Effect of calcite and calcite/zeolite hybrid fillers on LLDPE and PP composites

The comparative tensile and impact properties and fracture morphologies between calcite and calcite/zeolite (hybrid) filled linear low‐density polyethylene (LLDPE) and polypropylene (PP) composites have been studied. The incorporation of fillers into LLDPE, whether calcite or calcite/zeolite hybrid fillers, does not alter the Tm of LLDPE, but slightly reduces the Tm of PP. The melting peak area representing the heat of fusion of the crystal decreases with fillers; the effect of the calcite and the hybrid filler would be the same. The impact strength, Young's modulus, and yield stress of the calcite and the hybrid filled LLDPE increased, indicating a reinforcing effect of the fillers. In addition, the filled LLDPE decreases in elongation at break (EB) and ultimate tensile strength. However, the hybrid LLDPE composite exhibits slightly higher Young's modulus and ultimate tensile strength than the calcite one, while the same values of impact strength and yield stress were observed. In the PP system, the Young's modulus is enhanced, whereas the rest of the mechanical properties were reduced. From SEM photomicrographs of the hybrid filled composites, the tensile fractured surface of LLDPE dumbbell bar exhibits tearing surfaces while the composite shows formation of air holes and cracks in the LLDPE and PP system, respectively. Because of improved Young's modulus, yield strength, impact strength, and morphological observation along with substantial extension, the filled LLDPE composite with calcite/zeolite hybrid fillers is worth using for micro‐porous film applications. © 2004 Wiley Periodicals, Inc. Adv Polym Techn 23: 230–238, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20013