In:
Physical Chemistry Chemical Physics, Royal Society of Chemistry (RSC), Vol. 23, No. 35 ( 2021), p. 19795-19810
Abstract:
The phase transitions, crystallization kinetics and molecular dynamics of ( S )-4′-(1-methylheptylcarbonyl)biphenyl-4-yl 4-[5-(2,2,3,3,4,4,4-heptafluorobutoxy)pent-1-oxy] benzoate (3F5HPhH6) are investigated by differential scanning calorimetry, polarizing optical microscopy and broadband dielectric spectroscopy. The vitrification of the antiferroelectric hexatic phase is observed for cooling rates ≥5 K min −1 and the fragility index determined from dielectric data is m f ≈ 90. Two regimes of non-isothermal cold crystallization are distinguished using the Kissinger and Augis–Bennett methods in the heating rate ranges of 1–5 K min −1 (larger activation energy) and 8–20 K min −1 (lower activation energy). The correlation between the time of non-isothermal cold crystallization (using isothermal approximation) and relaxation time of the α-process is determined. The obtained coupling coefficient ξ ≈ 0.7 and temperature dependence of the crystallization rate Z from the Ozawa model imply a mainly diffusion-controlled cold crystallization below 275 K. The Avrami exponents n and Ozawa exponents n O determined for isothermal melt crystallization and non-isothermal cold crystallization, respectively, weigh in favour of two- rather than three-dimensional crystal growth. The transition between crystal phases is observed on heating, with a lower activation energy for 1–3 K min −1 than for 5–20 K min −1 rates.
Type of Medium:
Online Resource
ISSN:
1463-9076
,
1463-9084
Language:
English
Publisher:
Royal Society of Chemistry (RSC)
Publication Date:
2021
detail.hit.zdb_id:
1476283-3
detail.hit.zdb_id:
1476244-4
detail.hit.zdb_id:
1460656-2
