HongYe Machinery CO.

China

HongYe Machinery CO.

China

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Gao J.,Donghua University | Yu J.,Donghua University | Yu J.,Key Laboratory of Textile Science and Technology | Ma Y.,HongYe Machinery CO.
Surface and Interface Analysis | Year: 2012

A two-step process based on a low-pressure helium plasma treatment followed by acrylic acid-grafting copolymerization was used for the surface modification of expanded polytetrafluoroethylene (ePTFE) films. The effects of plasma treatment power and treatment time on the hydrophilicity of the film surface were investigated. The wettability of the ePTFE film surface was characterized by water contact angle, and the surface compositions of the untreated and treated ePTFE samples were evaluated by atomic force microscopy and XPS. Contact angle measurements revealed that the hydrophilicity of the ePTFE film surface was greatly enhanced by the combined actions of the plasma treatment and acrylic acid grafting, and the contact angle decreased from 145° to 66°. Atomic force microscopy analyses showed that the surface roughness increased after the plasma treatment. XPS analyses showed substantial increase in the concentration of carbon and oxygen atoms and a decrease in the concentration of fluorine atoms at the film surface. T-peel strength showed an improved bonding strength between the film and an adhesive tape after the treatment. Copyright © 2012 John Wiley & Sons, Ltd. Copyright © 2012 John Wiley & Sons, Ltd.


Chen K.,Donghua University | Gao J.,Donghua University | Yu J.,Donghua University | Huan W.,Hongye Machinery Co. | Ma Y.,Hongye Machinery Co.
Huagong Xuebao/CIESC Journal | Year: 2011

PTFE adheres poorly to other materials due to its low surface energy and chemical inertness, which leads to failure of PTFE in many industrial applications. To spread the applications, numerous methods for surface modification have been developed to activate the PTFE surface for improving its wettability and adhesion ability. This study focused on the surface modification of expanded poly(tetrafluoroethylene)(ePTFE) film by a two-step process based on low-pressure plasma treatment followed by acrylic acid (AAc) graft copolymerization. The influences of different plasma treatments and graft copolymerization conditions on the hydrophilicity of film surface were studied. The wettability of the ePTFE film surface was determined by water contact angle, and the surface elemental compositions and the type of functional groups on the surface of the treated ePTFE samples were evaluated by X-ray photoelectron spectroscopy (XPS). The results indicated that the contact angle of ePTFE film declined from 145° to 102° when it was only treated by plasma treatment. After AAc grafted copolymerization, the contact angle decreased further to a smaller value. And the wettability of the film was improved obviously and kept constant. The condition of plasma treatment was He, 100 W, 90 s. The condition of AAc graft copolymerization was 30%(vol.), 70°C, 3 h. XPS analysis showed that the element ratio of F/C declined from 1.960 to 0.853, while the element ratio of O/C rose from 0 to 0.147. The result indicated that plasma treatment could greatly change the surface chemistry as well as morphology of ePTFE films. The surface roughness increased with plasma treatment time. From XPS measurements, it could be seen that the polar hydrophilic groups had been successfully grafted onto the ePTFE surface. The inert fluorine elements were partly replaced by oxygen polar groups, which was the fundamental reason for the improvement of hydrophilicity of ePTFE film.

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