Title: Examining Isocyanate Reactivity and Ambinet Processability on Polyurethane Formation

Authors: Aynslie J. Fritz, Jeffrey S. Wiggins

DOI: 10.33599/nasampe/s.22.0712

Abstract: Isocyanate molecular structure not only drives polyurethane architecture, but also influences synthetic reactivity. Many engineering applications value high monomeric reactivity for reduced processing times, while also emphasizing low processing temperatures for manufacturing ease and safety. However, isocyanate reactivity and processability are often inversely related. The research presented herein evaluates the influence of isocyanate identity on reactivity and polymer network formation, while maintaining ambient processability. Specifically, polyurethanes are synthesized and characterized with the following isocyanates for comparison: 4,4’-methylenebis[cyclohexyl isocyanate] (HMDI), 4,4’-methylenebis[phenyl isocyanate] (MDI), 50 mol% HMDI/50 mol% MDI blend, and Desmodur VL R20 (pMDI). The chosen isocyanates display reactivity and initial physical state differences. HMDI pairs low reactivity with low viscosity (liquid) at 25 °C, MDI is highly reactive but a crystalline solid at 25 °C, blends of HMDI and MDI fall within the middle, and Desmodur VL R20 is a common, commercially available polymeric MDI advertised with high reactivity, while being liquid at 25 °C. While there are many routes to enhancing monomer reactivity and/or processability for PU synthesis, this study compares isocyanate reactivity and their subsequent, synthesized PU properties by examining differences in reaction rate, degree of conversion, and thermal transitions.

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Conference: SAMPE 2022

Publication Date: 2022/05/23

SKU: TP22-0000000712

Pages: 10

Price: $20.00