-Thanks, that was an interesting read. Although if I am not mistaken it pertains only to non-painted ABS. how much of our toys are made of ABS, vs PVC or other plastic compounds?
-Good point about heat cycles vs. dissimilar materials. In the case of my garage: it has cars in it. I know this is a weird concept but our house is an exception in our neighborhood.
Here's what I found out about...
Plastics
-Good article on degredation, highlighting the wide variety of interactions: https://en.wikipedia.org/wiki/Polymer_degradation
From it this section on Stabilizers for polymers: Hindered amine light stabilizers (HALS) stabilize against weathering by scavenging free radicals that are produced by photo-oxidation of the polymer matrix. UV-absorbers stabilizes against weathering by absorbing ultraviolet light and converting it into heat. Antioxidants stabilize the polymer by terminating the chain reaction due to the absorption of UV light from sunlight. The chain reaction initiated by photo-oxidation leads to cessation of crosslinking of the polymers and degradation the property of polymers.
Which lists nothing to stabilize polymers from ambient post-production heat. I conclude that ambient heat must be far less important (within industrial use anyway) than UV-caused degredation or oxidation.
-From this wiste (http://www.azom.com/article.aspx?ArticleID=1655): " For example, 40% of museums surveyed contain plastics objects manufactured and collected since 1980, and modem plastics are also showing symptoms of decay." Definitely heat is not a factor in a/c museums, so I would surmise the primary cause there is oxidation.
-Model forums seem to dismiss ambient heat as a problem for styrene plastics.
-From a Lego forum: A quick wikipedia search gives the operating temperature of ABS plastic as between −25 and 60 °C (-13 and 140 °F).
For whatever use it adds to the conversation, here's what a quick search on vinyl told me:
"Store in-use LPs at a temperature of 65 to 70 °F (18 to 21 °C). Those in long-term storage should be kept at 45 to 50 °F (7 to 10 °C). Though relative humidity (RH) is considered less an issue for vinyl than other recorded media, it is recommended that LPs be stored at 45 to 50% RH"
Silicone rubber
-WikiP: "Silicone rubber is generally non-reactive, stable, and resistant to extreme environments and temperatures from -55 °C to +300 °C while still maintaining its useful properties."
-From website: http://www.lifewithoutplastic.com/store/is_silicone_a_plastic#.Vw_diVLheIc
"They can leach certain synthetic chemicals at low levels, and the leaching is increased with fatty substances, such as oils."
Rubber
-From this article (http://www.newworldencyclopedia.org/entry/Rubber#Reason_for_vulcanizing) it seems that oxidation is the prime factor in rubber degredation.
Decals
-No scientific details yet. Concensus is to store between 60-80F with stable humidity 40-50%. Essentially the same directions as for vinyl LPs.
Stickers
-No scientific details yet. Concensus is to store between 60-80F with stable humidity 40-50%. Essentially the same directions as for vinyl LPs.
I'll post more if I find out more.