scholarly journals Blocking and Deblocking of Diisocyanate to Synthesize Polyurethanes

Polymers ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2875
Author(s):  
Sourita Jana ◽  
Debasis Samanta ◽  
Mirmuhammad Fahad ◽  
Sellamuthu N. Jaisankar ◽  
Hongdoo Kim
Keyword(s):  
Differential Scanning Calorimetry ◽  
Contact Angle ◽  
Thermogravimetric Analysis ◽  
Toluene Diisocyanate ◽  
Resonance Spectroscopy ◽  
Spectroscopic Techniques ◽  
Scanning Calorimetry ◽  
Molecular Weights ◽  
Contact Angle Analysis

Diisocyanates, particularly toluene diisocyanate (TDI), are useful for the preparation of various polyurethanes with specific applications as leather-like materials, adhesives and insoles, etc. Blocking agents can be used for the operational simplicity and to reduce the hazards of TDI. In this paper, we reported the use of 3-(4-bromo-phenyl)-1H-pyrazole to block toluene diisocyanate (TDI). FTIR, NMR, thermogravimetric analysis, contact angle analysis and differential scanning calorimetry (DSC) were used for the characterization. The effectiveness of the blocking was confirmed by spectroscopic techniques. The DSC thermogram showed that blocked adducts deblock at 240 °C, causing the regeneration of TDI, and causing the diisocyanates to react with polyols of different molecular weights, forming polyurethanes. The characterization of the polyurethanes was performed by infrared spectroscopy, nuclear magnetic resonance spectroscopy, thermogravimetric analysis, differential scanning calorimetry and a contact angle study.

scholarly journals Blocking and Deblocking of Diisocyanate to Synthesize Polyurethanes

2021 ◽  
Author(s):  
Sourita Jana ◽  
Debasis Samanta ◽  
Mir Muhammad Fahad ◽  
Sellamuthu N Jaisankar ◽  
Hongdoo Kim
Keyword(s):  
Differential Scanning Calorimetry ◽  
Contact Angle ◽  
Thermogravimetric Analysis ◽  
Toluene Diisocyanate ◽  
Resonance Spectroscopy ◽  
Spectroscopic Techniques ◽  
Scanning Calorimetry ◽  
Molecular Weights ◽  
Blocking Agents

Diisocyanates, particularly toluene diisocyanate (TDI) are useful for the preparation of various polyurethanes with specific applications as leather-like materials, adhesives, insoles etc. Blocking agents can be used for the operational simplicity and reducing the hazards of TDI. In this paper we reported the use of 3-(4-bromo-phenyl)-1H-pyrazole to block toluene diisocyanate (TDI). FTIR, NMR, thermogravimetric analysis, contact angle and differential scanning calorimetry (DSC) and were used for characterization. Effectiveness of blocking was confirmed by spectroscopic techniques. DSC thermogram shows that blocked adducts deblock at 240 °C causing the regeneration of TDI and blocking agents to react with polyols of different molecular weights forming polyurethanes. The characterization of polyurethanes has been done by Infrared spectroscopy, Nuclear magnetic resonance spectroscopy, thermogravimetric analysis, differential scanning calorimetry and contact angle study.

scholarly journals Synthesis and Characterization of Lateral Fluoro-substituents Liquid Crystals

2021 ◽  
Vol 11 (5) ◽  
pp. 12495-12505
Keyword(s):  
Molecular Structure ◽  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
Linkage Group ◽  
Optical Microscope ◽  
Synthesis And Characterization ◽  
Spectroscopic Techniques ◽  
Dielectric Measurements ◽  
Scanning Calorimetry

Lateral difluoro substituent liquid crystal based on a three-aromatic core has been synthesized. It has been designed to correlate the molecular structure and mesomorphism with reference to the difluoro substituent and -COO- linkage group. This compound was characterized by elementary analyses and spectroscopic techniques such as FTIR and 1H-NMR. The synthesis compound's mesomorphic behavior was studied by polarizing optical microscope, differential scanning calorimetry, and dielectric measurements. The recent investigation reveals only SmB phase.

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