scholarly journals Comparative Study of Lightweight Cementitious Composite Reinforced with Different Fibre Types and the Effect of Silane-Based Admixture

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Geok Wen Leong ◽  
Hui Loo Chua ◽  
Kim Hung Mo ◽  
Zainah Ibrahim ◽  
Zhi Pin Loh
Keyword(s):  
Water Absorption ◽  
Lightweight Concrete ◽  
Water Repellent ◽  
Cementitious Composite ◽  
Hydrophobic Properties ◽  
Water Contact ◽  
Fine Grained ◽  
Overall Performance ◽  
Hardened Properties ◽  
Softening Coefficient

This study aims to develop a type of fine-grained lightweight concrete, also known as lightweight cementitious composite (LCC), containing perlite microsphere (PM) and fibres with enhanced impermeability. The effect of polypropylene (PP), polyvinyl alcohol (PVA), and basalt fibres on the fresh and hardened properties of LCC was investigated. Besides, silane-based water repellent admixture was incorporated to reduce the water absorption and enhance the hydrophobicity of LCC. The dry densities of LCC developed were in the range of 912–985 kg/m3. PP fibres have lesser influence on the strengths of LCC. However, PVA fibres enhanced the strength of LCC by up to 35.2% and 28% in the compressive strength and flexural strength, respectively, while the basalt fibres increased both strengths up to 30.1% and 43.5%, respectively. By considering the overall performance, LCC with 0.5% PVA fibres has achieved a good balance in workability and strength. Additionally, silane-based water repellent admixture had an excellent effect in reducing the water absorption and improving the hydrophobicity of LCC. By incorporating 1% of silane-based water repellent admixture, the LCC with 0.5% PVA fibres obtained water-resistant properties with the softening coefficient of 0.85 and water contact angle of 128.2°. In conclusion, a combination of PVA-LCC with 1% waterproofing admixture showed the best performance in terms of mechanical strength as well as hydrophobic properties and had the potential to be used in the fabrication of concrete façade.

Nanostructured superhydrophobic lyocell fabrics with asymmetric moisture absorbency: Moisture managing properties

2016 ◽  
Vol 87 (7) ◽  
pp. 807-815 ◽  
Author(s):  
Seong-ok Kwon ◽  
Jooyoun Kim ◽  
Myoung-Woon Moon ◽  
Chung Hee Park
Keyword(s):  
Water Absorption ◽  
Transmission Rate ◽  
Chemical Vapor ◽  
Absorption Capacity ◽  
Wound Dressings ◽  
Water Repellent ◽  
Water Contact ◽  
Moisture Management ◽  
Vertical Wicking ◽  
Opposite Face

This study investigated moisture management properties of a single-faced superhydrophobic fabric. A single-faced superhydrophobic lyocell fabric, where one face of the surface is superhydrophobic and the opposite face is hydrophilic, was produced by a two-step plasma process on one side of the fabric: (1) the addition of nano-scale roughness by 5 minutes of O2 plasma etching; (2) subsequent 30 seconds of plasma enhanced chemical vapor deposition with hexamethyldisiloxane to lower the surface energy of lyocell fibers. As a result, the superhydrophobic lyocell fabric exhibited water repellency with a static water contact angle greater than 161° on the treated surface, allowing water absorption from the untreated face. The nanometer depth of the superhydrophobic layer in the hydrophilic textile affected water absorption capacity, drying rate, vertical wicking rate, and moisture management properties. The air permeability and water vapor transmission rate of the superhydrophobic treated lyocell fabric were hardly changed. The superhydrophobic properties were maintained after a gentle wash cycle, although the level of superhydrophobicity was reduced, especially when it was washed with detergent. This superhydrophobic and moisture managing textile would be relevant for an application that requires a water repellent property on one face and water absorbing property on the opposite face, such as medical operation gowns, wound dressings, and hygienic products.

scholarly journals Water-Repellent Characteristics of Beech Wood Coated with Parylene-N

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2076
Author(s):  
Robert Köhler ◽  
Philipp Sauerbier ◽  
Mirco Weber ◽  
Roland-Christian Wander ◽  
Stephan Wieneke ◽  
...  
Keyword(s):  
Water Absorption ◽  
Photoelectron Spectroscopy ◽  
Beech Wood ◽  
Chemical Vapor ◽  
European Beech ◽  
Modern Society ◽  
Thin Layers ◽  
Water Repellent ◽  
Water Contact ◽  
Chemical Structures

In recent years, awareness regarding sustainability and the responsible usage of natural resources has become more important in our modern society. As a result, wood as a building material experiences a renaissance. However, depending on the use case, protective measures may be necessary to increase wood’s durability and prolong its service life. The chemical vapor deposition (CVD) of parylene-N layers offers an interesting alternative to solvent-based and potentially environmentally harmful coating processes. The CVD process utilized in this study generated transparent, uniform barrier layers and can be applied on an extensive range of substrates without the involvement of any solvents. In this study, European beech wood samples (Fagus sylvatica L.) were coated with parylene-N using the CVD process, with paracyclophane as a precursor. The aim of the study was to analyze the water absorption of beech wood, in relation to the different layer thicknesses of parylene-N. Therefore, four different coating thicknesses from 0.5 to 40 μm were deposited, depending on the initial amount of precursor used. The deposited layers were analyzed by reflection interference spectroscopy and scanning electron microscopy, and their chemical structures and compositions were investigated by X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy. Due to the chemical structure of parylene-N, the deposited layers led to a significantly increased water contact angle and reduced the water uptake by 25–34% compared to the uncoated reference samples. A linear correlation between layer thickness and water absorption was observed. The coating of wood with parylene-N provides a promising water barrier, even with thin layers.

Hydrophobic performance of electrospun fibers functionalized with TiO2 nanoparticles

2021 ◽  
pp. 004051752110106
Author(s):  
Vânia Pais ◽  
Miguel Navarro ◽  
Catarina Guise ◽  
Rui Martins ◽  
Raul Fangueiro
Keyword(s):  
Electron Microscopy ◽  
Polymer Concentration ◽  
Water Repellent ◽  
Scanning Calorimetry ◽  
Hydrophobic Properties ◽  
Water Contact ◽  
Force Microscopy ◽  
Transmission Electron ◽  
Biodegradable Poly ◽  
Needle Diameter

The development of materials with hydrophobic properties has been widely explored in areas such as textiles, healthcare, sports, and personal protective equipment. Hydrophobic properties that arise from nanoparticles (nPs) directly promote other valuable properties, including self-cleaning capabilities, decreased bacterial growth, and increased comfort. In this study, biodegradable poly(ε-caprolactone) (PCL) nanofibers were functionalized by the incorporation of titanium dioxide (TiO2) nPs to develop water-repellent materials. The membranes were produced through electrospinning, and variables such as the polymer concentration, nP concentration, and needle diameter were optimized to achieve PCL/TiO2 composite fibers with water-repellent capabilities. The nanofibers were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, atomic force microscopy, scanning electron microscopy, transmission electron microscopy, and the water contact angle (WCA). In general, it was observed that the nanofibers presented higher roughness values when TiO2 nPs were present and that this result promoted higher WCA values. The highest WCA value (156°) was obtained for the nanofiber mat produced with 20% weight-to-volume (w/v) PCL and 0.6% (w/v) TiO2.

Control of hydrophobic properties of polyester fabric coatings deposited with use of polytetrafluoroethylene telomers and silicon dioxide nanoparticles

2021 ◽  
Vol 22 (10) ◽  
pp. 447-457
Author(s):  
N. P. Prorokova ◽  
◽  
T. Yu. Kumeeva ◽  
I. V. Kholodkov ◽  
V. M. Bouznik ◽  
...  
Keyword(s):  
Silicon Dioxide ◽  
Water Absorption ◽  
Sio2 Nanoparticles ◽  
Polyester Fabric ◽  
Contact Angles ◽  
Water Repellent ◽  
Silicon Dioxide Nanoparticles ◽  
Hydrophobic Properties ◽  
Additional Increase

The control possibility assessment of the water-repellent properties of polyester (PEF) fabric when its hydrophobizing with tetrafluoroethylene (TFE) telomers due to texturing by applying nanosized SiO2 is discussed. It was established that the use of a compound containing SiO2 nanoparticles and TFE telomers for hydrophobization of PEF fabrics led to an increase in roughness of the coatings, however, a decrease in contact angles of fabric and an increase in its water absorption were observed. This is due to an additional increase in hardness of the coating based on TFE telomers, when combined with SiO2 nanoparticles.

Study on Waterproof and Water-Resistant Properties of Gypsum

2012 ◽  
Vol 476-478 ◽  
pp. 1585-1588
Author(s):  
Hong Pan ◽  
Guo Zhong Li
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Portland Cement ◽  
Water Absorption ◽  
Ordinary Portland Cement ◽  
Experimental Results ◽  
Softening Coefficient

The comprehensively modified effect of cement, VAE emulsion and self-made acrylic varnish on mechanical and water-resistant properties of gypsum sample was investigated and microstructure of gypsum sample was analyzed. Experimental results exhibit that absolutely dry flexural strength, absolutely dry compressive strength, water absorption and softening coefficient of gypsum specimen with admixture of 10% ordinary Portland cement and 6% VAE emulsion and acrylic varnish coated on its surface can respectively reach to 5.11MPa , 10.49 MPa, 8.32% and 0.63, respectively.

Properties of Artificial Lightweight Aggregates (ALAs) Made of Dredged Soil Mixed with Waste Catalyst Slag

2012 ◽  
Vol 174-177 ◽  
pp. 1079-1085 ◽  
Author(s):  
Si Nae Jo ◽  
Yoo Tack Kim ◽  
Seung Gu Kang ◽  
Chang Sam Kim
Keyword(s):  
Specific Gravity ◽  
Water Absorption ◽  
Lightweight Concrete ◽  
Sintering Temperature ◽  
Thermal Power ◽  
Lightweight Aggregates ◽  
Dredged Soil ◽  
Porous Carriers ◽  
Black Core ◽  
Sintering Method

The artificial lightweight aggregates (ALAs) were manufactured using dredged soil produced at thermal power plant and waste catalyst slag by direct sintering method at 1050~1250°C for 10min. The ALAs of 100% dredged soil showed the black core phenomenon even at the low sintering temperature as 1050°C and become lightened by bloating pores in black core area with sintering temperature. On the other hand, the aggregates with 100% waste catalyst slag did not showed black coring and bloating phenomenon and had the low forming ability and many cracks inside. Adding the dredged soil to the waste catalyst slag decrease the specific gravity by promoting the black coring and bloating inside. The water absorption(%) of ALAs decreased with sintering temperature. The ALAs fabricated in this study showed the specific gravity of 0.8~2.0 and water absorption of 2~16% so it could be applied to various fields such as the lightweight concrete or the field of the porous carriers for purification of a contaminated soil or water.

Fast and simple fabrication of SiO2/poly(vinylidene fluoride) coated cotton fabrics with asymmetric wettability via a facile spray-coating route

2018 ◽  
Vol 89 (6) ◽  
pp. 1013-1026 ◽  
Author(s):  
Rongrong Yu ◽  
Mingwei Tian ◽  
Lijun Qu ◽  
Shifeng Zhu ◽  
Jianhua Ran ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Contact Angle ◽  
Water Contact Angle ◽  
Vinylidene Fluoride ◽  
Spray Coating ◽  
Cotton Fabrics ◽  
Water Repellent ◽  
Water Contact ◽  
Repellent Property ◽  
Poly Vinylidene Fluoride

Cotton fabrics with hydrophilic-to-hydrophobic asymmetric surfaces are attractive as potential utilizable structures for functional garments. The spray-coating route could be deemed as a fast and simple way to achieve asymmetric surfaces. In this paper, SiO2 nanoparticles with size ∼ 205 nm were synthesized via the modified sol-gel method, and then modified with poly(vinylidene fluoride) (PVDF) to form a hydrophobic surface. The SiO2 nanoparticles modified with PVDF were uniformly deposited on the outer surface of cotton fabric aided with the robust air flow force from the sprayer. The morphology and chemical structures were characterized by scanning electron microscopy, mapping, atomic force microscopy, X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy. The results indicated that SiO2 nanoparticles were evenly deposited on the surface of cotton fibers and stable interfacial interaction occurred between SiO2 and PVDF molecular chains. The existence of SiO2 could increase the roughness of the fabric surface, which could enhance the water-repellent property of the coated fabrics. Furthermore, the water-repellent property and thermal insulation properties were evaluated via the water contact angle and thermal conductivity tests, respectively, and the results showed that 20 wt.% SiO2/PVDF fabric achieved a desirable level of contact angle, 136.6°, which was the largest water contact angle among all the samples, and the lowest thermal conductivity of 0.033 W/mK, resulting from the existence of SiO2 nanoparticles. Such a fast and simple spray-coating strategy could be widely introduced into asymmetric fabric modification, and such asymmetric fabrics with reasonable water-repellent and thermal insulating outer surfaces could act as candidates in the field of functional garments.

scholarly journals Preparation of Assembled Carbon Soot Films and Hydrophobic Properties

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2318 ◽  
Author(s):  
Lei Zhao ◽  
Kang Zhao ◽  
Wei-Guo Yan ◽  
Zhifeng Liu
Keyword(s):  
Self Assembly ◽  
Lithium Ion ◽  
Deionized Water ◽  
Mixed Solution ◽  
Hydrophobic Properties ◽  
Water Contact ◽  
Wetting Properties ◽  
Candle Soot ◽  
Number Of Layers ◽  
Carbon Soot

In this paper, a simple, inexpensive, and rapid method for the fabrication of controlled layer candle soot film has been reported by interface self-assembly and transferred method. The mechanism of candle soot self-assembly is explained and their morphology, elemental composition, optical, and wetting properties are characterized. The uniformity and thickness of prepared films especially depend on the concentration of candle soot mixed solution (alcohol and deionized water). The results show that the optimal concentration of candle soot solution is approximately ~0.2% wt/mL. In addition, the absorption spectra of the controlled-layer candle soot films are determined by the number of layers and the surface morphology. The hydrophobic properties of candle soot films are closely related to their layer number. When these films reach to the fourth layer, the water contact angle and roll-off angle are measured as 142° ± 2° and 6°, respectively. The controlled assembly CS films have the potential application in photo/electrocatalysis, solar cells, lithium-ion batteries, and water splitting.

scholarly journals Production of Electroconductive, Superhydrphobic and Flame-Retardant Cotton Fibers via Pad-Dry-Cure Process using Silicone Rubber and Ammonium Polyphosphate

2021 ◽  
Author(s):  
Abdullah M. Al-Enizi ◽  
Asma A. Alothman ◽  
Mohd Ubaidullah ◽  
Ayman Nafady
Keyword(s):  
Flame Retardant ◽  
Silicone Rubber ◽  
Ammonium Polyphosphate ◽  
Cotton Fibers ◽  
Water Repellent ◽  
Step Method ◽  
Water Contact ◽  
Car Seat ◽  
One Step ◽  
Blend Fabric

Abstract Although pyrovatex has been widely utilized as commercial flame-retardant material, the discharge of poisonous formaldehyde is still a major concern. On the other side, fluorine-based materials have been successfully used to impart superhydrophobic textile surfaces, but they are highly expensive and extremely toxic. Based on these challenging concerns, we report a simple one-step method for the production of flame-retardant and water-repellent coating onto an electroconductive cotton-nickel (Cot-Ni) blend fabric. Firstly, the electroconductive cotton was prepared by weaving nickel strip twisted around cotton core yarns, which were then weaved with pure cotton yarns to introduce Cot-Ni blend fabric. Secondly a composite comprising ammonium polyphosphate (APP) and room-temperature vulcanized silicone rubber (RTV) was applied onto the electroconductive cotton fabrics via one-step pad-dry-cure technique. Results showed that the flame-retardant effect of cotton was enhanced due to the high binding of RTV with both APP and cotton fibers. Thus, different concentrations of APP were implemented in the composite to establish that only 100 g/L of APP with RTV presented an improved fire-retardancy. The surface of Cot-Ni fabric displayed different hierarchical morphologies relying on the concentration of APP. Moreover, RTV further enhanced the superhydrphobic nature of cotton surface. Importantly, the superhydrophobic activity was characterized by static water contact angle of the coated Cot-Ni blend. The CIE Lab colorimetric measurements of the coated Cot-Ni blend were also explored. The comfort characteristics of the coated Cot-Ni blend were assessed by measuring their air permeability and stiffness. Ultimately, these multifunctional cotton-nickel (Cot-Ni)/RTV-APP treated fabrics could be suitable for diverse applications, including firefighters’ wear, car seat mats, and grain storage containers.

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