scholarly journals Effect of Storage Conditions on the Thermal Stability and Crystallization Behaviors of Poly(L-Lactide)/Poly(D-Lactide)

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 238
Author(s):  
Tien-Wei Shyr ◽  
Huan-Chieh Ko ◽  
Tzong-Ming Wu ◽  
Meifang Zhu
Keyword(s):  
Thermal Stability ◽  
Room Temperature ◽  
Crystallization Behavior ◽  
Gel Permeation Chromatography ◽  
Storage Conditions ◽  
Aliphatic Polyester ◽  
X Ray Diffraction ◽  
Melting Points ◽  
X Ray ◽  
Thermal Stability Of

Polylactide (PLA) is a biodegradable thermoplastic aliphatic polyester. The thermal stability and crystallization behavior of PLA are extremely sensitive to storage, processing, and usage conditions. This work systematically studied the thermal stability and crystallization behavior of poly(L-lactide) (PLLA), poly(D-lactide) (PDLA), and a PLLA/PDLA (LD) blend, which were stored under two sets of laboratory storage conditions: (1) stored in a vacuum-free desiccator and (2) stored in vacuum-sealed bags. Both were stored at room temperature for 3 years. Gel permeation chromatography results revealed that the PLLA, PDLA, and LD samples hydrolyzed slowly when stored in vacuum-sealed bags and degraded significantly when stored in a vacuum-free desiccator; this process significantly reduced the thermal stability of the samples stored in the vacuum-free desiccator. Owing to hydrolysis, the levorotation and dextrorotation (L- and D-) molecular chains were shortened; consequently, more nuclei were formed, and this caused the melting points of the PLLA, PDLA, and LD samples to decrease and the melting enthalpy of the crystals in these samples to increase. Wide-angle X-ray diffraction analysis revealed that when the L- and D- molecular chains were packed side by side to form stereocomplex crystals and the randomly arranged L- and D- molecular chains were easy hydrolyzed and degraded, this interfered with the formation of homocrystals in LD. When PLLA, PDLA, and LD samples are stored in a vacuum-free desiccator, they will be significantly hydrolyzed, resulting in the formation of only stereocomplex crystals, and no homocrystals are observed.

scholarly journals Stable Organic-Inorganic Hybrid Bismuth-Halide Monocrystalline Compounds With Adjustable Optoelectronic Properties

2021 ◽  
Author(s):  
Xinru Hu ◽  
Jilin Wang ◽  
Jian He ◽  
Guoyuan Zheng ◽  
Disheng Yao ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Room Temperature ◽  
Diffuse Reflectance ◽  
Decomposition Temperature ◽  
X Ray Diffraction ◽  
Monoclinic System ◽  
X Ray ◽  
Good Thermal Stability ◽  
Chemical Groups ◽  
Thermal Stability Of

Abstract Two kinds of novel organic-inorganic bismuth-halide hybrid monocrystalline compounds (C6H5CH2NH3)2BiCl5 and (C6H5CH2NH3)BiI4 were synthesized and characterized. The crystal structure, intermolecular interaction, morphology, chemical groups and bonds, optical and thermal stability of the samples were systematically investigated through single crystal X-ray diffraction, Hirshfeld surface analysis, SEM, FTIR, TG and UV-vis diffuse reflectance spectra. The results indicated that (C6H5CH2NH3)2BiCl5 and (C6H5CH2NH3)BiI4 crystals displayed a monoclinic system with the space group P21/c and P21/n at room temperature, respectively. These materials showed strong absorption in the ultraviolet and visible light regions, resulting in very low Eg, which could be continuously adjustable from 1.67 eV to 3.21 eV by changing the halogen ratio. In addition, these hybrid materials also exhibited good thermal stability. The decomposition temperature of (C6H5CH2NH3)2BiCl5 and (C6H5CH2NH3)BiI4 were 260℃ and 300℃ respectively. Therefore, these organic-inorganic bismuth-halide hybrid compounds have excellent development potential in the field of solar cell research.

Formation and Thermal Stability of Nd0.32Y0.68Si1.7 Layers Formed by Channeled Ion Beam Synthesis

1998 ◽  
Vol 514 ◽  
Author(s):  
M. F. Wu ◽  
A. Vantomne ◽  
S. Hogg ◽  
H. Pattyn ◽  
G. Langouche ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Ion Beam ◽  
Hexagonal Structure ◽  
Orthorhombic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Good Crystalline Quality ◽  
Ion Beam Synthesis ◽  
Thermal Stability Of

ABSTRACTThe Nd-disilicide, which exists only in a tetragonal or an orthorhombic structure, cannot be grown epitaxially on a Si(111) substrate. However, by adding Y and using channeled ion beam synthesis, hexagonal Nd0.32Y0.68Si1.7 epilayers with lattice constant of aepi = 0.3915 nm and cepi = 0.4152 nm and with good crystalline quality (χmin of Nd and Y is 3.5% and 4.3 % respectively) are formed in a Si(111) substrate. This shows that the addition of Y to the Nd-Si system forces the latter into a hexagonal structure. The epilayer is stable up to 950 °C; annealing at 1000 °C results in partial transformation into other phases. The formation, the structure and the thermal stability of this ternary silicide have been studied using Rutherford backscattering/channeling, x-ray diffraction and transmission electron microscopy.

Study of Thermal Behaviour of EPDM/SBR Blends and Carbon Nanocoatings Deposited by Sputtering

2021 ◽  
Vol 875 ◽  
pp. 116-120
Author(s):  
Muhammad Alamgir ◽  
Faizan Ali Ghauri ◽  
Waheed Qamar Khan ◽  
Sajawal Rasheed ◽  
Muhammad Sarfraz Nawaz ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Weight Loss ◽  
Thermogravimetric Analysis ◽  
Thermal Behavior ◽  
Thermal Behaviour ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermal Stability Of

In this study, the effect of SBR concentration (10 Phr, 20 Phr & 30 Phr ) on the thermal behavior of EPDM/SBR blends was studied. Thermogravimetric analysis (TGA) was used to check weight loss of samples as function of temperature by heating upto 600°C. X-ray diffraction (XRD) was performed to determine quality and % crystallinity of the elastomer blends. It was seen that % crystallinity improved with an increase in the content of SBR in EPDM/SBR blends. TGA revealed that the thermal stability of EPDM/SBR blends has improved by 17% than neat EPDM. Carbon nano-coatings produced by sputtering have no beneficial influence on thermal behaviour of elastomers.

Syntheses, Crystal Structures and Thermal Stability of Co(II) and Zn(II) Complexes with Ethyl Carbazate

2005 ◽  
Vol 60 (5) ◽  
pp. 505-510 ◽  
Author(s):  
Tong-Lai Zhang ◽  
Jiang-Chuang Song ◽  
Jian-Guo Zhang ◽  
Gui-Xia Ma ◽  
Kai-Bei Yu
Keyword(s):  
Thermal Stability ◽  
Aqueous Solutions ◽  
Diffraction Analysis ◽  
Single Crystals ◽  
Slow Evaporation ◽  
X Ray Diffraction ◽  
Element Analysis ◽  
Thermal Stabilities ◽  
X Ray ◽  
Thermal Stability Of

Cobalt(II) and zinc(II) complexes of ethyl carbazate (ECZ), [Co(ECZ)3](NO3)2 and [Zn(ECZ)3] (NO3)2, were synthesized. Single crystals of these two compounds were grown from aqueous solutions using a slow evaporation method. Their structures have been determined by X-ray diffraction analysis. Both of them are monoclinic with space group P21/n. The complexes are further characterized by element analysis and IR measurements. Their thermal stabilities are studied by using TG-DTG, DSC techniques. When heated to 350 °C, only metal oxide was left for both complexes.

Immobilization of hemoglobin on stable mesoporous multilamellar silica vesicles and their activity and stability

2005 ◽  
Vol 20 (10) ◽  
pp. 2682-2690 ◽  
Author(s):  
Yufang Zhu ◽  
Weihua Shen ◽  
Xiaoping Dong ◽  
Jianlin Shi
Keyword(s):  
Thermal Stability ◽  
Pore Size ◽  
X Ray Diffraction ◽  
X Ray ◽  
Practical Applications ◽  
Silica Material ◽  
Transmission Electron ◽  
Mesoporous Support ◽  
Adsorption Desorption ◽  
Thermal Stability Of

A stable mesoporous multilamellar silica vesicle (MSV) was developed with a gallery pore size of about 14.0 nm. A simulative enzyme, hemoglobin (Hb), was immobilized on this newly developed MSV and a conventional mesoporous silica material SBA-15. The structures and the immobilization of Hb on the mesoporous supports were characterized with x-ray diffraction, transmission electron microscopy, N2 adsorption-desorption isotherms, Fourier transform infrared, ultraviolet-visible spectroscopy, and so forth. MSV is a promising support for immobilizing Hb due to its large pore size and high Hb immobilization capacity (up to 522 mg/g) compared to SBA-15 (236 mg/g). Less than 5% Hb was leached from Hb/MSV at pH 6.0. The activity study indicated that the immobilized Hb retained most peroxidase activity compared to free Hb. Thermal stability of the immobilized Hb was improved by the proctetive environment of MSV and SBA-15. Such an Hb-mesoporous support with high Hb immobilization capacity, high activity, and enhanced thermal stability will be attractive for practical applications.

Thermal stability of Mg3Sb1.475Bi0.475Te0.05 high performance n-type thermoelectric investigated through powder X-ray diffraction and pair distribution function analysis

2018 ◽  
Vol 6 (35) ◽  
pp. 17171-17176 ◽  
Author(s):  
Lasse Rabøl Jørgensen ◽  
Jiawei Zhang ◽  
Christian Bonar Zeuthen ◽  
Bo Brummerstedt Iversen
Keyword(s):  
Thermal Stability ◽  
Distribution Function ◽  
Pair Distribution Function ◽  
High Performance ◽  
Function Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermal Stability Of

The thermal stability of the high performance n-type Te-doped Mg3Sb1.5Bi0.5 system is investigated.

scholarly journals Physical Stability and Viscoelastic Properties of Co-Amorphous Ezetimibe/Simvastatin System

2019 ◽  
Vol 12 (1) ◽  
pp. 40 ◽  
Author(s):  
Justyna Knapik-Kowalczuk ◽  
Krzysztof Chmiel ◽  
Karolina Jurkiewicz ◽  
Natália Correia ◽  
Wiesław Sawicki ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Viscoelastic Properties ◽  
Room Temperature ◽  
Physical Stability ◽  
Ternary Systems ◽  
Storage Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Conditions ◽  
First Time

The purpose of this paper is to examine the physical stability as well as viscoelastic properties of the binary amorphous ezetimibe–simvastatin system. According to our knowledge, this is the first time that such an amorphous composition is prepared and investigated. The tendency toward re-crystallization of the amorphous ezetimibe–simvastatin system, at both standard storage and elevated temperature conditions, have been studied by means of X-ray diffraction (XRD). Our investigations have revealed that simvastatin remarkably improves the physical stability of ezetimibe, despite the fact that it works as a plasticizer. Pure amorphous ezetimibe, when stored at room temperature, begins to re-crystallize after 14 days after amorphization. On the other hand, the ezetimibe-simvastatin binary mixture (at the same storage conditions) is physically stable for at least 1 year. However, the devitrification of the binary amorphous composition was observed at elevated temperature conditions (T = 373 K). Therefore, we used a third compound to hinder the re-crystallization. Finally, both the physical stability as well as viscoelastic properties of the ternary systems containing different concentrations of the latter component have been thoroughly investigated.

scholarly journals Exploring the Complexation of Counterion in Novel Family of Polyelectrolytes with Unexpected Solubility Behaviour

2020 ◽  
Vol 869 ◽  
pp. 61-68
Author(s):  
Egor A. Bersenev ◽  
Alina Maryasevskaya ◽  
Evgenii V. Komov ◽  
Denis V. Anokhin ◽  
Dimitri A. Ivanov
Keyword(s):  
Thermal Stability ◽  
Ir Spectroscopy ◽  
Lithium Salt ◽  
Ionic Form ◽  
X Ray Diffraction ◽  
X Ray ◽  
Alkali Ions ◽  
In Series ◽  
Chelating Complex ◽  
Thermal Stability Of

In the present paper we study the effect of complexation in linear negatively charged polyelectrolytes with different alkali ions. With combination of IR-spectroscopy, X-ray diffraction and nanocalorimetry, we attempted to explain unusual solubility, crystallinity and thermal stability of these polymers. The increase of thermal stability and insolubility in water in series of semi-crystalline polysalts as K+ ≤ H+ <Na+ was explained by effectiveness of formation of chelating complex. Insoluble in water sodium salt shows the highest thermal stability of crystal phase up to . In contrast, well soluble in water amorphous lithium salt does not self-organize in chelating complex and is presented in ionic form.

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