Phenolic rigid organic filler/isotactic polypropylene composites. II. Tensile properties

Abstract

A novel phenolic rigid organic filler (KT) was used to modify isotactic polypropylene (iPP). The influence of KT particles on the tensile properties of PP/KT microcomposites was studied by uniaxial tensile test and the morphological structures of the stretched specimens were observed by scanning electron microscopy (SEM) and polarized optical microscopy (POM). We found that the Young's modulus of PP/KT specimens increased with filler content, while the yield and break of the specimens are related to the filler particles size. The yield stress, the breaking stress and the ultimate elongation of PP/KT specimens were close to those of unfilled iPP specimens when the maximal filler particles size is less than a critical value, which is 7 mm at a crosshead speed of 10 mm/min and 3 mm at 200 mm/min, close to that of glass bead but far more than those of other rigid inorganic filler particles. The interfacial interaction was further estimated from yield stress, indicating that KT particles have a moderate interfacial interaction with iPP matrix. Thus, the incorporation of small KT particles can reinforce iPP matrix and simultaneously cause few detrimental effects on the other excellent tensile properties of iPP matrix, due to their organic nature, higher specific area, solid true-spherical shape and the homogenous dispersion of the ROF particles in microcomposites.

Phenolic rigid organic filler/isotactic polypropylene composites. III. Impact resistance property

“…Being similar with the analysis in tensile test [23], the matrix near impact surface can be extensively divided into many relatively independent ligaments, which resulted from the debonding of filler particles from matrix [3,4]. These interparticles ligaments were more favorable of plastic deformation, due to the thin thickness of interparticles ligaments, the moderate interfacial interaction between this ROF and iPP matrix [23], and more important to the reduced plastic resistance of the preferentially oriented crystallites layer surrounding filler particles [8]. Thus, these interfacial ligaments, both on the impact plane and under the impact plane, can be stretched into microfibers effectively.…”

“…However, the stress concentration is positively correlated with filler dimension, while the debonding resistance is inversely correlated with filler dimension, as shown the interfacial interaction analysis in tensile test [23]. This means that with filler particles size is decreased, the stress concentration is decreased, but the debonding resistant energy is increased sharply [24].…”

Polypropylene/combinational inorganic filler micro‐/nanocomposites: Synergistic effects of micro‐/nanoscale combinational inorganic fillers on their mechanical properties

“…Some drawbacks, however, such as low‐temperature brittleness, low modulus, and large shrinkage ratios have limited its applications in high‐performance engineering areas 7–10. To overcome these limitations, scientists have developed a number of methods to modify PP‐matrix composites 11–14. Microsized inorganic fillers, including talc, wollastonite, calcium carbonate, barium sulfate, carbon black, magnesium hydroxide, hydroxyapatite, glass beads, montmorillonite, and aluminum, have been applied not only to lower the material costs but also to enhance the moduli and toughnesses of PP‐matrix materials and reduce their shrinkage rates of forming 6, 13, 15–23.…”

“…[7][8][9][10] To overcome these limitations, scientists have developed a number of methods to modify PP-matrix composites. [11][12][13][14] Microsized inorganic fillers, including talc, wollastonite, calcium carbonate, barium sulfate, carbon black, magnesium hydroxide, hydroxyapatite, glass beads, montmorillonite, and aluminum, have been applied not only to lower the material costs but also to enhance the moduli and toughnesses of PP-matrix materials and reduce their shrinkage rates of forming. 6,13,[15][16][17][18][19][20][21][22][23] The addition of microsized inorganic fillers usually damages the tensile and/or flexural strength of PPmatrix composites.…”