Determination of the Rheological Properties of Polypropylene Filled with Colemanite

Colemanite (Ca₂B₆O₁₁.H₂O) in powder form was filled to polypropylene (PP) at concentrations of 5, 7.5, 11.25, 16.875, and 25.312 wt%, and filled PP granules were obtained. To prevent oxidation, an antioxidant (Songnox 1010) was added to the colemanite-filled polypropylene mixture at a ratio of 0.2 wt%. The rheological properties of the resulting composite material were determined using a Melt Flow Index testing device, at four separate pressure settings (298.2, 524, 689.5, and 987.4 kPa) and four separate temperature settings (190°C, 200°C, 210°C, and 220°C). The viscosity, shear rate, shear stress, and power law index (n) values of the colemanite-filled PP were measured as part of the testing conducted. The study determined that viscosity values increased by approximately 60% in response to increasing colemanite content in the resulting filled material, while shear rate values decreased by 62%. The viscosity values were found to decrease with increasing temperature and pressure values, while shear rate values were found to increase. Additionally, Power Law Index value was found to vary between 0.561 and 0.687, with an average value of 0.608 based on the colemanite content used. Copyright © 2017 John Wiley & Sons, Ltd.