Skin-core structure–fatigue behavior relationships for injection-molded parts of polypropylene. II. Morphology–fatigue behavior relationships

Trotignon, J. P.; Verdú, J.

doi:10.1002/app.1987.070340102

Cited by 54 publications

(49 citation statements)

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“…Therefore the elucidation of the morphology and texture in the cross section of the mouldings is of great practical importance (cf. Trotignon & Verdu, 1987;Fujiyama, Wakino & Kawasaki, 1988).…”

Section: Introductionmentioning

confidence: 99%

Small- and wide-angle X-ray scattering investigations of injection-moulded polypropylene

Zipper¹,

Jánosi²,

Wrentschur³

et al. 1991

J Appl Cryst

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The layered structure in 2 mm thick discs injection moulded from industrial polypropylene (PP) was studied by scanning the cross section of the mouldings by means of small-and wide-angle X-ray scattering (SAXS and WAXS), using a Kratky collimation system for position-resolved quantitative scattering measurements in both angular domains. The registration of so-called scattering profiles of the mouldings and a texture analysis of the WAXS profiles were established as novel approaches for studying the cross-section architecture. The results of the investigations comprise statements on the preferential orientation and the local distribution of a-and fl-PP in different layers of the cross sections, on crystallite sizes and on the behaviour of individual layers in tensile tests.

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Section: Introductionmentioning

confidence: 99%

Small- and wide-angle X-ray scattering investigations of injection-moulded polypropylene

Zipper¹,

Jánosi²,

Wrentschur³

et al. 1991

J Appl Cryst

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“…Such stiffening has previously been reported in conditioned polyamide-66 [32], but not in a polyacetal copolymer with similar glass transition temperature and crystallinity index [32]. Differential scanning calorimetry (DSC) measurements on virgin and fatigued specimens of conditioned polyamide-66 [32] and of polypropylene [49] previously indicated small increases in crystallinity related to fatigue-induced damage. However, DSC measurements on material taken from fatigued specimens of PA6 and PA6NC did not reveal a difference in crystallinity or crystalline forms.…”

Section: Discussionmentioning

confidence: 75%

Bulk fatigue damage evolution in polyamide-6 and in a polyamide-6 nanocomposite

et al. 2005

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The mechanical response of a polyamide‐6 montmorillonite clay nanocomposite and of a polyamide‐6 was monitored during axial fatigue tests performed at R‐ratios of 0.1 and −1. For both materials, two transitions were usually observed in the evolution of all the stress‐strain‐time parameters studied after similar numbers of loading cycles, suggesting interrelationships between the mechanisms of molecular reorganization. Fatigue test monitoring indicated an initial decrease in the storage modulus and a subsequent trend for this modulus to increase, especially in polyamide‐6. During all tests, a partially recoverable strain was accumulated because of viscoelastic deformation. Nanoparticles reduced this strain in the initial cyclic straining regime but not in the last regime, probably because such particles cannot inhibit viscoelastic events constrained in a volume larger than their interaction volume within the matrix. Based on the accumulated volume variation measured, the nucleation and growth of microvoids can be expected to occur in the last cyclic straining regime. POLYM. COMPOS., 26:636–646, 2005. © 2005 Society of Plastics Engineers

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“…Crystallites of the b form were found in the subskin layer of both the gate part and far part, because of the strong shear force occurring at this layer. An index A 110 characterizing the orientation of a-crystallites along flow direction was adopted [18]. (The determination of A 110 is based on the vanishing of the reflections (111) and (ð 131 þ 040Þ) in the equatorial measurement when the axes of the crystallites orient in the direction of flow.…”

Section: Orientation and Crystallinitymentioning

confidence: 99%

“…Because of the different thermomechanical history the melt undergoes, the injection-molded parts often show a hierarchical multilayered structure through the thickness [1][2][3][4][5][6][7][8][9]. For the universal semicrystalline polymer, Polypropylene (PP), this layered structure has been widely studied with its heterogeneous crystallization because of the shear and temperature gradient [10][11][12][13][14][15][16][17][18][19]. It has been reported that the injection-molded PP parts often show three distinct crystalline zones: a highly oriented nonspherulitic skin, a shear zone with molecular chains oriented essentially parallel to the injection direction, and a spherulitic core with essentially no preferred orientation, respectively [10].…”

Section: Introductionmentioning

confidence: 99%

Structure and property of injection‐molded polypropylene along the flow direction

et al. 2009

Polymer Engineering & Sci

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The structure and mechanical properties of injectionmolded polypropylene along the flow direction were investigated in this article. A remarkable difference was found in morphology and mechanical properties of the injection-molded parts along the flow direction. The three-layered structure (namely the skin, subskin, and core layer) showed a gradient distribution along the flow direction. The IR and WAXD results showed that the orientation of the subskin layer in the gate part is much higher than that in the far part. DSC analysis results indicated that the two parts (gate part and far part) of injection-molded bar has the same degree of crystallinity that should not be responsible for the mechanical difference of the two parts. According to the measurement of residual internal stress, there is large difference between the gate part and far part, which is the main reason leading to the difference of impact behavior. The annealing treatment eliminated the internal stress, so the mechanical difference between the two parts decreased and the fracture type of the far part changed from brittle to ductile. POLYM. ENG. SCI., 49:703-712, 2009. ª

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Skin-core structure–fatigue behavior relationships for injection-molded parts of polypropylene. II. Morphology–fatigue behavior relationships

Cited by 54 publications

References 0 publications

Small- and wide-angle X-ray scattering investigations of injection-moulded polypropylene

Small- and wide-angle X-ray scattering investigations of injection-moulded polypropylene

Bulk fatigue damage evolution in polyamide-6 and in a polyamide-6 nanocomposite

Structure and property of injection‐molded polypropylene along the flow direction

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