Looking at the chemistry, waxes and polyethylene are reasonably closely related, the one being a shorter-chain version of the other.

So adding wax to HDPE sort-of-converts it to LDPE. Is this acceptable?

thank you,

I know there is in mexico something called :cera polyethilenica" polyethylenic waxI . I will find out if it can be used for that purpose.

Thanks

I think you are trying to use an extrusion grade HD for injection. There are lots of aftermarket products out there that could help you change the melt index of a particular plastic.

hi Nelson,

could you give me some leads on what kind of product would improve the melt index?

issatalamas@hotmail.com

I always thought the wax was added to stop it sticking to the mould itself, not for flow purposes.

I think you are referring to silicone.

Issa,
Who is your supplier for feedstock? I worked for years in the Phillips Chemical Complex in Pasadena, Texas, near Houston, Texas. They make polyethylene, polypropylene, and a high quality medical resin called K-resin. They are one of the major producers of this plastic. They can tailor the resins to meet any flow characteristic you require. I suggest you need to advise your supplier of you problem and have them obtain the proper resin(s) for you. You might want to do a google search, key words, 'HDPE' suppliers, and 'HDPE manufacturers' or what ever else you might want to look up in thsi regard.

thank you chtank.

My feedstock supply comes from poor people in the Haitian slumps that recollect recyclable solid residues in Haiti. So the price is so low that it compensate for the other inconveniences."specially on the todays oil commodity".

But perhaps you can confirm my theory that the smaller the reground particles the more one can achieve a homogeneous melt flow allowing a greater range of melt flow materials to be co-polymerized, this affecting less the structural integrity of the product. As you know smaller molecules of high melt materials melts first and slips in between the gaps leaved by the low melt big molecules, still unmelted , to fill unevenly the molds.So instead of regrinding and pelletized the materials ,I am thinking of pulverizing them so that heat, mostly by friction between the screw and the barrel can faster reach the low melt molecules.(assuming that the bigger the size of the reground the more time it takes the heat to reach the core of the pellet.)

Thanks anyhow, I sincerely appreciate

issa

You are correct in assuming that the mix should be as small as practicable and as uniform as practicable. However, I suggest you not attempt to mix polypropylene with polyethylene. The two should have a distinct marking on the base before you grind. Also, when attempting to recycle as you are, it is a good idea to blend in some fresh resin at about 50/50 mix, depending on what the final product will be. If it is a food or drink storage product, take into consideration the safety of using recycled plastic. There can be some sever health concerns. The main concern health-wise is the chemical leaching out into the stored produce and poisoning the consumer. For making park benches and the like, recycled plastic is fine. The resin producers would be a good source of information for this, try to talk to Phillips Chemical.

Would a product, applied to the mold surfaces, reduce the friction enough to allow the HDPE to flow adequately?

If you google injection moulding flow characteristics, you are likely to find manufacturers that will do special additives so it is constantly coating the mould rather than the old fashioned way of wiping silicon on them.

I found a few that seem to suggest there are many advanced technologies now to manipulate the flow, slip and release.

Hi theoilguys55

That is possible , but do you know which other product(s) aside of silicone that can perform? And how to use the silicone? on the mold or on the material itself. And that's a very important point...obtain an efficient mean to obtain high flow and easy release. A compounded material appears attractive .The wall thickness could then be proportionally be reduced.

issa

Hi Issa, I think that what you are trying achieve can be boosted by calcium carbonate which is a widely available product in our Haiti Cherie. check with our current Pvc industrialists or their technicians.

Nice idea. Pressuming that discoloration and finishing is not an issue.

I am a rep for Schaeffer Oil. I have sold our #0190 Penetro as a mold release. It did not affect the quality adversely.

Is food grade necessary? If so, Schaeffer's product #0190E Penetro might be tried to see if improvement occurs.

dear sir....

i got 1 material that can improve ur MFI for HDPE..this one used for plastic lumber epsecially for HDPE base... >> licomont et 141... its act as lubricant in your process... i hope this material can solve ur problem

Hi zunaida,

where are you based (country)

thanks for your commentrs. But could you be more explicit? Is it solid ? liquid, paste? Do you compound it? is it one or 2 products? who sells it or them? who do I contact the manufacturer?

Please let me know

issa

HI...DAVID

im from malaysia.... its solid in flakes condition yellow coloured...actually my fren use this material in plastic lumber..coz its difficult to process the HDPE with wood flour..coz the MFI for HDPE too low...so she decide to use this lubricant to make process become easier... my freind compound it using internal mixer...okie...i will ask her where she got it... n i will inform you later k....

Fluorinated additives are used commonly during fiber spinning and film extrusion.

Diego

Hi Diego,

whats a fluorinated additive? a commercial name? and website? if not google?

thanks

Issa