PVDF Membranes for Membrane Distillation: Controlling Pore Structure, Porosity, Hydrophobicity, and Mechanical Strength

2015 ◽  
pp. 276-311
Keyword(s):  
Mechanical Strength ◽  
Pore Structure ◽  
Membrane Distillation

Preparation Techniques and Property Evaluations of Highly Air Permeable Needle-Punched Geotextiles

2015 ◽  
Vol 749 ◽  
pp. 278-281
Author(s):  
Jia Horng Lin ◽  
Jing Chzi Hsieh ◽  
Jin Mao Chen ◽  
Wen Hao Hsing ◽  
Hsueh Jen Tan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Service Life ◽  
Mechanical Strength ◽  
Pore Structure ◽  
Test Results ◽  
Needle Punching ◽  
Pet Fibers ◽  
Environmental Requirements ◽  
Preparation Techniques

Geotextiles are made of polymers, and their conjunction with different processes and materials can provide geotextiles with desirable characteristics and functions, such as filtration, separation, and drainage, and thereby meets the environmental requirements. Chemical resistant and mechanical strong polymers, including polyester (PET) and polypropylene (PP), are thus used to prolong the service life of the products made by such materials. This study proposes highly air permeable geotextiles that are made with different thicknesses and various needle punching speeds, and the influences of these two variables over the pore structure and mechanical properties are then examined. PET fibers, PP fibers, and recycled Kevlar fibers are blended, followed by being needle punched with differing spaces and speeds to form geotextiles with various thicknesses and porosities. The textiles are then evaluated for their mechanical strength and porosity. The test results show that a thickness of 4.5 cm and 1.5 cm demonstrate an influence on the tensile strength of the geotextiles, which is ascribed to the webs that are incompletely needle punched. However, the excessive needle punching speed corresponding to a thickness of 0.2 cm results in a decrease in tensile strength, but there is also an increase in the porosity of the geotextiles.

Synthesis of Polyvinyl Formal Sponge for Wound Care Dressing Application

2010 ◽  
Vol 152-153 ◽  
pp. 1650-1659
Author(s):  
Qing Hao Yang ◽  
Guang Xu Cheng ◽  
Zhi Cheng Zhang
Keyword(s):  
Mechanical Properties ◽  
Mechanical Strength ◽  
Porous Structure ◽  
Pore Structure ◽  
Water Absorption ◽  
Wound Dressing ◽  
Wound Care ◽  
Acid Catalyst ◽  
The Other ◽  
Polyvinyl Formal

In an effort to seek poly(vinyl formal) (PVFM) foams based wound dressing pad material, a series of foamed PVFM materials have been synthesized under varied conditions. The influence of conditions on the properties of PVFM foam, such as mechanical properties, water absorption, pore structure and bulk density, is well discussed individually. It has been shown that both the reactant and acid catalyst affect the degree and speed of acetalization, therefore the mechanical properties, pores continuity and water absorption of the resultant sample. The addition of Na2CO3, surfactant and CMCNa are mainly influencing the porous structure as well as the mechanical properties and water absorption. One best sample with balanced properties is obtained. It possesses higher mechanical strength and water absorption while the other properties are similar, comparing with a commercial surgical PVFM sponge (YJ-1) currently used.

Zein: A Novel Porogen for the Preparation of PVDF Porous Membrane

2014 ◽  
Vol 1078 ◽  
pp. 45-48
Author(s):  
Hui Xia Xuan ◽  
Chun Ju He
Keyword(s):  
Mechanical Strength ◽  
Pore Structure ◽  
Membrane Surface ◽  
Water Flux ◽  
Porous Membrane ◽  
Pvdf Membrane ◽  
Flux Increase

Zein as the hydrophobic porogen was used to prepare the PVDF porous membrane, ATR demonstrate that zein can be washed away conveniently and no existed in membrane bulk. Compared to the reference PVDF membrane, Mechanical strength of modified PVDF membrane is improved and the water flux increase triple due to the large number of micro-sized pore structure on the membrane surface. Zein can be used for the preparation of hydrophobic porous membrane.

scholarly journals The influence of Fe2O3 doping on the pore structure and mechanical strength of TiO2-containing alumina obtained by freeze-casting

2015 ◽  
Vol 41 (10) ◽  
pp. 14049-14056 ◽  
Author(s):  
Alysson M.A. Silva ◽  
Eduardo H.M. Nunes ◽  
Douglas F. Souza ◽  
Dana L. Martens ◽  
João C. Diniz da Costa ◽  
...  
Keyword(s):  
Mechanical Strength ◽  
Pore Structure ◽  
Freeze Casting

scholarly journals The Effect of Filler Content on the Pore Structure and the Mechanical Strength of Filler-Loaded Paper.

1993 ◽  
pp. 874-878 ◽  
Author(s):  
Noriyoshi KINOSHITA ◽  
Takanori UEDA ◽  
Hidekazu SHOUJI ◽  
Hideo KATSUZAWA
Keyword(s):  
Mechanical Strength ◽  
Pore Structure ◽  
Filler Content

Study on the Influences of Foaming Gypsums Performance

2013 ◽  
Vol 743-744 ◽  
pp. 222-227 ◽  
Author(s):  
Bin Huang ◽  
Yi Zhang ◽  
Dong Xu Li
Keyword(s):  
Mechanical Strength ◽  
Pore Structure ◽  
Chemical Reaction ◽  
Apparent Density ◽  
Weight Ratio ◽  
Insulation Property ◽  
Foaming Agent ◽  
Fgd Gypsum ◽  
Foaming Process ◽  
Thermal Insulation Property

Utilizing the chemical reaction principles H2O2 was catalyzed by MnO2, instead of being catalyzed by warm water. In the gypsum slurry, due to the chemical reaction of hydrogen peroxide a large number of bubbles were produced, and the material was self-foaming. The H2O2 foaming agent and the method of foaming affected the performance of the foaming gypsum, such as mechanical strength, apparent density, thermal conductivity, and the pore structure of foaming gypsum. The result showed that with adding H2O2, the apparent density and mechanical strength decreased; the different water/plaster weight ratio ranged from 0.65 to 0.75, affecting the foaming process. The thermal insulation property of FGD gypsum is related to the content of H2O2, the water/plaster weight ratio, and the pore structure of foaming gypsum.

scholarly journals Enhancement of Physical Characteristics of Styrene–Acrylonitrile Nanofiber Membranes Using Various Post-Treatments for Membrane Distillation

Membranes ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 969
Author(s):  
Reza Sallakhniknezhad ◽  
Manijeh Khorsi ◽  
Ali Sallakh Niknejad ◽  
Saeed Bazgir ◽  
Ali Kargari ◽  
...  
Keyword(s):  
Mechanical Strength ◽  
Pore Size ◽  
Hot Pressing ◽  
Welding Process ◽  
Membrane Distillation ◽  
Solvent Vapor ◽  
Synthetic Seawater ◽  
Nanofiber Membranes ◽  
Styrene Acrylonitrile ◽  
Welding Processes

Insufficient mechanical strength and wide pore size distribution of nanofibrous membranes are the key hindrances for their concrete applications in membrane distillation. In this work, various post-treatment methods such as dilute solvent welding, vapor welding, and cold-/hot-pressing processes were used to enhance the physical properties of styrene–acrylonitrile (SAN) nanofiber membranes fabricated by the modified electrospinning process. The effects of injection rate of welding solution and a working distance during the welding process with air-assisted spraying on characteristics of SAN nanofiber membranes were investigated. The welding process was made less time-consuming by optimizing system parameters of the electroblowing process to simultaneously exploit residual solvents of fibers and hot solvent vapor to reduce exposure time. As a result, the welded SAN membranes showed considerable enhancement in mechanical robustness and membrane integrity with a negligible reduction in surface hydrophobicity. The hot-pressed SAN membranes obtained the highest mechanical strength and smallest mean pore size. The modified SAN membranes were used for the desalination of synthetic seawater in a direct contact membrane distillation (DCMD). As a result, it was found that the modified SAN membranes performed well (>99.9% removal of salts) for desalination of synthetic seawater (35 g/L NaCl) during 30 h operation without membrane wetting. The cold-/hot-pressing processes were able to improve mechanical strength and boost liquid entry pressure (LEP) of water. In contrast, the welding processes were preferred to increase membrane flexibility and permeation.

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