Role of the Entangled Amorphous Network in Tensile Deformation of Semicrystalline Polymers

Men, Yongfeng; Rieger, Jens; Strobl, G.

doi:10.1103/physrevlett.91.095502

Cited by 375 publications

(345 citation statements)

References 19 publications

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“…In addition, L pf increases with increasing T d . These findings are in perfect agreement with the melting-recrystallization concept already observed for various semi-crystalline polymers [49][50][51].…”

Section: Resultssupporting

confidence: 81%

On the strain-induced fibrillar microstructure of polyethylene: Influence of chemical structure, initial morphology and draw temperature

Xiong¹,

Lame²,

Chenal³

et al. 2016

Express Polym. Lett.

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A general feature of the morphogenesis of semicrystalline polymers is the regular stacking of chainfolded lamellar crystals alternating with amorphous layers. This stacking s characterized by an intercrystalline long period L p including the crystalline lamella and amorphous layer thicknesses. The stacking long period is in the range of a few nanometers to a few tens. When crystallization is performed from a quiescent melt, the resulting microstructure is isotropic with a spherulitic arrangement of the lamella stacks as a result of the radial growth of the crystals from a common multiple nucleus often designated as axialite [1]. The size scale of spherulites ranges from a few to several hundred microns. Upon plastic deformation at large strains, isotropic semicrystalline polymers transform into fibrillar materials that aroused a great interest from both academic and industrial standpoints owing to their remarkable mechanical performances [2-6] to be used as ropes, textile fibers for high performance tissues and fabrics, reinforcing fibers for polymer-based composites, etc. Abstract. The influence of crystalline microstructure and molecular topology on the strain-induced fibrillar transformation of semi-crystalline polyethylenes having various chemical structures including co-unit content and molecular weight and crystallized under various thermal treatments was studied by in situ SAXS at different draw temperatures. The long period of the nascent microfibrils, L pf , proved to be strongly dependent on the draw temperature but non-sensitive to the initial crystallization conditions. L pf was smaller than the initial long period. Both findings have been ascribed to the straininduced melting-recrystallization process as generally claimed in the literature. The microfibrils diameter, D f , was shown to depend on the draw temperature and initial microstructure in a different way as L pf . The evolution of D f was shown to correlate with the interfacial layer thickness that mainly depends on the chemical structure of the chains. It was concluded that, in contrast to L pf , the microfibril diameter should not be directly sensitive to the strain-induced melting-recrystallization. The proposed scenario is that after the generation of the protofibrils by fragmentation of the crystalline lamellae at yielding, the diameter of the microfibril during the course of their stabilization should be governed by the chain-unfolding and subsequent aggregation of the unfolded chains onto the lateral surface of the microfibrils. The morphogenesis of the microfibrils should therefore essentially depend on the chemical structure of the polymer that governs its crystallization ability, its chain topology and subsequently its fragmentation process at yielding. This scenario is summed up in a sketch.

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Section: Resultssupporting

confidence: 81%

On the strain-induced fibrillar microstructure of polyethylene: Influence of chemical structure, initial morphology and draw temperature

Xiong¹,

Lame²,

Chenal³

et al. 2016

Express Polym. Lett.

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“…1,[19][20][21][22][23] The behavior of the polymers during stretching is generally influenced by both the crystalline and the amorphous phases. 12,[24][25][26][27][28] The small-deformation properties are found to depend only on the nature of crystalline lamellae; whereas the ultimate properties are dominated by the entangled amorphous network. 11,13,25 Poly(ε-caprolactone) (PCL) is a biodegradable polymer, which can form homogeneous mixtures in the melt and solution with a wealth of other noncrystallizable compounds, including poly(vinyl methyl ether) (PVME), 24,29 poly(styrene-co-acrylonitrile), 30,31 and poly(vinyl chloride).…”

Section: Introductionmentioning

confidence: 99%

“…12,[24][25][26][27][28] The small-deformation properties are found to depend only on the nature of crystalline lamellae; whereas the ultimate properties are dominated by the entangled amorphous network. 11,13,25 Poly(ε-caprolactone) (PCL) is a biodegradable polymer, which can form homogeneous mixtures in the melt and solution with a wealth of other noncrystallizable compounds, including poly(vinyl methyl ether) (PVME), 24,29 poly(styrene-co-acrylonitrile), 30,31 and poly(vinyl chloride). 32,33 PCL is, therefore, a natural candidate to investigate the effect of blending on the mechanical properties and deformation behavior, thus providing new insight into the role of the entangled amorphous phase in the tensile deformation of semicrystalline polymers.…”

Section: Introductionmentioning

confidence: 99%

“…A variety of reports have addressed deformation characteristics and orientational behavior in PCL-based miscible blends under a tensile load utilizing true stress-strain measurements and infrared spectroscopy. 24,25,34,35 However, the structural and molecular parameters involved in the tensile deformation of PCL-based miscible mixtures are not yet completely understood, mainly because of the deficit of structural and morphological information at the molecular and nanometric length scales during stretching. Hence, it is essential to probe into the micro-and nanostructural development, which occurs during the mechanical deformation of the material, to gain further insight into the molecular mechanisms of tensile deformation and to provide possible routes for improvement of the material.…”

Section: Introductionmentioning

confidence: 99%

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Tensile Deformation of Oriented Poly(ε-caprolactone) and Its Miscible Blends with Poly(vinyl methyl ether)

Jiang

Wang

et al. 2013

Macromolecules

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The structural evolution of micro-molded poly(ε-caprolactone) (PCL) and its miscible blends with noncrystallizable poly(vinyl methyl ether) (PVME) at the nanoscale was investigated as a function of deformation ratio and blend composition using in situ synchrotron small-angle X-ray scattering (SAXS) and scanning SAXS techniques. It was found that the deformation mechanism of the oriented samples shows a general scheme for the process of tensile deformation: crystal block slips within the lamellae occur at small deformations followed by a stress-induced fragmentation and recrystallization process along the drawing direction at a critical strain where the average thickness of the crystalline lamellae remains essentially constant during stretching. The value of the critical strain depends on the amount of the amorphous component incorporated in the blends, which could be traced back to the lower modulus of the entangled amorphous phase and, therefore, the reduced network stress acting on the crystallites upon addition of PVME. When stretching beyond the critical strain the slippage of the fibrils (stacks of newly formed lamellae) past each other takes place resulting in a relaxation of stretched interlamellar amorphous chains. Because of deformation-induced introduction of the amorphous PVME into the interfibrillar regions in the highly oriented blends, the interactions between fibrils becomes stronger upon further deformation and thus impeding sliding of the fibrils to some extent leading finally to less contraction of the interlamellar amorphous layers compared to the pure PCL.3

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“…Men et al [34] has shown that this critical stress is in connection with the intrinsic stability of crystals, which is related to their theoretical equilibrium melting temperature. The low melting temperature of PCL leads to the deformation of crystallites at lower stresses, compared to other semi-crystalline polyolefins, polyesters and this also helps to minimize the cold-drawing and orientation of amorphous network.…”

mentioning

confidence: 99%

Towards the understanding of the molecular weight dependence of essential work of fracture in semi-crystalline polymers: A study on poly(ε-caprolactone)

Tuba¹,

Oláh²,

Nagy³

2014

Express Polym. Lett.

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Abstract. The plane-stress ductile fracture of poly(#-caprolactone) (PCL) has been investigated as a function of molecular weight and related crystalline structure. Because of the interacting effects in semi-crystalline polymers a separate study of a given structural parameter is rather challenging. Nevertheless, this polymer seems to be a good model material to study the effect of molecular weight on the essential work of fracture, as the interactions between the separate parameters, at room temperature, are negligible. The molecular characteristics of PCL were determined by size exclusion chromatography. To confirm the entangled molecular structure of studied polymers rheological measurements were performed. The crystalline morphology has been characterized by differential scanning calorimetry and wide angle X-ray diffraction. Quasi-static tensile tests and essential work of fracture tests were performed to study the mechanical behavior. Based on the experimental observations an empirical model has been proposed to outline the molecular weight and crystallinity dependence of the essential work of fracture in this semi-crystalline polymer.

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Role of the Entangled Amorphous Network in Tensile Deformation of Semicrystalline Polymers

Cited by 375 publications

References 19 publications

On the strain-induced fibrillar microstructure of polyethylene: Influence of chemical structure, initial morphology and draw temperature

On the strain-induced fibrillar microstructure of polyethylene: Influence of chemical structure, initial morphology and draw temperature

Tensile Deformation of Oriented Poly(ε-caprolactone) and Its Miscible Blends with Poly(vinyl methyl ether)

Towards the understanding of the molecular weight dependence of essential work of fracture in semi-crystalline polymers: A study on poly(ε-caprolactone)

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