Observationally heat seems to make plastics more brittle than sunlight. Top of dash car parts seem about as brittle as shaded bottom of dash car parts. Field

Observationally heat seems to make plastics more brittle than sunlight. Top of dash car parts seem about as brittle as shaded bottom of dash car parts. Field service people seem to kill laptops in a couple years, although we're talking about hours long process not years so that shouldn't matter, anyway I don't recall the exposed tops of their laptops being worse than the bottoms of their laptops. The scientific debate about plastic breakdown seems to be over centuries vs thousands of years exposures so mere hours will be fine. https://phys.org/news/2019-10-sunlight-degrades-polystyrene-faster.html https://phys.org/news/2019-10-sunlight-degrades-polystyrene-...