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Stress-strain curves of PP/EPDM (a), PP/CPE (b), PP/NBR (c) blends with PP/elastomer wt.% ratio 100/0 (1), 90/10 (2), 80/20 (3), 50/50 (4), 20/80 (5), 10/90 (6)
Source publication
In this work, composites of isotactic polypropylene (PP) with three unvulcanized elastomers – terpolymer of ethylene-propylene-dicyclopentadiene (EPDM), chlorinated polyethylene (CPE) and copolymer of acrylonitrile-butadiene (NBR) – have been investigated. The purpose of the investigation was to create PP/elastomer blend composites of significantly...
Contexts in source publication
Context 1
... typical stress-strain curves of PP blends with elastomers (PP/EPDM, PP/CPE, PP/NBR) strained at 50 mm/min rate are compared in Fig. 2. As expected, neat PP has relatively high tensile properties (tensile strength, deformation at break) and high toughness. However, the tensile behaviour of the investigated blends changes gradually from plastic to elastomeric with increase of the content of elastomers in the blends. The values of yield stress decrease with increment of ...
Context 2
... yield stress decrease with increment of the content of elastomers in composite blends. The PP/CPE blends with the content of CPE 10-50 wt.% show a typical deformation character with a typical elastic-plastic transition similar to neat PP with a change from yielding to plastic deformation with a strain hardening up to the fracture (curves 2-3 in Fig. 2b.), that indicate to the considerable influence of PP matrix on the tensile behaviour of the blends up the elastomer content of 50 wt.% In the case of PP/EPDM blends stress-strain behaviour at yield is not considerably changed until the elastomer content of 20 wt. % (curves 2-3 in Fig.2a), after that substantial drop of yield strength is ...
Context 3
... the case of PP/EPDM blends stress-strain behaviour at yield is not considerably changed until the elastomer content of 20 wt. % (curves 2-3 in Fig.2a), after that substantial drop of yield strength is observed. ...
Context 4
... is not considerably changed until the elastomer content of 20 wt. % (curves 2-3 in Fig.2a), after that substantial drop of yield strength is observed. Most dramatic changes in stress-strain behaviour are observed for PP/NBR blends. The blends with the content of NBR 10-50 wt.% show a brittle behaviour with an immediate rupture at yielding (2-4 in Fig. 2c). It can be judged that PP affects mechanical behaviour of PP/CPE blends more than any other investigated blends. Besides this can indicate to an increased phase interaction of CPE and PP in comparison to those of PP with EPDM and especially PP with NBR. The values of PP blends with EPDM and NBR content 80-90 wt.% show a character of ...
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Citations
... Neat PP has a high toughness, with an elongation at break >500%, and a relatively high tensile strength >25 MPa. This agrees with the findings that were reported in[19] [20]. As the amount of UHMWPE in the PP blends increases, the tensile behaviour gradually changes from plastic to elastomeric. ...
... To enhance the impact resistance of PP, a rubbery phase is conventionally incorporated into the polymer matrix. Numerous studies demonstrated superior mechanical and impact properties of PP blends with impact modifiers, including ethylene-propylene random copolymers and rubbers [1][2][3], ethylene-octene copolymers [4][5][6][7], ethylene-propylene-diene terpolymers [8,9], styrene-ethylene/butylene-styrene and styrene-ethylene/ propylene-styrene tri-block copolymers [10][11][12][13][14]. Although improvement of the toughness of PP induced by blending with impact modifiers is accompanied by a reduction in strength [15], this shortcoming may be overcome by crosslinking the blends [16,17] or their reinforcement with nanoparticles [18][19][20]. ...
... ε =ε ε ε e p a p c -- (8) and ε pa and ε pc denote plastic strains in amorphous and crystalline regions, respectively. The rate of plastic strain in the crystalline phase is proportional to the rate of strain under macro-deformation: ...
Observations are reported in impact tests, uniaxial tensile tests with various strain rates, relaxation tests with various strains and cyclic tests with a mixed deformation program and various maximum strains per cycle on neat polypropylene (PP) and a blend of PP with styrene-(ethylene-butylene)-styrene copolymer (SEBS). Experimental data demonstrate a pronounced enhancement of impact resistance of PP due to the presence of an impact modifier, accompanied by improvement of its properties under low-speed loading, observed as a decrease in relaxation rate and residual strain under cyclic deformation. Material constants in constitutive equations are determined by matching the experimental data. Correlations are established between changes in the viscoelastoplastic response of PP and evolution of its microstructure induced by the presence of an impact modifier.
