Curing Kinetics of Methylene Diphenyl Diisocyanate-Based Polyurethane Elastomers

Area of Science:

• Polymer Science
• Materials Chemistry
• Chemical Engineering

Background:

• Polyurethane elastomers are versatile materials used in various industrial applications.
• Understanding curing kinetics is crucial for optimizing material properties and processing.
• MDI-based polyurethanes are a significant class of elastomers requiring detailed kinetic analysis.

Purpose of the Study:

• To elucidate the curing kinetics of MDI-based polyurethane elastomers under non-isothermal conditions.
• To determine the kinetic parameters and reaction mechanism governing the curing process.
• To establish optimal curing conditions for enhanced material performance.

Main Methods:

• Non-isothermal differential scanning calorimetry (DSC) was employed to monitor the curing reaction.
• Kissinger, Flynn−Wall−Ozawa, and Friedman methods were utilized for kinetic parameter determination.
• Model-free fitting and autocatalytic models were applied to analyze the reaction mechanism.

Main Results:

• The curing reaction proceeds in two distinct stages, with a change in reaction order observed at α > 0.45.
• A piecewise curing mechanism function was deduced, indicating an autocatalytic model is applicable.
• Kinetic parameters were calculated, providing insights into the reaction's energy landscape.

Conclusions:

• The study successfully characterized the curing kinetics of MDI-based polyurethane elastomers.
• Optimal curing conditions were identified as 81 °C for 29 min constant temperature curing, followed by 203 °C post-curing.
• The established kinetic model accurately describes the curing process, enabling precise control over elastomer properties.