Morphology of High Impact Polypropylene Particles

Abstract

An extensive characterization (SEM, AFM, mercury porosimetry, sorption, and 13C NMR) of the particle morphology prior (isotactic PP particles) and after the gas phase reaction (hiPP particles) was performed in an attempt to gain some knowledge of the gas phase reaction of the hiPP process. It was found that the majority of the elastomer was finely dispersed in the i-PP matrix, but breaking the i-PP matrix and flowing into its pores. It was also found that the interior of the particles was readily accessible to the monomers because of the existence of a network of pores. The catalyst fragmented into small pieces with about ≈210 atoms of Ti per fragment. The copolymer is richer in ethylene than in propylene although the monomer concentration around the active center is [C3]/[C2] = 2.75. This behavior could not be justified on the basis of a faster diffusivity of the ethylene with respect to the propylene and hence must be due to higher activity of the catalyst for ethylene.

The functions of crystallizable ethylene‐propylene copolymers in the formation of multiple phase morphology of high impact polypropylene

“…2,3,9,[13][14][15] It is generally believed that the dispersed phase in hiPP exhibits a core-shell structure with PE core and EPR shell. [16][17][18][19] This coreshell structure has proven to be efficient for the toughness-rigidity balance of the material.…”

“…However, the understanding of the phase morphology of hiPP is far from perfect. Although one can obtain some information about the phase structure of hiPP bulk with the help of cryoultramicrotomy, staining, and surface etching techniques, 2,3,5,9,[13][14][15][16][17][18][19] it is very difficult to gain the structural details of the phase morphology of the material. The corresponding relationship between the complicated chain structure and phase morphology has not been completely established.…”

Molecular composition and properties of impact propylene copolymers

“…Additional papers that deal with the morphology of the IPCs are those by McKenna and coworkers [15,16] and Urdamilleta et al [16]. From the available literature it is quite clear that the morphology of the 'as-polymerized' reactor powders is quite different from the morphology that is obtained after the first processing step [17]. This is an aspect of the morphological and chemical composition development that still needs more investigation, but one that is not dealt with in this paper.…”

Natural Nanotubes Reinforcing Heterophasic Polypropylene

“…High-impact polypropylene (hiPP) is a type of polypropylene reactor blend formed by an array of isotactic polypropylene (iPP) in which an elastomeric copolymer (EPR) is finely dispersed, with much higher impact resistance at low temperatures than the polypropylene homopolymer, but with lower stiffness, modulus, density and glass transition temperature. It is widely used in injection molding of parts for the automotive industry, rigid packaging for household products, technical parts and coatings of steel pipes [1][2][3][4] . However, for broader applications it is necessary to further improve its stiffness/ toughness balance, increasing rigidity without sacrificing impact resistance, although the improvement of one of these properties generally compromises the other.…”

“…Halloysite polymer composites have attracted researchers' interest in recent years due to their unique structures and properties [11][12][13][14][15][16] . These nanotubes, with molecular formula Al 2 Si 2 O 5 (OH) 4 .nH 2 O, are naturally occurring multi-walled inorganic materials that have similar geometry to carbon nanotubes (CNTs). This aluminosilicate mineral clay can be found in different regions, varying in dimension.…”