Failure Mode of Plastic

The type of plastic often used to wrap cheese intrigues me - it is a devil to start a tear but once a tear is started ot goes all over the place with no effort.

What is going on with the material properties?

Reply to
DerbyBorn
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The same with the stuff that radishes are wrapped in. Almost impossible to start an opening, but once you have, it's no use as a wrapper any more.

It's all the responsibility of The Organisation, aka a TV series of many years ago, in which Donald Sinden was the head of a company whose sole purpose was to make life difficult for people. Examples were: Food Wrappers, as here, that drove people to distraction and even murder; and a little old lady in a blue Mini driving continuously around a roundabout with the left flashers on.

Reply to
Davey

It's from the same lab as the bags used to contain frozen fruit!

Reply to
Tim Watts

The first attempt at confounding the public was to vacuum pack sliced meats with a transparent piece over the top so you cannot tell how much water was added to make the weight up, they used to leave a corner free to pull it off with, but that was far too easy so now they glue it down firmly all the way around the edges, and then when you pierce it, usually with a tip of a fork, there is not enough to cover the meat up again so you need a bag or clingfilm to do that. It seems to me that most food packaging is specially designed to be convenient for the makers but inconvenient for the customer. The tearing issue is because once the surface is broken it unzips so to speak, but when complete and stretched it is very strong. Brian

Reply to
Brian Gaff

See my post about The Organisation programme with Donald Sinden!

Reply to
Davey

The Natural Philosopher wrote in news:nevks3$f8g$1 @news.albasani.net:

Thanks - that is the sort of info I wanted.

Reply to
DerbyBorn

You might Google for crack propagation in brittle and ductile materials if you want more info. Wiki has a general entry on fracture mechanics. Heavy stuff, though!

Reply to
Chris Hogg

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