Ein Torsionspendel zur genauen und schnellen Bestimmung der dynamisch-mechanischen Eigenschaften visko-elastischer Stoffe. (Messungen an Polycarbonaten)

Illers, K. H.; Breuer, H.

doi:10.1007/bf01753920

Cited by 132 publications

(15 citation statements)

References 11 publications

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“…); the other loss peak has been ascribed to reorientation of carboxyl dipoles. 22 Similar results have been obtained from mechanical measurements by IllersZ2 at low frequency and in our laboratory at acoustic frequencies (Fig. 15).…”

Section: Polycarbonatesupporting

confidence: 88%

Dielectric behavior of some polar high polymers at ultra‐high frequencies (microwaves)

Frosini

Butta

Calamia

1967

J of Applied Polymer Sci

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synopsisThe dielectric behavior of d8erent polar high polymers at ultra-high frequencies has been investigated by means of a &electrometer, suitably modified to permit measurements at d~e r e n t temperatures. Experimental measurements were made at about 9 x 10s cps over the temperature range of -150 to 200OC. for polyoxymethylene, polythiomethylene, poly(3,3'-chloromethyl)oxetane (Penton), polycarbonate of 4,4'-dioxydiphenyl-2,2'-propane (Makrolon), poly(viny1 alcohol), poly(viny1 acetate), poly-(vinyl chloride), vinyl chloride-vinyl acetate copolymer, and two ABS plastics, type B (blend) and type G (graft). On comparing the dielectric behavior of the examined materials at ultra-high frequencies with the corresponding ones determined at low or a t radiofrequencies, it is observed that, in the microwave region, all relaxation peaks, either connected with cooperative motions in main chain (primary processes) or with local motions in the backbone or in side chains (secondary processes), usually observed at lower frequencies, tend to disappear; the corresponding relaxation effects, however, manifest themselves through a progressive increase of losses with increasing temperature, which is particularly marked above the glass transition temperature T,. The latter transition, in spite of the very high frequency, is easily distinguished, in most cases, by the sudden change of slope in the tan 8 versus temperature curve which accompanies its onset. This is explained on the basis of the very wide distribution times of molecular relaxation processes in polymers and the increase in strength of the secondary relaxation effects, which is versed at T,, as a consequence of the increased kinetic energy of macromolecules and of the larger free volume for orientation of side chains. Each case is discussed separately and the experimental results interpreted on the basis of the molecular structure and chain mobility of the examined polymers.The increased interest in dielectrics for ultra-high frequency applications makes desirable a better knowledge of the dielectric properties of high polymers, which are employed in various sectors of electronics, in the microwave region of the electromagnetic spectrum. In the literature, in fact, there are not many data regarding this subject, and often the experimental results from different sources are not in a good agreement. In order to dispose of other experimental data and in an attempt to give to them a structural interpretation, a systematic investigation has been initiated in our laboratories on different classes of high polymers. Some of our first results are presented in this paper. 527

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Section: Polycarbonatesupporting

confidence: 88%

Dielectric behavior of some polar high polymers at ultra‐high frequencies (microwaves)

Frosini

Butta

Calamia

1967

J of Applied Polymer Sci

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“…approximately valid in a torsional experiment [13]. The calculations were performed by using experimentally determined Gi, Gj' and G s, G~' functions of a highmolecular, lightly crosslinked polyisoprene and a highmolecular polystyrene both polymerized at the same conditions as the blockpolymers.…”

Section: G2~(t) = Ci'(t) + I]"(t))/ij*(t)i 2 (9)mentioning

confidence: 99%

“…The position of the hard phase transition as measured by the logarithmic decrement A is connected with an error of about 4-1 deg due to high damping in this region and the approximation involved in relating the loss tangent tan 8 to A [13]. Electron micrographs were taken with a Siemens IA electron microscope.…”

Section: Preparation Of Samples and Measurementsmentioning

confidence: 99%

Blockpolymers of styrene and isoprene with variable interphase: Morphology and dynamic viscoelastic behaviour

Annighöfer

Gronski

1983

Colloid & Polymer Sci

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A method is described to prepare poly[isoprene-b-(isoprene-co-styrene)-bstyrene] threeblock polymers with variable interphase thickness by anionic polymerization. At constant overall molecular weight the total interlayer content multiply exceeds that of normal blockpolymers. At high copolymer content three-phase systems are obtained. The morphology is examined by electron microscopy under various staining conditions. The dynamic viscoelastic behaviour, determined with torsion pendulum experiment, has been simulated for lamellar two-and three-phase systems with different contents of copolymer material. A new interpretation of the Tg depression of the hard phase is given in terms of a cooperative softening of the pure hard phase and surface interlayer material.

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“…The relaxation parameter obtained as a function of temperature from these tests w a~ the internal friction, Q-l, which is defined by Q-' = (l/nr) ln(Ao/A,) = tan 6 where A. = the peak-to-peak amplitude of the first cycle counted, A, = the peak to peak amplitude of the nth cycle counted, n = the number of cycles counted, and 6 = the angle by which the strain lags the stress in the specimen.…”

Section: Materials and Experimental Proceduresmentioning

confidence: 99%

Mechanical relaxation in polycarbonate–polysulfone blends

Myers

Brittain

1973

J. Appl. Polym. Sci.

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synopsisLexan polycarbonate and polysulfone P-1700 were blended to various weight percentages by dissolution in methylene chloride. The blended material was rechimed in the form of evaporated thin films which were dried, ground, and molded. Low-frequency mechanical relaxation tests were run on specimens machined from this material aa a function of composition and thermal treatment. In addition to the @-peak, a second peak, D', was resolved in unannealed 75 wt/o P-1700 specimens. These results are presented and a possible interpretation is discussed and compared with previously proposed mechanisms.

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Ein Torsionspendel zur genauen und schnellen Bestimmung der dynamisch-mechanischen Eigenschaften visko-elastischer Stoffe. (Messungen an Polycarbonaten)

Cited by 132 publications

References 11 publications

Dielectric behavior of some polar high polymers at ultra‐high frequencies (microwaves)

Dielectric behavior of some polar high polymers at ultra‐high frequencies (microwaves)

Blockpolymers of styrene and isoprene with variable interphase: Morphology and dynamic viscoelastic behaviour

Mechanical relaxation in polycarbonate–polysulfone blends

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