scholarly journals Exploring the Effects of MXene on Nonisothermal Crystallization and Melting Behavior of β-Nucleated Isotactic Polypropylene

Polymers ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3815
Author(s):  
Wanxin Peng ◽  
Furui Sun ◽  
Yuke Liang ◽  
Jian Kang ◽  
Jinyao Chen ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Isotactic Polypropylene ◽  
Isothermal Crystallization ◽  
Polarized Light ◽  
Thermal Conditions ◽  
Melting Behavior ◽  
Polymorphic Behavior ◽  
Scanning Calorimetry ◽  
Cooling Rates ◽  
Thermal Stability Of

In this study, one of the commonly used MXene (Ti3C2Tx) and β nucleated isotactic polypropylene (β-iPP)/MXene composites of different compositions were fabricated. The effects of MXene on non-isothermal crystallization and polymorphic behavior of β-iPP/MXene composites were comparatively studied. The non-isothermal crystallization kinetics indicates that for all samples, the lower cooling rates promote composites to crystallize at higher temperatures. When MXene and β-Nucleating agent (β-NA) are added separately, the crystallization temperature of composites shifts towards higher temperatures at all cooling rates. When MXene and β-NA are added simultaneously, the composite shows different cooling rate dependence, and the effects of improving crystallization temperatures is more obvious under rapid cooling. The activation energy of four samples iPP, iPP/MXene, iPP/β-NA, and iPP/MXene/β-NA were −167.5, −185.5, −233.8, and −218.1 kJ/mol respectively, which agree with the variation tendency of crystallization temperatures. The polymorphic behavior analysis obtained from Differential Scanning calorimetry (DSC) is affected by two factors: the ability to form β-crystals and the thermal stability of β-crystals. Because β-crystals tend to recrystallize to α-crystals below a critical temperature, to eliminate the effect of β-α recrystallization, the melting curves at end temperatures Tend = 50 °C and Tend = 100 °C are comparatively studied. The results show that more thermally unstable β-crystals would participate in β-α recrystallization with higher cooling rates. Moreover, thermal stability of β-crystals is improved by adding MXene. To further verify these findings, samples of three different thermal conditions were synthesized and analyzed by DSC, X-Ray Diffraction (XRD), and Polarized Light Optical Microscopy (PLOM), and the results were consistent with the above findings. New understandings of synthesizing β-iPP/MXene composites with adjustable morphologies and polymorphic behavior were proposed.

Thermal and Thermomechanical Properties of Poly(butylene succinate) Nanocomposites

2008 ◽  
Vol 8 (4) ◽  
pp. 1679-1689 ◽  
Author(s):  
Mamookho E. Makhatha ◽  
Suprakas Sinha Ray ◽  
Joseph Hato ◽  
Adriaan S. Luyt
Keyword(s):  
Thermal Stability ◽  
Tensile Modulus ◽  
Melting Behavior ◽  
Mechanical Analysis ◽  
Thermomechanical Properties ◽  
Scanning Calorimetry ◽  
Melt Mixing ◽  
Butylene Succinate ◽  
Modulated Differential Scanning Calorimetry ◽  
Thermal Stability Of

This article describes the thermal and thermomechanical properties of poly(butylene succinate) (PBS) and its nanocomposites. PBS nanocomposites with three different weight ratios of organically modified synthetic fluorine mica (OMSFM) have been prepared by melt-mixing in a batch mixer at 140 °C. The structure and morphology of the nanocomposites were characterized by X-ray diffraction (XRD) analyses and transmission electron microscopy (TEM) observations that reveal the homogeneous dispersion of the intercalated silicate layers into the PBS matrix. The thermal properties of pure PBS and the nanocomposite samples were studied by both conventional and temperature modulated differential scanning calorimetry (DSC) analyses, which show multiple melting behavior of the PBS matrix. The investigation of the thermomechanical properties was performed by dynamic mechanical analysis. Results reveal significant improvement in the storage modulus of neat PBS upon addition of OMSFM. The tensile modulus of neat PBS is also increased substantially with the addition of OMSFM, however, the strength at yield and elongation at break of neat PBS systematically decreases with the loading of OMSFM. The thermal stability of the nanocomposites compared to that of the pure polymer sample was examined under both pyrolytic and thermooxidative environments. It is shown that the thermal stability of PBS is increased moderately in the presence of 3 wt% of OMSFM, but there is no significant effect on further silicate loading in the oxidative environment. In the nitrogen environment, however, the thermal stability systematically decreases with increasing clay loading.

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

2017 ◽  
Vol 52 (4) ◽  
pp. 503-517 ◽  
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.

Thermal behavior of modified poly(L-lactic acid): effect of aromatic multiamide derivative based on 1H-benzotriazole

e-Polymers ◽  
2016 ◽  
Vol 16 (4) ◽  
pp. 303-311 ◽  
Author(s):  
Yan-Hua Cai ◽  
Li-Sha Zhao
Keyword(s):  
Thermal Stability ◽  
Thermal Decomposition ◽  
Lactic Acid ◽  
Isothermal Crystallization ◽  
Crystallization Behavior ◽  
Nucleating Agent ◽  
Melting Behavior ◽  
Decomposition Temperature ◽  
Scanning Calorimetry ◽  
Onset Crystallization Temperature

AbstractThe goal of this work was to synthesis a novel aromatic multiamide derivative based on 1H-benzotriazole (PB) as an organic nucleating agent for poly(L-lactic acid) (PLLA), and investigate the effect of PB on the non-isothermal crystallization, melting behavior and thermal decomposition of PLLA. Here, PB was firstly synthesized through 1H-benzotriazole aceto-hydrazide and terephthaloyl chloride, then PB-nucleated PLLA was fabricated via melt-blending technology at various PB concentration from 0.5 wt% to 3 wt%. Finally, the thermal performances were evaluated through differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The high thermal decomposition temperature of PB indicated that PB possessed possibility as a nucleating agent for PLLA, and the non-isothermal crystallization behavior confirmed the crystallization accelerating effectiveness of PB for PLLA. Upon optimum concentration of 2 wt%, the onset crystallization temperature, the crystallization peak temperature and the non-isothermal crystallization enthalpy increased from 101.4°C, 94.5°C and 0.1 J·g-1 to 121.3°C, 115.8°C and 35.1 J·g-1, respectively. In addition, the non-isothermal crystallization behavior was also affected by the cooling rate and the final melting temperature. The melting behavior further evidenced the advanced nucleating ability of PB, and the competitive relationship between PB and the heating rate, the nuclear rate and crystal growth rate. Thermal stability measurement showed that PB with a concentration of 1 wt%–2 wt% could slightly improve the thermal stability of PLLA.

scholarly journals Poly (L-lactic acid) Modified by N, N -bis(Stearic acid)-1,4-Dicarboxybenzene Dihydrazide: Studies of Crystallization, Melting Behavior and Thermal Decomposition

2022 ◽  
Vol 58 (4) ◽  
pp. 73-83
Author(s):  
Hao Huang ◽  
Shuang-Qing Liu ◽  
Cheng-Pei Li ◽  
Shi-Tianle Luo ◽  
Li-Sha Zhao ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Thermal Decomposition ◽  
Lactic Acid ◽  
Stearic Acid ◽  
Isothermal Crystallization ◽  
Crystallization Process ◽  
Nucleating Agent ◽  
Melting Behavior ◽  
Melt Crystallization ◽  
Thermal Stability Of

In this study, a new organic nucleating agent N, N -bis(stearic acid)-1,4-dicarboxybenzene dihydrazide (PASH) to improve crystallization behavior of poly(L-lactic acid) (PLLA) along with the effect of PASH on melting behavior, thermal stability of PASH-nucleated PLLA was holistically reported. The melt-crystallization process illustrated that PASH as an effective heterogeneous nucleating agent could boost PLLA�s crystallization rate, but increasing PASH concentration and cooling rate conversely inhibited melt-crystallization process of PLLA in this study. With respect to melt-crystallization process, a larger amount of PASH leaded to a shift of cold-crystallization peak to lower temperature level. Isothermal crystallization revealed, in comparison to pure PLLA, that the half time of overall crystallization of PLLA/PASH was significantly decreased with PLLA containing 3 wt% PASH having the minimum t1/2= 67.3 s at 105şC. The different melting behaviors of PLLA/PASH under different conditions were attributed to the nucleating effect of PASH within PLLA. In particular, the melting behavior at a heating rate of 10�C/min after isothermal crystallization depended primarily on the crystallization temperature. Whereas, the impact of crystallization time on melting behavior was negligible. Nonetheless, the melting behavior was influenced by the heating rate after non-isothermal crystallization. The thermal stability of PLLA was detrimental with the addition of PASH owing to a typical drop in onset thermal decomposition temperature.

Thermal Analysis of Chitosan-Lactate and Chitosan-Aluminum Monostearate Composite System

2012 ◽  
Vol 506 ◽  
pp. 278-281 ◽  
Author(s):  
Kotchamon Yodkhum ◽  
T. Phaechamud
Keyword(s):  
Thermal Stability ◽  
Thermal Analysis ◽  
Thermal Degradation ◽  
Chitosan Solution ◽  
Melting Behavior ◽  
Degradation Behavior ◽  
Scanning Calorimetry ◽  
Chitosan Derivatives ◽  
Thermal Degradation Behavior ◽  
Thermal Stability Of

Chitosan possess many attractive properties for applying as biomaterials. For some application, biomaterial devices have to be sterilized using high temperature, e.g. stream sterilizing process. However, thermal degradation behavior of chitosan has been reported previously. Many researchers have attempted to improve thermal degradation behavior of chitosan by synthesize chitosan derivatives or blending chitosan with other polymers or additives. However, chitosan derivatives found to be less thermal stability than chitosan itself. On the contrary, adding some lipid additive could improve thermal stability of chitosan. In this study, protecting effect of aluminum monostearate (Alst) on thermal stability of chitosan was investigated employing thermal analysis techniques, e.g. thermogravimetry (TG), differential scanning calorimetry (DSC) and hot-stage microscope. Lactic acid solution (2% w/v) was used as solvent for dissolving chitosan. Chitosan solution, named as chtiosan-lactate (CL) and chitosan solution contained 2.5% w/w Alst (CLAlst) were prepared and fabricated into sponges using freeze drying technique. Degradation temperature of CLAlst system investigated from TG was shifted to the higher temperature comparing that of CL which indicated that Alst could improve thermal stability of chitosan after processed as biomaterial. From DSC result, small endothermic peak was observed around 60-70°C for CLAlst whereas that of CL did not exhibit any peak. Melting behavior of the sponges observed under hot-stage microscope was demonstrated that chitosan was decomposed whereas Alst dispersed in chitosan backbone was gradually melted.

Preparation and characterization of carbon fiber/polylactic acid/thermoplastic polyurethane (CF/PLA/TPU) composites prepared by a vane mixer

2017 ◽  
Vol 37 (4) ◽  
pp. 355-364 ◽  
Author(s):  
Xiaochun Yin ◽  
Liang Wang ◽  
Sai Li ◽  
Guangjian He ◽  
Zhitao Yang ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Polylactic Acid ◽  
Storage Modulus ◽  
Mixing Time ◽  
Thermoplastic Polyurethane ◽  
Complex Viscosity ◽  
Melting Behavior ◽  
Scanning Calorimetry ◽  
Crystallization And Melting Behavior ◽  
Thermal Stability Of

Abstract Various quantities of carbon fibers (CFs) (from 5% to 20% in weight) were added to matrix by melt blending to produce polylactic acid (PLA)/thermoplastic polyurethane (TPU)/CF composites. Differential scanning calorimetry measurements revealed that the CF content and mixing time had little influence on the crystallization and melting behavior of PLA. Thermogravimetric analysis showed that the introduction of CFs tended to decrease the thermal stability of PLA/TPU/CF composites, and the increase of mixing time tended to increase the thermal stability of PLA/TPU/CF composites when the mixing time is <5 min. Rheological results showed that all the samples exhibited non-Newtonian and shear thinning characteristics. The storage modulus and complex viscosity both increased with the increase of the CF content. It also showed that the increase of mixing time tended to increase the storage modulus and complex viscosity of PLA/TPU/CF composites when the mixing time is <5 min. Scanning electron microscopy images showed that the TPU/PLA blends contain a continuous PLA phase with evenly distributed TPU particles in the size range of 0.25–3 μm, and the blends are immiscible at the micron scale. Mechanical properties showed that the addition of proper CF content could lead to an obvious increase (about 11.43%) in tensile strength.

Thermal Stability of N-Heterocycle-Stabilized Iodanes – A Systematic Investigation

2019 ◽  
Author(s):  
Andreas Boelke ◽  
Yulia A. Vlasenko ◽  
Mekhman S. Yusubov ◽  
Boris Nachtsheim ◽  
Pavel Postnikov
Keyword(s):  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Thermogravimetric Analysis ◽  
Systematic Investigation ◽  
Scanning Calorimetry ◽  
Thermal Stability Of

<p>The thermal stability of pseudocyclic and cyclic <i>N</i>-heterocycle-stabilized (hydroxy)aryl- and mesityl(aryl)-l<sup>3</sup>-iodanes (NHIs) through thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) is investigated. NHIs bearing <i>N</i>-heterocycles with a high N/C-ratio such as triazoles show among the lowest descomposition temperatures and the highest decomposition energies. A comparison of NHIs with known (pseudo)cyclic benziodoxolones is made and we further correlated their thermal stability with reactivity in a model oxygenation. </p>

scholarly journals Isothermal Vulcanization and Non-Isothermal Degradation Kinetics of XNBR/Epoxy/XNBR-g-Halloysite Nanotubes (HNT) Nanocomposites

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2872
Author(s):  
Seyed Mohamad Reza Paran ◽  
Ghasem Naderi ◽  
Elnaz Movahedifar ◽  
Maryam Jouyandeh ◽  
Krzysztof Formela ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Degradation Kinetics ◽  
Halloysite Nanotubes ◽  
Butadiene Rubber ◽  
Order Model ◽  
Scanning Calorimetry ◽  
Theoretical Methods ◽  
Vulcanization Kinetics ◽  
Kinetics Of ◽  
Thermal Stability Of

The effect of several concentrations of carboxylated nitrile butadiene rubber (XNBR) functionalized halloysite nanotubes (XHNTs) on the vulcanization and degradation kinetics of XNBR/epoxy compounds were evaluated using experimental and theoretical methods. The isothermal vulcanization kinetics were studied at various temperatures by rheometry and differential scanning calorimetry (DSC). The results obtained indicated that the nth order model could not accurately predict the curing performance. However, the autocatalytic approach can be used to estimate the vulcanization reaction mechanism of XNBR/epoxy/XHNTs nanocomposites. The kinetic parameters related to the degradation of XNBR/epoxy/XHNTs nanocomposites were also assessed using thermogravimetric analysis (TGA). TGA measurements suggested that the grafted nanotubes strongly enhanced the thermal stability of the nanocomposite.

Grain Growth in Nanocrystalline Nickel

1999 ◽  
Vol 580 ◽  
Author(s):  
G.D. Hibbard ◽  
U. Erb ◽  
K.T. Aust ◽  
G. Palumbo
Keyword(s):  
Thermal Stability ◽  
Grain Size ◽  
Grain Growth ◽  
Size Distributions ◽  
Nanocrystalline Nickel ◽  
Scanning Calorimetry ◽  
Solute Content ◽  
Grain Size Distributions ◽  
Thermal Stability Of ◽  
Total Solute Content

AbstractIn this study, the effect of grain size distribution on the thermal stability of electrodeposited nanocrystalline nickel was investigated by pre-annealing material such that a limited amount of abnormal grain growth was introduced. This work was done in an effort to understand the previously reported, unexpected effect, of increasing thermal stability with decreasing grain size seen in some nanocrystalline systems. Pre-annealing produced a range of grain size distributions in materials with relatively unchanged crystallographic texture and total solute content. Subsequent thermal analysis of the pre-annealed samples by differential scanning calorimetry showed that the activation energy of further grain growth was unchanged from the as-deposited nanocrystalline nickel.

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