scholarly journals Engineering the Surface and Mechanical Properties of Water Desalination Membranes Using Ultralong Carbon Nanotubes

Membranes ◽  
2018 ◽  
Vol 8 (4) ◽  
pp. 106 ◽  
Author(s):  
Yehia M. Manawi ◽  
Kui Wang ◽  
Viktor Kochkodan ◽  
Daniel J. Johnson ◽  
Muataz A. Atieh ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Aspect Ratio ◽  
Water Flux ◽  
Contact Angles ◽  
Water Desalination ◽  
Membrane Properties ◽  
Porous Membranes ◽  
Water Contact ◽  
And Performance

In this work, novel polysulphone (PS) porous membranes for water desalination, incorporated with commercial and produced carbon nanotubes (CNT), were fabricated and analyzed. It was demonstrated that changing the main characteristics of CNT (e.g., loading in the dope solutions, aspect ratio, and functionality) significantly affected the membrane properties and performance including porosity, water flux, and mechanical and surface properties. The water flux of the fabricated membranes increased considerably (up to 20 times) along with the increase in CNT loading. Conversely, yield stress and Young’s modulus of the membranes dropped with the increase in the CNT loading mainly due to porosity increase. It was shown that the elongation at fracture for PS/0.25 wt. % CNT membrane was much higher than for pristine PS membrane due to enhanced compatibility of commercial CNTs with PS matrix. More pronounced effect on membrane’s mechanical properties was observed due to compatibility of CNTs with PS matrix when compared to other factors (i.e., changes in the CNT aspect ratio). The water contact angle for PS membranes incorporated with commercial CNT sharply decreased from 73° to 53° (membrane hydrophilization) for membranes with 0.1 and 1.0 wt. % of CNTs, while for the same loading of produced CNTs the water contact angles for the membrane samples increased from 66° to 72°. The obtained results show that complex interplay of various factors such as: loading of CNT in the dope solutions, aspect ratio, and functionality of CNT. These features can be used to engineer membranes with desired properties and performance.

Functionalization and Tip-open of Carbon Nanotubes for High-Performance Symmetric Supercapacitor

2021 ◽  
Author(s):  
Yaxiong Zhang ◽  
Erqing Xie
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Aspect Ratio ◽  
Specific Surface ◽  
Surface Area ◽  
Chemical Stability ◽  
High Aspect Ratio ◽  
High Performance ◽  
Large Specific Surface Area ◽  
Symmetric Supercapacitor

Carbon nanotubes (CNTs) have been widely studied as supercapacitor electrodes because of their excellent conductivity, high aspect ratio, excellent mechanical properties, chemical stability, and large specific surface area. However, the...

Facile fabrication of photoinduced superhydrophobic–superhydrophilic surfaces on cellulose substrate without strength loss

2018 ◽  
Vol 89 (9) ◽  
pp. 1807-1822
Author(s):  
Yunjie Yin ◽  
Yanyan Zhang ◽  
Xiaoqian Ji ◽  
Tao Zhao ◽  
Chaoxia Wang
Keyword(s):  
Mechanical Properties ◽  
Uv Irradiation ◽  
Uv Curing ◽  
Contact Angles ◽  
Curing Process ◽  
Water Contact ◽  
Cellulose Substrate ◽  
Cellulose Substrates ◽  
Uv Curing Process ◽  
Modified Cellulose

A novel strategy was reported on the design and fabrication of functional photosensitive hybrid sols (FPHSs) by non-alcoholic emulsification in the presence of a TiO2 nanoparticle and photoinitiator via a sol-gel process using tetraethylorthosilicate, γ-methacryloxypropyltrimethoxysilane (MPS) and hydrophobic silane coupling agents as precursors. Smart cellulose substrates with alterable superhydrophobic–superhydrophilic conversion were fabricated using FPHS via the ultraviolet (UV) curing process. The liquid FPHS was photocured into solid gel during UV irradiation for 40 s with MPSs in FPHS, which was verified via Fourier transform infrared spectra. The cellulose substrates were modified with FPHSs, and the water contact angles of the modified cellulose substrates were more than 150°. The superhydrophobicity was improved by the gathering of hydrophobic chains and particle deposition of hybrid gel on the fiber surface. Nevertheless, the water contact angles of the modified cellulose substrates were receded with UV irradiation from 158° to 0° in 200 min, due to TiO2 photoinduction. The irradiated cellulose substrates were placed in the dark, and the water contact angles were recovered to about 130°, gradually. What is more, the reversible process can be repeated more than eight times. The modified cellulose substrate presented excellent washing fastness, even suffering 10 times washing processing. The mechanical properties, including breaking strength and elongation rate, were improved after the coating and UV curing process, which considerably remedied the defects of the heating curing process on the mechanical properties.

ELASTOMERIC COMPOSITES BASED ON NANOSPHERICAL PARTICLES AND CARBON NANOTUBES: A COMPARATIVE STUDY

2013 ◽  
Vol 86 (3) ◽  
pp. 423-448 ◽  
Author(s):  
Liliane Bokobza
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Electrical Properties ◽  
Aspect Ratio ◽  
Carbon Black ◽  
Spherical Particles ◽  
Styrene Butadiene Rubber ◽  
Mechanical And Electrical Properties ◽  
Polymer Filler ◽  
Spherical Silica

ABSTRACT The reinforcement of elastomeric materials by addition of mineral fillers represents one of the most important aspects in the field of rubber science and technology. The improvement in mechanical properties arises from hydrodynamic effects depending mainly on the amount of filler and the aspect ratio of the particles and also on polymer–filler interactions depending on the surface characteristics of the filler particles and the chemical nature of the polymer. The past few years have seen the extensive use of nanometer-scale particles of different morphologies on account of the small size of the filler and the corresponding increase in the surface area that allow a considerable increase in mechanical properties even at very low filler loading. Among these nanoparticles, spherical particles (such as silica or titania) generated in situ by the sol-gel process and carbon nanotubes are typical examples of materials used as a nanosize reinforcing additive. Specific features of filled elastomers are discussed through the existing literature and through results of the author's research based on poly(dimethylsiloxane) filled with spherical silica or titania particles and on styrene–butadiene rubber filled with multiwall carbon nanotubes. The reinforcing ability of each type of filler is discussed in terms of morphology, state of dispersion (investigated by transmission electron microscopy, atomic force microscopy, small-angle neutron scattering), and mechanical and electrical properties. In addition, the use of molecular spectroscopies provides valuable information on the polymer–filler interface. Spherical silica and titania spherical particles are shown to exhibit two distinct morphologies, two different polymer–filler interfaces that influence the mechanical properties of the resulting materials. The superiority of carbon nanotubes over carbon black for mechanical reinforcement and electrical conduction is mainly attributed to their large aspect ratio rather than to strong polymer–filler interactions. The use of hybrid fillers (carbon nanotubes in addition to carbon black or silica, for example) has been shown to give promising results by promoting an enhancement of mechanical and electrical properties with regard to each single filler.

Evaluation of mechanical and dynamic mechanical properties of multiwalled carbon nanotube-based ethylene–propylene copolymer composites mixed by masterbatch dilution

2016 ◽  
Vol 50 (29) ◽  
pp. 4093-4101 ◽  
Author(s):  
Maija Hoikkanen ◽  
Minna Poikelispää ◽  
Amit Das ◽  
Uta Reuter ◽  
Wilma Dierkes ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Aspect Ratio ◽  
Melt Mixing ◽  
Multiwalled Carbon ◽  
Mixing Processes ◽  
Ethylene Propylene ◽  
Dynamic Mechanical ◽  
Mixing Method

A two-step masterbatch mixing technique was studied for preparation of carbon nanotube-filled ethylene–propylene diene elastomer compounds, and compared to conventional one-step mixing process. In the two-step process, a masterbatch compound with carbon nanotube content of 50 parts per hundred was prepared by melt-mixing ethylene–propylene diene elastomer. This material was then compounded with pristine ethylene–propylene diene elastomer and composites with different carbon nanotube concentrations were compared. The aim of this study is to compare the efficiency of two different mixing processes on the dispersion of carbon nanotubes and to facilitate the handling of carbon nanotubes, as the masterbatch can be prepared in a controlled way and used for further dilution without the problems related to carbon nanotube processing. The compound properties were studied with emphasis on mechanical characterization and dynamic mechanical thermal analysis. Masterbatch mixing resulted in the similar mechanical properties of the composites compared to the direct mixing method. At the relatively low loadings of carbon nanotubes, the considerable improvements of the mechanical properties were observed. The aspect ratio of the carbon nanotubes determined by transmission electron microscope was found to be similar to the one calculated from the Guth equation. It showed a considerable reduction in aspect ratio independent of the used mixing method.

Morphology and Properties of a Series of PVDF Blend Membranes

2013 ◽  
Vol 750-752 ◽  
pp. 1941-1944
Author(s):  
Jiao Jiao Dong ◽  
Yu Feng Zhang ◽  
Dong Qing Liu
Keyword(s):  
Mechanical Properties ◽  
Pure Water ◽  
Water Flux ◽  
Transformation Method ◽  
Mass Ratio ◽  
Pvdf Membrane ◽  
Blend Membranes ◽  
Pure Water Flux ◽  
And Performance ◽  
Pure Pvdf

In this article, a series of the PVDF/PPTA blend membranes with porous structure and excellent performance were successfully prepared by the phase transformation method. The effect of the mass ratio of W(PVDF)/W(PPTA) was systematically investigated.The morphology of the blend membranes were examined using scanning electron microscope (SEM). The permeation performance was characterized by measuring pure water flux. Meanwhile, the mechanical properties of membranes were researched. The experiment results confirmed that the blending ratio is a major factor to influence the structure and performance of PVDF/PPTA blend membrane. The blend membranes possess much better permeability than pure PVDF membrane and fairly good the mechanical properties especially for the membrane made by PVDF : PPTA=6 : 1.

scholarly journals Surface Modification of Additively Manufactured Nitinol by Wet Chemical Etching

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7683
Author(s):  
Denis Nazarov ◽  
Aida Rudakova ◽  
Evgenii Borisov ◽  
Anatoliy Popovich
Keyword(s):  
Mechanical Properties ◽  
Free Surface ◽  
Surface Energy ◽  
Surface Composition ◽  
Three Dimensional ◽  
Physicochemical Characteristics ◽  
Contact Angles ◽  
Free Surface Energy ◽  
Flat Plates ◽  
Water Contact

Three-dimensional printed nitinol (NiTi) alloys have broad prospects for application in medicine due to their unique mechanical properties (shape memory effect and superplasticity) and the possibilities of additive technologies. However, in addition to mechanical properties, specific physicochemical characteristics of the surface are necessary for successful medical applications. In this work, a comparative study of additively manufactured (AM) NiTi samples etched in H2SO4/H2O2, HCl/H2SO4, and NH4OH/H2O2 mixtures was performed. The morphology, topography, wettability, free surface energy, and chemical composition of the surface were studied in detail. It was found that etching in H2SO4/H2O2 practically does not change the surface morphology, while HCl/H2SO4 treatment leads to the formation of a developed morphology and topography. In addition, exposure of nitinol to H2SO4/H2O2 and HCl/H2SO4 contaminated its surface with sulfur and made the surface wettability unstable in air. Etching in NH4OH/H2O2 results in surface cracking and formation of flat plates (10–20 microns) due to the dissolution of titanium, but clearly increases the hydrophilicity of the surface (values of water contact angles are 32–58°). The etch duration (30 min or 120 min) significantly affects the morphology, topography, wettability and free surface energy for the HCl/H2SO4 and NH4OH/H2O2 etched samples, but has almost no effect on surface composition.

scholarly journals Improved salt rejection, hydrophilicity and mechanical properties of novel thermoplastic polymer/chitosan nanofibre membranes

2020 ◽  
Vol 15 ◽  
pp. 155892502092317
Author(s):  
Fahad S Al-Mubaddel ◽  
Hamad S AlRomaih ◽  
Mohammad Rezaul Karim ◽  
Monis Luqman ◽  
Maher M Al-Rashed ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Contact Angle ◽  
Polyvinylidene Fluoride ◽  
Phase Inversion ◽  
Water Flux ◽  
Tensile Tests ◽  
Membrane Properties ◽  
Inversion Method ◽  
Thermoplastic Polymer ◽  
Salt Rejection

The present study reports on the preparation of novel nanofibre membranes from the thermoplastic polymer polyvinylidene fluoride coated with chitosan to enhance membrane properties such as hydrophilicity, mechanical properties, water flux and salt rejection. Initially, a supporting layer was produced from polyvinylidene fluoride using phase inversion methods, followed by being coated with chitosan using either electrospinning or immersion methods. Two types of fabricated membranes with different coating methods were characterized and tested for physical and chemical performance using field-emission scanning electron microscopy, tensile tests, permeation tests (water flux and salt rejection) and contact angle measurements. It was found that the support membrane (polyvinylidene fluoride) produced by the phase inversion method that was coated with chitosan using electrospinning showed better performance, with a salt rejection up to 70% for MgSO4, a decreased the contact angle (52°) and improved the elongation at the breaking point (~82%).

scholarly journals Effect of the Formation of Ultrathin Selective Layers on the Structure and Performance of Thin-Film Composite Chitosan/PAN Membranes for Pervaporation Dehydration

Membranes ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 153 ◽  
Author(s):  
Mariia Dmitrenko ◽  
Andrey Zolotarev ◽  
Tatiana Plisko ◽  
Katsiaryna Burts ◽  
Vladislav Liamin ◽  
...  
Keyword(s):  
Thin Film ◽  
Optimal Transport ◽  
Interfacial Polymerization ◽  
Contact Angles ◽  
Layer By Layer ◽  
Water Contact ◽  
Selective Layer ◽  
Film Composite ◽  
Thin Film Composite ◽  
And Performance

The aim of the study is to improve the performance of thin-film composite (TFC) membranes with a thin selective layer based on chitosan (CS) via different approaches by: (1) varying the concentration of the CS solution; (2) changing the porosity of substrates from polyacrylonitrile (PAN); (3) deposition of the additional ultrathin layers on the surface of the selective CS layer using interfacial polymerization and layer-by-layer assembly. The developed membranes were characterized by different methods of analyses (SEM and AFM, IR spectroscopy, measuring of water contact angles and porosity). The transport characteristics of the developed TFC membranes were studied in pervaporation separation of isopropanol/water mixtures. It was found that the application of the most porous PAN-4 substrate with combination of formation of an additional polyamide selective layer by interfacial polymerization on the surface of a dense selective CS layer with the subsequent layer-by-layer deposition of five bilayers of poly (sodium 4-styrenesulfonate)/CS polyelectrolyte pair led to the significant improvement of permeance and high selectivity for the entire concentration feed range. Thus, for TFC membrane on the PAN-4 substrate the optimal transport characteristics in pervaporation dehydration of isopropanol (12–90 wt.% water) were achieved: 0.22–1.30 kg/(m2h), 99.9 wt.% water in the permeate.

scholarly journals Preparation of microcrystalline cellulose from Rabdosia rubescens and study on its membrane properties

2021 ◽  
Author(s):  
Tong Wei ◽  
Meng Li ◽  
Wenrui Shi ◽  
Zhengyong Liang
Keyword(s):  
Mechanical Properties ◽  
Acid Hydrolysis ◽  
Microcrystalline Cellulose ◽  
Water Flux ◽  
Great Influence ◽  
Rejection Rate ◽  
Membrane Properties ◽  
Type I ◽  
Hydrochloric Acid Concentration ◽  
Rabdosia Rubescens

Abstract Microcrystalline cellulose (MCC) from Rabdosia rubescens was prepared by acid hydrolysis, and the corresponding yield of MCC was about 94% when the hydrochloric acid concentration was 10%, the acid hydrolysis time was 70min and the acid hydrolysis temperature was 70℃. The MCC was dissolved in N-methylmorpholine-N-oxide(NMMO)by phase transformation method to prepare MCC membrane. The structure and mechanical properties of MCC membrane were studied systemically. The results showed that the cellulose structure changed from type I to type II in the process of membrane formation, and the thermal stability also decreased. The content of MCC in the casting solution has a great influence on the mechanical properties of the membranes. The higher the content of MCC, the better the comprehensive mechanical properties of the membranes. When the MCC content is 9%, the tensile strength is 8.38 MPa and the elongation at break is 26.72%. Finally, the separation properties of membrane studed by separation bovine serum albumin (BSA) from water. The results showed that the rejection rate and water flux changed positively and negatively with the change of MCC content. When the content was 5%, MCC membrane showed the best comprehensive performance, its rejection of BSA was 37.23 g/(m2·h), and the corresponding rejection rate and water flux were 88.87% and 41.89 L/(m2·h) respectively.

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