Heating glass transition

Differential scanning calorimetry Change in molecular heat Glass transition and eutectic melt... 

Differential scanning calorimetry (DSC) The method to measure the heat flow to a sample as a function of temperature. It is used to measure, for example, specific heats, glass transition temperatures, melting points, melting profiles, degree of crystallinity, degree of cure, and purity. 

List the dry product properties, such as powder size distribution, particle shape, bulk density, specific heat, glass transition temperature, hygroscopicity, powder flammability. 

As mentioned above, van Krevelen (1990) presents semi-empirical, group-contribution methods and data for each group in a polymer repeating unit. Data are provided to estimate a host of polymer properties, including the density, specific heat, glass-transition temperature, water absorption, and refractive index. For a specific property, these are in one of two forms ... 

Injection molding binders have been characterized for thermal conductivity, specific heat, glass transition temperature and pressure-volume-temperature (p-v-t) correlation. These properties have also been used for the FEM (finite element method) analysis of the injection molding process. DSC and Gel Permeation Chromatography techniques were also utilized to characterize the virgin binder and the molding compound for Q.C purposes. 

Material properties can be further classified into fundamental properties and derived properties. Fundamental properties are a direct consequence of the molecular structure, such as van der Waals volume, cohesive energy, and heat capacity. Derived properties are not readily identified with a certain aspect of molecular structure. Glass transition temperature, density, solubility, and bulk modulus would be considered derived properties. The way in which fundamental properties are obtained from a simulation is often readily apparent. The way in which derived properties are computed is often an empirically determined combination of fundamental properties. Such empirical methods can give more erratic results, reliable for one class of compounds but not for another. 

The glass-transition temperature, T, of dry polyester is approximately 70°C and is slightly reduced ia water. The glass-transitioa temperatures of copolyesters are affected by both the amouat and chemical nature of the comonomer (32,47). Other thermal properties, including heat capacity and thermal conductivity, depend on the state of the polymer and are summarized ia Table 2. 

Most Kaminsky catalysts contain only one type of active center. They produce ethylene—a-olefin copolymers with uniform compositional distributions and quite narrow MWDs which, at their limit, can be characterized by M.Jratios of about 2.0 and MFR of about 15. These features of the catalysts determine their first appHcations in the specialty resin area, to be used in the synthesis of either uniformly branched VLDPE resins or completely amorphous PE plastomers. Kaminsky catalysts have been gradually replacing Ziegler catalysts in the manufacture of certain commodity LLDPE products. They also faciUtate the copolymerization of ethylene with cycHc dienes such as cyclopentene and norhornene (33,34). These copolymers are compositionaHy uniform and can be used as LLDPE resins with special properties. Ethylene—norhornene copolymers are resistant to chemicals and heat, have high glass transitions, and very high transparency which makes them suitable for polymer optical fibers (34). 

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