Chance of CD melting in hot climates?

In the oven, with the cookies.

Natalie

Sticks and stones can break my bones but whips and chains excite me.

What part wasn't quoted? Mike's own statement you cut and pasted in your first reply?mark_

Next you'll be telling us the pavement was so hot you could fry a CD on it, which would be closer to reality than your dream.

mark_

The part he didn't quote from my post he responded to was:

You can see it if you go back to my post.

I think they're made of a completely different type of plastic. Not 100% sure though.

those are much cheesier

We spend a lot of time at the river in Parker Arizona. In the summer it is not safe to leave a CD anywhere in a car with the windows up there. Anything like that has almost no chance. Well maybe in a nice hard back case under the seat and some luck.

Keep in mind 120F degree days are not unusual there.

Deviant

Natalie

"mark_digital©" ..

What dream? The thing melted.

Natalie

Maybe you can convince Mark D that they really do melt there.

Natalie

You are still confused. The speed of the outer tracks is LOWER when being read because the RPM of the disk is slowed down (200 RPM?). The inner tracks are read at a higher speed (600 RPM?). Effectively, because of the speed change, the size and frequency of the pits representing the data stays constant throughout the disc. The speed change occurs gradually as the disc is being read.

---MIKE---

This was copied from google-

The disc is rotated by a drive system that regulates the speed of rotation so that data is read at the same speed regardless of the laser detector's position. This means that rotation speed decreases as the laser detector slowly traverses from the center to the periphery of the disc in order to maintain a constant rate of data acquisition

---MIKE---

I did a little research and here's what I found:

"Polycarbonate has outstanding dimensional stability up to 130oC. For glass fibre reinforced grades this value is raised to 140oC. Above these temperatures polycarbonate begins to soften. From about 220oC melting commences, reaching a state of flow at 240-260oC, which permits processing by injection moulding or extrusion." Ok, 130 C is 266F. I think I could see a direct surface inside a glassed-in area like a car getting up to that temperature when exposed to direct sunlight. It's a bit of a stretch, though. Even if it's 130 degrees outside, that's still 136 degrees over ambient air temperature, but I will not rule it out because I have never been in Arizona in the summer so I don't have enough experience to really know.

Now, the report says that outstanding dimensional stability up to 130oC, so that means that at 266 degrees it has not started to soften yet. Above that temperature it starts to soften.

How hot do flat surfaces exposed to the sun get in Arizona? Has anyone gathered data on this? 266 degrees is more than hot enough to boil water, you'd think there would be nothing to setting up a solar-powered steam-driven electricity generator.

When you guys say that the CDs melted, do you mean they got soft and warped or wilted out of shape, or that they turned to liquid? I can buy them getting soft enough to bend or warp but actually melting completely into free-flowing liquid would take a lot more heat than I'd believe could be generated by the sun (without help like lenses or mirrors.)

---MIKE---

I see! In your post, "you're confused" means "you misunderstood what I was trying to say." After I re-read and eventually deciphered your original post, I realize that we are both saying basically the same things.

Mine only warped, but it may has well have turned to liquid, since it was unplayable

:-)

Natalie

Maybe those are much cheesier

not safe to leave a CD anywhere

Well maybe in a nice hard back case under the seat

fibre reinforced grades this value is raised to 140oC.

melting commences, reaching a state of flow at

area like a car getting up to that temperature when

in Arizona in the summer so I don't have enough

that means that at 266 degrees it has not started to

gathered data on this? 266 degrees is more than hot

solar-powered steam-driven electricity generator.

wilted out of shape, or that they turned to liquid?

completely into free-flowing liquid would take a lot more

or mirrors.)

I don't actually remember the CD so maybe not. I don't even have a car CD player. I did melt my damm portable radio it was in but so many things meet that fate.

I can hardly believe that I still remember this from so long ago. So don't hold me to it.

Solar energy from the sun into a black surface, right angle's, at the equator. Energy 330 Btu per hour. per sq. ft. Temperature direct 250f degree Temperature trapped behind glass 620f degree

Dan

I should have said warped or some word other than melt as well.

Well, that certainly didn't take long. I was about ready to ask if you like soft butter in your popcorn or would you really like it thoroughly melted.

mark_