Experimental validation of the modified Avrami model for non-isothermal crystallization conditions

Lam, R.; Rogers, Michael A.

doi:10.1039/c0ce00523a

Cited by 44 publications

(8 citation statements)

References 49 publications

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“…The model describes sigmoidal transformations which are most frequently measured by differential scanning calorimetry or by a mass change determined from X-ray diffraction [16,17]. We have adopted an approach, not previously reported, that employs apatite coherence length as the independent variable as this also appears to be isothermally sigmoidal in its transformation.…”

Section: Methodsmentioning

confidence: 99%

Bone mineral crystallisation kinetics

Greenwood

Rogers

Beckett

et al. 2012

J Mater Sci: Mater Med

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The kinetics of bone apatite crystallisation are examined using a novel approach to obtain quantitative, direction dependence features such as growth rate and activation energy. X-ray diffraction was employed for analysis of bovine, porcine and 'anorganic' bone specimens. Apatite coherence length was utilised as the independent variable within a Johnson-Mehl-Avrami (JMA) model. A direction averaged crystallisation activation energy of 183 ± 8 kJ mol(-1) was observed for the three bone groups. The Johnson-Mehl-Avrami 'n' exponent decreased with increasing temperature for all bone groups, indicating that apatite crystallisation changes to a diffusion limited process at higher temperatures. The results revealed little evidence to support any organic component 'protective' effect, and, on the contrary indicated that the organic matrix promotes apatite crystallisation.

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Section: Methodsmentioning

confidence: 99%

Bone mineral crystallisation kinetics

Greenwood

Rogers

Beckett

et al. 2012

J Mater Sci: Mater Med

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“…The experimental time dependence of the conductivity shown in ( Figure 3 ) was successfully fitted by a formula derived by the authors from a core-shell model and the Avrami approach (e.g., [ 38 ]). The formula reads [ 37 ]:

where

represent the electronic conductivities of the glassy and the nanocrystallized sample (in S/cm), respectively, n is the exponent, related to the dimensionality of the process [ 39 ], K is a constant depending on the crystallization rate (in hr −n ), and t 0 is the time (expressed in hours) when crystallized phase starts to be detectable. The exponent of 2/3 in the above formula is the ratio of the dimensionalities of the shell (2D) and the bulk (3D).…”

Section: Enhancement Of Electrical Conductivity Of Glasses By Their Nanocrystallizationmentioning

confidence: 99%

“…where σ g , σ n represent the electronic conductivities of the glassy and the nanocrystallized sample (in S/cm), respectively, n is the exponent, related to the dimensionality of the process [39], K is a constant depending on the crystallization rate (in hr −n ), and t 0 is the time (expressed in hours) when crystallized phase starts to be detectable. The exponent of 2/3 in the above formula is the ratio of the dimensionalities of the shell (2D) and the bulk (3D).…”

Section: Electronic Conductivity Enhancement In V 2 O 5 -P 2 O 5 Systemmentioning

confidence: 99%

Towards Higher Electric Conductivity and Wider Phase Stability Range via Nanostructured Glass-Ceramics Processing

2021

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This review article presents recent studies on nanostructured glass-ceramic materials with substantially improved electrical (ionic or electronic) conductivity or with an extended temperature stability range of highly conducting high-temperature crystalline phases. Such materials were synthesized by the thermal nanocrystallization of selected electrically conducting oxide glasses. Various nanostructured systems have been described, including glass-ceramics based on ion conductive glasses (silver iodate and bismuth oxide ones) and electronic conductive glasses (vanadate-phosphate and olivine-like ones). Most systems under consideration have been studied with the practical aim of using them as electrode or solid electrolyte materials for rechargeable Li-ion, Na-ion, all-solid batteries, or solid oxide fuel cells. It has been shown that the conductivity enhancement of glass-ceramics is closely correlated with their dual microstructure, consisting of nanocrystallites (5–100 nm) confined in the glassy matrix. The disordered interfacial regions in those materials form “easy conduction” paths. It has also been shown that the glassy matrices may be a suitable environment for phases, which in bulk form are stable at high temperatures, and may exist when confined in nanograins embedded in the glassy matrix even at room temperature. Many complementary experimental techniques probing the electrical conductivity, long- and short-range structure, microstructure at the nanometer scale, or thermal transitions have been used to characterize the glass-ceramic systems under consideration. Their results have helped to explain the correlations between the microstructure and the properties of these systems.

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“…In any case, the n 1 values decrease with increasing cooling rate indicating that the nucleation mechanism was less complicated at higher cooling rates due to the shorter crystallization time 69 . These n 1 values of neat SCB‐PE at 20, 10 and 5°C min −1 cooling rates suggest a two‐dimensional crystal growth 70 while for lower cooling rates, the n 1 exponent increases indicating that the crystal growth of the polymer chains occurs in three‐dimensions 70 . SCB‐PE/GNPs nanocomposites present slightly higher values of n 1 when the cooling rate is higher than 1°C min −1 compared to neat SCB‐PE.…”

Section: Resultsmentioning

confidence: 89%

“…SCB‐PE/GNPs nanocomposites present slightly higher values of n 1 when the cooling rate is higher than 1°C min −1 compared to neat SCB‐PE. More specifically, the n 1 exponent of the composites in both cases (SCB‐PE/M5 no BM and SCB‐PE/M5 w BM) indicates a two‐dimensional crystal growth for 20 and 10°C min −1 , while a three‐dimensional crystal growth occurs at lower cooling rates 70 …”

Section: Resultsmentioning

confidence: 97%

Effect of ball milling on the mechanical properties and crystallization of graphene nanoplatelets reinforced short chain branched‐polyethylene

Kourtidou

Grigora

Tsongas

et al. 2021

J of Applied Polymer Sci

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Short‐chain‐branched‐polyethylene (SCB‐PE) is extensively used in domestic hot and cold piping systems. SCB‐PE nanocomposites using graphene nanoplatelets (GNPs) as a filler, were prepared in this work. The effect of ball‐milling as a premixing technique prior to melt‐mixing, on the crystallization and the nanomechanical properties of the composites has been studied. Two sets of SCB‐PE/GNPs nanocomposites with various filler loadings were prepared; one with and one without the ball‐milling step. The dispersion of the filler was evaluated by optical microscopy while the crystallization process was studied using differential scanning calorimetry. The nonisothermal crystallization's experimental data were analyzed using various methods. The materials' nanomechanical behavior was investigated by conducting nanoindentation tests. A finite element analysis process was developed to extract the composites' stress–strain behavior. The composites prepared with ball‐milling presented improved dispersion of GNPs in the SCB‐PE matrix, which affected the crystallization, while nanoindentation tests showed significantly enhanced mechanical properties.

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Experimental validation of the modified Avrami model for non-isothermal crystallization conditions

Cited by 44 publications

References 49 publications

Bone mineral crystallisation kinetics

Bone mineral crystallisation kinetics

Towards Higher Electric Conductivity and Wider Phase Stability Range via Nanostructured Glass-Ceramics Processing

Effect of ball milling on the mechanical properties and crystallization of graphene nanoplatelets reinforced short chain branched‐polyethylene

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