Mechanical properties, morphology, and crystal structure of polypropylene/chemically modified attapulgite nanocomposites

Abstract

Atactic polypropylene (aPP) was chemically grafted onto attapulgite (ATP) via the bridge linking of a polymerizable cationic surfactant and poly(octadecyl acrylate) in the presence of ultrasonic oscillation and dicumyl peroxide, and then, the modified ATP was added to a polypropylene (PP) matrix to obtain PP nanocomposites by melt blending. The results of Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirmed that aPP and poly(octadecyl acrylate) were chemically grafted onto ATP through a graft polymerization reaction. The results of the mechanical properties testing showed that the addition of modified ATP improved the toughness and strength of PP remarkably. The dynamic mechanical analysis indicated that the modified ATP significantly increased the storage modulus and decreased the glasstransition temperature of PP. The results of scanning electron microscopy and transmission electron microscopy showed that the modified ATP was uniformly dispersed into the PP matrix as crystal needles; this proved the presence of strong interactions between modified ATP and PP. The crystal structure analysis revealed that the b-form crystalline of PP was formed within the modified ATP.

Effect of Surface Modification of Palygorskite on the Properties of Polypropylene/Polypropylene-g-Maleic Anhydride/Palygorskite Nanocomposites

“…The enhancement of hydrophobicity in the organically modified clays could lead to an improvement in the dispersion/exfoliation of clay within the polymer [51]. It may be that, at this relatively high concentration of Pal, the agglomeration of silicate fibers acts as a stress concentrator, as reported in other studies [35,37]. However, the nanocomposites containing Pal-2 and Pal-3 exhibited higher values of Young's modulus compared with Pal-1 nanocomposites; the results suggest that the reduction of surface energy of silicate fibers promoted its dispersion and compatibility with the polymeric matrix, increasing the stiffness of nanocomposites at low concentration of Pals.…”

“…Pal contents were 0.5, 1, and 2 wt.%. Other studies have reported that the tensile mechanical properties of PP did not increase considerably at concentrations higher than 2 wt.% of Pal [35,37]. The composites were compression molded at 190 ∘ C in a lab press for 3 min at 45 kN clamping load; specimens for further characterization were obtained from the above plates (120 × 120 mm, 1 mm thick).…”

“…Several studies have been devoted to improving the mechanical 2 International Journal of Polymer Science [27][28][29][30] and thermal properties of PP [31] by incorporating mineral fillers (i.e., clay) in an effort to diversify the use of PP. The intrinsic nonpolar nature of PP makes it incompatible with clay fillers; the use of modified clays and compatibilizers (such as polypropylene grafted maleic anhydride [32][33][34]) is a common approach to produce PP/clay nanocomposites.…”

“…The intrinsic nonpolar nature of PP makes it incompatible with clay fillers; the use of modified clays and compatibilizers (such as polypropylene grafted maleic anhydride [32][33][34]) is a common approach to produce PP/clay nanocomposites. A number of studies have focused on the preparation of PP/PP-g-MAH/Pal nanocomposites [35][36][37][38], but despite these efforts, the factors promoting the dispersion of Pal and improvement of the properties are not yet completely understood.…”

Structure and Properties of Polyamide 11 Nanocomposites Filled with Fibrous Palygorskite Clay

“…In fact, the inversion of the tetrahedral sheet results in the discontinuity of the octahedral sheets, thus forming open channels of 3.7 Å x 6.4 Å along the fiber axis. Because of its special fibrous structure, higher aspect ratio, thermal/mechanical stability, and high density of silanol groups on the structural cavities [9], nowadays, palygorskite is attracting much attention in many areas of nanotechnology, especially in the preparation of polymer-clay nanocomposites [11][12][13][14][15][16][17][18][19][20][21]. However, single rod crystals of palygorskite usually exist as crystal bundles or aggregates owing to the electrostatic charge, the stronger hydrogen bonding and Van der Waals interaction between the fibers.…”