Processing and physical property relationships in injection‐molded isotactic polypropylene. 2. morphology and crystallinity

Phase morphology and mechanical properties of iPP/SEP blends

“…The addition of SEP gradually reduces the stiffness of the blend in comparison with the pure iPP, although the presence of the ␤ phase of iPP additionally contributes to the Young's modulus reduction, as shown by Kalay and Bevis. 46 For a further analysis of the E data, the experimental values were compared with the values calculated by different theoretical models based on the modulus-concentration dependence of twophase polymeric materials. 1,47,48 A parallel model, which assumes an uniform strain and represents the upper bound of Young's modulus, is given by the equation…”

The Nonlinear Time‐Dependent Response of Semicrystalline Polymers: Correlations Between the Configurational Entropy and the Rate of Rearrangement of Chains

“…Given a stress, , Equation (18)- (20), (31) and (33)- (35) are determined by four material constants: the elastic modulus, E, the strain, ", that describes transition to a steady plastic flow, the attempt rate, À 0 , for detachment of active chains, and the dimensionless parameter, AE, that characterizes the distribution of MRs.…”

“…As is well-known, [31] injection-molded specimens of polyolefins are spatially heterogeneous: their cross-sections display a skin-core structure where thickness and crystalline morphology of the skin layers are strongly affected by the processing conditions. In what follows, this inhomogeneity of samples is disregarded, which implies that the material constants determined by matching observations should be treated as average (over the cross-section of a sample) quantities.…”

“…At rapid cooling of the melt (which is typical of the injection-molding process), crystallites and smectic mesophase are mainly developed, whereas and polymorphs are observed as minority components. [31] The characteristic size of spherulites is estimated as 100 to 200 lm. These spherulites consist of crystalline lamellae with thickness of 10 to 20 nm.…”

“…These spherulites consist of crystalline lamellae with thickness of 10 to 20 nm. [31,32] The amorphous phase is located (i) between spherulites, (ii) in liquid pockets 33] between lamellar stacks inside spherulites, and (iii) between lamellae in lamellar stacks.…”