scholarly journals Non-Isothermal Crystallization Kinetics of Injection Grade PHBV and PHBV/Carbon Nanotubes Nanocomposites Using Isoconversional Method

2020 ◽  
Vol 4 (2) ◽  
pp. 52
Author(s):  
Thaís Larissa do Amaral Montanheiro ◽  
Beatriz Rossi Canuto de Menezes ◽  
Larissa Stieven Montagna ◽  
Cesar Augusto Gonçalves Beatrice ◽  
Juliano Marini ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Crystallization Kinetics ◽  
Isothermal Crystallization ◽  
Model Fitting ◽  
Polarized Light ◽  
Isoconversional Method ◽  
Degree Of Crystallinity ◽  
Gamma Aminobutyric Acid ◽  
Scanning Calorimetry ◽  
Kinetics Of

Carbon nanotubes (CNT)-reinforced polymeric composites are being studied as promising materials due to their enhanced properties. However, understanding the behavior of polymers during non-isothermal crystallization is important once the degree of crystallinity and crystallization processes are affected when nanoparticles are added to matrices. Usually, crystallization kinetics studies are performed using a model-fitting method, though the isoconversional method allows to obtain the kinetics parameter without assuming a crystallization model. Therefore, in this work, CNTs were oxidized (CNT-Ox) and functionalized with gamma-aminobutyric acid (GABA) (CNT-GB) and incorporated into a poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) matrix. The influence of the addition and functionalization of CNT in the crystallization kinetics of PHBV was evaluated using the isoconversional method with differential scanning calorimetry (DSC), and by polarized light optical microscopy (PLOM) and Shore D hardness. The incorporation and functionalization of CNT into PHBV matrix did not change the Šesták and Berggren crystallization model; however, the lowest activation energy was obtained for the composite produced with CNT-GB, suggesting a better dispersion into the PHBV matrix. PLOM and Shore D hardness confirmed the results obtained in the kinetics study, showing the smallest crystallite size for CNT-containing nanocomposites and the highest hardness value for the composite produced with CNT-GB.

scholarly journals Non-Isothermal Crystallization Kinetic of Polyethylene/Carbon Nanotubes Nanocomposites Using an Isoconversional Method

2019 ◽  
Vol 3 (1) ◽  
pp. 21 ◽  
Author(s):  
Beatriz Menezes ◽  
Tiago Campos ◽  
Thais Montanheiro ◽  
Renata Ribas ◽  
Luciana Cividanes ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Kinetic Parameters ◽  
Isothermal Crystallization ◽  
Crystallization Kinetic ◽  
Model Fitting ◽  
Kinetic Studies ◽  
Isoconversional Method ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
Crystallite Sizes

Behavior studies of thermoplastic polymers during non-isothermal crystallization are extremely important since most of their properties are influenced by degree of crystallinity and the crystallization process. In general, an approach based on a model-fitting method is used to perform crystallization kinetic studies. Due to their inability to uniquely determine the reaction mode, many studies have used the isoconversional method, where it is not necessary to assume a crystallization model to obtain the kinetic parameters. Therefore, in this work, the influence of acid and octadecylamine functionalized carbon nanotubes (CNTs) in the crystallization kinetic of polyethylene (PE) was studied using an isoconversional method with differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The kinetic parameters and the crystallization model were determined. The incorporation of functionalized and non-functionalized CNTs into PE did not change the Johnson-Mehl-Avrami crystallization model. However, the CNTs increased the crystallization temperature and reduced the activation energy for crystallization. In addition, the Avrami coefficient values were lower for the nanocomposites when compared to pure PE. The incorporation of CNTs accelerated the crystallization of PE, reducing the crystallite sizes and modifying their morphology.

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 Thermal Properties and Non-Isothermal Crystallization Kinetics of Poly (δ-Valerolactone) and Poly (δ-Valerolactone)/Titanium Dioxide Nanocomposites

Crystals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 452 ◽  
Author(s):  
Waseem Saeed ◽  
Abdel-Basit Al-Odayni ◽  
Abdulaziz Alghamdi ◽  
Ali Alrahlah ◽  
Taieb Aouak
Keyword(s):  
Titanium Dioxide ◽  
Crystallization Kinetics ◽  
Isothermal Crystallization ◽  
Three Dimensional ◽  
Degree Of Crystallinity ◽  
Simultaneous Occurrence ◽  
Scanning Calorimetry ◽  
Isothermal Crystallization Kinetics ◽  
The Stability ◽  
Kinetics Of

New poly (δ-valerolactone)/titanium dioxide (PDVL/TiO2) nanocomposites with different TiO2 nanoparticle loadings were prepared by the solvent-casting method and characterized by Fourier transform infra-red, differential scanning calorimetry, X-ray diffraction and scanning electron microscopy, and thermogravimetry analyses. The results obtained reveal good dispersion of TiO2 nanoparticles in the polymer matrix and non-formation of new crystalline structures indicating the stability of the crystallinity of TiO2 in the composite. A significant increase in the degree of crystallinity was observed with increasing TiO2 content. The non-isothermal crystallization kinetics of the PDVL/TiO2 system indicate that the crystallization process involves the simultaneous occurrence of two- and three-dimensional spherulitic growths. The thermal degradation analysis of this nanocomposite reveals a significant improvement in the thermal stability with increasing TiO2 loading.

Parameters characterizing the kinetics of the non-isothermal crystallization of polyamide 5,6 determined by differential scanning calorimetry

2014 ◽  
Vol 34 (4) ◽  
pp. 353-358 ◽  
Author(s):  
Yassir A. Eltahir ◽  
Haroon A.M. Saeed ◽  
Chen Yuejun ◽  
Yumin Xia ◽  
Wang Yimin
Keyword(s):  
Crystallization Kinetics ◽  
Isothermal Crystallization ◽  
Crystallization Rate ◽  
Degree Of Crystallinity ◽  
Avrami Equation ◽  
Scanning Calorimetry ◽  
Isothermal Crystallization Kinetics ◽  
Ozawa Model ◽  
Kinetic Crystallization ◽  
Kinetics Of

Abstract The non-isothermal crystallization behavior of polyamide 5,6 (PA56) was investigated by differential scanning calorimeter (DSC), and the non-isothermal crystallization kinetics were analyzed using the modified Avrami equation, the Ozawa model, and the method combining the Avrami and Ozawa equations. It was found that the Avrami method modified by Jeziorny could only describe the primary stage of non-isothermal crystallization kinetics of PA56, the Ozawa model failed to describe the non-isothermal crystallization of PA56, while the combined approach could successfully describe the non-isothermal crystallization process much more effectively. Kinetic parameters, such as the Avrami exponent, kinetic crystallization rate constant, relative degree of crystallinity, the crystallization enthalpy, and activation energy, were also determined for PA56.

Effect of Graphene Oxide on Non-Isothermal Melt Crystallization Kinetics of Poly(Trimethylene Terephthalate)

2017 ◽  
Vol 748 ◽  
pp. 74-78
Author(s):  
Kun Yan Wang ◽  
Bin Li
Keyword(s):  
Graphene Oxide ◽  
Crystallization Kinetics ◽  
Isothermal Crystallization ◽  
Degree Of Crystallinity ◽  
Crystallization Time ◽  
Melt Crystallization ◽  
Scanning Calorimetry ◽  
Melt Mixing ◽  
Trimethylene Terephthalate ◽  
Kinetics Of

Poly (trimethylene terephthalate) (PTT)/graphene oxide (GO) nanocomposites were prepared by melt mixing. The effect of GO on non-isothermal melt crystallization kinetics of PTT with different amounts of GO were investigated by differential scanning calorimetry (DSC). The Avrami, Ozawa and Mo were used to analyze the non-isothermal crystallization process. The results of Avrami analysis showed that adding GO into PTT matrix changed the crystallization nucleation of PTT. Ozawa analysis could not be used for the non-isothermal crystallization of PTT/GO nanocomposites. According to the results of Mo analysis, a higher cooling rate would be needed in order to obtain a higher degree of crystallinity at unit crystallization time.

Engineering the microstructure of milk fat by blending binary and ternary mixtures of its fractions

RSC Advances ◽  
2016 ◽  
Vol 6 (47) ◽  
pp. 41189-41194 ◽  
Author(s):  
Pere R. Ramel ◽  
Alejandro G. Marangoni
Keyword(s):  
Light Microscopy ◽  
Crystallization Kinetics ◽  
Isothermal Crystallization ◽  
Milk Fat ◽  
Polarized Light ◽  
Ternary Mixtures ◽  
Avrami Model ◽  
Binary And Ternary Mixtures ◽  
Milk Fat Fractions ◽  
Kinetics Of

The microstructure and crystallization kinetics of binary and ternary mixtures of milk fat fractions during isothermal crystallization at 5, 15, and 20 °C were characterized using polarized light microscopy and the Avrami model.

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