LDPE low durometer

[mjh368]

Hello All,
I am looking for injection moldable LDPE with the lowest possible durometer. So far i have located a 41D but i would like lower. Let me know what you think or even if you know some big PE suppliers to check out.
Thanks
MJH

 

[mjh368]

Is it possible to further lower the durometer with additives?

 

[Demon3]

As you are aware a Durometer measures surface hardness which is more or less the same as measuring the modulus (

http://www.matweb.com/reference/shore-hardness.asp)

You can go to

http://www.matweb.com

to search for the LDPE with the lowest modulus or possibly surface hardness. Additives can also be used to lower the hardness, for example mineral oil should work well for LDPE. Another way is to blend some miscible, softer polymer with the LDPE, for example Styroflex works.

Why does it need to be LDPE? What about other polymers including EVA (polyethylene-vinylacetate) or Surlyn / Iotek PE based ionomers?

Why do you want a low hardness in the first place?

 

[mjh368]

Thanks for the speedy response, as for your questions.

I manufacture wet processing equipment. The resin will be used in two inch conveyor wheels. The current resins used are santoprene and geolast TPE in durometers ranging from 55A to 45D. I need the resin to have chemical resistance to a broad range of chemicals. Polypro PE and PVC are my most cost effective chemically resistant resins (i use PVDF and other flouro carbons for nasty chemistry). The hardness has to be low for two reasons. 1) transport of thin and delicate circut boards(hard whells scrape the board and cause shorts) 2)operators stick their hands in there. the first is obviously the most important.

I have done LDPE wheel before but they are just a little to hard at around 47-50D. Maybe the additive route would be my best choice
thanks

 

[Demon3]

Hi,

Thanks for the extra info. Well, adding oil will work but I would advise against it as it may leak out slowly and contaminate your circuit boards. In that case adding something soft and polymeric would be preferable. Have you considered ionomer? E.g. Surlyn from DuPont or Iotek from ExxonMobil, it is PE based, available in many types / hardnesses and has great resistance to wear and good against chemicals too.

 

[patprimmer]

Blending EVA with the polyethylene will give the result you want. Some grades of PE already have some vinyl acetate in them to improve environmental stress crack resistance. The E in EVA is ethylene as in polyethylene. The ethylene or polyethylene content of the eva determines it hardness and melting temperatures.

High VA compounds are so soft and have such a low melting temp that they can be formed by rubbing between your hands. Some are also used as hot melt adhesives.

VA and PE can be mixed in any ratio.

Regards

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[mjh368]

My process runs at 130-160F, i need to have melt temps well above that.

 

[Pud]

Hi,

You might have a look at an SEBS (trade name e.g. Evoprene G). The data sheets I have indicate a Shore D 25 grade has service temp of -30 Deg C to +120 Deg C. I guess a Google for SEBS will get a few hits......

Will cost more than LDPE though!


Best Regards


Harry

 

[mjh368]

I am looking to replace sanotprene and geolast (Evoprene).