Toughening of polypropylene-ethylene copolymer with nanosized CaCO3 and styrene-butadiene-styrene

Nanocomposites of nanosized CaCO3/polypropylene-ethylene copolymer (PPE) and nanosized CaCO3/PPE/styrene-butadiene-styrene (SBS) were prepared by using a two-roll mill and a single-screw extruder. By adding CaCO3 nanoparticles into the PPE matrix, the toughness of the matrix substantially improved. At a nanosized CaCO3 content of 12 phr (parts per hundred PPE resin by weight), the impact strength of CaCO3/PPE at room temperature reached 61.6 kJ/m(2), which is 3.02 times that of unfilled PPE matrix. In the nanosized CaCO3/PPE/SBS system, the rubbery phase and filler phase are independently dispersed in the PPE matrix. As a result of the addition of nanosized CaCO3, the viscosity of PPE matrix significantly increased. The increased shear force during compounding continuously breaks down SBS particles, resulting in the reduction of the SBS particle size and improving the dispersion of SBS in the polymer matrix. Thus the toughening effect of SBS on matrix was improved. Simultaneously, the existence of SBS provides the matrix with a good intrinsic toughness, satisfying the condition that nanosized inorganic particles of CaCO3 efficiently toughen the polymer matrix. The synergistic toughening function of nanosized CaCO3 and SBS on PPE matrix was exhibited. (C) 2004 Wiley Periodicals, Inc.