Negative air ion releasing properties of tourmaline/bamboo charcoal compounds containing ethylene propylene diene terpolymer/polypropylene composites

The average concentrations of negative air ions ( C ion− ) emitted from tourmaline (T), bamboo charcoal (B) particles, and tourmaline/bamboo charcoal (T/B) compounds containing polypropylene (PP) and ethylene propylene diene terpolymer/polypropylene (EPDM/PP) composite specimens under varying testing conditions were investigated in this study. The C ion− values emitted from T or B filled PP and EPDM/PP composite specimens reached a maximum value as their T or B contents approached the 5 and 3 wt % optimum values, respectively. In contrast, the C ion− values of T/B compounds filled PP and EPDM/PP composite specimens were significantly higher than their theoretical C ion− values estimated using the “simple mixing rule,” and reached a maximum value as the weight ratio of T to B reaches an optimum value. At this optimum T/B weight ratio, the C ion− values of T/B compounds filled PP and EPDM/PP composite specimens reached another maximum as their total compound loadings reached the optimum loading of 6 and 4 wt %, respectively. The C ion− values of the PP/T/B and EPDM/PP/T/B specimens increased significantly as they were tested under dynamic mode or by increasing the testing temperatures. The T and/or T/B powders filled PP and EPDM/PP specimens exhibited significantly higher tensile strength (σ f ) and elongation at break (ε f ) values than did the B filled PP and EPDM/PP specimens with the same filler loadings, respectively. Energy dispersive X‐rays, particle size, and SEM morphology analysis of the filler particles present in the T, B, and T/B filled composite specimens were performed to understand these interesting negative air ion and tensile properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009