Performance improvement of photocurable methacrylate resins with fillers for custom-fit earphones
Why this work is in the frame
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Bibliographic record
Abstract
Custom-fit earphones are an emerging class of wearable technology composed of a malleable prepolymer resin.The earphones are molded during a 60 second curing process to the exact shape of one's ear, delivering a snug fit.The resin is composed of a mixture of methacrylates, cured into a photocurable thermoset, similar to dental composites.Enclosed in the earphones are blue LEDs (=470 nm) which initiates curing.Two key issues were identified.Photopolymerization is highly exothermic, making the process unsafe for users.The cured resin also exhibits volumetric shrinkage resulting in poor resin-sleeve adhesion.This study aims at developing the ideal prepolymer mixture: one that has a low temperature increase (exotherm) and minimal shrinkage while maintaining high mechanical strength and degree of cure (conversion).Exotherms were determined by a customized apparatus used to cure the resin while recording temperature.With the help of a 3D printer, parts were constructed and used as the sample holder that had the same volume as an ear sleeve.The rest of the apparatus consisted of blue LED arrays, LCD display, thermocouple, a microcontroller, and MATLAB interface.Volumetric shrinkage was determined using density measurement via Archimedes method and pycnometry.Material strength was determined using tensile tests.Degree of cure was determined via vinyl conversion using FT-IR spectroscopy.The monomers diurethane dimethacrylate (UDMA), urethane acrylate methacrylate (UAM), bisphenol A glycidyl methacrylate (BisGMA) and bisphenol A dimethacrylate (BisDMA) were used as the main monomer in conjunction with crosslinkers 1,6-hexanediol dimethacrylate (HDDMA), trimethylolpropane triacrylate (TMPTA) and trimethylolpropane trimethacrylate (TMPTMA).Results showed high exotherm for crosslinkers (>27.3C).Replacing small molecule crosslinkers with oligomeric crosslinkers such as poly(ethylene glycol) diacrylate (PEGDA) and poly(ethylene glycol) diacrylate (PEGDMA) showed less pronounced exotherms.BisGMA:PEGDA in a 1:2 ratio resulted in an exotherm of 19.3C and was used as the baseline for filler introduction.Inorganic fillers including fumed silica (FS), silica gel (SG), and commercial ground silica MIN-U-SIL US 5 (m) and 15 (m) silica were pre-treated and mixed with the baseline resin at several loadings.FS/resin blends showed a decreased exotherm (13.6C at 25% wt.) while SG/resins blends showed an increased exotherm (30.0C at 25 wt.%).All filled samples had lower volumetric shrinkage compared to the baseline (5.1%).Degree of cure increased with filler loading for FS (40% at 25 wt.%) and SG (40% at 25 wt.%)) and remained neutral for the rest compared to the baseline (28%).FS and SG filled resins had tensile
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it