Good morning everyone.
I am making PU from my synthesized polyols which has low Mw(
Dear Dieu Minh Ngo, similar discussions are available on RG. Generally speaking, reactants MW, stochiometry, hard/soft segments, mixing intensity and time are the most influencing factors. Please check the following links. My Regards
https://www.researchgate.net/post/What_are_the_factors_of_synthesis_that_affect_properties_of_thermoplastic_polyurethane_TPU
https://link.springer.com/article/10.1007/s10973-016-5928-2
Abdelkader BOUAZIZ thank you very much for your answer. I will check and follow the instruction.
Hello Dieu Minh Ngo. I am also trying to get Polyurethane from Vegetable oil and IPDI. I have exactly the opposite problem that you have. I am trying to make a hard and brittle PU. The fundamental difference in our processes is I am not using a chain extender and a solvent while synthesizing the PU. I think you have to reduce the molecular weight of your hard segment. I attach my PU texture that you can see which is very sticky.
Here is my sticky PU process :(
After synthesizing the partial glycerides from sunflower oil, I add IPDI with the presence of a stannous octoate catalyst at 50 Celcius degrees. The reaction carried 40 mins at 50 Celcius and then heated to 95 Celcius and continued until the isocyanate will disappear in FTIR (it takes approximately 2 hours) I use equivalent moles of NCO for OH groups (NCO:OH ratio is 1:1 in the polyurethane.) After the reaction was completed, I put the polyurethane into a petri dish and hold 24 hours in a oven at 50-60 degrees. Even if I put 48 h into the oven, it is still sticky :(
And btw you said that "I used ratio of Polyols:NCO:BD=2:3:1" are they molar ratios? Can you give further details about the process?
Thank you,
Sedef
Hello Sedef Cansız
I also tried one-pot process like you are doing now and my samples were still hard and brittle. With one-pot process, I mixed polyol and IPDO together with DBTDL catalyst at low temp (because my reaction was really fast even at RT), then casted it in the mold at 60 degree for 3 days.
Now I am trying with prepolymer process hoping to get a flexible PU. "I used ratio of Polyols:NCO:BD=2:3:1" means molar ratio of OH-polyol:NCO-IPDI:OH-BD. I am sorry for this confusion.
I think the main difference in our experiment is the polyols. In my case, I am using low Mw polyester polyol.
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