Cycle times, colorant application

To date, with the exception of vehicle tires, TPEs have been replacing TS rubbers in virtually all applications. Unlike natural TS rubbers, most TPEs can be reground and reused, thereby reducing overall cost. There are types where the need to vulcanize them is eliminated, reducing cycle times, and products can be molded to tighter tolerances. Most TPEs can be colored, whereas natural rubber is available only in black. TPEs also weigh 10 to 40% less than natural rubber (166). 

For these applications cycle times have been reduced by between 18 and 36% with the use PET/PC blends. The blends having a tensile strength of 56 MPa, a tensile modulus of 2.3 GPa, and a heat distortion temperature of 113°C at 1.8 MPa offer good colorability, gloss and... 

Using only insulation to get a pass through runner is surely a fascinating cost cutting method but limited in application only a short cycle time is allowed and only plastic materials not solidifying too fast. Such alternative solutions deserve consideration for specific applications mainly for cost reasons. A continuous production should be granted because frequent interruptions and color changes will restrict the applicability considerably. 

Major fields of application of this additive, typically used in a concentration between 0.1 and l.Owt.%, are thick section injection molded, even glass filled and/or pigmented resins, thin section fibers, monofilaments, films, and blow molded articles. Important benefits of Nylostab S-EED are improved thermo-oxidative and UV light stability enhanced output rates due to lowered and constant pressure during processing (see Figure 25), reduced cycle times and lower discoloration, respectively, nonstaining effects. Furthermore, this additive proteas colorants and provides better bleach resistance. 

It is important, however, to realize that whilst many types of chemical species exhibit electro-chromism, only those with favorable electrochromic performance parameters1 are potentially useful in commercial applications. Thus, most applications require electrochromic materials with a high contrast ratio, coloration efficiency, cycle life, and write-erase efficiency.1 Some performance parameters are application dependent displays need low response times, whereas smart windows can tolerate response times of up to several minutes. 

Electrochromic materials are electroactive compounds whose visible spectra depend on the oxidation state. Possible applications are smart windows, displays, mirrors, and so on. Among the most important performance aspects in electrochromic materials, the reversibility and lifetime of the material to repeated cycles, the time of response (usually in order of seconds), the colors of the oxidized/reduced forms and the change in absorbance upon redox switching (contrast) are of interest. 

Practical applications of photochromism at first (ca. 1955-70) concentrated on the spiropyrans, and especially on BIPS compounds, because of their ready availability, photosensitivity, convenient thermal fade rates, and good color contrast when perceived by the human eye. However, applications in which the dye was required to cycle very many times (e g., an optical binary switch for a photochemical computer memory) or be irradiated continuously (e g., sunglasses, vehicle windshields) were impractical because of the rapid fatigue of these dyes.196... 

Figure 3 Progress of frontal zone under application of pulsed electric field. A pulsed electric field was applied in 2-s cycles (electric field was applied for half of the period, and was stopped for the other half). Frontal zone positions were measured from the digital picture on a CRT. The perpendicular line shows the direction of movement of the frontal zone, and 1 mm in length is equal to 167 pixels. The horizontal line shows the time, and the minimum time scale observed is equal to one-fifteenth. A round open-tubular capillary column 75 pm in diameter and 28 mm in length was used. Applied voltage, 1 50 V. Colored sample methanol solution of 1 mM Rhodamine 6G.

Diarylethenes with heterocyclic aryl groups are newcomers to the photochromic field. They belong to the thermally irreversible (P-type) photochromic compounds. The most striking feature of the compounds is their fatigue resistance. The coloration/decoloration cycle can be repeated more than 10 times while retaining the photochromic performance. Both properties, thermal stability of both isomers and fatigue resistance, are indispensable for application to optoelectronic devices, such as devices for memory and switches. In this chapter, recent research on diarylethene derivatives will be described. 

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