Polyurethane dispersion/carboxylated nitrile butadiene rubber blends produced by a greener dual crosslinking approach

A latex blend comprising polyurethane dispersion (PUD) and carboxylated nitrile butadiene rubber (XNBR) in an 80:20 ratio was prepared in the presence of epoxide and organo-modified siloxane crosslinkers. The aim of the study was to enhance the tensile, thermal, and chemical properties of the PUD/XNBR latex blend without the incorporation of sulphur and accelerator. Studies revealed that the combined action of epoxide and organo-modified siloxane crosslinker demonstrated adequate intermolecular hydrogen bonding, thereby resulting in superior tensile strength. Differential scanning calorimetry (DSC) analysis showed alterations in chain orientation and melting enthalpy due to the introduction of two crosslinkers that impart ordered hydrogen bonding to a certain degree. The compactness of the structure of the cure molecule may be closely related to the heating enthalpy, as in the following sequence, PUD80/XNBR20/E1 will have a loosely packed structure, followed by PUD80/XNBR20/E0.5S0.5 and PUD80/XNBR20/S1. Chemical swelling studies revealed the impact of crosslinker combinations on hydrogen bonding (both ordered and disordered), affirming the consequential enhancement in chemical resistance. This study confirms that the attained intermolecular hydrogen bonding results in desirable mechanical and chemical resistance performance, making the latex blend suitable for glove applications.