Thermo-recording

Fig. 27a and b. Scheme of thermorecording using the film of the homeotropic-oriented nematic LC polymer (a) and thermorecording of letters on the film of polymer XII at 105,5° (film thickness 40 pm) (b) I — initial homeotropic texture II — texture with the laser thermo-recorded letters... 

In this paper, one of the examples of the use of such oriented films as film matrix for information recording is examined. We used the principle of thermo-recording, which is well known for low molecular mass liquid crystals >. On the transparent film of the homeotropi-cally oriented LC polymers (Fig. la), regions of local overheating are created with the aid of a laser beam. 

Fig. 1. Scheme of thermo-recording using the film of the homeotropically oriented nematic LC polymer. 

Fig. 2. Schematic drawing of the measuring arrangement for thermo-recording 1-laser, 2-attenuator, 3-focused lens, 4-electro-optical cell, 5-a.c. voltage generator. ...

Fig. 5. a - transparent film with laser thermo-recorded letters b- this film after application of an electric field. 

Shibaev VP, Kostromin SG, Plate NA, Ivanov SA, Vetrov VY, Yakovlev lA. Thermotropic-liquid-crystalline polymers. 14. Thermo-recording on liquid-crystalline polymers with the aid of a laser beam. Polym Commun 1983 24 364-5. 

Figure Bl.27.8. Schematic view of Picker s flow microcalorimeter. A, reference liquid B, liquid under study P, constant flow circulating pump and 2, Zener diodes acting as heaters T and T2, thennistors acting as temperature sensing devices F, feedback control N, null detector R, recorder Q, themiostat. In the above A is the reference liquid and C2is the reference cell. When B circulates in cell C this cell is the working cell. (Reproduced by pemiission from Picker P, Leduc P-A, Philip P R and Desnoyers J E 1971 J. Chem. Thermo. B41.)...

Figure 6.8. Structure of thermo sensitive recording paper.

Samples were characterized by FTIR spectroscopy with a Perkin Elmer (Spectrum BX) spectrometer using KBr pressed disks as matrices. The DRIFT experiments were carried out with a Broker IFS 55 spectrometer equipped with a Thermo Spectra Tech reacting cell. UV-vis Diffuse Reflectance spectra were recorded on a Perkin Elmer Lambda 45 spectrophotometer equipped with a diffuse reflectance attachment. Raman spectra were collected with Perkin Elmer system 2000 NIR FT-Raman using as excitation radiation the 5th harmonic of a diode pumped Nd YAG laser (1065 nm). 

The FT-IR spectra were obtained on a Nicolet IR-300 spectrometer from Thermo-Electron Corp. The spectra were recorded either in transmittance or in reflectance mode using respectively KBr or Ge as windows. 

The FT-IR spectra were recorded on samples embedded in KBr pellets at a resolution of 4 or 1 cm-1 on a spectrometer Nicolet IR-300 from Thermo-Fischer Corp. 

Fig. 12. Thermal change of the cw-ESR of PMMA y-irradiated to a dose of 5 kGy and photobleached with visible light at 77 K. Each spectrum was recorded after successive warming to temperatures indicated in the figure for 15 min. The spectrum for 295 K was recorded exceptionally after thermo-stating for 24 hours...

Characterization. CHNS analysis was carried using the Thermo Finnigan FLASH EA 1112 CHNS analyzer. Energy dispersive analysis of X-rays (EDAX) was carried using the OXFORD ED AX system. Infrared spectroscopic studies of KBr pellets were recorded in the mid-IRregion (Bruker IFS-66v). Thermogravimetric analysis was carried out (Metler-Toledo) in nitrogen atmosphere (flow rate... 

Thermo gravimetric Analyzer (TGA). A strain gauge is also used in a TGA (thermogravimetric analyzer), a commercial instrument that incorporates a strain gauge to record mass loss, an optional gas inlet (for H2, He, 02, N2, Ar), and a furnace to heat a small sample (50 mg) of material between room temperature and 1000°C the resulting thermogram (mass loss versus temperature) detects mass changes as small as 1 part in 104, and it is used to follow desorption of water or solvent and chemical decomposition. 

Discs of paper, %-in diameter, were punched from sheets. The discs were placed in 4-in diameter aluminum foil pans and covered with 80-mesh stainless steel screen to prevent coiling. The samples were then linearly temperature programmed at various rates in a DuPont 990 differential thermal analyzer under a 50-cc/min flow of air or oxygen. The paper reaction peaks were recorded, and the peak maximum temperatures were measured and corrected for thermal resistance, thermo-... 

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