Rheological behaviour of unvulcanised natural rubber compounded with cryogenically pulverised polyurethane foam particles

Cryogenically flexible polyurethane (PU) foam particles at various concentr ations were introduced as a new filler into the natural rubber compounds an d the rheological properties were studied using a Davenport Capillary Rheom eter. The effect of mastication time and die temperature on rheological pro perties and extrudate swell behaviour of the rubber compounds was also inve stigated. It was found that rheological properties and extrudate swell rati o changed considerably with addition of PU filler, mastication time and die temperature. With respect to rheological behaviour, it is recommended that 20-30 pph PU filler is the optimum concentration to be introduced into nat ural rubber compounds under the mastication time of 15 minutes for a given die temperature.