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DMA Equipment

The response of a polymeric material to an applied stress shows both an elastic and a viscous component i.e. a polymer behaves visco-elastic. DMA equipment measures dynamically the E or G moduli the polymer samples are assumed to behave linearly visco-elastic i.e. the stress/strain relation is only a function of time. An oscillating (sinusoidal) strain,... [Pg.94]

The analyses of several polymers by dynamic mechanical analysis, DMA, are described in Sect. 4.5 in connection with the brief description of the DMA equipment. It was observed in such experiments that neither the viscosity nor the modulus are constant, as is assumed for the discussion of energy and entropy elasticity, outlined in Sects. 5.6.4 and 5.6.5, respectively. One finds a stress anomaly when the elastic limit of a material has been exceeded and plastic deformation occurs. Other deviations have the stress depend both on strain and rate of strain. Finally, a time anomaly exists whenever the stress/strain ratio depends only on time and not on the stress magnitude. [Pg.583]

Dynamic mechanical analyzers can be divided into resonant and d ined frequency instruments. The torsion pendulum just described is, for example, a resonant instrument The schematic of a defined-frequency instrument is shown at the bottom of Fig. 6.18. The basic elements are the force generator and the strain meter. Signals of both are collected by the module CPU (central processing unit) and transmitted to the computer for data evaluation. This diagram is drawn after a modern, commercial DMA produced by Seiko. For the address of this company see Ref. 18 of Chapter 5. Several of the other thermal analysis manufacturers also produce DMA equipment (for example Du Pont, PL Thermal Sciences, Netzsch, and more recently also Perkin-Elmer). [Pg.352]

Analyses were performed on a DMA equipped with force rebalancing transducers and liquid nitrogen (LN2) dewars capable of controlling the oven temperature below and above room temperature. Erequency-temperature sweeps were performed on the test specimens. Data was taken at 10 points per decade over a frequency range of 0.1 rad/s to 100 rad/s. To ensure optimal overlap during the construction of the master curves, the -150 °C to 280 °C temperature range was covered using 4 °C temperature steps and a 2 min initial soak time after each temperature step. [Pg.2596]

Thermal analysis iavolves techniques ia which a physical property of a material is measured agaiast temperature at the same time the material is exposed to a coatroUed temperature program. A wide range of thermal analysis techniques have been developed siace the commercial development of automated thermal equipment as Hsted ia Table 1. Of these the best known and most often used for polymers are thermogravimetry (tg), differential thermal analysis (dta), differential scanning calorimetry (dsc), and dynamic mechanical analysis (dma). [Pg.149]

Densities were measured using a Paar DMA 60 meter equipped with DMA 512 and DMA 601 HP external cells. Values in the 50-150°C range were interpolated from measured data (3-5 points) values above 150°C were extrapolated and are less accurate. Interfacial tension measurements at the minimum density difference encountered (0.05 g/cm3) could be in error by as much as 10%, which is within the repeatability of measurements with heavy crude oil samples (see below). [Pg.332]

B. 1,3-Dimethyl-6H-benzo[b]naphtho[1,2-d]pyran-6-one (4). Under an argon atmosphere, a 250-mL, oven-dried, round-bottomed flask, equipped with a reflux condenser, is charged with freshly distilled N,N-dimethylacetamide (DMA, 130 mL), 3,5-dimethylphenyl 1-bromo-2-naphthoate (3, 3.24 g, 9.12 mmol), palladium(ll) acetate (205 mg, 0.913 mmol), triphenylphosphine (481 mg, 1.83 mmol), and sodium acetate (1.50 g, 18.3 mmol) (Notes 4 and 5). The orange suspension is degassed three times, placed in a preheated (130°C) oil bath (Note 5), and stirred at 130°C for 12 hr (Note 6). Removal of the solvent at 40°C (0.1 mbar, 0.075 mm) gives a black oily residue, which is Chromatographed (5 x 40 cm column, silica gel 0.063 - 0.2 mm, 170 g, 1 cm of charcoal at the top of the column eluent hexane / diethyl ether 5 1), to yield 2.00 g (80%) of the lactone 4 as a slightly yellow solid. Recrystallization from diethyl ether / hexane delivers 1.63 g (65%) of colorless or pale yellow crystals (Note 7). [Pg.184]

Monomer conversion has traditionally been determined gravitimetrically by drying emulsion samples to constant weight. The procedure is slow, requiring several hours for analysis, and precludes automated data acquisition. A new method has been developed based on the DMA-series digital densitometers manufactured by Anton Paar of Austria, and marketed in the United States by Mettier Instrument Corporation. (Very recently Dr. Kirk Abbey made us aware of his parallel work in these directions and of some initial data reported from his laboratory [1, 2]). This instrument is capable of immediate determination of the density of any test fluid, and, if equipped with a flow cell, can continuously monitor the density of a process stream. Results are displayed locally and can be transmitted digitally to a data acquisition computer. [Pg.500]

Fig. 1 Torsion vs. axial analyzers The PerkinElmer Diamond DMA (A) is an axial analyzer while the ATS Rheo (B) is a torsional instrument. Both are controlled stress but can act as strain controlled because of the feedback programmed in. Photos taken by the author of Equipment at the University of North Texas (C) shows the TBA. (Courtesy of Dr. John Enns of Polymer Network Characterizations, Inc.) (View this art in color at www.dekker.com.)... Fig. 1 Torsion vs. axial analyzers The PerkinElmer Diamond DMA (A) is an axial analyzer while the ATS Rheo (B) is a torsional instrument. Both are controlled stress but can act as strain controlled because of the feedback programmed in. Photos taken by the author of Equipment at the University of North Texas (C) shows the TBA. (Courtesy of Dr. John Enns of Polymer Network Characterizations, Inc.) (View this art in color at www.dekker.com.)...
Dynamic Mechanical Analysis (DMA) is a technique in which the elastic and viscous response of a sample under oscillating load, are monitored against temperature, time or frequency. This technique became well known by the impressive amount of information about the structure of polymers obtained with the torsion pendulum apparatus. The torsion pendulum DMA apparatus is a so-called resonant system i.e. the measuring frequency is not constant. The modern DMA systems are nearly always fixed frequency systems operating at frequencies between about 0.01 and 100 Hz. and in a temperature region ranging from about -150°C to 300°C. A survey of the DMA technique and the available commercial equipment was given by Wunderlich [1]. [Pg.94]

It is important when conducting expensive test programmes that the constituents be checked for quality prior to use and that the fabricated materials be checked after manufacture, or on receipt if already fabricated. The techniques used vary from the Barcol hardness test (see below) to the more rigorous DMA (dynamic mechanical analysis ISO 6721 (ten parts) [14]) or DSC [differential scanning calorimetry ISO 11,357 (7 parts) [15]) test methods. There is some concern that these tests do not give the same values due to subtle variations between different manufacturers equipment. [Pg.411]

To a 2- mL screw-cap vial equipped with a magnetic stir bar, were added 2 eq. potassium acetate, 0.1 eq. Pd(OH)2/C, and 1 eq. A-phenyl-A-(6>-iodo)benzyl 4-hydroxy-benzoamide loaded on Wang resin and 0.2 mL DMA under nitrogen atmosphere. The reaction mixture was then heated overnight at 145°C under stirring. After the reaction was judged complete by TLC analysis, the heat source was removed, and the reaction mixture was allowed to cool. The crude mixture was then treated with trifluoroacetic acid in THF to cleave the product off the Wang resin. The solution was evaporated, and the residue was... [Pg.2144]

Fig. 3. Modern DMAs are shown. The PerkinElmer Diamond DMA (a) is an axial instrument while the Parr Physica (b) and the ATS Rheo (c) are torsional DMAs, (d) shows a TEA. Photos of the equipment were taken by the author at the University of North Texas Materials Science and Engineering Department, (d) is used with the permission of Dr. John Enns, Polymer Network Characterizations, Inc., Jacksonville, Fla. Fig. 3. Modern DMAs are shown. The PerkinElmer Diamond DMA (a) is an axial instrument while the Parr Physica (b) and the ATS Rheo (c) are torsional DMAs, (d) shows a TEA. Photos of the equipment were taken by the author at the University of North Texas Materials Science and Engineering Department, (d) is used with the permission of Dr. John Enns, Polymer Network Characterizations, Inc., Jacksonville, Fla.
The DuPont 983 DMA is a versatile laboratory instrument for characterising the viscoelastic and rheological behaviour of materials. This system is designed to operate in any of four modes fixed frequency, resonant frequency, stress relaxation, or creep. It is discussed in detail next as an example of the type of equipment now available. [Pg.455]

The Mettler-Toledo Inc., SDTA 861 DMA analyser [6] is capable of providing DMA measurements over wide frequency ranges (from 1 mHz to 1 kHz) and large dynamic stiffness ranges. A schematic of the instrument is illustrated and examples are presented of test data for various rubbers obtained using this equipment. [Pg.463]

Low-temperature loss peak measured by DMA correlates with the ASTM DWI values. Since DMA values are more precise than DWI measurements, as few as four determinations can be used to rank impact resistance. Sample preparation for DMA is not as lengthy and does not require sophisticated processing equipment since surface effects are not critical and smaller samples are used. Figure 18.49 shows the comparative DMA profiles for a series of impact-modified PR The intensity of the damping peak at -110 °C correlates well with the DWI values at -29 Using these kinds of data, a suitable calibration curve can be developed so that future formulations can be rapidly screened by DMA. [Pg.580]

Reaction Procedure (Scheme 2.17) A Schlenk tube equipped with a strong magnetic stir bar was charged with Cul (57 mg, 0.3 mmol, 0.15 equiv.), morpholine-4-carboxamidine hydrobromide (588 mg, 2.8 mmol, 1.4 equiv.), and CS2CO3 (2.6 g, 8 mmol, 4 equiv.). The Schlenk tube was evacuated and backfilled with N2 three times. Under a N2 atmosphere, DMA or NMP (5 mL), 1,2-diiodobenzene (659 mg, 2 mmol, 1.0 equiv.) and iV,iV -dimethylethylenediamine (53 mg, 0.6 mmol, 0.3 equiv.) were added sequentially via syringe. The reaction mixture was stirred in a preheated oil bath at 150 °C for 24 h and then cooled to room temperature. EtOAc (25 mL) was added, and the suspension was stirred for 30 min. The inorganic salt was filtered off and washed with EtOAc. The volatile EtOAc was removed under reduced pressure, and the remaining DMA or NMP solution was directly loaded on a preparatory HPLC for purification to afford the product. [Pg.17]


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