Gamma irradiation effects on UV-cured polymers based on acrylate oligomers studied by positron annihilation lifetime spectroscopy

Hyla, M.; Filipecki, J.; Świątek, J.; Mervinskii, R. I.

doi:10.1016/j.jnoncrysol.2005.03.031

Cited by 7 publications

(6 citation statements)

References 9 publications

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“…Undoubtedly, the channel of Ps-trapping determined by fractional free-volume F v plays a decisive role in this kinetics in view of narrow scattering of experimental variances err = 0.04⋅10 −3 (Table 1 ). These changes occur under light exposure mainly due to polymer chain cross-linking in DRC, causing appearance of ever smaller voids owing to fragmentation of Ps-trapping sites [ 32 – 35 ]. Noteworthy, the sizes of Ps-trapping free-volume holes R 3 (~0.24–0.27 nm) defined by longest-lived lifetime τ 3 due to Eq.…”

Section: Resultsmentioning

confidence: 99%

Light-Curing Volumetric Shrinkage in Dimethacrylate-Based Dental Composites by Nanoindentation and PAL Study

et al. 2017

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Light-curing volumetric shrinkage in dimethacrylate-based dental resin composites Dipol® is examined through comprehensive kinetics research employing nanoindentation measurements and nanoscale atomic-deficient study with lifetime spectroscopy of annihilating positrons. Photopolymerization kinetics determined through nanoindentation testing is shown to be described via single-exponential relaxation function with character time constants reaching respectively 15.0 and 18.7 s for nanohardness and elastic modulus. Atomic-deficient characteristics of composites are extracted from positron lifetime spectra parameterized employing unconstrained x3-term fitting. The tested photopolymerization kinetics can be adequately reflected in time-dependent changes observed in average positron lifetime (with 17.9 s time constant) and fractional free volume of positronium traps (with 18.6 s time constant). This correlation proves that fragmentation of free-volume positronium-trapping sites accompanied by partial positronium-to-positron traps conversion determines the light-curing volumetric shrinkage in the studied composites.

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Section: Resultsmentioning

confidence: 99%

Light-Curing Volumetric Shrinkage in Dimethacrylate-Based Dental Composites by Nanoindentation and PAL Study

et al. 2017

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“…Changes in Ps-trapping modes can be ascribed preferentially to cross-linking of structural chains dominated in pure polymer matrix, like it occurs in other polymers under UV light exposure [18], vulcanization (thermal curing) [19], or γ-irradiation [20]. In fact, this photoinduced process causes smaller voids in DRC owing to overall free-volume fragmentation in both o-Ps and positron trapping sites.…”

Section: Resultsmentioning

confidence: 99%

Free Volume Structure of Acrylic-Type Dental Nanocomposites Tested with Annihilating Positrons

2016

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Positron annihilation spectroscopy in lifetime measuring mode exploring conventional fast-fast coincidence ORTEC system is employed to characterize free volume structure of commercially available acrylic-type dental restorative composite Charisma® (Heraeus Kulzer GmbH, Germany). The measured lifetime spectra for uncured and light-cured composites are reconstructed from unconstrained x3-term fitting and semi-empirical model exploring x3-x2-coupling decomposition algorithm. The governing channel of positron annihilation in the composites studied is ascribed to mixed positron-Ps trapping, where Ps decaying in the third component is caused entirely by input from free-volume holes in polymer matrix, while the second component is defined by free positron trapping in interfacial free-volume holes between filler nanoparticles and surrounded polymer matrix. Microstructure scenario of the photopolymerization shrinkage includes cross-linking of structural chains in polymer matrix followed by conversion of bound positron-electron (positronium) traps in positron-trapping interfacial free-volume voids in a vicinity of agglomerated filler nanoparticles.

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“…Fast neutron fluency and displacement per atom (dpa) have been used as exposure parameters for predicting material property changes. Recently, the influences of gamma rays on material degradation have also been studied [20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Displacement per atom calculation in YBCO superconductors through Monte Carlo simulation

Piñera

Cruz

Leyva

et al. 2007

Nuclear Instruments and Methods in Physics Research Section B:

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Gamma irradiation effects on UV-cured polymers based on acrylate oligomers studied by positron annihilation lifetime spectroscopy

Cited by 7 publications

References 9 publications

Light-Curing Volumetric Shrinkage in Dimethacrylate-Based Dental Composites by Nanoindentation and PAL Study

Light-Curing Volumetric Shrinkage in Dimethacrylate-Based Dental Composites by Nanoindentation and PAL Study

Free Volume Structure of Acrylic-Type Dental Nanocomposites Tested with Annihilating Positrons

Displacement per atom calculation in YBCO superconductors through Monte Carlo simulation

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