Temperature dependency of elastic moduli and internal dilational and shear frictions of polyetherimide

Fukuhara, Mikio

doi:10.1002/app.12717

Cited by 27 publications

(26 citation statements)

References 32 publications

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“…In addition, generally the glass transition occurs from T g -50 K for bulk polymers. Therefore, E bulk ( T ) for bulk PS at T < T g -50 K is a linear function, which can be deduced from the experimental data obtained from E bulk ( T ) = -0.00189 T + 4.558 [19]. The result is also in agreement with another experimental result where the elastic modulus of bulk PS, E bulk = 4.0 GPa at T = 294 ± 3 K [12].…”

Section: Resultssupporting

confidence: 87%

Temperature- and thickness-dependent elastic moduli of polymer thin films

2011

Nanoscale Res Lett

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The mechanical properties of polymer ultrathin films are usually different from those of their counterparts in bulk. Understanding the effect of thickness on the mechanical properties of these films is crucial for their applications. However, it is a great challenge to measure their elastic modulus experimentally with in situ heating. In this study, a thermodynamic model for temperature- (T) and thickness (h)-dependent elastic moduli of polymer thin films Ef(T,h) is developed with verification by the reported experimental data on polystyrene (PS) thin films. For the PS thin films on a passivated substrate, Ef(T,h) decreases with the decreasing film thickness, when h is less than 60 nm at ambient temperature. However, the onset thickness (h*), at which thickness Ef(T,h) deviates from the bulk value, can be modulated by T. h* becomes larger at higher T because of the depression of the quenching depth, which determines the thickness of the surface layer δ.

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Section: Resultssupporting

confidence: 87%

Temperature- and thickness-dependent elastic moduli of polymer thin films

2011

Nanoscale Res Lett

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“…The C O group becomes progressively stretched through mechanical shear stresses and minor heating of the sliding surface, determining the polymer chain mobility. Fukuhara [8] investigated the thermally activated structural changes in polyetherimide by internal friction and also concluded that relaxation induced important C O motions. However, the relative intensity remains constant at 140-180…”

Section: Surface Characterisation Raman Spectroscopymentioning

confidence: 99%

Tribochemical reactions on polyimide sliding surfaces evaluated with Raman spectroscopy and atomic force microscopy

Samyn

Schoukens

2008

Surface & Interface Analysis

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The friction and wear properties of polyimide at high temperatures are influenced by important tribochemical reactions on the sliding surfaces. Hydrolysis at 100-140• C causes high friction and low wear whereas imidisation at 180-260 • C causes low friction and high wear. Raman spectroscopy confirms that the imidised structure that forms during sliding is characterised by reorientation of the C-N-C imide bonds from transverse into axial conformation. Also, the C O and C-O-C groups become more flexible and reorient in the worn imide structure. Depending on the normal loads, reorientation is either concentrated on the C O side groups at low loads or on the C-N-C and C-O-C backbone structure at high loads. Black spots on the surface represent a degraded fraction of polyamic acid monomers. Different surface morphologies are observed from atomic force microscopy. Hydrolysed structures correspond to an irregular surface pattern with pits and are preferentially worn parallel to the sliding direction. The imidised surface is smoother due to high strength and has a structure oriented along the sliding direction. However, it is more brittle and hence craters are formed that are larger compared to those formed under low-temperature sliding conditions. Depositions on the sliding surfaces at 220-260• C represent interaction of debris particles on the polyimide surface. On the nanometer scale, a progressive orientation of polyimide clusters parallel to the sliding direction is detected.

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“…The imide I band intensifies as a function of bulk temperatures at 50 N. The C --O group becomes progressively stretched through shear stresses and minor heating of the sliding surface, determining the polymer chain mobility. Fukuhara et al [107] investigated the thermally activated structural changes in poly(ether imide) by internal friction and also concluded that relaxation induced important C --O motions. However, the relative intensity remains constant at 140 to 180 8C sliding temperatures because the previously detailed hydrolysis reactions restrict the molecular mobility in this temperature range.…”

Section: Sintered Polyimidementioning

confidence: 99%

Friction and Wear Mechanisms of Sintered and Thermoplastic Polyimides under Adhesive Sliding

Samyn

Schoukens

Verpoort

et al. 2007

Macro Materials & Eng

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Polyimides function under high‐temperature sliding. The available literature explains transitions in friction and wear mainly by mechanical effects, such as influences of normal load, sliding velocity and humidity on polymer transfer to steel counterfaces. Theoretical models are evaluated for sintered and thermoplastic polyimides. Tribologists have been interested in tribochemical and tribophysical reactions in the sliding interface for about 25 years. Reactions such as hydrolysis, imidisation and/or degradation occur as a function of sliding temperature and are reviewed in this paper. An overview of polyimide synthesis and degradation is presented, while new insights in sliding mechanisms are obtained from a detailed study of Raman spectroscopy on worn polymer surfaces.magnified image

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Temperature dependency of elastic moduli and internal dilational and shear frictions of polyetherimide

Cited by 27 publications

References 32 publications

Temperature- and thickness-dependent elastic moduli of polymer thin films

Temperature- and thickness-dependent elastic moduli of polymer thin films

Tribochemical reactions on polyimide sliding surfaces evaluated with Raman spectroscopy and atomic force microscopy

Friction and Wear Mechanisms of Sintered and Thermoplastic Polyimides under Adhesive Sliding

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