Posted by Terry Davey on November 20, 2000 at 09:41:34:
Your experience of hardening and post cure are similar to HotVac's, it is dramatic. I am glad to have you confirm our results.
Also, your observation that removal of phthalic acid is made easier by its being in solution with other residues is in line with our findings.
I am puzzled though, as phthalic acid is clear and odourless. Could the smell you are describing be from the breakdown product Phthalic anhydride? This certainly exists in laminates as it may be dicovered condensed on the interior of our equipment pipes.
About your claim to be the only method that removes acid from deep within the laminate.
The vapour point of phthalic acid or anhydride is around 210 celcius. How does your flame and abrupt cooling cause this to melt deep within the laminate and travel rapidly through a semi-porous composite? Your flame only dwells for very short time, believed to be seconds.
Our HotVac machine holds the pressure/temperature criteria accurately and for as long as is necessary and yet safely within the temperature tolerance of polyester.
In these conditions the laminate is heat 'soaked' and very permeable while the temperature is maintained.
During this period, the evaporation of esters of phthalic acid, various glycols and moisture is very effective.
Keep up the good work.
Best regards, Terry Davey. HotVac Hull Cure Ltd.
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