OT: What kind of plastic is this?...

P

Pimpom

Guest
Occasionally I come across a plastic bag that looks like the
once-ubiquitous polythene bags but is much softer to the touch.
It crackles less when crumpled. It looks identical to polythene
at a casual glance but not quite so once one is aware of its
existence. What can it be - polyurethane? Some biodegradable
material?
 
Pimpom <nobody@nowhere.com> wrote:

Occasionally I come across a plastic bag that looks like the
once-ubiquitous polythene bags but is much softer to the touch.
It crackles less when crumpled. It looks identical to polythene
at a casual glance but not quite so once one is aware of its
existence. What can it be - polyurethane? Some biodegradable
material?
Click to expand...

My help to see a picture. Plastic comes in many different forms. Great
stuff. The perhaps sarcastic quip in The Graduate (1967)... \"PLASTICS\"
was rather prophetic.
 
On 31/07/2020 08:02, Pimpom wrote:
Occasionally I come across a plastic bag that looks like the
once-ubiquitous polythene bags but is much softer to the touch. It
Click to expand...

Not enough information here. Do you have an IR spectrum of it?

crackles less when crumpled. It looks identical to polythene at a casual
glance but not quite so once one is aware of its existence. What can it
be - polyurethane? Some biodegradable material?
Click to expand...

It could just be polythene with an unholy amount of plasticiser in it.

The modern starch substitutes for plastic bags are starting to make an
appearance on periodical magazines now but few are clear. The clear
grade is OK for envelope windows but is somewhat more brittle.


--
Regards,
Martin Brown
 
Often there is a code on the plastic for correct recycling

https://www.google.com/amp/s/blog.ansi.org/2016/09/iso-11469-2016-marking-plastics-products/amp/
 
On 7/31/2020 12:39 PM, John Doe wrote:
Pimpom <nobody@nowhere.com> wrote:

Occasionally I come across a plastic bag that looks like the
once-ubiquitous polythene bags but is much softer to the touch.
It crackles less when crumpled. It looks identical to polythene
at a casual glance but not quite so once one is aware of its
existence. What can it be - polyurethane? Some biodegradable
material?

My help to see a picture. Plastic comes in many different forms. Great
stuff. The perhaps sarcastic quip in The Graduate (1967)... \"PLASTICS\"
was rather prophetic.
Click to expand...
I thought of posting a picture but saw little point as it
probably looks identical to polythene in a photo. I\'ll post one
anyway when I\'ve had time to take it.
 
On 7/31/2020 12:52 PM, Martin Brown wrote:
On 31/07/2020 08:02, Pimpom wrote:
Occasionally I come across a plastic bag that looks like the
once-ubiquitous polythene bags but is much softer to the touch. It

Not enough information here. Do you have an IR spectrum of it?

No.
Click to expand...

crackles less when crumpled. It looks identical to polythene at a casual
glance but not quite so once one is aware of its existence. What can it
be - polyurethane? Some biodegradable material?

It could just be polythene with an unholy amount of plasticiser in it.

The modern starch substitutes for plastic bags are starting to make an
appearance on periodical magazines now but few are clear. The clear
grade is OK for envelope windows but is somewhat more brittle.
Click to expand...
It\'s very soft, not at all brittle, and crumples and folds very
easily.
 
On 7/31/2020 1:11 PM, klaus.kragelund@gmail.com wrote:
Often there is a code on the plastic for correct recycling

https://www.google.com/amp/s/blog.ansi.org/2016/09/iso-11469-2016-marking-plastics-products/amp/
Click to expand...
No code. It\'s a simple clear general purpose bag.
 
Pimpom wrote:
On 7/31/2020 1:11 PM, klaus.kragelund@gmail.com wrote:
Often there is a code on the plastic for correct recycling

https://www.google.com/amp/s/blog.ansi.org/2016/09/iso-11469-2016-marking-plastics-products/amp/


No code. It\'s a simple clear general purpose bag.
Click to expand...

Carefully burn a small piece. If it smells similar to candle wax its
polypropylene.

https://www.boedeker.com/Technical-Resources/Technical-Library/Plastic-Identification
 
Bert Hickman wrote:
Pimpom wrote:
On 7/31/2020 1:11 PM, klaus.kragelund@gmail.com wrote:
Often there is a code on the plastic for correct recycling

https://www.google.com/amp/s/blog.ansi.org/2016/09/iso-11469-2016-marking-plastics-products/amp/


No code. It\'s a simple clear general purpose bag.

Carefully burn a small piece. If it smells similar to candle wax its
polypropylene.

https://www.boedeker.com/Technical-Resources/Technical-Library/Plastic-Identification
Click to expand...

Oops - should be polyethylene...

sorry
 
On 2020-07-31 03:59, Pimpom wrote:
On 7/31/2020 12:39 PM, John Doe wrote:
Pimpom <nobody@nowhere.com> wrote:

Occasionally I come across a plastic bag that looks like the
once-ubiquitous polythene bags but is much softer to the touch.
It crackles less when crumpled. It looks identical to polythene
at a casual glance but not quite so once one is aware of its
existence. What can it be - polyurethane? Some biodegradable
material?

My help to see a picture. Plastic comes in many different forms. Great
stuff. The perhaps sarcastic quip in The Graduate (1967)... \"PLASTICS\"
was rather prophetic.

I thought of posting a picture but saw little point as it probably looks
identical to polythene in a photo. I\'ll post one anyway when I\'ve had
time to take it.
Click to expand...

Might be Saran (PVDC)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
On Fri, 31 Jul 2020 12:32:19 +0530, Pimpom <nobody@nowhere.com> wrote:

Occasionally I come across a plastic bag that looks like the
once-ubiquitous polythene bags but is much softer to the touch.
It crackles less when crumpled. It looks identical to polythene
at a casual glance but not quite so once one is aware of its
existence. What can it be - polyurethane? Some biodegradable
material?
Click to expand...

My guess(tm) is that the PE (polyethylene or polythene) has been doped
with something to make it more biodegradable:
<http://www.biosphereplastic.com/biodegradable-plastic-additive/>
<http://www.biosphereplastic.com/information-and-help/biodegradable-plastic-additive-faqs/>
The additive creates voids or caves in the PE which make it look like
a sponge under a sufficiently powerful microscope. The microbes that
can eat plastic live in the caves, thus accelerating decomposition.
The addition of these caves slightly weakens the plastic, which is
usually made slightly thicker to compensate. The plastic also tears
more easily and has a rather \"soft\" feel instead of the usual PE
smooth slick finish. Such bags often have some kind of identifying
mark or advertisement indicating that it\'s more biodegradable, which
makes me wonder if this is a correct guess(tm).
<https://sustainability.stackexchange.com/questions/2507/how-can-i-tell-biodegradable-plastic-bags-apart-from-non-biodegradable>
Since the doping level is only about 1% of the plastic volume,
detecting the density difference between regular PE bags and doped PE
bags might prove tricky. Throw the bag into a working compost heap.
If it falls apart and disappears in a few years, it\'s biodegradable
PE.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
 
On Fri. 31 Jul.-20 10:11 a.m., Bert Hickman wrote:
Pimpom wrote:
On 7/31/2020 1:11 PM, klaus.kragelund@gmail.com wrote:
Often there is a code on the plastic for correct recycling

https://www.google.com/amp/s/blog.ansi.org/2016/09/iso-11469-2016-marking-plastics-products/amp/


No code. It\'s a simple clear general purpose bag.

Carefully burn a small piece. If it smells similar to candle wax its
polypropylene.

https://www.boedeker.com/Technical-Resources/Technical-Library/Plastic-Identification
Click to expand...
Careful on the smell test. Plastic outgassing tends to be carcinogenic
like the vaporized PVC on overheated wires during 3 Mile island long ago.

Why so much interest in this? We also see the crinkly grey bags used
here for groceries but I prefer the brown soft as silicone plastic bags
that are silent when crunched up for doggy poop bags.
 
On 31/07/2020 09:03, Pimpom wrote:
On 7/31/2020 12:52 PM, Martin Brown wrote:
On 31/07/2020 08:02, Pimpom wrote:
Occasionally I come across a plastic bag that looks like the
once-ubiquitous polythene bags but is much softer to the touch. It

crackles less when crumpled. It looks identical to polythene at a casual
glance but not quite so once one is aware of its existence. What can it
be - polyurethane? Some biodegradable material?

It could just be polythene with an unholy amount of plasticiser in it.

The modern starch substitutes for plastic bags are starting to make an
appearance on periodical magazines now but few are clear. The clear
grade is OK for envelope windows but is somewhat more brittle.


It\'s very soft, not at all brittle, and crumples and folds very easily.
Click to expand...

Try putting a piece in a small jar with some biological detergent. If it
is a biopol or modified starch that will dissolve it in just a few days.
True olefin polymers will just sit there untouched.

Almost all magazines in the UK that arrive by post use the biodegradable
starch based polymer for their outer mailing envelope now. It is thin
and soft and waterproof for a couple of days in transit at most.

--
Regards,
Martin Brown
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top