The hardnesses of poly(methylmethacrylate)

Briscoe, B.J.; Evans, P.D.; Biswas, SK; Sinha, Sujeet K.

doi:10.1016/0301-679x(95)00045-6

Cited by 137 publications

(71 citation statements)

References 16 publications

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“…This mechanical property can be calculated via dividing the normal load by the projected area of the surface on which it is imposed. The hardness or the normal hardness (H n ) can be calculated in the nano-indentation test from [45]:…”

Section: B Hardnessmentioning

confidence: 99%

Mechanical Properties of a Dental Nano-Composite in Moist Media Determined by Nano-Scale Measurement

Karimzadeh¹,

Ayatollahi²,

Shirazi³

2014

IJMMM

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Abstract-The aim of this study was to evaluate the influence of thermocycling on the mechanical properties of a commercial dental nanocomposite by using the nano-indentation experiment. The resin-based nanocomposite contained silica and zirconia nanofillers. Some disk specimens, each with the diameter of 10 mm and the thickness of 4 mm were prepared and the specimens were stored at various environmental conditions. Some of the samples were kept in the ambient condition, other samples were stored in distilled water at room temperature and other ones were thermocycled in distilled water for 1000 cycles between 5°C and 55°C. After preparation of samples, the nano-indentation test was applied on the prepared specimens by Triboscope setup. Then the modulus of elasticity and hardness of the test samples were calculated from the Oliver-Pharr's method using the data obtained from nano-indentation test. The present research showed that the samples stored in distilled water without thermocycling exhibited the highest elasticity modulus when compared to the other samples. In addition, the maximum hardness was observed for thermocycled specimens in distilled water.

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Section: B Hardnessmentioning

confidence: 99%

Mechanical Properties of a Dental Nano-Composite in Moist Media Determined by Nano-Scale Measurement

Karimzadeh¹,

Ayatollahi²,

Shirazi³

2014

IJMMM

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“…They are tough and brittle at low temperature and/or high strain rate and rather soft and ductile at higher temperature and/or low strain rate [10,11]. Previous experiemental work carried out by Briscoe [4,5] and later Gauthier [9] has characterized the behaviour of the amorphous glassy polymers during scratch tests. Through the infuence of the scratching velocity, at fixed temperature, they have shown a behaviour both viscoelastic and viscoplastic.…”

Section: Introductionmentioning

confidence: 99%

Mechanical study of polymers in scratch test

et al. 2008

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The numerical study of the scratch test on glassy polymers needs a well adapted mechanical behaviour law both viscoelastic and viscoplastic. To test different models, an algorithm which allows to assembly in series two models has been developped. In our cas, it is used to associate a viscoelastic model with viscoplastic one. The simulations carried out lead to some phenomenological results showing the importance to account for the time dependency of the stiffness modulus.

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“…With blunter cones, i.e. lower β, deformation occurred elastoplasticly resulting in little or no pile-up [112]. In nanoscratch studies on PMMA, Adams et al have demonstrated that the height of the pile-up will increase with tanβ [113].…”

Section: 2mentioning

confidence: 99%

“…Pile-up formation in viscoelastic materials is also dependent on the strain rate. At high strain rates, PMMA displays a noticeable strain softening behavior that becomes more pronounced with increasingly higher strain rates and is absent at reduced strain rates (<~10 -5 s -1 ) [112]. Consequently, the yield stress decreases with increased strain rate, and is accompanied by the appearance of shear bands, which have been attributed to the onset of pile-up [116,117].…”

Section: 2mentioning

confidence: 99%