Characterization of stress-strain behavior for binary blends of isotactic polypropylene with ethylene-?-olefin copolymer

LLDPE/LDPE blends. II. Viscoelastic properties in solid state

“…The applicability of eq. (3) also has been reported for polyethylene and polypropylene with spherulitic structure 5–9, 12, 13…”

“…Furthermore, the nonlinear relaxation moduli can be superposed onto each other in the experimental range from the phenomenological point of view. According to numerous studies,5–9, 12, 13 the nonlinear relaxation modulus E ( t : γ) is often described by the following relation: where Γ(γ) represents the degree of mechanical nonlinearity. The applicability of eq.…”

“…Following that idea, Knauss and Emri,11 and Popelar and Kenner8 predicted the stress‐strain curves of polyethylene. Furthermore, Nitta and Yamaguchi12, 13 have also proposed a nonlinear constitutive equation for crystalline polymers, in which anharmonicity of elasticity and plastic deformation are concerned. According to the constitutive equation,12 Grüneisen constant,14 which represents the anharmonicity of molecular potential, and the degree of plastic deformation decide the mechanical nonlinearity in the strain region below the yield point.…”

Microstructural Interpretation of Influences of Molecular Weight on the Tensile Properties of High-Density Polyethylene Solids Using Rheo-Raman Spectroscopy

“…Morphological transformation during the tensile deformation of semicrystalline polymers has been widely studied, and it has been revealed that the lamellar alternating structure within the spherulites plays an essential role in microscopic deformation. ,− In the initial elastic region, spherulite deformation is mainly concentrated on the interlamellar amorphous layers, − and Young’s modulus is dominantly dependent on the thickness of the amorphous layer . In the yielding region, the tie molecules linking the crystalline phases act as stress transmitters, leading to the fragmentation of the lamellar crystals. , Beyond the yield point, the morphological transformation from a spherulitic to a fibrillar structure has been assigned to the origin of the macroscopic plasticity in the semicrystalline polymers.…”

LLDPE/LDPE blends. II. Viscoelastic properties in solid state

“…[5][6][7][8][9] Ferry and Stratton 10 have considered that the degree of nonlinearity is decided by the change of the free volume fraction. Furthermore, Nitta and Yamaguchi 12,13 have also proposed a nonlinear constitutive equation for crystalline polymers, in which anharmonicity of elasticity and plastic deformation are concerned. Furthermore, Nitta and Yamaguchi 12,13 have also proposed a nonlinear constitutive equation for crystalline polymers, in which anharmonicity of elasticity and plastic deformation are concerned.…”