Softening ranges determination

Refractoriness. Most refractories are mixtures of different oxides, sometimes with significant quantities of impurities. Thus, they do not have sharp melting points but a softening range. Refractoriness is the resistance to physical deformation under the influence of temperature. It is determined by the pyrometric cone equivalent (PCE) test for aluminosiHcates and resistance to creep or shear at high temperature (see Analytical methods). 

Laminate expansion/contraction characteristics were determined with a DuPont Model 942 TMA. In this test the movement of an 0.38 cm diameter, hemispherical-tipped quartz probe resting on the specimen was monitored as the specimen was heated from room temperature through its softening range. 

Softening ranges are dependent on the technique and procedure used to determine them. Thus information on softening ranges should be accompanied by information on the specific technique and procedure employed for the determination. 

Softening ranges were determined using a Fisher Mel-Temp apparatus equipped with a thermometer calibrated to 300 C. 

Both Tg and Tm are important parameters that serve to characterize a given polymer. While Tg sets an upper temperature limit for the use of amorphous thermoplastics like poly(methyl methacrylate) or polystyrene and a lower temperature limit for rubbery behavior of an elastomer-like SBR rubber or 1,4-cw-polybutadiene, Tm or the onset of the melting range determines the upper service temperature for semicrystalline thermoplastics. Between T,n and Tg, these polymers tend to behave as a tough and leathery material. They are generally used at temperatures between Tg and a practical softening temperature that lies above Tg and below Tm-... 

The nature (e.g., the softening range) of a hard occlusion in the interior of a rubber particle can never be determined by dynamic mechanical methods. Any dispersed phase can only be characterized in the region of higher modulus. Its low modulus or higher temperature properties are completely lost. Thus, the relaxation spectrum of a composite is generally not a superposition of the component spectra. 

A qualitative approach is to determine the range in which the polymer melts or softens on the TMA. These data can then be compared with the TGA curve within the melting and softening range to observe any degradation or cure. 

The properties of vinyl resins, paints, and coatings are chiefly determined by the nature and number of substituents. The substituents influence the crystallization behavior and thus the properties of interest in paint technology such as the softening range, mechanical properties (film flexibility, cold embrittlement tendency, film hardness), the film-forming temperature in dispersions, solubility, and compatibility... 

In the case of crystalline polymers such as types E and F the situation is somewhat more complicated. There is some change in modulus around the which decreases with increasing crystallinity and a catastrophic change around the. Furthermore there are many polymers that soften progressively between the Tg and the due to the wide melting range of the crystalline structures, and the value determined for the softening point can depend very considerably on the test method used. 

The spectrum recorded at 230 K was discarded in the fit procedure because above 200 K the effective thickness decreases drastically because of a significant softening of protein-specific modes [16]. From the simultaneous fit of the spectra in the temperature range 3.2-200 K, the Debye temperature was determined as do = 215 K. AEq proved to be a temperature-dependent quantity, which is discussed later (see Sect. 9.4.2). 

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