Surface Free Energy Of Samples Research Articles

EXPERIMENTAL INVESTIGATION AND MODELING OF MODIFICATION AGENT ON SURFACE PROPERTY OF AEROGEL PRODUCED VIA AMBIENT PRESSURE DRYING

A crucial properties for hydrophobic silica aerogels such as surface free energy surface tension contact angle has been determines experimentally and theoretically in the present work, the modification was by hexamethyldisilazane (HMDZ) and trimethylchlorosilane (TMCS) with different concentration from 5% to 15% , two step acid base catalysis followed in preparation, using (TEOS) ethanol and [0.001M] hydrochloride acid with molar ratio was 1:2.8:0.19*10 -3 respectively , the effect study upon analysis of FTIR spectra and the degree of hydrophobicity was estimated by contact angle measurements. The results refer that the contact angle of aerogel from 130 to 151 by modifying by HMDZ and from 122 to 153 by modifying by TMCS, Neumann’s and Young’s equation of state depend to determine surface free energy and surface tension of samples, while the specific surface area is measured by using the Brunauer –Emmett–Teller (BET) method. Here, we have confirmed that the surface free energy of samples can be regulated in varied range from 4.4997 to 0.3115 and 4.1419 to 0.5112 mJ/m 2 by adjusting their surface by TMCS and HMDZ. From results the modification with TMCS is best from HMDZ, theoretical part give a good results to estimate the important information about hydrophobic silica aerogel. Article DOI: https://dx.doi.org/10.20319/mijst.2019.51.8598 This work is licensed under the Creative Commons Attribution-Non-commercial 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc/4.0/ or send a letter to Creative Commons, PO Box 1866, Mountain View, CA 94042, USA.

THE INFLUENCE OF THE METHOD OF RUBBER ISOLATION FROM LATEX ON THE PROPERTIES OF ELASTOMERIC MATERIALS BASED ON BUTADIENE-NITRILE RUBBERS

The properties of butadiene-nitrile rubbers obtained by various methods of synthesis and isolation from latex and rubbers based on them were studied in the article. The surface free energy of samples was determined using the Owens, Wendt, Rabel and Kaelble method. It was shown that the surface energy of elastomeric materials is affected 1) by non-rubber components, the content and nature of which are determined by the method of obtaining and isolating rubber from latex and 2) by the number of nitrile groups in the rubber macromolecule. The kinetics of vulcanization of rubber compounds based on the investigated rubbers has been studied. It was shown that rubber compounds based on rubbers containing a residual emulsifier are vulcanized longer. Elastic-strength properties were studied, and it was concluded that rubbers based on butadienenitrile rubbers synthesized by various methods with the same content of bound nitrilacrylic acid have different physico-mechanical properties and cannot be used interchangeably without changing the formulation and technological parameters of their processing.

Effect of low-surface-tension EDTA solutions on the wettability of root canal dentin

This study was conducted to evaluate the effect of reducing the surface tension of ethylenediaminetetraacetic acid (EDTA) solutions on the wettability of root canal dentin. Forty-two extracted teeth were sectioned at the crown, and the apical third and remaining mid-root portion was bisected longitudinally. The root halves were embedded in resin blocks. The experimental groups were treated with 17% EDTA, EDTA-T, and REDTA alone or followed by 2.5% NaOCl. Surface free energies of samples were calculated by measuring contact angles. Surface tension measurements of all solutions were performed with pendant drop method. The addition of surfactant to the EDTA solution significantly decreased the surface tension of solutions (P < .01). Combined and single use of experimental solutions and NaOCl significantly decreased the water contact angle and increased the surface free energy of root canal dentin (P < .05). EDTA-T alone or combined with NaOCl also increased surface free energy compared with EDTA solution (P < .05). The use of low-surface-tensioned EDTA compounds alone or in combination with NaOCl increased the wettability of root canal dentin.

Effect of different solid matrixes on surface free energy of EGDMA and TRIM polymers

Advancing and receding contact angles of water, formamide, glycerol and diiodometane were measured on the two polymers; EGDMA (dimethacrylate of ethylene glycol) and TRIM (trimethacrylate-1,1,1-trihydroksymethylopropane) which were polymerized next to glass, silanized glass, stainless steel, mica and silicon surfaces as the matrices. Then from the contact angle hystereses (CAH) and van Oss, Good, Chaudhury (LWAB) approaches the apparent surface free energies were evaluated. The measured contact angles not only depend solely on the polymer chemical structure but also, to some extent, on the solid matrix next to whose surface the sample has polymerized. Surface free energy of the polymer samples calculated from the LWAB approach shows that they interact mainly by dispersive forces. The apparent surface free energy of the polymers calculated from the diiodomethane contact angles hysteresis is practically the same irrespective of the kind of the matrix used. Therefore it can be concluded that the observed weak polar interactions in the surface free energy of the samples depend on the polymer surface preparation. The AFM images show that the obtained surfaces are of different roughness. The RMS values of roughness range between 3.7–90.2 nm for EDGMA, and 5.3–124.5 nm for TRIM. However, as reported in literature, rather protrusions bigger than 1 μm may significantly affect the contact angles, especially the receding ones.

Surface free energy of ultra-high molecular weight polyethylene modified by electron and gamma irradiation

Surface free energy of biocompatible polymers is important factor which affects the surface properties such as wetting, adhesion and biocompatibility. In the present work, the change in the surface free energy of ultra-high molecular weight polyethylene (UHMWPE) samples, which is produced by electron beam and gamma ray irradiation were, investigated. Mechanism of the changes in surface free energy induced by irradiations of doses ranging from 25 to 500 kGy was studied. FTIR technique was applied for sample analysis. Contact angle measurements showed that wettability and surface free energy of samples have increased with increasing the irradiation dose, where the values of droplet contact angle of the samples decrease gradually with increasing the radiation dose. The increase in the wettability and surface free energy of the irradiated samples are attributed to formation of hydrophilic groups on the polymer surface by the oxidation, which apparently occurs by exposure of irradiated samples to the air.