scholarly journals Preparation, Structure and Properties of Acid Aqueous Solution Plasticized Thermoplastic Chitosan

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 818 ◽  
Author(s):  
Yu Zhang ◽  
Biao-Lan Liu ◽  
Liang-Jie Wang ◽  
Ying-Hua Deng ◽  
Shi-Yi Zhou ◽  
...  
Keyword(s):  
Hydrochloric Acid ◽  
Acid Solution ◽  
Solution Concentration ◽  
Structure And Properties ◽  
X Ray Diffraction ◽  
Simple Method ◽  
Characterization Methods ◽  
Modified Chitosan ◽  
Acid Aqueous Solution ◽  
And Performance

This work provides a simple method for the preparation of thermoplastic chitosan using the most common dilute inorganic and organic acids in aqueous solutions, namely hydrochloric acid (HCl) and acetic acid (HAc). The melting plasticization behavior of chitosan under different concentrations and types of acid solution was investigated. By means of infrared spectra (IR), scanning electron microscope (SEM), X-ray diffraction (XRD), and other characterization methods, as well as a mechanical property test, it was found that as the acid solution concentration increased, the protonation effect was stronger and the plasticization performance showed a better trend. The structure and performance of the modified chitosan were optimal when the concentration of HCl was around 8 wt %. In addition, it was found that HCl had a better effect on the plasticization of chitosan than HAc, which was because the protonation ability of HCl was stronger than that of HAc. Unlike the casting method, the structure and properties of chitosan sheets prepared by thermoplastic processing were directly affected by protonation, however not by the interaction of anionic-cationic electrostatic attractions between the –NH3+ groups of chitosan chains and the carboxyl groups of acetic acids or the chloridoid groups of hydrochloric acid.

scholarly journals Electrodeposited Benzothiazole Phthalocyanines for Corrosion Inhibition of Aluminium in Acidic Medium

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Nnaemeka Nnaji ◽  
Njemuwa Nwaji ◽  
Tebello Nyokong
Keyword(s):  
Hydrochloric Acid ◽  
Acid Solution ◽  
Corrosion Inhibition ◽  
Hydrochloric Acid Solution ◽  
Electrochemical Impedance ◽  
X Ray Diffraction ◽  
Corrosion Attack ◽  
X Ray ◽  
Eis Measurements ◽  
Better Than

Tetrakis[(benzo[d]thiazol-2-yl-thio) phthalocyaninato] gallium(III)chloride (1) and tetrakis[(benzo[d]thiazol-2ylphenoxy) phthalocyaninato] gallium(III)chloride (2) were successfully electrodeposited onto aluminium for corrosion retardation in 1.0 M hydrochloric acid solution. The aim of this study was to compare the corrosion resistance of electrodeposited metallated phthalocyanines. Scanning electron microscopy, X-ray diffraction, electrochemical impedance spectroscopy (EIS), and polarization confirmed the aluminium corrosion inhibition potentials of complexes 1 and 2. EIS and polarization techniques showed that complex 2 performed better than complex 1, with values from EIS measurements of 82% for 1 and 86% for 2 in 1.0 M hydrochloric acid solution. The importance of electrodeposition in industries and a dearth of research on the use of electrodeposited metallated phthalocyanines necessitated this study, and results show that coatings formed by electrodeposition of 1 and 2 onto aluminium reduced its susceptibility to corrosion attack.

Kinetics of Bamboo Fiber Hydrolysis Reaction in Saturated Formic Acid

2012 ◽  
Vol 531-532 ◽  
pp. 679-683 ◽  
Author(s):  
Jun Ping Zhuang ◽  
Lu Lin ◽  
Chun Sheng Pang ◽  
Ying Liu
Keyword(s):  
Activation Energy ◽  
Hydrochloric Acid ◽  
Acid Solution ◽  
Formic Acid ◽  
Arrhenius Equation ◽  
Bamboo Fiber ◽  
Hydrolysis Reaction ◽  
Exponential Factor ◽  
Practical Applications ◽  
And Performance

Kinetic models can have practical applications for the optimization of the process and performance analysis, or economic estimations, so investigate the bamboo fiber kinetics is necessary. In this paper, effects of temperature and time on bamboo fiber hydrolysis in saturated formic acid with 4% hydrochloric acid solution reaction kinetics have been investigated. The rate constants, average apparent activation energy and frequency factors were evaluated according to the Arrhenius equation. The results showed that the hydrolysis velocities of bamboo fiber were 1.63×10-2 h-1 at 55 °C, 2.59×10-2 h-1 at 60 °C, 4.56×10-2 h-1 at 65 °C, 6.75×10-2 h-1 at 70 °C and 0.10 h-1 at 75 °C in formic acid solution with 4 % hydrochloric acid. The degradation velocities of glucose were 6.57×10-3 h-1 at 55 °C, 1.98×10-2 h-1 at 60 °C, 2.53×10-2 h-1 at 65 °C, 7.47×10-2 h-1 at 70 °C and 0.14 h-1 at 75 °C. The pre-exponential factor of Arrhenius equation of bamboo fiber hydrolysis reaction and glucose decomposition was 1.48×1014 h-1 and 2.32×1020 h-1 respectively. The activation energy of bamboo fiber hydrolysis was 87.65kJ/mol, and the activation energy of glucose degradation was 141.44kJ/mol.

scholarly journals Redefining Solution-Mediated Transformations: Pharmaceutical Systems

2014 ◽  
Vol 70 (a1) ◽  
pp. C1571-C1571
Author(s):  
Marcus O'Mahony ◽  
Anthony Maher ◽  
Denise Croker ◽  
Ake Rasmuson ◽  
Benjamin Hodnett
Keyword(s):  
Reaction Pathway ◽  
Metastable Phase ◽  
Active Pharmaceutical Ingredient ◽  
Solution Concentration ◽  
Stable Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
And Performance ◽  
State Composition

Engineering the isolation of a metastable or stable crystalline phase of an active pharmaceutical ingredient (API) is of critical importance when crystallizing from solution as an uncontrolled outcome can directly affect API manufacture and performance. The theoretical framework for understanding solution-mediated crystal phase or polymorphic transformation (SMPT) was first established by Cardew & Davey.[1] The process is defined to consist of a metastable phase that dissolves and a stable phase that nucleates and grows independently from the solution. That paper also identified that in terms of a reaction pathway, SMPT could be controlled in either of two ways: by growth of the stable phase or dissolution the metastable phase. Studies concerning SMPT since then have brought the definition and those conclusions into question. Firstly, the recent case of the SMPT from FI to FIII carbamazepine and FII to FIII piractem were studied separately where data on both the solid state composition and solution concentration were collected during the transformation using powder X-ray diffraction and in situ infra-red spectroscopy, respectively. These studies, in combination with a brief review of the literature, reveal that SMPT can be controlled not only in the two ways described by Cardew & Davey but rather in 4 principal ways (Figure 1).[2] Secondly, many studies now identify that nucleation of the stable phase often occurs on the surface of the metastable phase during SMPT [3] and not independently from solution. Again when the literature is examined, this surface supported nucleation event is identified as being either epitaxial in nature or having no or inconclusive evidence of epitaxy. It is concluded that the term "independently" in the definition by Cardew & Davey be redefined to recognize that the crystallization of the stable phase during SMPT is often dependent on the surface of the metastable phase in solution.

scholarly journals Influence of early thermal-oxidative ageing on the structure and properties of polyoxymethylene copolymer

2021 ◽  
Vol 8 (6) ◽  
pp. 210034
Author(s):  
Yuan-Jin Pang ◽  
Wen-Shuai Xu ◽  
Ben-Tengzi Yang ◽  
Hai-Ying Ni ◽  
Jun Chen
Keyword(s):  
Amorphous Region ◽  
Chain Scission ◽  
Structure And Properties ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Crystallinity Degree ◽  
Region I ◽  
The Difference ◽  
And Performance ◽  
Oxidative Ageing

Thermal-oxidative ageing of polyoxymethylene (POM) copolymer in the oven at 100°C for 1, 2, 3, 5, 7, 10, 14 and 21 days and the influence of early thermal-oxidative ageing on POM structure and properties were studied by means of wide-angle X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry and tensile test. Based on the results, we found that the early thermal-oxidative ageing of POM copolymer can be divided into three regions. The region I is the initial 3 days. In this region, some molecular chains rearranged, resulting in internal stress relaxation, increase of crystallinity degree and grain size due to the perfection of crystal structure; both extended chain crystal (ECC) and folded chain crystal (FCC) increased and ECC grew faster than FCC. The region II is from 3 days to 10 days, and in this region, chain scission took place in amorphous region and led to chemi-crystallization. The region III is after 10 days. In this region, the structure and performance of POM copolymer reached a stable situation at this stage. In this work, the difference between skin and core were also analysed.

scholarly journals Triazole-modified chitosan: a biomacromolecule as a new environmentally benign corrosion inhibitor for carbon steel in a hydrochloric acid solution

RSC Advances ◽  
2019 ◽  
Vol 9 (26) ◽  
pp. 14990-15003 ◽  
Author(s):  
Dheeraj Singh Chauhan ◽  
M. A. Quraishi ◽  
A. A. Sorour ◽  
Sourav Kr. Saha ◽  
Priyabrata Banerjee
Keyword(s):  
Carbon Steel ◽  
Hydrochloric Acid ◽  
Acid Solution ◽  
Corrosion Inhibitor ◽  
Hydrochloric Acid Solution ◽  
Environmentally Benign ◽  
Environment Friendly ◽  
Modified Chitosan

A novel derivative of chitosan is evaluated as an environment-friendly corrosion inhibitor for carbon steel in hydrochloric acid solution.

scholarly journals A Review of Piezoelectric PVDF Film by Electrospinning and Its Applications

Sensors ◽  
2020 ◽  
Vol 20 (18) ◽  
pp. 5214
Author(s):  
Gulnur Kalimuldina ◽  
Nursultan Turdakyn ◽  
Ingkar Abay ◽  
Alisher Medeubayev ◽  
Arailym Nurpeissova ◽  
...  
Keyword(s):  
Polyvinylidene Fluoride ◽  
Performance Enhancement ◽  
Solution Concentration ◽  
Pvdf Film ◽  
Simple Method ◽  
Preparation Conditions ◽  
Β Phase ◽  
And Performance ◽  
Mechanical Stretching ◽  
Selection Of

With the increase of interest in the application of piezoelectric polyvinylidene fluoride (PVDF) in nanogenerators (NGs), sensors, and microdevices, the most efficient and suitable methods of their synthesis are being pursued. Electrospinning is an effective method to prepare higher content β-phase PVDF nanofiber films without additional high voltage poling or mechanical stretching, and thus, it is considered an economically viable and relatively simple method. This work discusses the parameters affecting the preparation of the desired phase of the PVDF film with a higher electrical output. The design and selection of optimum preparation conditions such as solution concentration, solvents, the molecular weight of PVDF, and others lead to electrical properties and performance enhancement in the NG, sensor, and other applications. Additionally, the effect of the nanoparticle additives that showed efficient improvements in the PVDF films was discussed as well. For instance, additives of BaTiO3, carbon nanotubes, graphene, nanoclays, and others are summarized to show their contributions to the higher piezo response in the electrospun PVDF. The recently reported applications of electrospun PVDF films are also analyzed in this review paper.

Structural studies of technetium complexes. III. The crystal structure of Tris[2-aminobenzenethiolato(2 - )-S, N]technetium(VI) : a trigonal-prismatictechnetium geometry

1982 ◽  
Vol 35 (12) ◽  
pp. 2413 ◽  
Author(s):  
J Baldas ◽  
J Boas ◽  
J Bonnyman ◽  
MF Mackay ◽  
GA Williams
Keyword(s):  
Crystal Structure ◽  
Hydrochloric Acid ◽  
Acid Solution ◽  
Room Temperature ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Full Matrix ◽  
X Ray ◽  
Trigonal Prismatic

Tris[2-aminobenzenethiolato(2–)-S,N]technetium(VI), Tc(NHC6H4S)3, has been prepared by the reaction of ammonium pertechnetate with 2-aminobenzenethiol in 0.1 M hydrochloric acid solution at room temperature. The crystal structure of Tc(NHC6H4S)3 has been determined by single-crystal X-ray diffraction methods at 17�C. Crystals are orthorhombic, space group P212121, with a 10.696(2), b 11.363(1), c l5.220(2) �, and Z 4. Automatic diffractometry has provided significant Bragg intensities for 1413 independent reflections, and the structure of the correct enantiomorph has been refined by full-matrix least-squares methods to R 0.044. The compound, which is isostructural with the molybdenum analogue, consists of discrete molecules of Tc(NHC6H4S)3. The environment about the technetium atom closely approximates a trigonal-prismatic geometry. This is the first example where this geometry has been established with technetium. Differences in detail between the structures of TC(NHC6H4S)3 and its molybdenum analogue are discussed. In particular the S3N3 coordination polyhedron in TC(NHC6H4S)3is contracted and the distortions from ideal trigonal-prismatic geometry are less than in the molybdenum analogue.

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