scholarly journals Fabrication of Bifunctional Chitosan-Based Flocculants: Characterization, Assessment of Flocculation, and Sterilization Performance

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2009 ◽  
Author(s):  
Moxi Wang ◽  
Li Feng ◽  
Xiaowei Fan ◽  
Dongmei Li ◽  
Wenqi Qu ◽  
...  
Keyword(s):  
Quaternary Ammonium ◽  
Sem Analysis ◽  
Resonance Spectroscopy ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
1H Nuclear Magnetic Resonance ◽  
Simulated Wastewater ◽  
Sterilization Mechanism ◽  
Sterilization Effect ◽  
Flocculation Effect

In this study, a series of chitosan-based quaternary ammonium graft flocculants, namely chitosan-graft-poly(acrylamide and methacryloyl ethyl trimethyl ammonium chloride) [CTS-g-P(AM-DMC)], was successfully synthesized by plasma initiation, and the as-prepared [CTS-g-P(AM-DMC)] had both flocculation and sterilization functions. Various characterization techniques were used to study the structure and physicochemical properties of the chitosan-based flocculants. 1H nuclear magnetic resonance spectroscopy (1H NMR), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD), and thermogravimetric analysis/differential scanning calorimetry (TG/DSC) confirmed the successful synthesis of CTS-g-P(AM-DMC). Scanning electron microscopy (SEM) analysis exhibited that CTS-g-P(AM-DMC) contained a smooth convex and porous structure with an enormous surface area. CTS-g-P(AM-DMC) was then used to flocculate the simulated wastewater of the kaolin suspension and the Salmonella suspension. Besides external factors, such as the dosage of flocculant and pH, the effect of the internal factor graft ratio was also evaluated. The experimental results showed that CTS-g-P(AM-DMC) also revealed a strong sterilization effect, aside from the excellent flocculation effect. Moreover, the sterilization mechanism was investigated through a series of conductivity measurements and the analysis of fluorescence-based cell live/dead tests. The results indicated that CTS-g-P(AM-DMC) destroyed the cell membrane of Salmonella through its grafted quaternary ammonium salt, thereby exhibiting sterilization property.

scholarly journals Synthesis and Characterization of N-Substituted Polyether-Block-Amide Copolymers

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 773
Author(s):  
Jyun-Yan Ye ◽  
Kuo-Fu Peng ◽  
Yu-Ning Zhang ◽  
Szu-Yuan Huang ◽  
Mong Liang
Keyword(s):  
Titanium Isopropoxide ◽  
Decomposition Temperature ◽  
Phenyl Isocyanate ◽  
Cross Linking ◽  
Resonance Spectroscopy ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Degradation Temperature ◽  
Melt Polycondensation ◽  
Structural Regularity

A series of N-substituted polyether-block-amide (PEBA-X%) copolymers were prepared by melt polycondensation of nylon-6 prepolymer and polytetramethylene ether glycol at an elevated temperature using titanium isopropoxide as a catalyst. The structure, thermal properties, and crystallinity of PEBA-X% were investigated using nuclear magnetic resonance spectroscopy, Fourier-transform infrared spectroscopy, differential scanning calorimetry, wide angle X-ray diffraction, and thermogravimetric analysis. In general, the crystallinity, melting point, and thermal degradation temperature of PEBA-X% decreased as the incorporation of N-methyl functionalized groups increased, owing to the disruption caused to the structural regularity of the copolymer. However, in N-acetyl functionalized analogues, the crystallinity first dropped and then increased because of a new γ form arrangement that developed in the microstructure. After the cross-linking reaction of the N-methyl-substituted derivative, which has electron-donating characteristics, with poly(4,4′-methylenebis(phenyl isocyanate), the decomposition temperature of the resulting polymer significantly increased, whereas no such improvements could be observed in the case of the electro-withdrawing N-acetyl-substituted derivative, because of the incompleteness of its cross-linking reaction.

Effect of Sonication Time and Clay Loading on Nanoclay Dispersion and Thermal Property of Epoxy-Clay Nanocomposite

2011 ◽  
Vol 471-472 ◽  
pp. 490-495 ◽  
Author(s):  
M.J. Adinoyi ◽  
Necar Merah ◽  
Zuhair M. Gasem ◽  
N. Al-Aqeeli
Keyword(s):  
Differential Scanning Calorimetry ◽  
Sem Analysis ◽  
Clay Nanocomposites ◽  
Sonication Time ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Clay Loading ◽  
Polymer Clay Nanocomposite ◽  
Nano Clay ◽  
Xrd Patterns

The development of nanoclay-epoxy nanocomposite material requires a suitable blending process to be employed. Amongst blending techniques, sonication has been one of the promising means for polymer-clay nanocomposite fabrication. In this study, epoxy-clay nanocomposites with 2, 4 and 5% clay loadings were fabricated using different sonication periods ranging from 5 to 60 minutes. The effect of sonication time and clay loading on the nanocomposite structure was investigated using Differential Scanning Calorimetry (DSC), X-ray diffraction (XRD), Scanning Electron Micropscope (SEM) and Energy Dispersive Spectroscopy (EDS). Differential Scanning Calorimetry analysis indicated that while clay loading reduced the glass transition temperature (Tg), sonication time did not alter Tg significantly. Upon examining the structure of the resulting nanocomposites both exfoliation and intercalation structures were present, yet, neither structure was fully achieved; evident by the XRD patterns. Nonetheless, the predominant structures for most of the nanocomposites were intercalation. Intergallery spacing of the nanocomposites were enhanced with increased sonication time mainly at 2%wt loading; whereas further increase in nano-clay loading resulted in a reduction of the d-spacing. SEM analysis showed that clay agglomerates were present in the nanocomposites irrespective of the sonication time. However, the analysis revealed that dispersion of clay was better in the nanocomposite fabricated at higher sonication time. From the EDS analysis, the different sites in the nanocomposites’ microstructure were identified which were then correlated with the observation made in the fractographic analysis.

Synthesis and Characterization of a New Organometallic Palladium Coordinated Liquid Crystal

2010 ◽  
Vol 428-429 ◽  
pp. 117-121 ◽  
Author(s):  
Jian Qiang Liu ◽  
Xing Cheng Zhang ◽  
You Yong Dai ◽  
Hong Di Xiao ◽  
Shi Shen Yan ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Optical Microscope ◽  
Resonance Spectroscopy ◽  
Functional Material ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Liquid Crystallinity ◽  
New Type ◽  
Clearing Temperature

A new organometallic palladium coordinated liquid crystal that is written by PdS4 has been synthesized by chelating reaction of the tetrachloropalladate (PdCl42-) and the star-like liquid crystal (S4) containing four butoxyazobenzene mesogens in its periphery. The structure and liquid crystallinity (LC) of PdS4 were characterized by infrared absorption spectroscopy (IR), ultraviolet absorption spectra (UV), nuclear magnetic resonance spectroscopy (NMR), elemental analysis (EA), polarizing optical microscope (POM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The phase behavior of PdS4 is Cr167N232I200N170Cr, its melting point and clearing temperature are higher than those of the free azo ligand S4, its mesophase range is broader than S4’s. It will be used as a new type photoelectric functional material in the future.

Synthesis and properties of pyrazine-based oligomeric phthalonitrile resins

2019 ◽  
Vol 31 (9-10) ◽  
pp. 1075-1084 ◽  
Author(s):  
Yao Liu ◽  
Puguang Ji ◽  
Zhenjiang Zhang ◽  
Xiaoyan Yu ◽  
Kimiyoshi Naito ◽  
...  
Keyword(s):  
Complex Viscosity ◽  
Resonance Spectroscopy ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
One Pot ◽  
X Ray ◽  
Tetragonal System ◽  
End Capping ◽  
Initial Storage ◽  
Reaction Activation Energy

The pyrazine-based oligomeric phthalonitrile (PN) monomer, 2,6-bis[3-(3,4-dicyanophenoxy)phenoxy]pyrazine (BCPP), was synthesized from the reaction of an excess amount of resorcinol with 2,6-dichloropyrazine in the presence of potassium carbonate, followed by end-capping with 4-nitrophthalonitrile in a two-step, one-pot reaction. 4-(Aminophenoxy)phthalonitrile was applied to promote the curing reaction. The curing behavior was investigated by differential scanning calorimetry and rheological behavior, showing a wide processing window of 94°C, a complex viscosity of less than 1.5 Pa·s and a lower reaction activation energy of 32.57 kJ mol−1. The structure of the BCPP monomer was confirmed by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The unit cell was determined to be tetragonal system by wide-angle X-ray diffraction. The monomer was cured to yield cross-linked polymers, which exhibited a high initial storage modulus, excellent glass transition temperature, outstanding thermal stability, and low water uptake.

scholarly journals Green anionic polymerization of vinyl acetate using Maghnite-Na+ (Algerian MMT): synthesis characterization and reactional mechanism

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Badia Imene Cherifi ◽  
Mohammed Belbachir ◽  
Abdelkader Rahmouni
Keyword(s):  
Vinyl Acetate ◽  
Polymerization Reaction ◽  
Resonance Spectroscopy ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
H Nmr ◽  
Simple Filtration ◽  
Renewable Material ◽  
Ft Ir ◽  
C Nmr

AbstractIn this work, the green polymerization of vinyl acetate is carried out by a new method which consists in the use of clay called Maghnite-Na+ as an ecological catalyst, non-toxic, inexpensive and recyclable by simple filtration. X-ray diffraction (XRD) showed that Maghnite-Na+ is successfully obtained after cationic treatment (sodium) on raw Maghnite. It is an effective alternative to replace toxic catalysts such as benzoyl peroxide (BPO) and Azobisisobutyronitrile (AIBN) which are mostly used during the synthesis of polyvinyl acetate (PVAc) making the polymerization reaction less problematic for the environment. The synthesis reaction is less energetic by the use of recycled polyurethane as container for the reaction mixture and which is considered as a renewable material and a good thermal insulator which maintains the temperature at 0 °C for 6 h. The reaction in bulk is also preferred to avoid the use of a solvent and therefore to stay in the context of green chemistry. In these conditions, the structure of obtained polymer is established by Nuclear Magnetic Resonance Spectroscopy 1H NMR and 13C NMR. Infrared spectroscopy (FT-IR) is also used to confirm the structure of PVAc. Thermogravimetric analysis (TGA) showed that it is thermally stable and it starts to degrade from 330 °C while Differential Scanning calorimetry (DSC) shows that this polymer has a glass transition temperature (Tg  = 50 °C). The composition in PVAc/Maghnite-Na+ (7 wt% of catalyst) is the most tensile resistant with a force of 182 N and a maximum stress of 73.16 MPa, the most flexible (E  = 955 MPa) and the most ductile (εr  = 768%).

scholarly journals Reactive Energetic Plasticizers Utilizing Cu-Free Azide-alkyne 1,3-dipolar Cycloaddition for In-Situ Preparation of Poly(THF-co-GAP)-Based Polyurethane Energetic Binders

2018 ◽  
Author(s):  
Mingyang Ma ◽  
Younghwan Kwon
Keyword(s):  
Thermal Stability ◽  
Dipolar Cycloaddition ◽  
Resonance Spectroscopy ◽  
Solid Propellants ◽  
Scanning Calorimetry ◽  
In Situ Preparation ◽  
1H Nuclear Magnetic Resonance ◽  
Energetic Plasticizers ◽  
Thermal Stability Of

Reactive energetic plasticizers (REPs) coupled with hydroxy-telechelic poly(glycidyl azide-co-tetrahydrofuran) (PGT)-based energetic polyurethane (PU) binders for use in solid propellants and plastic-bonded explosives (PBXs) were investigated. The generation of gem-dinitro REPs along with a terminal alkyne stemmed from a series of finely designed approaches to not only satisfy the common demands as conventional energetic plasticizers but prevent the migration of plasticizers. The miscibility and rheological behavior of a binary mixture of PGT/REP with various REP fractions were quantitatively determined by differential scanning calorimetry (DSC) and rheometer, respectively, highlighting the promising performance of REPs in the formulation process. The kinetics on the distinct reactivity of propargyl vs. 3-butynyl species of REPs towards the azide group of the PGT prepolymer in terms of Cu-free azide-alkyne 1,3-dipolar cycloaddition (1,3-DPCA) was studied by monitoring 1H nuclear magnetic resonance spectroscopy and analyzing the activation energies (Ea) obtained using DSC. The thermal stability of the finally cured energetic binders with the incorporation of REPs indicated that the thermal stability of the REP/PGT-based PUs was maintained independently of the REP content. The tensile strength and modulus of the PUs increased with increasing the REP content. In addition, the energetic performance and sensitivity of REP and REP triazole species was predicted.

scholarly journals Kinetics of the Solution-Mediated Polymorphic Transformation of the Novel l-Carnitine Orotate Polymorph, Form-II

Pharmaceutics ◽  
2018 ◽  
Vol 10 (4) ◽  
pp. 171 ◽  
Author(s):  
Ji-Hun An ◽  
Wonno Youn ◽  
Alice Kiyonga ◽  
Changjin Lim ◽  
Minho Park ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Solid State ◽  
Polymorphic Transformation ◽  
Transformation Process ◽  
Resonance Spectroscopy ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Treatment And Prevention ◽  
Transfer Equations ◽  
Reactive Crystallization

Research studies related to the polymorphs of l-Carnitine orotate (CO), a medication used for the treatment and prevention of liver diseases, are insignificant or almost nonexistent. Accordingly, in the present study, l-Carnitine orotate (CO) was prepared for investigating CO polymorphs. Here, a reactive crystallization was induced by reacting 1g of l-Carn (1 equivalent) and 0.97 g of OA (1 equivalent) in methanol (MeOH); as a result, CO form-I and CO form-II polymorphs were obtained after 1 h and 16 h of stirring, respectively. The characterization of CO polymorphs was carried out utilizing Powder X-ray diffraction (PXRD), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA) and solid-state Nuclear Magnetic Resonance Spectroscopy (solid-state CP/MAS 13C-NMR). The solution-mediated polymorphic transformation (SMPT) of CO polymorphs was investigated in MeOH at controlled temperature and fixed rotational speed. The results revealed that CO form-I is a metastable polymorph while CO form-II is a stable polymorph. From the same results, it was confirmed that CO form-I was converted to CO form-II during the polymorphic phase transformation process. Moreover, it was assessed that the increase in temperature and supersaturation level significantly promotes the rate of nucleation, as well as the rate of mass transfer of CO form-II. In addition, nucleation and mass transfer equations were employed for the quantitative determination of SMPT experimental results. Lastly, it was suggested that CO form-II was more thermodynamically stable than CO form-I and that both polymorphs belong to the monotropic system.

scholarly journals Influence of the Ammonium Nitrate(V) Porous Prill Assortments and Absorption Index on Ammonium Nitrate Fuel Oil Blasting Properties

Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3763
Author(s):  
Andrzej Biessikirski ◽  
Mateusz Pytlik ◽  
Łukasz Kuterasiński ◽  
Michał Dworzak ◽  
Michał Twardosz ◽  
...  
Keyword(s):  
Ammonium Nitrate ◽  
Crystal Surface ◽  
Sem Analysis ◽  
Absorption Index ◽  
Fuel Oil ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Velocity Of Detonation ◽  
Blasting Test ◽  
Toxic Fumes

Ammonium nitrate fuel oil (ANFO) samples, which were obtained by blending two different types of ammonium nitrate porous prills (i.e., AN-PP7 and AN-PP8) with fuel oil (FO) were studied. Measurements of structure, crystallinity and morphology were performed using X-ray Diffraction (XRD), Infrared Spectroscopy (IR) and Scanning Electron Microscopy (SEM), respectively. From the SEM analysis, it was indicated that a “wrinkled” structure characterized the crystal surface of the samples, which were based on two types of ammonium nitrate porous prill. Thermogravimetric analysis and differential scanning calorimetry (TGA/DSC) confirmed that AN-PP7 had a higher absorption index in comparison to AN-PP8. Furthermore, it was shown that continuous AN phase transformations at precise temperatures took place. From the blasting test, it was indicated that the absorption index only had an influence on the content of toxic fumes. However, the velocity of detonation (VOD) depended solely on the ANFO density as well as the total volume of post-blast fumes.

scholarly journals Microstructure and Crystallization Kinetics of Polyurethane Thermoplastics Containing Trisilanol Isobutyl POSS

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Vinicius Pistor ◽  
Daniela de Conto ◽  
Felipe Gustavo Ornaghi ◽  
Ademir José Zattera
Keyword(s):  
Crystal Size ◽  
Sem Analysis ◽  
Crystal Formation ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Thermoplastic Polyurethanes ◽  
Physical Interactions ◽  
Oligomeric Silsesquioxane ◽  
Kinetics Of ◽  
Batch Mixer

The synthesis of thermoplastic polyurethanes (TPU) from the reaction of a NCO group-containing prepolymer and 0, 1.14, 1.71, and 2.28 wt% of trisilanol isobutyl polyhedral oligomeric silsesquioxane (POSS) was carried out in an instrumented batch mixer. The samples were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and scanning electron microscopy (SEM). SEM analysis shows that the incorporation of POSS promoted strongly aggregation through physical interactions (formation of POSS-rich domains). Modifications in the TPU microstructure and the reduction in the crystal size were observed in the XRD diffractograms. The incorporation of POSS equally altered the TPU crystallization, and samples bearing higher concentrations of POSS formed two distinct types of crystalline structures. The kinetics of crystallization showed that nucleation strongly depends on the balance between TPU crystal formation and POSS-rich domains.

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