Mechanical improvement of polyurethane dispersion by castor oil

Nowadays, the utilization of renewable materials in synthesis of waterborne, polyurethane dispersions (PUDs) has significantly received attention. Biodegradable polyurethane dispersions (PUDs) based on the different proportion of castor oil and polyethylene glycol (PEG) were synthesized via methyl ethyl ketone (MEK) process. Isophorone diisocyanate (IPDI) and dimethylol propanoic acid (DMPA) were used as hard segments. The appearance evaluation has shown that obtained PUD become more yellowish by rising in castor oil content. Furthermore, mechanical tests like gloss, hardness, drying time, MEK resistance, and water resistance have been conducted as shown in Table 1. It was proved that the increase in the castor oil/ PEG ratio has risen the gloss and hardness. Drying time has reached from 8625 to 67 minutes as the amount of castor oil increased. Besides, PEG is a biodegradable material thanks to its hydrophilicity. Though, PEG raise the hydrophilicity of the PUD, castor oil increases the water resistance of resin. The suitable proportion of castor oil/ PEG can keep the balance between biodegradability and water resistance. Also, as the ratio of castor oil/ PEG goes up, the MEK and water resistance of PUD increase. The appropriate proportion of castor oil/ PEG in this matter is belongs to sample with Castor oil/ PEG=4/1 (C:P-4/1). The thermal analysis illustrated that castor oil raises the flexibility of PUD, which results in a lower glass transition temperature (Tg) as shown in Fig. 1. The biorenewable PUD of C:P-4:1 exhibited mechanical behavior and can serve as excellent model systems for more detailed explorations and macromolecular structure for other PUDs It is expected this study opens a new horizon to produce PUDs with higher quality and properties.