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Jay, F.; Haudin, Jean‐Marc; Monasse, Bernard

doi:10.1023/a:1004563827491

Cited by 126 publications

(89 citation statements)

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“…In the past years Flow Induced Crystallization (FIC) of macromolecular systems has been largely investigated [1][2][3][4][5][6][7][8][9][10] to understand the role of the thermo-mechanical history applied during polymer processing on the final morphology and properties of polymeric materials. A good level of knowledge has been reached and it is well established that application of flow fields before and/or during polymer solidification results in a large increase of nucleation density and, as a consequence, of the overall crystallization rate [1][2][3]7,[10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

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Flow induced crystallization of LDPE nanocomposites: A rheological and morphological characterization

Azzurri

Stagnaro²,

Conzatti³

et al. 2011

E-Polymers

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Abstract:The flow induced crystallization behaviour of a LDPE:PE-g-MA:D72T 90:9:1 nanocomposite has been investigated by in-situ Rheo-SALS technique and data have been compared with those obtained from a reference LDPE:PE-g-MA 90:9 sample. Rheo SALS results, confirming thermal analysis findings, indicate that under mild shear flow fields the organoclay exhibits a negligible nucleating effect. Both nucleation density and, as a consequence, crystallization rate, are not appreciably affected by the application of external flow field for both the examined systems, revealing that no evident synergic effects between the organoclay and the shear flow are present. On the other hand, Rheo SALS analysis indicates that the nanocomposite submitted to flow exhibits a higher level of crystal orientation. TEM morphological analyses support this observation suggesting that the orientation of the nanofiller along the flow direction templates the growth of oriented crystals.

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Section: Introductionmentioning

confidence: 99%

“…A good level of knowledge has been reached and it is well established that application of flow fields before and/or during polymer solidification results in a large increase of nucleation density and, as a consequence, of the overall crystallization rate [1][2][3]7,[10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Flow induced crystallization of LDPE nanocomposites: A rheological and morphological characterization

Azzurri

Stagnaro²,

Conzatti³

et al. 2011

E-Polymers

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“…the formation of the final structure. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] For example, when high flow and high cooling rates exist, oriented structures, such as shish kebab or lamellae row structures, are preferably formed. In addition, Varga et al [6,7] found that the supermolecular structure formed in the vicinity of the sheared layer is generally rich in the b-modification of isotactic polypropylene (iPP).…”

Section: Introductionmentioning

confidence: 99%

Processing, Morphology, and Mechanical Properties of Liquid Pool Polypropylene with Different Molecular Weights

Stern

Frick

Weickert

et al. 2005

Macro Materials & Eng

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Summary: The processability, morphology, and resulting mechanical properties of novel polypropylene (PP) samples of varying molecular weight ($\overline M _{\rm w}$) were studied. A series of homopolymer PP in a wide $\overline M _{\rm w}$ range from 101 000 to 1 600 000 g · mol−1 was polymerised in a liquid pool (LP) under defined conditions. The LP‐PP with a well‐known polymerisation history was manufactured into micro dumbbell specimens by means of a micro injection‐moulding process. The morphology and mechanical properties of the samples were studied by light microscopy, transmission and scanning electron microscopy, and a quasi‐static tensile test. Simulation of the filling behaviour of the molten polymer inside the mould shows that the shear rate increases as the molecular weight increases, up to a maximum shear rate of 750 000 s−1. In addition, the present crystallisation time of the high‐molecular‐weight PP samples is clearly lower than their retardation time; the long macromolecules do not have sufficient time to retard while cooling. As a result of the shear‐induced crystallisation, a highly oriented crystalline structure is formed as a function of the acting shear rate. SEM and TEM investigations show the existence of an oriented shish kebab structure. The density of the shish kebab increases as the molecular weight increases. Evaluations of the shear rate and the morphological structure indicate a critical shear rate of about 300 000 s−1. Above this shear rate level, shish kebab structures are favourably formed. The shear‐induced crystallisation and, therefore, the preferred formation of a highly oriented shish kebab structure lead, obviously, to unusual solid‐state properties of the analysed LP‐PP samples. With a tensile strength up to 100 N · mm−2 and an attainable strain at break of more than 30%, the mechanical performance is much higher than results ever reported in literature.True strain–stress behaviour of moulded the LP‐PP samples of different molecular weight.magnified imageTrue strain–stress behaviour of moulded the LP‐PP samples of different molecular weight.

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“…44 SEM and DSC revealed that the essence of ␤ crystallite toughening originates from the stress induced phase transformation from less dense ␤ form to more dense ␣ form at the root of a growing crack in the stress whitened plastic zone caused by the mechanical loading. 45 The transformation increases the volume-specific plastic work consumed in the necked zone during tensile test 46 resulting in crack blunting and toughening enhancement.…”

Section: Dsc Analysesmentioning

confidence: 99%

Modification of polypropylene by melt vibration blending with ultra high molecular weight polyethylene

Wang¹,

Zhou

Zhang

et al. 2002

Adv Polym Technol

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ABSTRACT:A novel vibration internal mixer was used to prepare polypropylene/ultra high molecular weight polyethylene PP/UHMWPE blends with two additional adjustable processing parameters (vibration frequency and vibration amplitude) as compared with those prepared in the steady mode. Microscopy, mechanical tests, and differential scanning calorimetry showed that vibration influenced the blend morphology and the product properties. The good phase homogeneity of the blends might be due to the variation of shear rate either spatially or temporally in blending. Additionally, the vibration internal mixer could be used to analyze the dependency of viscosity on the shear rate. Vibration enhanced the interpenetration of UHMWPE into PP and vice versa. Subsequently, the formed crystals of two components were connected, and there was epitaxy MODIFICATION OF POLYPROPYLENE BY MELT VIBRATION BLENDINGbetween PP and UHMWPE crystals. Moreover, the crystalline aggregates, with the amorphous UHMWPE, formed a complex network-like continuous structure, which improved the elongation ratio at the break and the yield strength. The higher the vibration frequency and/or the larger the vibration amplitude at a fixed average rotation speed of the mixer, the more significant these effects were. The larger amount of the connected crystals, especially of ␤ form of PP in the bulk ␣ form PP as well as with the continuous phase structure, led to a higher tensile properties of PP/UHMWPE vibration blended. C 2002 Wiley Periodicals, Inc.

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Cited by 126 publications

References 0 publications

Flow induced crystallization of LDPE nanocomposites: A rheological and morphological characterization

Flow induced crystallization of LDPE nanocomposites: A rheological and morphological characterization

Processing, Morphology, and Mechanical Properties of Liquid Pool Polypropylene with Different Molecular Weights

Modification of polypropylene by melt vibration blending with ultra high molecular weight polyethylene

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