Biaxial stretching behavior as a probe of H-bond organization in semi-crystalline polyamides

Pépin, Julie; Gaucher, Valérie; Lefebvre, Jean‐Marc; Stroeks, Alexander

doi:10.1016/j.polymer.2016.08.078

Cited by 29 publications

(40 citation statements)

References 38 publications

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“…In polyamide 11, this yield point is diffuse, and it appears at high strain of around 30-40% [35]. A structural transition from the triclinic α phase to the pseudo-hexagonal δ' smectic phase takes place during this necking [35][36][37]. Stress and strain at second yield increase significantly after annealing, respectively from 35 MPa to 40 MPa and from 30% to 40%.…”

Section: Effect Of Annealing On Mechanical Propertiesmentioning

confidence: 98%

“…At higher strain, this "glassy" yield is followed by a second yield associated with plastic deformation in the crystalline phase. In polyamide 11, this yield point is diffuse, and it appears at high strain of around 30-40% [35]. A structural transition from the triclinic α phase to the pseudo-hexagonal δ' smectic phase takes place during this necking [35][36][37].…”

Section: Effect Of Annealing On Mechanical Propertiesmentioning

confidence: 98%

“…The plateau strain range and the strain hardening slope depend on the annealing temperature. Both chain entanglements and inter-crystalline tie molecules, that have a major influence in this high strain range, have probably been modified during high temperature annealing [35].…”

Section: Effect Of Annealing On Mechanical Propertiesmentioning

confidence: 99%

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Simultaneous SAXS-WAXS Experiments on Semi-Crystalline Polymers: Example of PA11 and Its Brill Transition

Tencé‐Girault

Lebreton

Bunǎu³

et al. 2019

Crystals

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This manuscript of the special issue “Microstructural Evolution and Mechanical Behavior of Semi-Crystalline Polymers” aims to show that Small Angle X-ray Scattering (SAXS) and Wide Angle X-ray Scattering (WAXS) experiments performed simultaneously constitute a unique tool to obtain valuable information on the hierarchical structure of semi-crystalline polymers. These structural quantitative data are needed to model macroscopic properties of polymeric materials, for example their mechanical properties. To illustrate our point, we focus our study on the structure and morphology of polyamide 11. Through a simultaneous SAXS-WAXS experiment, we show that the absence of enthalpic signal in Differential Scanning Calorimetry (DSC) is not synonymous with the absence of structural and morphological evolution with temperature. The case of a thermally activated crystal–crystal transition, the Brill transition, is particularly detailed. Through this SAXS-WAXS study, we show, among other points, and for the first time, that the periodicity of crystalline lamellae (LP) changes at the transition, probably due to a modification of the amorphous phase’s free volume at the Brill transition. We also explain the crucial role of annealing to stabilize polymeric materials that may experience temperature changes over their lifetime. The influence of the annealing on the perfection of crystalline structure, morphology and mechanical behavior is more particularly studied.

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Section: Effect Of Annealing On Mechanical Propertiesmentioning

confidence: 98%

Section: Effect Of Annealing On Mechanical Propertiesmentioning

confidence: 98%

See 1 more Smart Citation

Simultaneous SAXS-WAXS Experiments on Semi-Crystalline Polymers: Example of PA11 and Its Brill Transition

Tencé‐Girault

Lebreton

Bunǎu³

et al. 2019

Crystals

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“…The correlation between macroscopic mechanical properties and crystal structure of semicrystalline polymers is also helpful for understanding the structural modifications of polyamides at high temperature as previously attempted by Murthy et al [126] These authors concluded that the large change in mechanical properties of both PA6 and PA66 in the Brill's transition temperature domain was due to the increase of chain mobility in the crystalline phase, in the conceptual framework of preservation of the H-bonded sheet-like structure. A more recent study of the plastic behavior of PA6 under biaxial drawing by Pepin et al [133] provides a new insight on the high temperature structure. Indeed, contrary to polyethylene, polypropylene, and polyesters, polyamides can hardly be transformed by biaxial drawing [134][135][136][137][138][139] which is a largely used process for manufacturing packaging films with specific gas barrier properties together with high tear and puncture resistance.…”

Section: Brill's Transition and Of H-bond Distribution In Polyamidesmentioning

confidence: 99%

Overview and critical survey of polyamide6 structural habits: Misconceptions and controversies

Séguéla

2020

Journal of Polymer Science

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Various aspects of the structural habits and associated thermodynamic properties of polyamide6 are critically examined with regard to controversies that appeared in literature mainly due to misconceptions or erroneous/ambiguous interpretations of experimental findings. The structural habits under concern are the crystallization capabilities and chain topology, hydrogen bonds and sheet-like structure, crystalline polymorphism together with thermodynamic stability. Thermo-mechanical properties are also discussed for the sake of complementary argumentation. Comparisons are made with polycaprolactone, that is, the polyester homolog of polyamide6 regarding chain structure, in order to evaluate the actual role of the H-bonds on the structural habits. Additional comparisons with polyethylene and polypropylene are also made at several occasions for the sake of supporting argumentation on the structural behavior of polyamide6. A temperature-time-transformation diagram of polyamide6 is finally proposed from the gathering of plentiful literature data.

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“…However, up to now, almost no literatures on the biaxial stretching of PVDF films were reported. Compared with uniaxial stretching, biaxial stretching (BO) can change the microstructure and promote the transformation of crystalline phases of the film in each direction, thus endowing the films with good mechanical properties in both transverse direction (TD) and machine direction (MD), simultaneously bringing differences in other performances including transparency, gas barrier, etc. For example, S. Zekriardehani et al used biaxial stretching to significantly reduce the free volume of poly (ethylene terephthalate) (PET), thereby improving the gas barrier properties of biaxially stretched poly (ethylene terephthalate) (BOPET) films; Ilkka Rytöluoto et al found that higher biaxial stretching ratio could result in the improvement of the dielectric breakdown performance of biaxially stretched polypropylene (BOPP) film; Piyawanee Jariyasakoolroj et al established the relationship between the microstructure and mechanical properties of biaxially stretched polylactide (BOPLA) film by controlling the stretching rate and stretching ratio, etc.…”

Section: Introductionmentioning

confidence: 99%

Crystalline structure, dielectric, and mechanical properties of simultaneously biaxially stretched polyvinylidene fluoride film

2018

Polymers for Advanced Techs

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Biaxially stretched films have balanced properties in the film plane compared with uniaxially stretched films, thus having wider potential applications. In this paper, the simultaneously biaxial stretching (BO) technology had been applied to poly (vinylidene fluoride) (PVDF) melt extrusion film, and the crystalline structure, dielectric, and mechanical properties of the BOPVDF films were investigated. The results showed that during the simultaneous BO process, the applied stress on the film led to the alignment of PVDF chains into the crystals and the formation of all-trans planar zigzag (TTT) conformation, thus increasing the relative content of β phase and the crystallinity of BOPVDF films, as well as the dielectric response. When the stretching ratio was 2.0 × 2.0, the dielectric constant of the film reached the maximum, ie,~12, and the dielectric loss was minimum, ie,~0.02. At the same time, the mechanical properties of the stretched films were significantly improved and reached the maximum tensile strength with 3.5 × 3.5 draw ratio, ie, 90 MPa.

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Biaxial stretching behavior as a probe of H-bond organization in semi-crystalline polyamides

Cited by 29 publications

References 38 publications

Simultaneous SAXS-WAXS Experiments on Semi-Crystalline Polymers: Example of PA11 and Its Brill Transition

Simultaneous SAXS-WAXS Experiments on Semi-Crystalline Polymers: Example of PA11 and Its Brill Transition

Overview and critical survey of polyamide6 structural habits: Misconceptions and controversies

Crystalline structure, dielectric, and mechanical properties of simultaneously biaxially stretched polyvinylidene fluoride film

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