Toughening of a propylene‐b‐(ethylene‐co‐propylene) copolymer by a plastomer

Abstract

Several blends, covering the entire range of compositions, of a metallocenic ethylene‐1‐octene copolymer (CEO) with a multiphasic block copolymer, propylene‐b‐(ethylene‐co‐propylene) (CPE) [composed of semicrystalline isotactic polypropylene (iPP) and amorphous ethylene‐co‐propylene segments], have been prepared and analyzed by differential scanning calorimetry, X‐ray diffraction, optical microscopy, stress‐strain and microhardness measurements, and dynamic mechanical thermal analysis. The results show that for high CEO contents, the crystallization of the iPP component is inhibited and slowed down in such a way that it crystallizes at much lower temperatures, simultaneously with the crystallization of the CEO crystals. The mechanical results suggest very clearly the toughening effect of CEO as its content increases in the blends, although it is accompanied by a decrease in stiffness. The analysis of the viscoelastic relaxations displays, first, the glass transition of the amorphous blocks of CPE appearing at around 223 K, which is responsible for the initial toughening of the plain CPE copolymer in relation to iPP homopolymer. Moreover, the additional toughening due to the addition of CEO in the blends is explained by the presence of the β relaxation of CEO that appears at about 223 K. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1869–1880, 2002

Rheological and structural details of biocidal iPP-TiO2 nanocomposites

“…The corresponding values obtained at room temperature are listed in Table 1. The degree of crystallinity is within the range of that found in analogous quenched metallocenic iPP specimens [26][27][28][29][30]. Under the quenching conditions imposed during film preparation, crystallization takes place at conditions far from equilibrium and the fast cooling applied limits even more the development of crystallites and their perfection.…”

Metallocenic Isotactic Poly(propylene) and its Copolymers with 1‐Hexene and Ethylene

“…Consequently, the use of coupling agents is necessary to attain an optimum blend and really improve the impact resistance. One possibility of overcoming the difficulties of miscibility of the different polymeric phases is the use of reactor-granule technology, which leads to the achievement of heterophasic copolymers [2] with an excellent stiffness/impact balance [3,4] and a wide range in ethylene content (up to 25% by weight) as the rubber phase.…”

“…Correlation of impact resistance with dynamic mechanical behavior has been indicated by many authors. [3,14,[34][35][36][37] The area under the loss-tangent curve from À150 to 30 8C provides an estimation of the impact strength, though it is not a direct measurement. A linear correlation between the notched Izod impact strength and the area under the loss-tangent curve has been observed for iPP/EVA (ethylene-vinyl acetate copolymer) blends [37] whereas an exponential relationship is found for the iPP/EPDM (ethylene-propylene-diene rubber terpolymer) blends.…”

Metallocenic Copolymers of Isotactic Propylene and 1‐Octadecene: Crystalline Structure and Mechanical Behavior

“…Correlation of impact resistance with dynamic mechanical behavior has been indicated by many authors. [54,[61][62][63][64] The area under the loss tangent curve from À150 to 30 8C provides an estimation of the impact strength though it is not a direct measurement. A linear correlation between notched Izod impact strength and the area under the loss tangent has been observed for iPP/EVA blends [63] whereas an exponential relationship is found for the iPP/ EPDM blends.…”