Yes, they will absorb to their saturation level...but most drink
containers for carbonated drinks are either thicker or (most common)
uses a multilayer construction, sandwiching something like EVOH and a
polyamide. I believe the plastic beer bottles use up to 7 layers
(maybe more now) of PA-EVOH-PA-EVOH-PA, etc...as for an actual vapor
barrier coating, I'm not sure what is used for that, as industrial and
food packaging are not my area of expertise.
Just making the bottles thinner (from what I understand) was
challenging enough. Thin cross sections are prone to pinholes and
uneven strain sections. I would think that the material manufacturers
had to really tweak the resin formulation as well as advancements in
blow molding technology were used to allow the PET bottles to be as
thin as they are now.
PVC is polymerized with water. It doesn't usually absorb, and is used
for waterproofing things, as well as for water and drain pipes. Other
things can cause it to swell, such as pool chemicals (the reason why
chemical balancing of a pool is different based on if it uses a liner
or not) or if it is not UV stable. Higher temperatures can also cause
problems for softer grades. Of course once again, PVC is not my
forte' so to speak, as very little of it is used in medical devices.
Wikipedia has some good info on PVC
Pretty impervious to most things. Even used for underground gasoline
In general polypro and polyethylene have specific gravities of <1
(water is 1),
Styrene will absorb moisture to it's saturation point. It won't "drip
through", but it will absorb too much from ambient air to process
Absorbed moisture needs to be driven out. Most engineering resins
specify a -40°c/f (the scales intersect at this point) in a desiccant
type system at a specific temperature. The air flow needs to go
through the pellets and be fairly well distributed, and the elevated
temp drives the moisture from the resin, and then the desiccant
absorbs it. Compressed air systems are used more frequently today as
well, as the capital investment is much less (no moving parts, no
regeneration or changing of desiccant).
There are some processors that use a hopper heater for surface
moisture on pellets, as well as to generate higher outputs.
I don't think that the absorption rate would apply directly to oil
itself, too many other factors involved. The thing about oil losing
moisture or evaporation is that the oil system in a vehicle is pretty
much a closed system (except for some pollution controls), so I would
have to believe there is a good chance most evaporation would be
they most definitely can mix. there are many examples, but a simple
illustration is water and chloroform. they "don't mix", but actually
they do for binaries in small percentages, and in the presence of a
ternary, in this case acetic acid, they do in large percentages:
there are loads of other examples. motor oil is far from being a simple
Yes and that in and of itself should make anyone suspicious of the
methods used to acquire the data.
There is an obvious bias in the way the measurements were made. The
miles/qt is almost always around 400 miles less for the measurements
labeled 1st than for the measurements labeled 2nd. There is not enough
info to determine exactly what the source of that bias is. All that can
be said is it is extremely unlikely that an honest and accurate
accounting of how much oil this engine consumes would show that the oil
is being consumed at a slower rate the longer it stays in the crankcase.
Except that in the real world it makes no significant difference in
terms of accuracy. It takes hours for oil that is in the bearings, oil
passages to the bearings and head and other crankcase locations to drain
back to the pan. That means that in many engines you get the exact same
reading when you check the oil a couple of minutes after hot engine shut
down as you do when it sat over night.
Anybody with a brain and sufficient curiosity will easily determine on
their own how this works. If you check the oil every 30 seconds after a
hot shut for a period of hour (about 120 dipstick checks) you will be
convinced that the reading is constantly changing.
Well, if it evaporates, I didn't notice it. Of course, it was
synthetic but I went 8k miles over about 5-6 months and added none,
and I could not discern any movement on my dipstick (maybe a mm or
I have not noticed signs of posts not appearing. I still read here
just about daily. Right now I am planning the first timing belt change
on my new-used 2003 Civic LX. I have my homemade tool for the pulley
bolt figured out. It is a little different from what is at Tegger's
site, because it seems there are clearance issues with the newer, say
2001-2005 Hondas for the pulley tools. See
Before you remove the old belt, mark a tooth on the cam cog and
a tooth on the crank cog (permanent marker) and count the teeth
on the belt between the marks. Write the number down and then
count the teeth again! Write the number down, and count the teeth
again for a third time! Mark the belt (yellow crayon?) at the cog
teeth. Remove belt, compare it to the new belt. Count the teeth
out on the new belt (3 times!), and mark with crayon(?). You want
it right! People who build engines double check every thing. People
who build racing engines triple check. If this is your first timing
belt, triple check it or more. You want it 100% right.
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