Hi FLO

[Plasticmeister]

Can SUPER - Hi Flo Base materials be mixed with Glass? LEXANS?

[Louis]

Are you asking about super high flow Lexan or super high flow materials in general?

[Plasticmeister]

Can i get a Hi Flow lexan base material to fill easier or will the glass just seperate? The GF PC we have is low melt flow index @ 6.5, kinda like an extruder grade. Flows like crap., and sticks to every core etc.....Its the material from hell. I need something that flows super well and doesnt stick.Whats the highest flow i can get in GF. Any input would help.

[Louis]

If I read you8 right, “Whats the highest flow i can get in GF” you are looking for the highest melt flow glass filled Polycarbonate, specifically Lexan. I would say that the manufacturer would be your best source for that information, or the custom compounder.

Sorry I can't be of more assistance, but I did want to clarify the request.

[rickbatey]

You can't increase the mold and melt temp enough to get the resin to flow better and open your process window? Mixing two resins, at least in my opinion, won't get you where you want to be. The glass is chemically coupled in the first resin, so all you will really do is lower the glass content, not significantly improve the melt index. Perhaps you need to ask the resin supplier for a better melt index, but I'm sure you will lose impact strength, which is why that resin was spec'ed in the first place. The resin grade may be over kill for the application, so perhaps you should open a dialogue with the customer.... Rick.

[Len]

Without knowing other critical performance properties it’s difficult to speculate on the effect of raising resin melt (higher MI). The usual result of raising MI in a GF filled PC is lower impact.

It might be possible to balance potential impact loss due to changing to a higher melt resin w/ slightly more GF or other formulation changes. Again, if the target properties are well defined, your compounder may be able to formulate a "way out" of the small processing window; smaller fiber length, alternative coupling agent, internal lubricants, PET or PBT alloying, etc.

I would not rule out a change in filler. As suggested earlier, the present grade may be over kill. A properly coupled (surface treated) mineral filled PC may do the job; meeting impact requirements and other key properties, while offering a wider processing window. Your compounder should be able to help you make a better resin selection suitable to address both desired end properties and ease of processing.

BTW - I think diluting your present resin w/ a higher flow PC will usher in other problems associated w/ poor dispersion and poor distribution of fibers, probable loss of impact is only one of the potential problems.

Len

[Plasticmeister]

Impact strength is not an issue. Easy fast flowing G/F P/C material is the target. Setting the supplier aside. Whats your suggestion on a material that fills fast with lowest viscosities. also Because of all variety of cores i need minimal shrinkage on ejection.

[Will Call]

It's been a while for me but if memory serves me correctly, if you process a higher melt or lower viscosity material doesn't it shrink more? The higher the melt=more shrinkage? Will this be a problem with all the cores you're talking about?

[Plasticmeister]

EXACTLY! THANKS

[rickbatey]

Shrinkage should be limited by the amount of glass. Are you sure that shrinkage is the cause for the core issues? I have seen issues with resin processed too cold and with too low a mold temp, and often times that relates to poorly packed parts (excessive shrinkage) and very high injection pressures. Is the sticking localized to a certain part or parts of the mold? Are there any cores that are breaking? Just trying to find more answers, to provide a better solution. Rick.