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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 39 (1986), S. 131-134 
    ISSN: 1432-0649
    Schlagwort(e): 42.60
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract A detailed analysis of a self-injected Nd: YAG laser with an unstable cavity is presented. With respect to the normal Q-switched laser-mode operation the pulse peak power is increased by a factor of eight with a pulse length of about 1 ns. Moreover single transverse mode operation is achieved, with divergence near the diffraction limit. An evaluation of the most significant parameters useful for the design of an unstable resonator for self-injection applications is also presented.
    Materialart: Digitale Medien
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  • 2
    ISSN: 1432-0649
    Schlagwort(e): 42.60 ; 07.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 27 (1989), S. 1057-1076 
    ISSN: 0887-6266
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Fourier-transform infrared (FTIR) spectroscopy was used to examine the interactions in miscible blends of a styrene (92%)/acrylic acid (8%) copolymer (SAA8) with poly(methyl methacrylate) (PMMA). From the residue or interaction spectra and shifts of carbonyl and carboxylic acid stretching bands, it is concluded that there is a significant specific interaction involving hydrogen bonding between the carbonyl groups of the PMMA and the carboxylic groups of the SAA8. Similar FTIR spectra of some low-molecular-weight liquid analogs for the various monomer units of these polymers do not indicate a comparable interaction. This explains why direct calorimetry with these compounds fails to model correctly the expected exothermic mixing of the blends. Furthermore, the role of the aromatic moiety in the SAA polymer appears to reduce the degree of self-association of the carboxylic acid groups based on results for the model compounds. Coupled with molecular rigidity, the above mechanism makes the carboxylic acid units in SAA8 more available for interaction with the PMMA carbonyls.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 29 (1991), S. 819-824 
    ISSN: 0887-6266
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The microhardness (H) of poly(ethylene terephthalate) (PET) containing catalysts, as well as of PET without catalysts has been investigated. Two types of morphologies have been examined: (a) structures where spherulitic growth is incomplete, resulting from a primary crystallization from the glassy state and (b) samples in which spherulitic crystallization is completed. It is shown that for the former materials, H is an increasing linear function of the volume of the spherulites and depends on annealing time and catalyst content. For the latter materials, H is nearly constant with increasing annealing temperature (TA). Results are discussed in the light of three principal structural factors which determine the microhardness behavior: (1) the volume content of spherulites within the material; (2) the value of crystallinity within the stacks of the lamella, which turns out to be a constant; (3) the average thickness of the crystals, which increases slightly with TA after crystallization is completed. An expression which takes into account the above parameters and offers a description of the H of polyethylene terephthalate is proposed.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 31 (1993), S. 557-565 
    ISSN: 0887-6266
    Schlagwort(e): poly(ethylene terephthalate), microhardness study of transitions and crystallization in ; microhardness study of transitions and crystallization in PET ; crystallization of PET, microhardness study of ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The crystallization behavior of poly(ethylene terephthalate) both with and without sodium montanate, a crystal nucleating agent, has been studied using the microhardness technique. The kinetics of crystallization from the glassy state were investigated in real time by measuring the microhardness H at different crystallization temperatures. Results are discussed in terms of the Avrami equation. Values of the Avrami exponent n of about 3 are observed for samples irrespective of nucleating agent. For samples with nucleant two crystallization ranges are observed: a first range which corresponds to a fast crystallization from nucleating agent particles and a second range which is associated with a slow self-crystallization mode. New transitions evidenced by the presence of a small maximum in H as a function of annealing time and temperature are detected at temperatures above Tg for physically aged samples. The kinetics of this transition have also been examined. It is further shown that the presence of nucleating agent induces a hardening at room temperature which is similar to the effect produced by the physical aging of the samples below Tg. Finally, it is found that aging reduces the rate of creep of the material under the indenter. © 1993 John Wiley & Sons, Inc.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 23 (1979), S. 575-587 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Melt blends of polycarbonate with Kodel, a homopolyester formed from 1,4-cyclohexanedimethanol and terephthalic acid, and with Kodar, a copolyester formed by replacing some of the terephthalic acid with isophthalic acid, were prepared and their transitional behavior were examined by thermal analysis and dynamic mechanical testing. Blends formed with either polyester were found to have a single Tg over the entire compositional range. Single composition-dependent α- and β-relaxation temperatures were also observed for blends made with either polyester at all compositions. From these data it is concluded that both Kodel and Kodar blends with polycarbonate form miscible amorphous phases. The role of ester-carbonate interchange reactions during melt mixing was experimentally examined and found to be unimportant, from which it is concluded that the observed miscible phase formation is due to physical interactions between the blend components.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 23 (1979), S. 589-600 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Polycarbonate blends with poly(ε-caprolactone) were prepared by both melt-blending and solution-blending techniques, and the properties of these blends were studied by thermal analytical and dynamic mechanical testing methods. Each blend composition was found to have a single glass transition temperature, and the temperature location of this transition was found to be a function only of blend composition and to be independent of the blending technique employed. This behavior led to the conclusions that these two polymers form blends containing a single amorphous phase comprised of the two materials and that this miscible phase results primarily from physical rather than chemical interactions between the two polymers. A reversible liquid-liquid-type phase separation was found to occur when the blend system was heated to high melt temperatures. The temperature required for phase separation, the lower critical solution temperature, was found to vary with blend composition and component molecular weight in the manner expected from thermodynamic considerations. The level of crystallinity of poly(ε-caprolactone) was affected by the presence of the polycarbonate. The polycarbonate also crystallized to an appreciable extent in many of the blends.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 25 (1980), S. 1549-1558 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Thermal analysis was used to show that blends of poly(1,4-cyclohexanedimethylene succinate) (PCDS) with polycarbonate (PC) are completely miscible in the amorphous phase. Blends of PC with poly(ethylene orthophthalate) (PEOP) were found to have a miscibility gap in the midconcentration range and are thus not miscible in all proportions. Similarly, a commercial copolyester formed from ethylene glycol, 1,4-cyclohexanedimethanol, terephthalic acid, and isophthalic acid is partially miscible with PC. These observations are discussed in terms of the structural features of the three polyesters.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 24 (1979), S. 2399-2405 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Polycarbonate blends with poly(pivalolactone) were found to be completely immiscible based on the glass transitional behavior observed by thermal analysis. Crystallinity of the poly(pivalolactone) was unaffected by blending with polycarbonate. The heat of mixing of low molecular weight analogs of this system, ethyl pivalate and diphenyl carbonate, were found to be endothermic, in contrast to exothermic mixing observed for similar linear esters. Methyl branching adjacent to the ester carbonyl is believed to shield the specific interaction of this unit with the aromatic carbonate structure which leads to exothermic mixing and miscibility of similar unbranched esters with polycarbonate. Blends of poly(2,2-dimethyl-1,3-propylene succinate) were found to be partially miscible with polycarbonate because the shielding is not so great since the methyl groups are further removed from the ester group.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 24 (1979), S. 2101-2112 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Polycarbonate blends with the linear aliphatic polyesters poly(ethylene succinate) (PES), poly(ethylene adipate) (PEA), poly(1,4-butylene adipate) (PBA), and poly(hexamethylene sebacate) (PHS) were prepared by solution casting. Blends containing PES, PEA, and PBA exhibited a single Tg by DSC and thus form a single, miscible amorphous phase with polycarbonate. However, blends containing PHS exhibited only partial miscibility. Crystallinity of the polyesters was reduced by mixing with polycarbonate; however, plasticization by the polyesters induced crystallization of the polycarbonate. Miscibility in these systems is the result of an exothermic heat of mixing stemming from an interaction of the carbonyl dipole of the ester group with the aromatic carbonate. The effect of polyester structure on miscibility with polycarbonate is interpreted by and correlated with heats of mixing obtained by direct calorimetry of low molecular weight liquid analogs of the polymers.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
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