC was studied. Discoloration time and fusion time of BMD-PVC is particularly dependent on the polymerization degree (Pw) of LMW-PVC and LMW-PVC content in the BMD-PVC samples. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 51 (1994), S. 749-753 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Poly(vinyl chloride) with relatively low molecular weight (LMW-PVC) was prepared by suspension polymerization in the presence of some chain-transfer agents, such as mercapto compounds. It is elucidated by means of thermogravimetry, dehydrochlorination, color difference, and discoloration that the resultant LMW-PVC has good thermal stability. The degree of dehydrochlorination of the LMW-PVC obtained by using n-dodecylmercaptan increases with increasing the content of component from the chain-transfer agent. It is found that the LMW-PVC obtained by using mercapto compounds shows better thermal stability (discoloration property) than does the one obtained without using these agents, at the same weight-average polymerization degree. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 53 (1994), S. 255-255 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 46 (1992), S. 1235-1243 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Moldings of ethylene-propylene block copolymer (block PP) are improved by annealing in their tensile impact strength (TIS) and brittle temperature (Tb). To elucidate the mechanism, the role of the poly(ethylene-co-propylene) (PEP) component was studied, and the component extracted with n-heptane from annealed test pieces was subjected to characterization by a fractionation technique. It is found that recrystallization takes place by annealing in the PP matrix and results in segregation of atactic PP and high molecular weight amorphous PEP from the crystal region to the amorphous region. Furthermore, crystalline PEP also undergoes recrystallization by annealing, increasing the miscibility in the interface of PP and PEP. These phenomena in the solid phase are discussed in connection with the annealing effect related to impact strength. © 1992 John Wiley & Sons, Inc.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 50 (1993), S. 753-758 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The blending effect of poly(vinyl chloride) with relatively higher molecular weight (HMW-PVC) and relatively lower molecular weight (LMW-PVC) has been investigated by measuring various mechanical properties: melt properties, tensile strength, tensile modulus, and impact strength. The blended PVC has slightly improved melt properties in comparison with the HMW-PVC used. The tensile strength of the blended PVC is related to the weight-average polymerization degree (Pω) of LMW-PVC and the LMW-PVC content. At the LMW-PVC content of 20%, the tensile strength of blended PVC is a maximum: approximately 58 MPa. © 1993 John Wiley & Sons, Inc.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 51 (1994), S. 755-759 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The blending effect of poly(vinyl chloride) (PVC) with relatively higher molecular weight (HMW-PVC) and relatively lower molecular weight (LMW-PVC) has been investigated by measuring various thermal stability and fusion times. The thermal stability of the blended PVC is improved when the small amount of LMW-PVC obtained using mercapto compounds as a chain-transfer agent is blended into PVC with HMW-PVC. At the LMW-PVC content from about 5-30 wt %, the thermal stability of the blended PVC is much more improved. Furthermore, the blended PVC with LMW-PVC, obtained using mercapto compounds, exhibits significant improvement in the discoloration time. The fusion time of the blended PVC is related to the weight-average polymerization degree of LMW-PVC and the LMW-PVC content. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Poly(vinyl chloride) (PVC) with relatively broader molecular weight distribution (BMD-PVC) was prepared by two-step suspension polymerization: (1) preparation of poly(vinyl chloride) with relatively higher molecular weight (HMW-PVC) and (2) successive preparation of poly(vinyl chloride) with relatively lower molecular weight (LMW-PVC) in the presence of the resultant HMW-PVC and 2-mercaptoethanol as a chain transfer agent. Some properties of BMD-PVC were investigated: fusion time, melt viscosity, discoloration time, tensile strength at yield, tensile modulus in tension, and elongation at break. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 46 (1992), S. 1221-1233 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Investigations were carried out regarding the effect of annealing of ethylene-propylene block copolymer (block PP) moldings on their tensile impact strength (TIS), brittle temperature (Tb), and other mechanical properties. Annealing near the melting point improves TIS and Tb as the result of recrystallization. With a system in which a minute amount of talc is added as a nucleating agent, the degree of improving TIS through annealing is considerably less than that with a nonnucleated system. The effect of annealing on the impact strength is due to changes of fine texture and morphology of crystallites and is explicable by recrystallization and polymer diffusion. © 1992 John Wiley & Sons, Inc.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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