Effect of addition of polyethylene on properties of polypropylene/ethylene‐propylene rubber blends

Mechanical and morphological characterization of polypropylene toughened with olefinic elastomer

“…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.…”

“…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. The most used industrial process is the incorporation of an elastomeric component 1 , which alters the stress distribution in the matrix and contributes in the control of cracks' propagation and termination.…”

“…This is done by mechanical blending in the melt state with various types of elastomers, such as olefinic rubbers based on ethylene and propylene 1,4 . The use of this type of elastomers is very convenient due to the similarity in the chemical composition, which can help the interfacial interaction and also its competitive price 5 . Even having low interfacial adhesion 6 these imiscible blends are widely used because they produce enough toughening to meet the automobile industry requirements 5 .…”

“…The use of this type of elastomers is very convenient due to the similarity in the chemical composition, which can help the interfacial interaction and also its competitive price 5 . Even having low interfacial adhesion 6 these imiscible blends are widely used because they produce enough toughening to meet the automobile industry requirements 5 . The presence of rubber particles dispersed in a polypropylene matrix normally does not affect its crystallinity, but they can act as nucleating agent of the matrix, reducing the size of the spherulites [6][7][8] .…”