Effect of orientation and crystallinty on the friction and wear of polytetrafluoroethylene

Gorokhovskii, G. A.; Agulov, I. I.

doi:10.1007/bf01198445

Cited by 2 publications

(2 citation statements)

References 1 publication

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“…During the initial sliding process the molecules on the top layer of the film get plastically deformed and oriented in the direction of sliding. Such orientation of the molecules has effect on increasing the relative crystallinity and the strengthening of the film [32]. Moreover, the density of the film depends on the number of sliding cycles.…”

Section: Discussionmentioning

confidence: 99%

Molecular Orientation, Crystallinity, and Topographical Changes in Sliding and their Frictional Effects for UHMWPE Film

Minn

Sinha

2009

Tribol Lett

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This paper presents a study on the frictional anisotropy of semi-crystalline UHMWPE polymer film deposited on DLC-overcoated Si substrate. For UHMWPE film slid against a silicon nitride ball, there is a remarkable difference in the coefficient of friction between the forward and reverse directions after the slider has been initially slid against the film for certain number of cycles. The changes in the friction are greatly influenced by the initial number of sliding cycles. This frictional behavior is explained in terms of crystallinity change and molecular orientational effects on UHMWPE and micro-topographical effects due to the initial sliding. Nanoscratch test is conducted to understand the friction of the polymer film in the sliding track and the data are compared with the macroscale friction data. The results show that the friction in the reverse of the initial sliding direction is high in comparison to that in the forward direction and this behavior mainly depends upon the number of initial sliding cycles. The initial sliding cycles affect the crystallinity and molecular orientation of the film, as well as the film topography. This combined effect on the polymer film results in an anisotropic frictional behavior of the film.

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Section: Discussionmentioning

confidence: 99%

Molecular Orientation, Crystallinity, and Topographical Changes in Sliding and their Frictional Effects for UHMWPE Film

Minn

Sinha

2009

Tribol Lett

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“…This initial crystallinity will affect the tribology of a (bulk) polymer; however, the wear life of a film is greatly influenced by the interfacial adhesion strength. Moreover, the crystallinity of more durable film is modified due to the sliding phenomenon [20].…”

Section: Effect Of Interfacial Energy (Hydrophobicity)mentioning

confidence: 99%

Effects of interfacial energy modifications on the tribology of UHMWPE coated Si

Minn¹,

Jonathan²,

Sinha³

2008

J. Phys. D: Appl. Phys.

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This paper presents results on the tribological properties of ultra-high molecular weight polyethylene (UHMWPE) films on Si substrates modified by interfacial layers of different surface energies (hydrophobicity). Five different interfaces, namely bare Si (i.e. no interfacial modification), heated Si, Si/3-aminopropyltrimethoxysilane (Si/APTMS), hydrogenated Si (Si–H) and Si/octadecyltrichlorosilane (Si/OTS) were prepared on a Si substrate by physical and chemical methods that gave water contact angles of the interfaces as 21°, 46°, 52°, 71° and 104°, respectively. UHMWPE (6 µm thickness) was coated onto surface energy modified Si substrates by the dip-coating method. The tribological tests were conducted using a ball-on-disc tribometer with a 4 mm diameter silicon nitride ball as the slider. Bare Si, which was the most hydrophilic of all, and Si/OTS, the most hydrophobic interface, showed much lower wear resistance when compared with heated Si, Si/APTMS and Si–H interfaces, with Si–H interface giving the best result. The results of a scratch test for adhesion strength between the interface and UHMWPE were consistent with the tribological properties of the films. It is concluded that the wear performance of ultra-thin UHMWPE films on Si substrates could be extended by several orders of magnitude by suitably modifying the interfaces (different surface energies) of the silicon substrates. The coefficient of friction also follows a similar trend with Si–H interface giving the lowest value among all samples.

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Effect of orientation and crystallinty on the friction and wear of polytetrafluoroethylene

Cited by 2 publications

References 1 publication

Molecular Orientation, Crystallinity, and Topographical Changes in Sliding and their Frictional Effects for UHMWPE Film

Molecular Orientation, Crystallinity, and Topographical Changes in Sliding and their Frictional Effects for UHMWPE Film

Effects of interfacial energy modifications on the tribology of UHMWPE coated Si

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