raw · notes · ingested 2026-07-02
PCM glazing haze & optical cycle-durability — data survey (research note)
confidence: medium
Source: https://doi.org/10.3390/nano16110648
Purpose: close gap #1 — numeric haze and clarity-vs-N-cycles data. Bottom line: The gap largely persists. PCM windows report transmittance, not haze; explicit ASTM-style haze numbers are almost exclusively from thermochromic/electrochromic (non-PCM) windows. Durability data exists but is shallow (50–1000 cycles, often qualitative).
Best hard numbers found
- n-Octadecane@SiO2 microcapsules (Nanomaterials 2026, 16(11):648) — 155.3 J/g; VLT 83.75% @550 nm; only 0.93% transmittance variation after 100 heat/cool cycles; explicitly engineers RI-matched matrix to suppress phase-transition scattering (the cause of PCM haze). Full haze table not extractable (Cloudflare). https://doi.org/10.3390/nano16110648
- Transparent PCM hydrogel (J. Energy Storage 2025) — <10 J/g energy-density loss and only minor melt-point shift after 500 cycles; 90% VLT / 78% solar, stable in both states.
- Biomass bistatic window (PMC11304258) — rare explicit haze <1%; Tlum 91%→56%; ΔTsol 61%; 1000 cycles “fairly constant” (qualitative). NOTE: electrochromic/bistatic, not PCM — use as a haze benchmark, not a PCM datapoint. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11304258/
- Thermoresponsive hydrogel (PMC12492321) — Tlum 92% (24 °C) → 0.4% (6 °C); ΔTsol ~82%; only 50 cycles tested, “unchanged,” no haze. Thermotropic-hydrogel comparison.
- ACS Omega passive-dimming PCM window (PMC11209917) — 74.5%→0.2% luminous; 161.9 J/g; single stability curve, no haze, no multi-cycle retention.
Durability failure modes
- Salt-hydrate container cracking from freeze-expansion stress (Energies 14(3):721); recommends ≤16 mm PCM layer to limit mushy-state inhomogeneous scattering.
- Fatty-acid oxidative yellowing degradation (PMC7918413 — lead, numbers not extracted this round).
Conclusion
Quantitative ASTM D1003 haze for shape-stabilized PCM films remains genuinely sparse. The two blocked papers worth institutional retrieval for actual haze tables: the MDPI n-octadecane@SiO2 paper, and S037877882500982X (a ~95% haze / 95.8 J/g optical-modulation window).