Moazie

Okay, Thank you, I will look into this matter

Well, CaCO3 is used as filler for the polyacrylate sealant. So, my goal is to determine the filler amount in this polyacrylate sample. The polyacrylate decomposition temperature is around 400°C. In my opinion, every mass loss before 400°C is caused by plasticizer and water, the mass loss at 400°C is caused by polyacrylate and every mass loss above 400°C is caused by CaCO3/Ca(OH)2. I've used the TGA to analyze an acrylate/water (50/50) dispersion and a pure CaCO3-sample. Here you can see how polyacrylate decomposes, and how CaO is formed out of CaCO3. But clearly, when combined in the polyacrylate mixture, CaCO3 doesn't decompose in the same way it does in pure form.

I'm trying to determine the CaCO3 amount in a polyacrylate sealant by using Thermogravimetric Analysis (TGA). Before I started testing the polyacrylate sample, I first did an analysis of pure CaCO3. The result proved my thoughts: one single mass drop due to CaCO3 degradation where CO2 leaves and CaO remains. But now, when I test the polyacrylate sample: the TGA-curve shows me 2 mass drops. I already figured that due to the inert atmosphere used for the TGA (N2 gas) and the polyacrylate is an aqueous system, I'm dealing with the following reaction: CaCO3 + H2O -> Ca(OH)2 + CO2 : Because of the N2-atmosphere I think that the equilibrium is pushed to the right side. When you look at the TGA-curve, the last 2 mass drops are caused by CaCO3/Ca(OH)2. I would think the first mass drop is caused by Ca(OH)2-degradation into CaO and H2O, where H2O instantly evaporates. Unfortunately the amount of water evaporating (about 15% of total mass) is too large , so there must be a mistake in my way of thinking. For the second mass drop, I think it's caused by excess CaCO3-degradation to CaO and CO2. Can somebody help me out? Many Thanks!