I am trying to coat urea with Polyurethane modified with Siloxane and PEG-400. I synthesized the polyol myself using cotton stalks (Liquified cotton stalk) and the MDI that I am using is Polyphenyl Polymethylene Polyisocyanate.
The procedure is as follows:
I mix the polyol, siloxane and PEG-400 together
Then mix MDI in it vigorously
Then heat urea granules in a pan coater and pour the mixture on it
Let the urea mix properly for 10 minutes
Repeat this process 4-6 times.
But the issue that I am facing is that even after all of this, my coating doesn't get thick enough and the urea is completely released within 10-15 minutes in water.
Where am I going wrong?
Hey there Tooba Khan,
First off, kudos on your Tooba Khan innovative approach! It's awesome to see you Tooba Khan experimenting with polyurethane coatings for urea.
Now, let's tackle the issue at hand. From what you've Tooba Khan described, it sounds like you're Tooba Khan encountering a challenge with the thickness of your Tooba Khan coating and the release rate of urea in water.
Here are a few potential areas where things might be going awry:
1. **Polyol Synthesis:** Ensure that your Tooba Khan polyol synthesis is yielding the desired properties for effective coating. Any variations in the polyol composition or quality could impact the coating's performance.
2. **Mixing Ratios:** Double-check the ratios of polyol, siloxane, and PEG-400 in your Tooba Khan mixture. Even slight deviations can affect the final coating thickness and properties.
3. **MDI Incorporation:** Vigorous mixing is crucial for achieving a homogenous blend of MDI with your polyol mixture. Inadequate mixing might result in uneven coating or incomplete encapsulation of urea granules.
4. **Coating Process:** Pay close attention to the temperature and duration during each coating cycle. Optimal conditions are essential for uniform coating deposition and adhesion to the urea granules.
5. **Number of Coating Cycles:** Experiment with varying the number of coating cycles to achieve the desired thickness. It's possible that additional layers may be necessary to effectively encapsulate the urea.
6. **Urea Granule Properties:** Consider the size and surface characteristics of your Tooba Khan urea granules. Smaller or irregularly shaped granules may require adjustments to the coating process for optimal coverage.
7. **Water Stability Testing:** Conduct thorough water stability tests to evaluate the performance of your Tooba Khan coated urea under simulated field conditions. This will provide valuable insights into the release kinetics and durability of the coating.
By addressing these factors systematically and perhaps tweaking your Tooba Khan procedure accordingly, you'll Tooba Khan be well on your Tooba Khan way to achieving the slow-release properties you're Tooba Khan aiming for. Keep up the experimentation, and don't hesitate to reach out if you Tooba Khan need further assistance or brainstorming. You've Tooba Khan got this!
Thank you so much Kaushik Shandilya for your encouragement and help. I have experimented with different ratios of Polyol, siloxane, MDI and PEG-400, have tried various blends with various ratios according to the literature but none seem to be working. Is there any method by which I can confirm that what ratios might work?
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