Authors:E. Medeiros, R. Tocchetto, L. Carvalho, M. Conceição, and A. Souza
In this work, the influence of attapulgite concentration on the nucleating efficiency of isotactic polypropylene (iPP) and
on the kinetics of non-isothermal crystallization were ascertained.The study was conducted by DSC. The nucleating efficiency
was determined according to the procedure described by Fillon and the kinetics of non-isothermal crystallization was determined
using Ozawa's method using cooling rates of 2, 5 and 10C min−1.Our results indicate that both the relative crystallinity and the crystallization temperature increase with filler content
and that a maximum occurs at 2% mass/mass filler content. Both parameters decrease with increasing cooling rates. The Ozawa's
exponent tended to increase with temperature and filler content.
Authors:J. Suñol, J. Saurina, R. Berlanga, D. Herreros, P. Pagès, and F. Carrasco
A crystallization kinetics analysis of several polypropylene-polyethylene (PP-PE), PP-rich copolymers was made by means of
differential scanning calorimetry. The crystallization was studied via calorimetric measurements at different cooling rates.
Several additives were added to the base material. Some test samples were subjected to artificial ageing processes. A modified
isoconversional method was used to describe the crystallization process under non-isothermal conditions. The value of the
Avrami parameter was determined for primary and secondary crystallization.
Normally, for Standard DSC, the PerkinElmer power-compensation setting is the low dynamic range mode (LDRM). In this mode,
a noise filter is applied to decrease the noise-to-signal ratio, which concomitantly gives rise to a delay in time of the
signal measured. In case the signal is expected to be of high intensity — experienced for instance at high scan rates using
High Performance DSC (HPer DSC) — the noise filtering could be diminished by which the associated delay in time would be less,
leading to a faster response of the instrument, also resulting in an improved resolution. In fact, such can be realized using
the faster noise filter of the high dynamic range mode (HDRM) available for the Pyris 1 and Diamond DSCs, which DSCs are both
equipped with the HyperDSCTM technique (HyperDSC being the commercial version of HPer DSC). The improvement in response is maximal for high rates like
100–500°C min−1 but even at low rates like 10°C min−1 it is still significant. Thus, taking advantage of HDRM, low-molar substances like indium and 4,4′-azoxyanisole show appreciable
increasing height-to-width ratios for signals caused by crystallization, melting and the crystal <>liquid crystal transition
respectively. Another advantage, the faster realization of steady state after the starting of the DSC, is of help in case
of overlapping starting and transition signals during dynamic crystallization and melting, and during isothermal crystallization
as elucidated for a HDPE. For 4,4′-azoxyanisole and for an ethylene-propylene copolymer having a broad melting range, it is
shown that such faster response leads to a still better resolution with respect to temperature, even at high scan rates.
Thus, the peaks belonging to the crystal-to-liquid crystal and the liquid crystal-to-isotropic liquid transitions of 4,4′-azoxyanisole
were completely resolved while a thermal fractionation of the copolymer by the successive self-nucleation and annealing (SSA)
technique with good resolution has been realized, both using rates as high as 200°C min−1.
Authors:Anikó Kovács, Lilla Körmendi, and Katalin Badakné Kerti
. , Truong , V. , Dewettinck , K. , and Bockstaele , F. V. ( 2020 ). Fat crystallization of blends of palm oil and anhydrous milk fat: a comparison between static and dynamic-crystallization . Food Research International , 137 ( 2020 ): 109412
Authors:Zhiyong Wei, Wanxi Zhang, Guangyi Chen, Jicai Liang, Ying Chang, Lian Liu, Pei Wang, and Juncai Sun
shifted to a low temperature below 138 °C, this indicated that MSW has an effective β-nucleation effect on iPP and PP-g-MAH suppressed the formation of β-iPP.
Nonisothermal crystallization behavior