Non-isothermal Crystallization of Semi-Crystalline Polymers: The Influence of Cooling Rate and Pressure

2016 ◽  
pp. 207-242 ◽  
Author(s):  
M. van Drongelen ◽  
P. C. Roozemond ◽  
G. W. M. Peters
Keyword(s):  
Cooling Rate ◽  
Isothermal Crystallization ◽  
Crystalline Polymers

scholarly journals Shear-Induced and Nanofiber-Nucleated Crystallization of Novel Aliphatic–Aromatic Copolyesters Delineated for In Situ Generation of Biodegradable Nanocomposites

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2315
Author(s):  
Ramin Hosseinnezhad
Keyword(s):  
Shear Rate ◽  
Cooling Rate ◽  
Isothermal Crystallization ◽  
Cellulose Nanofibers ◽  
Crystallization Time ◽  
Nucleation Density ◽  
Shear Rates ◽  
Biodegradable Nanocomposites ◽  
In Situ Generation

The shear-induced and cellulose-nanofiber nucleated crystallization of two novel aliphatic–aromatic copolyesters is outlined due to its significance for the in situ generation of biodegradable nanocomposites, which require the crystallization of nanofibrous sheared inclusions at higher temperatures. The shear-induced non-isothermal crystallization of two copolyesters, namely, poly(butylene adipate-co-succinate-co-glutarate-co-terephthalate) (PBASGT) and poly(butylene adipate-co-terephthalate) (PBAT), was studied following a light depolarization technique. To have a deep insight into the process, the effects of the shear rate, shear time, shearing temperature and cooling rate on the initiation, kinetics, growth and termination of crystals were investigated. Films of 60 μm were subjected to various shear rates (100–800 s−1) for different time intervals during cooling. The effects of the shearing time and increasing the shear rate were found to be an elevated crystallization temperature, increased nucleation density, reduced growth size of lamella stacks and decreased crystallization time. Due to the boosted nucleation sites, the nuclei impinged with each other quickly and growth was hindered. The effect of the cooling rate was more significant at lower shear rates. Shearing the samples at lower temperatures, but still above the nominal melting point, further shifted the non-isothermal crystallization to higher temperatures. As a result of cellulose nanofibers’ presence, the crystallization of PBAT, analyzed by DSC, was shifted to higher temperatures.

Non-Isothermal Crystallization Kinetics of Graphene Oxide-Carbon Nanotubes Hybrids / Polyamide 6 Composites

2019 ◽  
Vol 41 (3) ◽  
pp. 394-394
Author(s):  
Zhi Qiang Wang Zhi Qiang Wang ◽  
Yong Ke Zhao and Xiang Feng Wu Yong Ke Zhao and Xiang Feng Wu
Keyword(s):  
Carbon Nanotubes ◽  
Graphene Oxide ◽  
Cooling Rate ◽  
Crystallization Kinetics ◽  
Isothermal Crystallization ◽  
Crystallization Rate ◽  
Polyamide 6 ◽  
Degree Of Crystallinity ◽  
Isothermal Crystallization Kinetics ◽  
Kinetics Of

The hybrids combined by nano-materials with different dimensions usually possess much better enhancement effects than single one. Graphene oxide-carbon nanotubes hybrids / polyamide 6 composites has been fabricated. The non-isothermal crystallization kinetics of the as-prepared samples was discussed. Research results showed that increasing the cooling rate was in favor of increasing the crystallization rate and the degree of crystallinity for the as-prepared samples. Moreover, the crystallization rate was first decreased and then increased with increasing the hybrids loading. Furthermore, the crystallization mechanism was changed with increasing the crystallization temperature and the cooling rate. The nucleation and growth modes of the non-isothermal crystallization could be classified into three different types, according to the Ozawa’s theory. These complicated results could be attributed to the important role of crystallization rate as well as the simultaneous hindering and promoting effects of the as-prepared hybrids. This work has reference values for understanding the crystallization kinetics of the polyamide 6-based composites.

scholarly journals Non-Isothermal Crystallization Kinetics of Poly(ethylene glycol) and Poly(ethylene glycol)-B-Poly(ε-caprolactone) by Flash DSC Analysis

Polymers ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3713
Author(s):  
Xiaodong Li ◽  
Meishuai Zou ◽  
Lisha Lei ◽  
Longhao Xi
Keyword(s):  
Ethylene Glycol ◽  
Cooling Rate ◽  
Isothermal Crystallization ◽  
Three Dimensional ◽  
Crystallization Rate ◽  
Poly Ethylene Glycol ◽  
Avrami Model ◽  
Isothermal Crystallization Kinetics ◽  
Poly Ethylene ◽  
Kinetics Of

The non-isothermal crystallization behaviors of poly (ethylene glycol) (PEG) and poly (ethylene glycol)-b-poly(ε-caprolactone) (PEG-PCL) were investigated through a commercially available chip-calorimeter Flash DSC2+. The non-isothermal crystallization data under different cooling rates were analyzed by the Ozawa model, modified Avrami model, and Mo model. The results of the non-isothermal crystallization showed that the PCL block crystallized first, followed by the crystallization of the PEG block when the cooling rate was 50–100 K/s. However, only the PEG block can crystallize when the cooling rate is 200–600 K/s. The crystallization of PEG-PCL is completely inhibited when the cooling rate is 1000 K/s. The modified Avrami and Ozawa models were found to describe the non-isothermal crystallization processes well. The growth methods of PEG and PEG-PCL are both three-dimensional spherulitic growth. The Mo model shows that the crystallization rate of PEG is greater than that of PEG-PCL.

scholarly journals Non-Isothermal Crystallization Kinetics of Poly(4-Hydroxybutyrate) Biopolymer

Molecules ◽  
2019 ◽  
Vol 24 (15) ◽  
pp. 2840 ◽  
Author(s):  
Ina Keridou ◽  
Luis J. del Valle ◽  
Lutz Funk ◽  
Pau Turon ◽  
Lourdes Franco ◽  
...  
Keyword(s):  
Growth Rate ◽  
Cooling Rate ◽  
Crystallization Temperature ◽  
Isothermal Crystallization ◽  
Secondary Nucleation ◽  
Scanning Calorimetry ◽  
Limited Region ◽  
First Case ◽  
Biodegradable Poly ◽  
Insertion Mechanism

The non-isothermal crystallization of the biodegradable poly(4-hydroxybutyrate) (P4HB) has been studied by means of differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). In the first case, Avrami, Ozawa, Mo, Cazé, and Friedman methodologies were applied. The isoconversional approach developed by Vyazovkin allowed also the determination of a secondary nucleation parameter of 2.10 × 105 K2 and estimating a temperature close to 10 °C for the maximum crystal growth rate. Similar values (i.e., 2.22 × 105 K2 and 9 °C) were evaluated from non-isothermal Avrami parameters. All experimental data corresponded to a limited region where the polymer crystallized according to a single regime. Negative and ringed spherulites were always obtained from the non-isothermal crystallization of P4HB from the melt. The texture of spherulites was dependent on the crystallization temperature, and specifically, the interring spacing decreased with the decrease of the crystallization temperature (Tc). Synchrotron data indicated that the thickness of the constitutive lamellae varied with the cooling rate, being deduced as a lamellar insertion mechanism that became more relevant when the cooling rate increased. POM non-isothermal measurements were also consistent with a single crystallization regime and provided direct measurements of the crystallization growth rate (G). Analysis of the POM data gave a secondary nucleation constant and a bell-shaped G-Tc dependence that was in relative agreement with DSC analysis. All non-isothermal data were finally compared with information derived from previous isothermal analyses.

scholarly journals Study of Phase Transition by FTIR/SAXS/WAXD Simultaneous Measurement System

2014 ◽  
Vol 70 (a1) ◽  
pp. C1070-C1070
Author(s):  
Kohji Tashiro ◽  
Hiroko Yamamoto ◽  
Taiyo Yoshioka ◽  
Daisuke Tahara
Keyword(s):  
Phase Transition ◽  
Measurement System ◽  
Simultaneous Measurement ◽  
Isothermal Crystallization ◽  
Structural Phase ◽  
Structural Evolution ◽  
Crystalline Polymer ◽  
Soft Materials ◽  
Order Structure ◽  
Crystalline Polymers

FTIR/SAXS/WAXD simultaneous measurement system has been developed for the study of the structural phase transition behaviors of soft materials including crystalline polymers. The system consists of a transmission-type miniature FTIR spectrometer set around the sample stage and the 2-dimensional detectors for WAXD and SAXS measurements in a synchronized mode, as shown in Figure. The infrared and X-ray beams can pass through the same position of a sample, which is set on the various types of equipments such as a stretcher, a heater, a temperature-jump cell for isothermal crystallization, etc. The system has been successfully applied to the studies of the structural evolution processes of crystalline polymers. For example, an intimate relationship has been clarified between the structural change in the crystal lattice and the change in lamellar stacking mode during the stress-induced phase transition of poly(tetramethylene terephthalate). Another example is the study of phase transition of aliphatic nylons in the heating and cooling processes. So far the aliphatic nylons were considered to show the phase transition at a so-called Brill transition point, but the simultaneous measurement revealed another phase transition occurring in a temperature region immediately below the melting point. The structural evolution has been also studied for the isothermal crystallization process of crystalline polymer from the melt, as seen in the case studies of polyethylene, nylon, polyester, and so on. The concrete description was made for the regularization process viewed from the various hierarchical levels of molecular chain conformation, chain packing mode, and lamellar stacking mode or higher-order structure.

Non-isothermal crystallization of polyethylenes as function of cooling rate and concentration of short chain branches

2004 ◽  
Vol 78 (3) ◽  
pp. 885-895 ◽  
Author(s):  
I. S. Kolesov ◽  
R. Androsch ◽  
H. -J. Radusch
Keyword(s):  
Cooling Rate ◽  
Isothermal Crystallization ◽  
Short Chain

RheoDSC Analysis of Hardening of Semi-Crystalline Polymers during Quiescent Isothermal Crystallization

2010 ◽  
Vol 25 (4) ◽  
pp. 304-310 ◽  
Author(s):  
V. Janssens ◽  
C. Block ◽  
G. Van Assche ◽  
B. Van Mele ◽  
P. Van Puyvelde
Keyword(s):  
Isothermal Crystallization ◽  
Crystalline Polymers

scholarly journals Isothermal crystallization of blends containing two thermotropic liquid crystalline polymers

2016 ◽  
Vol 9 ◽  
pp. 16-21 ◽  
Author(s):  
Chen Qian ◽  
Guigui Wan ◽  
Charles E. Frazier ◽  
Donald G. Baird
Keyword(s):  
Isothermal Crystallization ◽  
Liquid Crystalline ◽  
Liquid Crystalline Polymers ◽  
Crystalline Polymers ◽  
Thermotropic Liquid Crystalline Polymers
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