Synthesis and Characterisation of Waterborne Polyurethane

Beh, Lee Yek (2020) Synthesis and Characterisation of Waterborne Polyurethane. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

This research study aims to prepare waterborne polyurethanes (WPUs) with different solvent systems such as n-methyl pyrrolidone (NMP) and di(propylene glycol) dimethyl ether (DPGDME) and solid content ranging from 25 solid % to 60 solid % for determination of the effect of different solid content and solvent system on the property of synthesized WPUs. Pre-polymer polyurethane (PU) was first synthesized based on the acetone method with step-growth addition polymerization and followed by dispersion process using distilled water as a dispersing agent to produce WPU. The amount of acetone and distilled water used was adjusted for different solid content of WPUs. The structure, particle size and viscosity of synthesized WPUs were analyzed by Fourier transform infrared spectroscopy (FTIR), nanoparticle analyser and rheometer respectively. Furthermore, the synthesized WPUs were dried at 80 °C for overnight to form WPU films for determination of thermal properties through thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) while the surface morphology is characterized using mini scanning electron microscopy (Mini-SEM). The acquired results indicated that the solvent system plays a less significant role in affecting the properties of synthesized WPUs. This means the more toxicity solvent such as NMP can be replaced with low harmful DPGDME solvent without significantly changing the final properties of the WPU. A practically similar in thermal properties and surface morphology were observed for the synthesized WPUs with different solid content. However, WPUs with a lower solid content exhibited a lower viscosity and smaller particle size due to better dispersibility as compared to higher solid content WPUs.