Crystallization, degree

The crystallization degree was higher in the case of a polyetheric material of the type PUc3 when the introduction in the reaction of DBDI was performed in the second stage, because the HS sequence of the EG-DBDI type becomes preponderant. 

An increase in temperature leads to a decrease in crystallization time because the solubility of the aluminosilicate hydrogel is enhanced at higher temperatures. Thus, the aging is accelerated, incubation period shortened, and crystallization velocity increased. The latter increases steadily with time and drops after a relatively high crystallization degree has been obtained. The reaction is commonly monitored by means of x-ray powder diffraction and is stopped at this point [104,110,137]. 

While microimpurities in particular have an impact on phenomena at the crystal-liquid interface, large impurity contents may influence the solubility and driving force of crystallization (degree of supersaturation), the physical and chemical properties of the solution and of the crystalline product (particle size and particle size distribution, purity), and the phenomena at the crystal-liquid interface. 

The composites formed by type I collagen and hydroxyapatite have been extensively studied and characterized after chemical treatments and extraction from tissue [9]. The crystallization degree, crystaUlte size, texture, chemical substitution and solubility are the most important parameters when characterizing hydroxyapatite, while for type I collagen the analysis of the proteic structure or the variation of some parameters such as enthalpy and denaturation temperature (determined by calorimetry methods) is performed in order to find clues about the thermal stability of molecules [9]. 

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