Failure mechanics in elastomer toughened polypropylene

Mechanical and morphological characterization of polypropylene toughened with olefinic elastomer

“…PP copolymers tend to have lower stiffness and higher yield strain than homopolymers as the presence of the ethylene reduces the crystallinity and stress level to produce shear yielding 6 . Also the presence of the elastomer in the blends linearly reduces their stiffness because there is an associated reduction in the effective cross-section area of the sample 12 . To get at room temperature impact strength above 100 J/m, by adding up to 20% elastomer, there is a drop from approx.…”

“…Also one should consider that the presence of fewer tertiary hydrogen in these elastomers improve their thermal stability in comparison to EPR's 11 . For PP, a semicrystalline matrix, the most effective particle size range for obtaining the best rubber toughening behaviour observed by various authors [5][6][7][12][13][14][15] is sub-micron in the range of 0.5 to 1.0 µm. The particle size of the elastomer significantly affects the deformation and failure processes being small particle favouring shear yielding while coarser dispersion promotes crazing 7 .…”

“…The improvement of toughness in plastics [1][2][3] and in particular of isotactic polypropylene is a subject of great importance due to its inherent low impact strength, especially in applications that involve sub ambient temperatures [4][5][6][7][8][9][10][11][12][13][14][15] . Polypropylene can be toughened through incorporating low contents of ethylene during its copolymerization, resulting in random or block copolymers 4,5 or by the in situ method, inside the reactor, where are formed dispersed elastomeric domains of ethylene-propylene elastomer (EPR) in a polypropylene matrix, called heterophase polypropylene.…”

Elastomer Application in Microsystem and Microfluidics

“…For example, silver particles are added into silicone elastomer matrix to formation of conductive elastomer for highdensity electrical contacts in microelectronics. Polypropylene and ethylene-propylene copolymer elastomer significantly improves the dynamic mechanical, tensile and impact properties and even changes the modes of failure 10 . The size, shape and spatial packing of elastomer inclusions are the most significant factors in controlling the mechanical behavior of blends.…”

Blends of i‐PP and SBS. II. Influence of in situ compatibilization on the mechanical properties

“…Studies on the blends of i-PP with various elastomers have generated considerable interest owing to desirable improvement in certain properties useful for various specific applications. Elastomers such as the ethylene-propylene copolymer (EPR), [1][2][3][4][5][6][7] ethylene-propylene-diene terpolymer (EPDM), 8 -13 and styrene-butadiene block copolymer 14 -18 have been extensively used for this purpose. The morphology of the blend or, more specifically, the rubber particle size has a strong influence on the toughening, but its influence may vary widely from one system to another.…”