Glass transition phenomena in two-component plastic crystals: Study of hexasubstituted benzenes
Article Abstract:
The relaxation that is known to occur in the crystalline phase of pentachloronitrobenzene (PCNB) and 2,3,4,5,6-pentabromotoluene (PBT) is critically examined using dielectric spectroscopy and differential scanning calorimetry. Findings suggest that the hexasubstituted benzenes or their binaries do not reveal any well resolved secondary relaxation in their plastic crystalline phases within the resolution of the experimental setup and that the T dependence of the relaxation rate deviates from Arrhenius character near [T.sub.g] in PBT, PCNB, and PCT.
Publication Name: Journal of Physical Chemistry B
Subject: Chemicals, plastics and rubber industries
ISSN: 1520-6106
Year: 2006
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Relaxation dynamics of orientationally disordered plastic crystals: effect of dopants
Article Abstract:
The relaxation occurring in the supercooled plastic crystalline phases of pentachloronitrobenzene (PCNB), dichlorotetramethylbenzene (DCTMB), trichlorotrimethylbenzene (TCTMB) along with some of their deuterated samples and 1-cyanoadamantane (CNADM) is examined in the presence of dopants. The studies have shown that the changes in the dielectric strength of the [alpha]-process is because of the rotational hindrance caused by the presence of a small number of dopant molecules in the host crystalline lattice.
Publication Name: Journal of Physical Chemistry B
Subject: Chemicals, plastics and rubber industries
ISSN: 1520-6106
Year: 2008
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Dielectric and calorimetric study of orientationally disordered phases in two unusual two-component systems
Article Abstract:
Low-frequency dielectric spectroscopy and differential scanning calorimetry (DSC) are used for examining two unusual two-component solid solutions, where one is hydrogen (H-)-bonded pair and the other is a non-H-bonded pair. The relaxation phase observed in the plastic phase I of the cyclooctanol (COOL)-cycloheptanol (CHOL) binary system has corresponded to the [alpha] process, whose kinetic freezing has caused the glass transition event.
Publication Name: Journal of Physical Chemistry B
Subject: Chemicals, plastics and rubber industries
ISSN: 1520-6106
Year: 2008
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