A reactive blending method for preparation of polyvinyl chloride/thermosetting polyurethane blends

An attempt was made to prepare polyvinyl chloride (PVC)/thermosetting polyurethane (PU) blends via direct formation of the thermosetting minor phase from its reactants during blending into PVC. Chemorheological approaches were employed in order to investigate the formation reaction of PU. The results of chemorheological analyses were utilized to adjust appropriate reactive blending temperature. PVC/PU reactive blending process was carried out in a laboratory internal mixer. PVC and PU reactive mixture were fed into the internal mixer using two different feed orders. In the first method, porous particles of PVC and liquid mixture of PU monomers were premixed in a high-speed mixer at ambient temperature. The blending was then followed by processing the prepared paste in the preheated internal mixer. In the second method, PVC was loaded into the internal mixer. Afterward, PU reactive compound was introduced into the PVC after torque equilibrium. For both feed orders, the PU content of blends and rotor speed were among parameters studied. The mechanical properties of PVC/PU blends prepared by reactive blending and pure PVC showed that incorporation of PU elastomer into PVC through the proposed reactive blending technique resulted in an increase in the elongation at break and toughness of the brittle PVC.