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

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.

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

Journal of Composites Science ◽

10.3390/jcs4020052 ◽

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.

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

Journal of the chemical society of pakistan ◽

10.52568/000760/jcsp/41.03.2019 ◽

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.

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

Crystals ◽

10.3390/cryst8120452 ◽

2018 ◽

Vol 8 (12) ◽

pp. 452 ◽

Cited By ~ 3

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.

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Kinetic Analysis of the Thermal Decomposition of Polymer-Bonded Explosive Based on PETN: Model-Fitting Method and Isoconversional Method

Advances in Materials Science and Engineering ◽

10.1155/2020/9260818 ◽

2020 ◽

Vol 2020 ◽

pp. 1-12

Author(s):

Trung Toan Nguyen ◽

Duc Nhan Phan ◽

Van Thom Do ◽

Hoang Nam Nguyen

Keyword(s):

Thermal Decomposition ◽

Kinetic Parameters ◽

Model Fitting ◽

Isoconversional Method ◽

Isothermal Tg ◽

Decomposition Reactions ◽

Model Free ◽

Negative Effect ◽

Adverse Influence ◽

Vacuum Stability Test

This work investigates kinetics and thermal decomposition behaviors of pentaerythritol tetranitrate (PETN) and two polymer-bonded explosive (PBX) samples created from PETN (named as PBX-PN-85 and PBX-PP-85) using the vacuum stability test (VST) and thermogravimetry (TG/DTG) techniques. Both model-free (isoconversional) and model-fitting methods were applied to determine the kinetic parameters of the thermal decomposition. It was found that kinetic parameters obtained by the modified Kissinger–Akahira–Sunose method (using non-isothermal TG/DTG data) were close to those obtained by the isoconversional and model-fitting methods that use isothermal VST data. The activation energy values of thermal decomposition reactions were 125.6–137.1, 137.3–144.9, and 143.9–152.4 kJ·mol−1 for PBX-PN-85, PETN, and PBX-PP-85, respectively. The results demonstrate the negative effect of the nitrocellulose-based binder in reducing the thermal stability of single PETN, while the polystyrene-based binder seemingly shows no adverse influence on the thermal decomposition of PETN in our presented PBX compositions.

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Non-isothermal crystallization kinetic studies on a ternary, Sb0.14As0.38Se0.48 chalcogenide semi-conducting glass

Physica B Condensed Matter ◽

10.1016/j.physb.2005.11.145 ◽

2006 ◽

Vol 373 (2) ◽

pp. 211-216 ◽

Cited By ~ 27

Author(s):

E.R. Shaaban

Keyword(s):

Isothermal Crystallization ◽

Crystallization Kinetic ◽

Kinetic Studies

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Non-isothermal crystallization behavior of polypropylene/zinc oxide composites

Science and Engineering of Composite Materials ◽

10.1515/secm-2014-0078 ◽

2016 ◽

Vol 23 (5) ◽

pp. 505-510 ◽

Cited By ~ 1

Author(s):

Jianqiang Fang ◽

Minghua Lang ◽

Xuchu Ye ◽

Wei Zhang ◽

Kongjun Zhu

Keyword(s):

Activation Energy ◽

Zinc Oxide ◽

Isothermal Crystallization ◽

Crystallization Behavior ◽

Crystallization Kinetic ◽

Exothermic Peak ◽

Crystallization Time ◽

Scanning Calorimetry ◽

Relative Crystallinity ◽

Oxide Composites

AbstractThe non-isothermal crystallization behavior of polypropylene (PP)/zinc oxide composites with various mass ratios was investigated by differential scanning calorimetry. The Jeziorny and Mo models were applied to calculate the non-isothermal crystallization kinetic parameters of the composites. During non-isothermal crystallization, the width of the exothermic peak increased from 7°C to 12°C with increasing cooling rate. The exothermic peak position at 10°C shifted to a lower temperature, and the half crystallization time t1/2 decreased from 2.86 min to 0.51 min. The Friedman model was used to determine the variation of activation energy at each stage of crystallization. The crystallization activation energies obtained varied significantly at each stage of crystallization. The crystallization activation energy of PP was -126.8 kJ/mol at 70% relative crystallinity but reached -232.8 kJ/mol at 10% relative crystallinity.

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PP/MWCNTs composites: Effects of length of MWCNTs on isothermal crystallization behaviors, crystalline structure, and thermal stability

Journal of Composite Materials ◽

10.1177/0021998317710084 ◽

2017 ◽

Vol 52 (4) ◽

pp. 503-517 ◽

Cited By ~ 2

Author(s):

Zheng-Ian Lin ◽

Ching-Wen Lou ◽

Yi-Jun Pan ◽

Chien-Teng Hsieh ◽

Chien-Lin Huang ◽

...

Keyword(s):

Carbon Nanotubes ◽

Thermal Stability ◽

Crystalline Structure ◽

Isothermal Crystallization ◽

Crystallization Rate ◽

Nucleating Agent ◽

Scanning Calorimetry ◽

Crystallization Behaviors ◽

Walled Carbon Nanotubes ◽

Thermal Stability Of

This study adopts the melt compounding method to prepare /mutli-walled carbon nanotubes composites. The effects of different lengths of the mutli-walled carbon nanotubes on the isothermal crystallization behaviors, crystalline structure, and thermal stability of the polypropylene/mutli-walled carbon nanotubes composites are examined. The PLM results show that the combination of mutli-walled carbon nanotubes prevents the growth of polypropylene spherulites, and thus results in a small size of spherulites. The differential scanning calorimetry results show that the short (S-) or long (L-) mutli-walled carbon nanotubes can function as the nucleating agent of polypropylene, which accelerates the crystallization rate of polypropylene. Avrami theory analyses indicate that the addition of short-mutli-walled carbon nanotubes particularly provides polypropylene/mutli-walled carbon nanotubes composites with a high crystallization rate. The X-ray diffraction results show that the combination of mutli-walled carbon nanotubes does not pertain to the crystal structure. The TGA test results show that long-mutli-walled carbon nanotubes outperform short -mutli-walled carbon nanotubes in improving the thermal stability of polypropylene, and both can significantly improve it.

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Drug Nanoparticle Stability Assessment Using Isothermal and Nonisothermal Approaches

Journal of Nanomaterials ◽

10.1155/2018/3047178 ◽

2018 ◽

Vol 2018 ◽

pp. 1-7 ◽

Cited By ~ 2

Author(s):

Javier Santamaría-Aguirre ◽

Robert Alcocer-Vallejo ◽

Mónica López-Fanárraga

Keyword(s):

Mathematical Model ◽

Shelf Life ◽

Kinetic Parameters ◽

Heterogeneous Systems ◽

Preexponential Factor ◽

Storage Conditions ◽

Isoconversional Method ◽

Heating Rates ◽

Scanning Calorimetry ◽

Drug Products

Many drugs are administered in the form of liquid-dispersed nanoparticles. Frequently, one of the overlooked aspects in the development of this drug delivery system is the loss of efficacy and the degradation of the carried drugs. Estimating the shelf life of drug products implies the storage of samples under controlled conditions of temperature and humidity for different periods, ranging from months to years, delaying decisions during development, manufacturing, and commercialization. Adapting well-known isothermal and nonisothermal methods to nanoparticles would allow correlating kinetic parameters obtained in a single mathematical model and predicting the shelf life faster than traditional methods. Unlike the traditional approaches, the isoconversional method (i) considers drug products as heterogeneous systems, without a unique kinetic order, (ii) establishes a maximum percentage of degradation, (iii) assumes the same kinetics for all processes regardless of the conditions, and (iv) includes the influence of humidity by a modification of Arrhenius equation. This method serves in calculating the kinetic parameters and shelf life derived from them, in a few weeks. In the same way, nonisothermal treatments allow obtaining these parameters by differential scanning calorimetry. Samples are subjected to different heating rates to establish the temperature at which the thermal decomposition event occurs and, thus, to calculate in a few days the activation energy and the preexponential factor using the Kissinger method. But this approach has limitations: the isoconversional method does not consider crystalline state of the sample, while nonisothermal method ignores the effect of the storage conditions. Processing nanoparticles for isothermal and nonisothermal treatments would allow accurate and fast prediction of the drug-loaded nanoparticle shelf life correlating parameters obtained using a single mathematical model. The accuracy of the prediction would be assessed by comparison of estimated shelf life versus data coming from traditional stability studies.

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