Deformation behavior of isotactic polypropylene crystallized via a mesophase

Zia, Qamer; Radusch, Hans‐Joachim; Androsch, René

doi:10.1007/s00289-009-0151-y

Cited by 92 publications

(155 citation statements)

References 43 publications

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“…The reason for this is the reduced crystallinity. In agreement with literature, the yield stress decreases with increasing cooling rate at constant pressure [29]. As a result of this, the natural draw ratio decreases (see Fig.…”

Section: Methodssupporting

confidence: 91%

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Fast cooling of (non)-nucleated virgin and recycled poly(propylenes): Effect of processing conditions on structural and mechanical properties

et al. 2015

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. Fast cooling of (non)-nucleated virgin and recycled poly(propylenes) : effect of processing conditions on structural and mechanical properties. Thermochimica Acta, 603, 94-102. DOI: 10.1016/j.tca.2014 General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. A B S T R A C TIn this study, the effect of processing parameters, i.e., the cooling rate and pressure, on the structureproperty relationships for nucleated and non-nucleated i-PP from virgin and recycled sources was investigated. Special attention was given to the brittle-to-ductile transition of nucleated i-PP from plastic packaging waste. Differential fast scanning calorimetry and dilatometry were used to mimic industrial process conditions. From the calorimetric experiments, it was observed that under ambient pressure the mesomorphic phase was formed upon fast cooling, which was confirmed by WAXD analysis. The dilatometry results showed that by applying pressure also g-phase crystals are formed. Nucleated samples showed an increased tendency for the g-phase formation and a decreased tendency for mesomorphic phase formation. Up to now, recycled i-PP showed a brittle behavior, but this study showed that by applying a sufficiently high cooling rate, the yield stress can be reduced and a stabilization of the deformation can be obtained leading to a ductile behavior for recycled i-PP.

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Section: Methodssupporting

confidence: 91%

“…Lowering the yield stress of recycled i-PP could result in ductile instead of brittle behavior. Earlier results showed that, for the same crystallinity, the nodular mesomorphic phase was ductile with elongations-at-break up to 450%, while brittle fracture was observed for a spherulitic a-crystal phase in the same i-PP [29].…”

Section: Introductionmentioning

confidence: 91%

Fast cooling of (non)-nucleated virgin and recycled poly(propylenes): Effect of processing conditions on structural and mechanical properties

et al. 2015

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“…[2] While highly crystalline samples of iPP crystallized in the stable a form results in a rigid material, the same sample crystallized in the mesophase by rapid quenching of the melt at low temperature results in a ductile and flexible material with greatly enhanced deformability. This effect has been related to the different morphology of the mesomorphic crystals.…”

Section: Claudio De Rosa* and Finizia Auriemmamentioning

confidence: 99%

“…Similar data have been reported and extensively discussed by Androsch and co-workers. [2,9] The sample slowly solidified from the melt and crystallized in the stable a form, as shown by the presence of the typical 110, 040, and 130 reflections of the a form at 2q = 14, 16.8, and 18.68 of the …”

mentioning

confidence: 99%

The Deformability of Polymers: The Role of Disordered Mesomorphic Crystals and Stress‐Induced Phase Transformations

Rosa¹,

Auriemma²

2011

Angew Chem Int Ed

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Isotactic polypropylene (iPP) is of enormous and still increasing commercial importance because of its favored combinations of properties, such as good rigidity, high thermal resistance, low density, and ease of processability, which can be achieved at relatively low costs.[1] The wide range of applications of iPP results from its versatility and the variety of possible modifications of the basic material, which already starts in the polymerization reactor [1] and can be further achieved during crystallization and processing. In particular, the full understanding of the crystallization and complex polymorphic behavior made it possible to tailor the properties through control of the crystallization of the different crystalline forms (a, b, and g forms) and of the mesophase.As examples for these concepts, many properties are changed and enhanced by modification of the neat polymer, such as the mechanical strength by incorporation of glass fibers, optical clarification by addition of nucleation agents, [1] or enhancement of the ductility and flexibility by crystallization in the mesophase.[2] While highly crystalline samples of iPP crystallized in the stable a form results in a rigid material, the same sample crystallized in the mesophase by rapid quenching of the melt at low temperature results in a ductile and flexible material with greatly enhanced deformability. This effect has been related to the different morphology of the mesomorphic crystals. Mesophases are highly disordered crystals, characterized by a degree of order intermediate between the disorder of the amorphous phase and the order of crystalline phases, and are generally easily obtained by quenching the melt at low temperatures. In the cases of iPP the crystallization of solid mesophases by quenching the melt produces defective crystals of size and morphology which are very different from the spherulites obtained at low cooling rates or high crystallization temperatures. In general, with the transformation from ordered crystals to mesomorphic entities, a change of the crystallite morphology from almost perfect spherulites to bundlelike or nodular crystals is observed. [3][4][5] All these variations in number, size, and perfection of the crystallites and morphological details significantly influence the mechanical behavior of the materials, that is, the rigidity, impact strength, and ductility.[2]The crystallization of iPP in the mesophase may offer additional options for tailoring the properties.[2] In fact, optically transparent but highly crystalline films of iPP can be prepared by nonspherulitic crystallization, without employing optical clarifiers, [5b] through crystallization of the nonspherulitic mesophase by rapid cooling of the melt, and then in a second step through tailoring the crystallinity and mechanical characteristics by annealing at elevated temperature, to induce the transformation from the mesophase to crystals of the a form, and maintaining the absence of higher-order organization in a spherulitic superstructure. [4] Here, we ...

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“…This conclusion agrees well with the analysis of Haudin 39 claiming a quantitative correlation between the intensity of scattered light and the size of the spherulites. Although processing conditions, especially cooling rate, influence supermolecular structure (nucleus density and spherulite size) and consequently haze [40][41] , all samples were prepared and experiments carried out under the same conditions thus we do not consider and discuss crystallization kinetics in the subsequent analysis. …”

Section: Crystalline Structure and Optical Propertiesmentioning

confidence: 99%

Effect of the Molecular Structure of the Polymer and Nucleation on the Optical Properties of Polypropylene Homo- and Copolymers

Horváth

Menyhárd

Doshev

et al. 2014

ACS Appl. Mater. Interfaces

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Two soluble nucleating agents were used to modify the optical properties of nine PP homo-and random copolymers. The ethylene content of the polymers changed between 0 and 5.3 wt%.Chain regularity was characterized by the stepwise isothermal segregation technique (SIST), while optical properties by the measurement of the haze of injection molded samples.Crystallization and melting characteristics were determined by differential scanning calorimetry (DSC). The analysis of the results proved that lamella thickness and change in crystallinity influence haze only slightly. A model was introduced which describes quantitatively the dependence of nucleation efficiency and haze on the concentration of the nucleating agent. The model assumes that the same factors influence the peak temperature of crystallization and optical properties. The analysis of the results proved that the assumption is valid under the same crystallization conditions. The parameters of the model depend on the molecular architecture of the polymer. Chain regularity determines supermolecular structure and thus the dependence of optical properties on nucleation.

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Deformation behavior of isotactic polypropylene crystallized via a mesophase

Cited by 92 publications

References 43 publications

Fast cooling of (non)-nucleated virgin and recycled poly(propylenes): Effect of processing conditions on structural and mechanical properties

Fast cooling of (non)-nucleated virgin and recycled poly(propylenes): Effect of processing conditions on structural and mechanical properties

The Deformability of Polymers: The Role of Disordered Mesomorphic Crystals and Stress‐Induced Phase Transformations

Effect of the Molecular Structure of the Polymer and Nucleation on the Optical Properties of Polypropylene Homo- and Copolymers

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