Stick temperature

Thermoplasticity of lactose. Unless certain precautions are taken during the drying of whey or other solutions containing high concentrations of lactose, the hot, semi-dry powder may adhere to the metal surfaces of the dryer, forming deposits. This phenomenon is referred to as thermoplasticity. The principal factors influencing the temperature at which thermoplasticity occurs ( sticking temperature ) are the concentrations of lactic acid, amorphous lactose and moisture in the whey powder. 

Figure 2.13 Influence of moisture content on the temperature of powder in a spray dryer (tp), dryer outlet temperature (f0) and sticking temperature (rs). The minimum product tempera-tured required to avoid problems with sticking is at TPC with the corresponding dryer outlet temperature TOC. (Modified from Hynd, 1980.)...

Sticking temperature is about 445=F (229QC). Melts between 480 and 5253F 1249 and 274X), Some yellow slightly if held at 300 F tl5(>°C) for several hours. Decomposes between MX) and 730"F (316 and 388 C ). ... 

Amorphous polyester polymers are usually converted from the amorphous state to the crystalline state prior to solid state polymerization to raise their sticking temperature. This is performed in order to keep pellets or chips of the polyester prepolymer from stieking together as a solid mass when later handled at an elevated temperature. ... 

When an amorphous polyester is heated from an ambient temperature to above its glass transition temperature Tg, it will beeome soft and sticky before it starts to crystallize. The sticking temperature of an amorphous polyester is usually about 20°C above its Tg. The caystalUzation rate of the polyester will not be fast enough for technieal operations until its temperature is further raised to about 30°C above its stieking temperature. To achieve the maximum crystalUzation rate, the temperature of the polyester... 

PEN has a 7 of about 120°C and a crystalUne melting point of 270°C. It exhibits a crystallization peak between 180°C and 220°C. Its sticking temperature is about 140-150°C, when it is in the amorphous state. The recommended crystallization temperature range for PEN is 180-220°C. 

Suitable solid state polymerization temperatures can range from a temperature just above the threshold temperature of the polymerization reaction up to a temperature within a few degrees of the sticking temperature of the PEN prepolymer. 

In the solid state polymerization of crystalline PEN, the temperature employed ranges from 240°C to about 265°C. As the solid state polymerization of PEN prepolymer proceeds, its sticking temperature increases. Thus, the solid state polymerization temperature can be gradually increased in the course of the process. ... 

Likewise, if the powder depth was one-half of Lc in Fig. 9-19, the thickness of polymer at or above the sticking temperature was... 

Polymerization Example Catalyst (Initiator), parts Polymerization VDF Charged, parts Comonomer Charged, parts VDF in the Copolymer, % weight Thermal Stability Sticking Temperature, C (to Cu)... 

Figure 11.4. Stick temperature measured for EVA. containing 500 ppm of fatty acid amide, pata from Botros, M. G, J. Plast. Film Sheeting, 11,4, 326-37,1995.1...

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