Emulsifier

Apr 05, 2007 3 Replies
I

i'm working with fatty acid (palm oil based) based emulsifiers for ABS polymerization. i observed that above at 80-100 deg C..the fatty acids oxidizes..changes color from colorless intor slightly yellow liquid and pungent odor is released. besides that, the emulsifier color also changes into slightly yellowish.



why does the fatty acid oxidises ? is it because of the presence of oleic acid? the ABS color polymerized with the oxidized fatty acid is affected too. The yellowness index of the ABS increases too. why is that so ?



can low molecular weight fatty acids effect the impact strength of ABS ? i observed that the low MW fatty acids exhibit low conversion%. can this be the cause of the low impact strength of ABS ?



thank you..i hope someone out there can provide me with some information.



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M

Of course they will oxidize and yellow. The composition of many of these fatty acids are mixtures of multiple components with unsaturation Oleic and Linoleic are among the many but even stearic acid will oxidize without the proper stabilization and turn yellow. Yes impact proporties over time will be affect due to the oxidization of the fatty acid attacking the butadiene phase of the ABS which will ultimately under insitu degradation which is oxygen diffusion dependent in amorphous polymers. You need to balance the system out with effective primary and secondary antioxdiants and maybe a long term thioether.

JRW

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E

Impact strength can be reduced by several things:

  1. Lower MW matrix phase

  1. Problems with elastomer particle size -- compare electron micrographs of good and "bad" products.

  2. Reduced compatiblizer layer (reduced grafting) during polymerization -- "old fashioned" extraction with various solvents can be very helpful; search literature for ABS grafting.

  1. Stress risers -- chunks of incompatible PAN?

Ernie

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U

Hi

What u use to neutralize fatty acid & Mw. range of those fatty acids

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