Kinetics of Non-Isothermal and Isothermal Crystallization in a Liquid Crystal with Highly Ordered Smectic Phase as Reflected by Differential Scanning Calorimetry, Polarized Optical Microscopy and Broadband Dielectric Spectroscopy
The kinetics of the non-isothermal and isothermal crystallization of the crystalline smectic B phase (soft crystal B, SmB<sub>cr</sub>) in 4-n-butyloxybenzylidene-4′-n′-octylaniline (BBOA) was studied by a combination of differential scanning calorimetry (DSC), broadb...
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2019-04-01
|
| Series: | Crystals |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2073-4352/9/4/205 |
| _version_ | 1797999247660941312 |
|---|---|
| author | Małgorzata Jasiurkowska-Delaporte Tomasz Rozwadowski Ewa Juszyńska-Gałązka |
| author_facet | Małgorzata Jasiurkowska-Delaporte Tomasz Rozwadowski Ewa Juszyńska-Gałązka |
| author_sort | Małgorzata Jasiurkowska-Delaporte |
| collection | DOAJ |
| description | The kinetics of the non-isothermal and isothermal crystallization of the crystalline smectic B phase (soft crystal B, SmB<sub>cr</sub>) in 4-n-butyloxybenzylidene-4′-n′-octylaniline (BBOA) was studied by a combination of differential scanning calorimetry (DSC), broadband dielectric spectroscopy (BDS) and polarized optical microscopy (POM). On cooling, part of the SmB<sub>cr</sub> phase undergoes conversion to a crystalline phase and the remainder forms a glassy state; after the glass softens, crystallization is completed during subsequent heating. By analyzing the area of the crystal growing in the texture of SmB<sub>cr</sub> as a function of time, the evolution of degree of crystallinity, <i>D</i>(t), was estimated. It was demonstrated that upon heating, <i>D</i>(t) follows the same Avrami curve as the crystallization during cooling. Non-isothermal crystallization observed during slow cooling rates (3K/min ≤ ϕ ≤ 5K/min) is a thermodynamically-controlled process with the energy barrier Ea ≈ 175 kJ/mol; however, the crystallization occurring during fast cooling (5 K/min > ϕ ≥ 30K/min) is driven by a diffusion mechanism, and is characterized by E<sub>a</sub> ≈ 305 kJ/mol. The isothermal crystallization taking place in the temperature range 274 K and 281 K is determined by nucleus formation. |
| first_indexed | 2024-04-11T11:01:39Z |
| format | Article |
| id | doaj.art-25b96cf6c66d4c0290af8dbcb19ae07e |
| institution | Directory Open Access Journal |
| issn | 2073-4352 |
| language | English |
| last_indexed | 2024-04-11T11:01:39Z |
| publishDate | 2019-04-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Crystals |
| spelling | doaj.art-25b96cf6c66d4c0290af8dbcb19ae07e2022-12-22T04:28:31ZengMDPI AGCrystals2073-43522019-04-019420510.3390/cryst9040205cryst9040205Kinetics of Non-Isothermal and Isothermal Crystallization in a Liquid Crystal with Highly Ordered Smectic Phase as Reflected by Differential Scanning Calorimetry, Polarized Optical Microscopy and Broadband Dielectric SpectroscopyMałgorzata Jasiurkowska-Delaporte0Tomasz Rozwadowski1Ewa Juszyńska-Gałązka2The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, 31-342 Kraków, PolandThe Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, 31-342 Kraków, PolandThe Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, 31-342 Kraków, PolandThe kinetics of the non-isothermal and isothermal crystallization of the crystalline smectic B phase (soft crystal B, SmB<sub>cr</sub>) in 4-n-butyloxybenzylidene-4′-n′-octylaniline (BBOA) was studied by a combination of differential scanning calorimetry (DSC), broadband dielectric spectroscopy (BDS) and polarized optical microscopy (POM). On cooling, part of the SmB<sub>cr</sub> phase undergoes conversion to a crystalline phase and the remainder forms a glassy state; after the glass softens, crystallization is completed during subsequent heating. By analyzing the area of the crystal growing in the texture of SmB<sub>cr</sub> as a function of time, the evolution of degree of crystallinity, <i>D</i>(t), was estimated. It was demonstrated that upon heating, <i>D</i>(t) follows the same Avrami curve as the crystallization during cooling. Non-isothermal crystallization observed during slow cooling rates (3K/min ≤ ϕ ≤ 5K/min) is a thermodynamically-controlled process with the energy barrier Ea ≈ 175 kJ/mol; however, the crystallization occurring during fast cooling (5 K/min > ϕ ≥ 30K/min) is driven by a diffusion mechanism, and is characterized by E<sub>a</sub> ≈ 305 kJ/mol. The isothermal crystallization taking place in the temperature range 274 K and 281 K is determined by nucleus formation.https://www.mdpi.com/2073-4352/9/4/205non-isothermal and isothermal crystallization processesliquid crystalsdifferential scanning calorimetrybroadband dielectric spectroscopypolarized optical microscopy |
| spellingShingle | Małgorzata Jasiurkowska-Delaporte Tomasz Rozwadowski Ewa Juszyńska-Gałązka Kinetics of Non-Isothermal and Isothermal Crystallization in a Liquid Crystal with Highly Ordered Smectic Phase as Reflected by Differential Scanning Calorimetry, Polarized Optical Microscopy and Broadband Dielectric Spectroscopy Crystals non-isothermal and isothermal crystallization processes liquid crystals differential scanning calorimetry broadband dielectric spectroscopy polarized optical microscopy |
| title | Kinetics of Non-Isothermal and Isothermal Crystallization in a Liquid Crystal with Highly Ordered Smectic Phase as Reflected by Differential Scanning Calorimetry, Polarized Optical Microscopy and Broadband Dielectric Spectroscopy |
| title_full | Kinetics of Non-Isothermal and Isothermal Crystallization in a Liquid Crystal with Highly Ordered Smectic Phase as Reflected by Differential Scanning Calorimetry, Polarized Optical Microscopy and Broadband Dielectric Spectroscopy |
| title_fullStr | Kinetics of Non-Isothermal and Isothermal Crystallization in a Liquid Crystal with Highly Ordered Smectic Phase as Reflected by Differential Scanning Calorimetry, Polarized Optical Microscopy and Broadband Dielectric Spectroscopy |
| title_full_unstemmed | Kinetics of Non-Isothermal and Isothermal Crystallization in a Liquid Crystal with Highly Ordered Smectic Phase as Reflected by Differential Scanning Calorimetry, Polarized Optical Microscopy and Broadband Dielectric Spectroscopy |
| title_short | Kinetics of Non-Isothermal and Isothermal Crystallization in a Liquid Crystal with Highly Ordered Smectic Phase as Reflected by Differential Scanning Calorimetry, Polarized Optical Microscopy and Broadband Dielectric Spectroscopy |
| title_sort | kinetics of non isothermal and isothermal crystallization in a liquid crystal with highly ordered smectic phase as reflected by differential scanning calorimetry polarized optical microscopy and broadband dielectric spectroscopy |
| topic | non-isothermal and isothermal crystallization processes liquid crystals differential scanning calorimetry broadband dielectric spectroscopy polarized optical microscopy |
| url | https://www.mdpi.com/2073-4352/9/4/205 |
| work_keys_str_mv | AT małgorzatajasiurkowskadelaporte kineticsofnonisothermalandisothermalcrystallizationinaliquidcrystalwithhighlyorderedsmecticphaseasreflectedbydifferentialscanningcalorimetrypolarizedopticalmicroscopyandbroadbanddielectricspectroscopy AT tomaszrozwadowski kineticsofnonisothermalandisothermalcrystallizationinaliquidcrystalwithhighlyorderedsmecticphaseasreflectedbydifferentialscanningcalorimetrypolarizedopticalmicroscopyandbroadbanddielectricspectroscopy AT ewajuszynskagałazka kineticsofnonisothermalandisothermalcrystallizationinaliquidcrystalwithhighlyorderedsmecticphaseasreflectedbydifferentialscanningcalorimetrypolarizedopticalmicroscopyandbroadbanddielectricspectroscopy |