Effects of humidity on environmental stress cracking behavior in poly(methyl methacrylate)

Ishiyama, Chiemi; Sakuma, Toshio; Shimojo, M.; Higo, Y.

doi:10.1002/polb.10045.abs

Cited by 5 publications

(6 citation statements)

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“…The absorbed moisture undermines bonding durability by accelerating the hydrolytic degradation of the bonding interface [28]. It may also induce structural defects in the resin, which further accelerates moisture sorption and generates internal swelling stress [29]. In this study, the teeth were kept in distilled water for 24 hours after sealant application and were thermocycled in water, which implies that water sorption by the hydrophilic monomers may played a role in the increasing microleakage.…”

Section: ⅳ Discussionmentioning

confidence: 93%

In Vitro Evaluation of Microleakage and Penetration of Hydrophilic Sealants Applied on Dry and Moist Enamel

Ku¹,

Lee²,

Ra³

2017

THE JOURNAL OF THE KOREAN ACADEMY OF PEDTATRIC DENTISTRY

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This study aimed to evaluate the microleakage and penetration of two hydrophilic sealants, Embrace Wetbond™ and Ultraseal XT ® hydro™, when applied on dry and moist enamel, as compared to a conventionally used hydrophobic sealant, Clinpro™. A total of 60 sound human third molars were randomly divided into 5 groups according to the enamel moisture control and the sealant material used. After sealant application, the teeth were thermocycled and immersed in 1% methylene blue dye. Subsequently, the teeth were sectioned twice and the sections were examined using an optical microscope and image analysis software. Application of Embrace Wetbond™ on either dry or moist enamel resulted in more microleakage than Clinpro™. Application of Ultraseal XT ® hydro™ on dry enamel showed a similar level of microleakage to Clinpro™, but application on moist enamel resulted in more microleakage. There were no significant differences between the groups in penetration. In conclusion, application of hydrophilic sealants on moist enamel did not improve the sealing ability and showed lower sealing ability than that of Clinpro™ applied on dry enamel.

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Section: ⅳ Discussionmentioning

confidence: 93%

In Vitro Evaluation of Microleakage and Penetration of Hydrophilic Sealants Applied on Dry and Moist Enamel

Ku¹,

Lee²,

Ra³

2017

THE JOURNAL OF THE KOREAN ACADEMY OF PEDTATRIC DENTISTRY

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“…K IC was observed to vary from 0.7 MPam 0.5 to 0.95 MPam 0.5 with water concentration, where the threshold of 0.8 %wt. water [41] (75% relative humidity in a laboratory environment [41]) distinguished between the fracture propagation modes as well as the corresponding fractography [78]. Following from the toughness, the work of fracture is increased four-fold for wet PMMA [66].…”

Section: Literature Review: Anticipated Lens Durability Issuesmentioning

confidence: 99%

“…The maximum strain to failure was identified for the water concentration of 1.1% wt., above which elongation was reduced by clustering of water within PMMA [72]. To explain, a population of crazes will form ahead of the crack, which advances through advantageous coalescence in relatively dry or mildly water-saturated PMMA, whereas crack advancement occurs at a continuous rate along a single craze in wet PMMA [78]. The displacement rate of 10 -1 Hz was identified as the threshold between elastic and combined viscoelastic response (where craze formation is subject to plasticization) [46].…”

Section: Literature Review: Anticipated Lens Durability Issuesmentioning

confidence: 99%

An end of service life assessment of PMMA lenses from veteran concentrator photovoltaic systems

Miller

Khonkar

Herrero

et al. 2017

Solar Energy Materials and Solar Cells

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The optical performance of poly(methyl methacrylate) lenses from veteran concentrator photovoltaic modules was examined after the end of their service life. Lenses from the Martin-Marietta and Intersol module designs were examined from the “Solar Village” site near Riyadh, Saudi Arabia, as well as the Phoenix Sky Harbor airport, followed by the Arizona Public Service Solar Test and Research (APS-STaR) center in Tempe, Arizona. The various lens specimens were deployed for 20, 27, and 22 years, respectively. Optical characterizations included lens efficiency (Solar Simulator instrument), material transmittance and haze (of coupons cut from veteran lenses, then measured again after their faceted back surface was polished, and then measured again after the incident front surface was polished), and direct transmittance (as a function of detector's acceptance angle, using the Very Low Angular Beam Spread (“VLABS”) instrument). Lens efficiency measurements compared the central region to the entire lens, also using hot and cold mirror measurements to diagnose differences in performance. A series of subsequent characterizations was performed because a decrease in performance of greater than 10% was observed for some of the veteran lenses. The optimal focal distance of the lenses was quantified using the Solar Simulator, and then correlated to lens curvature using a recently developed measurement technique. Surface roughness was examined using atomic force microscopy and scanning electron microscopy. Facet geometry (tip and valley radius) was quantified on cross-sectioned specimens. Molecular weight was compared between the incident and faceted surfaces of the lenses

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“…The variation of the mechanical properties of PMMA due to water sorption has been investigated previously for different loading conditions, temperatures, geometries and compositions. These studies include deformation, fracture strength and crack propagation [1,[3][4][5][6][7][8][9][10]. For each of these studies, the maximum water content level reached at saturation is less than 2 wt % because PMMA and water do not have high chemical compatibility.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the effect of water content on the stress optical coefficient in PMMA

2016

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A series of experiments was completed to study the effect of water content on the stress optical coefficient of PMMA samples under uniaxial tension. The stress optical coefficient is an inherent material property that is utilized in interferometric techniques, classical photoelasticity and the method of caustics to obtain deformation measurements and fracture values. The stress optical coefficient depends on the variation of the mechanical properties and the refractive index of the polymer, both of which are affected by water uptake. The main objective of this study was to quantify the variation of the stress optical coefficient with water uptake, so that it can be utilized in the analysis of visualization techniques and applied to deformation and fracture studies in humid or liquid environments. Experiments were performed at two different strain rates, 5x10-4-5x10-3 s-1 , on both dry and pre-conditioned samples. The preconditioned samples were submerged in distilled water for either 8 or 40 days, allowing samples to reach water contents of 0.8 wt % and 1.4 wt %, respectively. Measurements were completed utilizing a Fizeau interferometer and high-speed photography. Results showed a variation on the stress optical coefficient of up to 11% for a water content of 0.8 wt % and a strain rate of 5x10-4 s-1. This variation was no longer observed when the strain rate was increased by an order of magnitude.

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Effects of humidity on environmental stress cracking behavior in poly(methyl methacrylate)

Cited by 5 publications

References 0 publications

In Vitro Evaluation of Microleakage and Penetration of Hydrophilic Sealants Applied on Dry and Moist Enamel

In Vitro Evaluation of Microleakage and Penetration of Hydrophilic Sealants Applied on Dry and Moist Enamel

An end of service life assessment of PMMA lenses from veteran concentrator photovoltaic systems

Evaluation of the effect of water content on the stress optical coefficient in PMMA

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