Identifying a Resin, Can you identify two different brands of the same resin?

[ryandias]

I have an older part and a newer part built from the same mold. Resin batches were obviously not the same. New parts all crack easily.

My first question is; was the correct resin used? Can PBTGF30 be compared and identified from Sabic, 3M, BASIF, Dupont?
Would the FTIR test be a good choice? Sabic Valox 470 PBTGF30 was the resin on the drawing, but I am not clear how to verify if this was the one used.

How would you compare the parts for mold parameters? IE would the hardness test reveal this? Other suggestions?

My problem here;
The parts were last molded in 2007. Today it is my problem to figure out why they are different. The supplier is not the same for both parts, but the mold is the same (on a different machine, with a new guy driving it). Latest supplier doesn't have records of the mold parameters apparently.

 

[CoryPad]

A battery of tests can be run to learn more about the material and processing:

FTIR, DSC, TGA, hardness, tensile testing, DMA, TMA, MFR, and molecular weight distribution by chromatography

 

[Pud]

I would put money on material not dried sufficiently. "Damp" PBT moulds lovely - parts are like dog biscuits long before excess moisture level shows on parts. Material should only be in hopper for a couple of hours unless using hopper dryer.

Vacuum or dessicant dryer needed. Hot air dryer useless.

H

www.tynevalleyplastics.co.uk

It's ok to soar like an eagle, but weasels don't get sucked into jet engines.

 

[ryandias]

Hi Pud,

Thanks for your input. I am not really clear on the dampness/water affects on the resin.

Is this affect only while the resin is peletized? Or does it affect the molded part as well? If only the pellets, what mechanism restricts the affect after molding?

 

[Pud]

See section 2: Crastin
With particular attention to para. 2.2.

H

www.tynevalleyplastics.co.uk

It's ok to soar like an eagle, but weasels don't get sucked into jet engines.