Single frequency temperature scan

Townend. D., A computerised technique for producing WLF shifted data from a single frequency. Temperature scan without graphical manipulation. NATAS Meeting, Kingston. Ont, August. 1982. 

WLF Shifted Data from a Single Frequency Temperature Scan, "Proceedings of the 7th International Conference on Thermal Analysis," B. Miller, ed.,... 

FX-90Q instrument and infrared spectra were recorded on a Nicolet MX-1 or Digilab FTS 2 FT-IR instrument. All norbornene resins and intermediates were completely characterized via HPLC, NMR, FT-IR, and GC analytical techniques and gave satisfactory results. Silicone prepolymers were compounded with 35% of a reinforcing fumed silica filler and photoinitiator. All formulations were cured under a medium pressure mercury vapor lamp until constant durometer values were obtained. Differential photocalorimetric studies were carried out on a DuPont Model 930 photocalorimeter in air at several temperatures. D)mamic mechanical analyses were performed on a Polymer Laboratories DMTA instrument. Organic resins were analyzed as single cantilevered beams at 1 Hz frequency with a temperature scan of 5°C per minute. Silicone dastomers were analyzed under the same conditions. 

The 983 analyser can be programmed to measure a sample s viscoelastic characteristics at up to 57 frequencies during a single test. In such multiplexing experiments, an isothermal step method is used to hold the sample temperature constant while the frequencies are scarmed. The sample is allowed to reach mechanical and thermal equilibrium at each frequency before the data are collected. After all the frequencies have been scanned, the sample is automatically stepped to the next temperature and the frequency scan is repeated. Multiplexing provides a more complete rheological assessment than is possible with a single frequency. 

There is also a step-based equivalent technique founded on linear-response theory. This has been presented by Schick and co-workers [19] and is formally equivalent to the real and imaginary heat capacities generated by modulation at a single frequency. In principle, it is therefore possible to apply a Fourier transform to step-scan type data and break down the overall response into heat flow responses to a series of sinusoidal temperature modulations. 

Figure 1 Experimental and simulated EPR spectra of oxidized CooA at pH 7.4. Experimental conditions temperature, 2 K microwave frequency, 35.106GHz microwave power, 20p,W 100 kHz field modulation amplitude, 0.4 mT time constant, 128 ms scan time, 4 min. Lower traces, in absorption line-shape (due to rapid-passage conditions), are the experimental spectrum (blue) and a digital integration of the simulated spectrum (red). Upper traces in first-derivative lineshape are a digital derivative of the experimental spectrum (blue) and the simulated spectrum (red). Simulation parameters component (a) g = [2.60, 2.268, 1.85], (b) g = [2.47, 2.268, 1.90] Gaussian single-crystal linewidths (half-width at half-maximum) W = [500, 200, 400] MHz. Simulated spectra for (a) and (b) are added in the ratio 2 1 to give the summed spectrum shown...

A DuPont Model 990 Thermal Analysis Console with Model 910 DSC accessory was interfaced to a minicomputer system by means of a microcomputer for automated data collection. A program to provide the analysis of reaction kinetics data by the single dynamic scan method for DSC kinetics was developed. Features of this program include a fit of the data to a single equation by multiple regression techniques to yield the reaction order, the energy of activation and the Arrhenius frequency factor. The rate constant k(T) is then calculated and conversion data as a function of time and temperature can be generated at the operator s option. 

The single edge specimens were loaded under three-point bending at cyclic frequency of 10 Hz, stress ratio of 0.1. The FCGR tests were carried out in the laboratory air at the temperature of 20 °C and 700 °C. Several control tests of the composites were performed at the temperature of 800 °C. Optical and scanning electronic microscopy was used for analysis of microstructure and fracture micromechanisms of the materials. 

The LCR single program measures the dielectric properties of one sample cell as a function of the temperature and frequency. The HP4284A LCR meter measures at frequencies between 20 Hz. and 1 MHz. The LCR multiple program controlls an additional scanner which makes measurements on maximally five samples during one measuring scan possible. 

The lifetimes of the sublevels of the excited triplet state of the Rh-trisdiimine complexes have been determined using the microwave recovery and adiabatic rapid passage techniques mentioned in Sect. 4.2. At (pumped) liquid helium temperatures it turned out that the triplet state sublevels have distinct lifetimes. As an example, we show in Fig. 8 the optically detected adiabatic transient signal as monitored for the zero-field D -1 resonance, at 2320 MHz, of the photo-excited [Rh(bpy)3] (0104)3 single crystal, at 1.4 K. The microwave frequency scan was at a rate of 2 x 10 Hz/s. Similar transients were obtained by rapid scans through the zero-field microwave transitions for the other compounds of the [Rh(phen)u(bpy)3 n] (0104)3 series. The transients fitted a biexponential function of the form... 

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