Physical aging process analysis

The polymers physical aging represents itself the structure and properties change in time and is the reflection of the indicated materials thermodynamically nonequilibriiun nature [61, 62], As a rule, the physical aging results to polymer materials brittleness enhancement and therefore, the ability of structural characteristics in due course prediction is important for the period of estimation of pol5mier products safe exploitation. For cross-linked polymers the quantitative estimation of structure and properties changes in physical aging process was conducted in Refs. [63, 64] within the frameworks of fracture analysis [65] and cluster model of polymers amorphous state structure [7, 66]. The authors of Ref. [67] use the indicated theoretical models for the description of PC physical aging. Besides, for PC behavior closer definition in the indicated process such theoretical notions were drawn as structure quasiequilibrium state [68] and the thermal cluster model [69], which is one from variants of percolation theory. 

Thus, the theoretical description of physical aging process of amorphous polymers (on the example of their typical representative-polycarbonate) within the frameworks of fractal analysis and thermal cluster model. It has... 

Let us note the following in respect to description of the physical ageing process within the frameworks of fractal analysis. The study of the dynamics of reactions in disordered systems showed [96] that allowance for both types of disorder was necessary. The majority of the subordination takes place over large durations for the reactions, expressed by the common relationship [96] ... 

Physical aging, defined, 10 424 Physical analysis, of wine, 26 324 Physical bonding processes, 17 496 Physical-chemical waste treatment,... 

The vast expansion of the use of DMA has occurred in the field of polymeric material analysis. First, DMA is one of the best techniques for assessing the amorphous content of a material. It is important to know how much amorphous material is present in a number of situations. Since DMA is sensitive to molecular structure it is frequently used to check one sample against another that is meant to be the same. Also, processing can have a large effect on final properties. For thermoplastics DMA is sensitive to the level of crystaUinity, physical age state and polymerisation. For thermosets, the state of cure can be readily determined and as DMA is a mechanical test useful information can be obtained on interfacial properties for composite materials. To a certain extent this category overlaps with the first, except that fewer measurements are made and a complete molecular profile of the material under test is not obtained. This general usage probably accounts for 40-50% of all DMA. 

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