Impact‐toughening mechanisms of calcium carbonate‐reinforced polypropylene nanocomposite

Abstract

ABSTRACT:The impact fracture mechanisms of polypropylene (PP), containing 9.2 vol % of calcium carbonate (CaCO 3 ) nanoparticles, were investigated using optical microscopy and transmission electron microscopy. The incorporation of CaCO 3 nanoparticles reduces the size of spherulites and induces the formation of ␤-phase crystallites, which leads to a more ductile PP matrix. Double-notch four-point bending (DN-4PB) Charpy impact specimens and notched Izod impact specimens were utilized to study the fracture mechanism(s) responsible for the observed toughening effect. A detailed investigation reveals that the CaCO 3 nanoparticles act as stress concentrators to initiate massive crazes, followed by shear banding in PP matrix. These toughening mechanisms are responsible for the observed, improved impact strength. A comparison of the fracture mechanisms observed between DN-4PB Charpy and Izod impact tests is also made to show the effectiveness of DN-4PB for investigation of impact fracture mechanisms of polymeric systems.

Effects of SEBS-g-MAH on the properties of injection moulded poly(lactic acid)/nano-calcium carbonate composites

“…This is in line with the micro-mechanistic model for toughening using filler particles as proposed by Kim and Michler [20]. According to Weon et al [26], toughenability of PP has been positively altered by the incorporation of calcium carbonate, which is also related to the massive crazing and shear banding of the PP matrix in the presence of the filler. From Table 4, it can be seen that the modulus and strength of PLA/NPCC composites reduced marginally with the increasing content of SEBS-g-MAH.…”

Optimization of mechanical properties of PP/Nanoclay/CaCO3 ternary nanocomposite using response surface methodology

“…5,6 Calcium carbonate (CaCO 3 ) is also usual filler developing the mechanical properties of polymers, especially the toughness due to the distinct growth in the interfacial area between the filler and the matrix. [7][8][9] When CaCO 3 nanoparticles are added to the polymer matrix, agglomeration of nanoparticles occurs owing to high surface energy. Therefore, treatment of CaCO 3 nanoparticles is performed applying stearic acid or titane coupling agent to increase the interface adhesion between nanoparticles and matrix resulting to good dispersion of CaCO 3 nanoparticles in polymer matrix.…”

Fracture resistance improvement of polypropylene by joint action of core–shell particles and nucleating agent

“…Especially, Karger-Kocsis proposed that the enhanced toughness of ␤-phase could be attributed to a stress-induced transformation from less dense (␤-phase) to denser (␣-phase) crystalline structure at the root of a growing crack [18,19]. Thus, the nucleation effect of CaCO 3 in promoting the formation of ␤-phase is also thought to be one of the toughening mechanisms of PP toughened by CaCO 3 [4,[20][21][22][23].…”

“…Especially, the application of rigid particles is greatly dependent upon the nature of polymer. For PP, only calcium carbonate (CaCO 3 ) has been reported to be efficient in toughening PP [1][2][3][4][5][6][7]. The combination of elastomer and rigid particles to achieve so-called core-shell particles has been proved to be another way to toughen PP [8][9][10][11][12], and the ternary composites usually exhibit balanced performance.…”