Melting behaviour

Lin, S. and Koenig, J., The transitions and melting behaviour of thermally crystallized poly(ethylene terephthalate) and their correlations with FTIR and density measurements, J. Polym. Sci., Polym. Symp. Ed., 71, 121-135 (1984). 

Fontaine, F., Ledent, J., Groeninckx, G. and Reynaers, H Morphology and melting behaviour of semi-crystalline poly(ethylene terephthalate) 3. Quantification of crystal perfection and crystallinity, Polymer, 23,185-191 (1982). 

Buchner, S., Wiswe, D. and Zachman, H. G., Kinetics of crystallization and melting behaviour of poly(ethylene naphthalene-2,6-dicarboxylate),... 

The first system concerns refractory (high melting) alloys, the second one very low melting (close to room temperature) alloys. However, both diagrams are representative of the melting behaviour of binary systems in which the two components are mutually and completely (in all proportions) soluble with each other in the liquid and in the solid state. 

Figure 2.1. Examples of melting phase diagrams of binary systems showing complete mutual solubility in the solid and in the liquid states (L liquid field, S solid field). The melting behaviour of the Mo-V, Cs-Rb and Ca-Sr alloys is presented. Notice the different ranges of temperature involved. The melting points of the pure metal components are shown on the corresponding vertical axes. The Cs-Rb is an example of a system showing a minimum in the melting temperature. In the Sr-Ca system complete mutual solid solubility is shown in both the allotropic forms a and (3 of the two metals.

We have adjusted the parameters X, X, t, tg in order to obtain the best fit with the experimental points (the numerical values are given in Ref (6). In Figure 2-b, one can see that both hypothesis seem to be in a reasonable agreement with the experiments. The phenomenological analysis is unable to give an indication of the microscopic mechanisms involved. Further information on the structure is necessary. Some is provided by the melting behaviour of the gels. 

We conclude the structural analysis by stressing on two points. First, the disorder of the structure appears both from the melting behaviour and from the micrographs inspection. This character inherently belongs to the gel state, which is not an equilibrium state. 

Water crystallization in frozen whippable emulsions such as ice cream or aerated desserts, may be analysed by the NMR technique similar to that described for solid fat content analysis. Again, this technique is best used for only relative studies on the effects of ingredient composition on freezing/melting behaviour. 

This multitude of functions makes it impossible to process a variety of polymers with one and the same screw. Each polymer has its own demands, concerning, i.a., granule size, required compression ratio, melting behaviour, risks of degradation, etc. 

Sequence distribution studies on several types of rubber by 13C-NMR technique have been reported. Some of the more recent reports include silicone rubbers [28-30], SBR [31], acrylonitrile-butadiene rubber (NBR) [32,33], polyurethane [34,35], polyepichlorohydrin [36], ethylene-norbonene [37] and ethylene-propylene rubber [4, 16, 25, 38-44]. The NMR studies on EPDM have been carried out extensively, because it is one of the important parameters, which control the physical properties of the elastomer. For example, ethylene sequence can influence the crystallisation kinetic and melting behaviour of the rubber [38]. 

The pellets are then delivered in bulk by lorry, train or boat and also in large or small sacks to consumers. Pellets are burned in pellet furnaces to produce heat in small-, medium- and large-scale facilities. Since the quality of pellets may vary during production there are some parameters that can be used to evaluate this. The most important physical parameters are bulk density, pellet density, durability, which can be measured by determining the amount of fines, and particle size distribution of the raw material. Chemical parameters include pellet moisture content, calorific heat value as a determinant of energy content, element content (such as K, Mg, Ca, N, S, Cl), ash content and ash melting behaviour in order to prevent the agglomeration of the ash in the furnace. The net calorific heat value of pellets is about 19 MJ kg-1, which is less than 50% of the oil equivalent. Pellets consist... 

The bead must be hot enough to ensure that the surfaces of the films being welded are melted adequately to ensure fusion. The method is particularly suitable for use with polyethylene because of the melting behaviour of that material. 

For CBE manufacture, fractionation is preferred to hardening by hydrogenation, which causes melting behaviour unsuitable for bar chocolate. Hydrogenation is however used to produce CBR and CBS from palm or palm kernel oil and rapeseed oil. Fats containing a substantial proportion of lauric acid (lauric fats) which are not compatible with cocoa butter are used in CBS and CBR. 

Nuclear magnetic resonance (NMR) can be used as a rapid alternative to differential scanning calorimetry in the determination of the solid fat content and studies on the melting behaviour. The determination is based on detection of the different populations of protons in solid and liquid phases, which indicates the hardness of the fat. Hernandez and Rutledge (1994b) used low resolution pulse NMR to compare melting curves of roasted and non-roasted cocoa butters from Africa, Indonesia and South America. Discriminant analysis techniques showed... 

Melting behaviour and spherulitic crystallization of polycaproamid (nylon 6). Polymer 3, 43—51 (1962). 

From a technological point of view, the dynamic crystallization of composites is of a great interest, because most of processing routes take place under these conditions. Generally, the crystallization and melting behaviour of polymer/CNT nanocomposites is analyzed by differential scanning calorimetry (DSC) analysis the transition temperatures are taken as the peak maximum or minimum in the... 

The unusual optical properties of liquid crystals had been remarked upon and described for several centuries before their uniqueness as a state of matter was recognised. Their early reports described the strange melting behaviour and appearance of some naturally occurring materials, either as pure compounds or as gels in water, which have now been shown to be thermotropic or lyotropic liquid crystals. Thermotropic liquid crystalline phases are formed under the action of heat, see Figures 2.1 and 2.2, and the lyotropic liquid crystalline phases are formed by the action of a solvent, such as water, usually with an amphiphilic compound. However, the nature of these materials, or indeed their exact... 

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