Properties of fractions of ultradisperse polytetrafluoroethylene soluble in supercritical carbon dioxide

Vopilov, Yu. E.; Никитин, Л. Н.; Бузин, М. И.; Заиков, Г. Е.; Kharitonova, E. P.; Khokhlov, Alexei R.; Yurkov, G. Yu.; Бузник, В. М.

doi:10.1134/s0965545x12060089

Cited by 5 publications

(3 citation statements)

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“…It contains low and high molecular weight fractions [21]. Its low molecular weight fractions contain, on average, 10-20 monomer units and dissolve in supercritical carbon dioxide (SC-CO 2 ) [22]. SC-CO 2 was selected as the medium for hydrophobing the fabrics due to its unique set of properties.…”

Section: Introductionmentioning

confidence: 99%

Wear-Resistant Hydrophobic Coatings from Low Molecular Weight Polytetrafluoroethylene Formed on a Polyester Fabric

2022

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The paper presents a comparative analysis of the surface structure and morphology of hydrophobic coatings formed on a polyester fabric from various types of low molecular weight tetrafluoroethylenes by a new method. The low molecular weight compounds used include: ultrafine polytetrafluoroethylene of the FORUM® trademark prepared through thermo-gas-dynamic decomposition of industrial polytetrafluoroethylene waste, and tetrafluoroethylene telomers, synthesized by radiation-chemical initiation from fluoromonomers in acetone, butyl chloride and trimethylchlorosilane solutions. The formation of coatings consists in deposition of low molecular weight tetrafluoroethylenes from solutions in supercritical carbon dioxide and organic solvents. The contact angle and water absorption of the polyester fabric with coatings containing the specified water-repellents are determined. The resistance of the achieved effect to various types of wear—washing, dry cleaning and abrasionis evaluated. The hydrophobic properties of the fabric are found to be affected by the coating plasticity characterized by the stiffness coefficient. The importance of this indicator to targeted changes in fabric properties is proved. All the considered types of low molecular weight polytetrafluoroethylene (PTFE) are shown to be effective water-repellents for the polyester fabric.

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Section: Introductionmentioning

confidence: 99%

Wear-Resistant Hydrophobic Coatings from Low Molecular Weight Polytetrafluoroethylene Formed on a Polyester Fabric

2022

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“…The agent was developed by the Institute of Chemistry, Far-Eastern Branch, Russian Academy of Sciences [15,16]. According to the data obtained in the Institute of Organoelement Compounds, Russian Academy of Sciences, the low-molecular-weight fraction of Forum consists of molecules with 10 to 20 units and is suffi ciently soluble in SC CO 2 [17].Low-molecular-weight PTFE was deposited onto polyester fabric using a high-pressure installation schematically shown in [12], at 90°С and a pressure of 20 MPa for 60 min. The fi lm deposition was based on a controllable decrease in the solubility of low-molecularweight PTFE in SC СО 2 with a decrease in the pressure and temperature [18].…”

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confidence: 99%

Analysis of a polytetrafluoroethylene coating deposited onto polyester fibers from supercritical carbon dioxide

et al. 2012

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A low-molecular-weight polytetrafl uoroethylene coating deposited onto a polyester textile material from supercritical carbon dioxide with the aim to make the material hydrophobic was analyzed. The hydrophobic properties of the coating were examined in comparison with those of the hydrophobizing agent produced by Nuva (Switzerland).The most effective surface modifi ers used for making the surface unwettable are fl uorinated hydrocarbons having low surface energy (18.5-26 mJ m -2 ) [1]. In hydrophobization of textile materials, these substances are traditionally used in the form of suspensions or emulsions [2].Surface modification of fibrous materials causes changes in their structure and surface energy, which is a direct manifestation of intermolecular interactions. It should be noted that the surface free energy is determined by surface forces, which rapidly decrease with the depth [3]. Therefore, to make the surface hydrophobic, it is suffi cient to apply an ultrathin layer of an appropriate material onto a high-energy surface [4].Today polyester fibers play an important role in industry [5]. The majority of them are produced from poly(ethylene terephthalate) (PET). These fi bers are widely used owing to their cheapness, feasibility of dressing, and suffi cient strength and wear resistance, but are insuffi ciently hydrophobic.To obtain a hydrophobic material, additional modifi cation aimed to decrease its surface energy by deposition of a stable low-energy coating is necessary. The hydrophobizing agents used in textile industry cannot ensure formation of a high-quality hydrophobic coating on the PET surface, because they are diffi cultly soluble in the traditionally used aqueous medium.Among the known materials, polytetrafl uoroethylene (PTFE) has the lowest surface energy. However, it is practically insoluble in all the known solvents, its processing is diffi cult, and its adhesion is poor [6]. The negative properties of PTFE are due, to some extent, to the high molecular weight of the polymer. Therefore, coatings are usually deposited from emulsions and suspensions of specially synthesized fl uorinated substances of lower molecular weights [7-10]. However, with this deposition procedure, the coatings are contaminated with trace amounts of emulsifi ers [2]. To attain the required effect, multiple layers of a fl uorinated substance are deposited in succession onto a support [11].The problem of depositing ultrathin polymeric coatings can be solved by using supercritical carbon dioxide (SC CO 2 ) as a solvent for fl uorinated hydrophobizing agents [12]. This solvent is characterized by high solubility of nonpolar substances in it and by absolute wettability of the material being modifi ed. Owing to unique dissolving properties, high diffusion mobility, and easy complete removal from the material after the end of the process, SC CO 2 shows promise for wide use in diverse branches of chemical technology. The supercritical state of carbon dioxide is attained at relatively low parameters (P c = 7.39 MPa, T c = 31.6°С...

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The structural features of fluorinated paraffins

et al. 2015

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Properties of fractions of ultradisperse polytetrafluoroethylene soluble in supercritical carbon dioxide

Cited by 5 publications

References 6 publications

Wear-Resistant Hydrophobic Coatings from Low Molecular Weight Polytetrafluoroethylene Formed on a Polyester Fabric

Wear-Resistant Hydrophobic Coatings from Low Molecular Weight Polytetrafluoroethylene Formed on a Polyester Fabric

Analysis of a polytetrafluoroethylene coating deposited onto polyester fibers from supercritical carbon dioxide

The structural features of fluorinated paraffins

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