If someone were to leave their plates in a carrier, in their car year-round... Lets go with midwest climate so extremes on both ends of temperature and precipitation ranges. Any negative effects on steel vs. ceramic (levels III, IIIA, IV, etc.)

Thanks,

MPNelson81

Shouldn't be, unless steel isn't coated it could rust

Hard armor should be OK.  Soft armor will not deal well with the extremes and breakdown.

Plastic items degrade under heat.  They also get brittle under extreme cold.  That is well-known.  How much/what temp depends on the plastic, and other variables.  There are industry specs/standards which are widely known.

If leaving one's plastic items, including both soft and hard armor, in the trunk of one's car during winter and summer, I believe the various temps incurred during the summer will have negative effects on one's body armor.

I am NO expert, but I believe the above is correct.

I'm sure others will chime in

Shouldn't be an issue with steel or ceramic.  The temperatures inside a car aren't high or low enough to change the temper of the steel and ceramics aren't "tempered" in the first place.  

The issue would be if you had ICW plates, the soft armor backers wouldn't like the temperature swings.

Agreed with steel plates.  Not so sure on ceramic plates.  Awaiting definitive posts.

I've always wanted to see what happens to a UHMWPE plate at sub zero temps and at higher temps. I tested a steel plate years ago. Cooled to -60F for 48 hrs.  Shot it with the same threats on the same day for a room temp plate. Both performed the same.

Good info, but one expects steel plates to be fairly invulnerable to ambient temps.  Let's see how plastic plates do at -30 F and +120F temps.  Same for ceramic plates.

Of course, this assumes plastic plates are invulnerable as to water-- and temps.  Hmmmmmmmm.

Also, some plates require backers.  Usually such backers are of the usual aramid fibers, and so are quite susceptible to heat and moisture.

It's my opinion that we all have a lot to learn about hard armor, and soft armor, under different temperatures.

We don't know until we have good info.

I've been told that any temperatures a car can reach inside would not affect UHMWPE, however, Long term cycling may be troublesome if we're talking huge temperature swings, it may be possible for the layers to delaminate.
I would venture to say quite a few NIJ plate offerings these days are standalone. Most of them are going to use UHMWPE as a backer material.  
The subzero temperature for ceramic wouldn't be a bad idea. Any "hot temps" against ceramic should be a non concern since alumina (white ceramic material in armor) is rated over 1700F. It is susceptible to thermal shock, but it recommends thermal rise of like 300F an hr.

I could see if I can get a set of 3 UHMWPE plates. Run 1 at ambient temps for threat profile. M193 x 3 hits, and M80 Ball at 3 hits. Maybe one M855. Cool one plate to -60F for 2 days (Thermotron makes A LOT OF heat), repeat threat profile. And then one at say 180F for 2 days and repeat?

I'm not trying to say anything other than reasonable questions/misgivings about plastics being subjected to fairly intense heat, over a period of time.  My original point concerning high temps was concerning typical soft armor.

Certainly NO expert, but exposure to very high temps degrades plastics.  Less well known s the effect of extreme cold on plastics.

Just raising questions.  Not being an expert, I have no verifiable answers.  If you, or anyone else can point in the right direction, I'd be obliged.

I certainly have just as many questions too. I asked a manufacturer for some reports on plastics in cold. Waiting to receive them, but they said plastic performance in cold is even better than ambient.

:D

Been a while since I’ve had any materials science classes but with how ceramic is made, and one original use was as a heat resistant material, I can’t see the relatively low temperatures encountered in a vehicle being an issue. Agree it would be best to have something definitive from a manufacturer.

Keep in mind many ceramic plates also have layers made from a sheet of UHMWPE, plus the adhesives used to affix the nylon wrap.  Heating/cooling cycles may lead to some form of de-lamination of these various layers and materials due to differential thermal expansion properties and so on.

True. Varying "attachment" methods are used to hold the materials together. The covering itself isn't much of a concern IMO, because a non ballistic part of the plate.

My gut says that big temp swings and moisture would eventually expedite delamination but I have no data on it.

Even though it’s pretty minor in comparison you could also have mold and mildew issues if left alone too long.

I'm certainly no expert on the matter.  Having said that, it's important to distinguish between soft armor and hard armor.

They might have different characteristics.   Might be very similar.  Dunno.

All I know (or at least believe to be true) is that soft armor degrades severely if the encapsulating waterproof nylon is worn/penetrated enough to allow the inner fabric to become wet.  I also believe that, like any plastic, the inner material can be degraded with enough exposure to high heat.  How much exposure, and for how long, I have no idea.

In the same light, ceramic armor is subject to being struck, and possibly cracked.  GIs are instructed on ow to examine their plates for problems.  They are also issued "practice plates" for training, so as to avoid damage to expensive "ballistic" plates.  Aside from inadvertent impact damage, I'm not aware of other problems,  although if the outside of the plate can allow water to enter the inside of the plate, then things might change; Again, just guessing.  I very much doubt if the effectiveness/lifespan of even ceramic plates is enhanced by prolonged exposure to high temps.  Of course, I admit my ignorance, and am looking for guidance.

From my personal state of ignorance, it seems prudent to store one's soft and hard armor in fairly cool temps, and in a very dry environment.

I have mentioned this elsewhere, but cops storing temperature-sensitive gear in the trunks of their cars should insist that the trunk lids be painted white, in order to reduce temps within the trunk.  Got laughed-at by some cops, them saying their dept had higher budgetary priorities.  OK, got that. but insisting on NEW cars having their trunk lids be white is not too much to ask, I think.  Hey, what do I know?

YMMV, and seeking guidance.

Ceramic plates aren’t just ceramic and when the different layers delaminate the plate is taken out of service even if the ceramic is totally intact. I wish the testing was mote public because it would be great to see how effective it is in different states of decay.

I don't think we disagree much. Concur that it would be ideal if there was trusted info available.