Two-dimensional solid-state NMR studies of ultraslow chain motion: glass transition in atactic poly(propylene) versus helical jumps in isotactic poly(propylene)

Schaefer, D.; Spiess, Hans Wolfgang; Suter, Ulrich W.; Fleming, William W.

doi:10.1021/ma00216a008

Cited by 157 publications

(113 citation statements)

References 6 publications

(7 reference statements)

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“…13 Form I crystals preserve the lamellae thickness and crystallinity that is induced by extremely high chain mobility in form II, depending on the crystallization temperature. As explained above, form I is a fixed crystal, which is largely different from the similar polyolefins PE, 16 iPP 17,18 and iP4M1P 19 (mobile crystals). There is a strong correlation between thermally activated molecular dynamics in the crystalline regions and dissipation of the bulk mechanical property.…”

Section: Materials Propertiesmentioning

confidence: 98%

“…Before investigating the molecular dynamics of iPB1, our pulse program was tested using iPP, for which the crystalline stems perform helical jump motions with a jump angle of 1201 at temperatures above 90 1C. 17,18 The structure and dynamics are shown in Figure 3a. Several works evaluated helical jump motions using the CODEX method.…”

Section: Differential Scanning Calorimetrymentioning

confidence: 99%

“…PE (orthorhombic), 16 iPP (a2 form) 17,18 and iP4M1P (form I) 19 commonly show helical jump motions in the crystalline regions. The helical jump motion accompanies jump rotations of overall stems to neighboring sites and translation of overall stems by one monomer unit.…”

Section: Molecular Dynamics Of Ipb1mentioning

confidence: 99%

“…Solid-state nuclear magnetic resonance (NMR) has been successfully applied to reveal the molecular dynamics of solid polymers in the amorphous and crystalline regions. [15][16][17][18][19][20] In the crystalline regions, the molecular dynamics of typical polyolefins such as PE, 16 iPP 17,18 and iP4M1P 19 were investigated by two-and one-dimensional exchange NMR, which can directly detect reorientations of magnetic anisotropic interactions that are due to molecular dynamics. 15 These crystalline polymers commonly display slow, helical jump motions in the crystalline regions, which include discrete jump motions around the chain axes and translations of overall stems by one monomer unit.…”

Section: Introductionmentioning

confidence: 99%

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Critical roles of molecular dynamics in the superior mechanical properties of isotactic-poly(1-butene) elucidated by solid-state NMR

Miyoshi

Mamun

2011

Polym J

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Isotactic-poly(1-butene) (iPB1) shows superior mechanical properties after crystal-crystal transitions. Recently, Miyoshi et al. found that crystalline stems in metastable tetragonal crystal perform uniaxial rotational diffusions accompanying side-chain conformational transitions in the fast motional limit (correlation time, /s c S o10 À7 s; Macromolecules 2010, 43, 3986-3989.). In this study, molecular dynamics in stable trigonal crystal is investigated by solid-state nuclear magnetic resonance, which indicates that crystalline stems and side-chain conformations are completely fixed up to melting points (/s c S 410 s). In addition, lamellar thickness, /lS of iPB1 and a low isotacticity iPB1 (low_iPB1) with /mmmmS¼78%, respectively, were investigated by small-angle X-ray scattering. The low_iPB1 sample shows very week supercooling dependence of /lS (B5 nm), whereas iPB1 shows strong supercooling dependence of /lS (10-28 nm). On the basis of molecular dynamics and /lS results, molecular dynamics effects on structures and unique mechanical property of iPB1 are discussed.

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Section: Materials Propertiesmentioning

confidence: 98%

Section: Differential Scanning Calorimetrymentioning

confidence: 99%

Section: Molecular Dynamics Of Ipb1mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Critical roles of molecular dynamics in the superior mechanical properties of isotactic-poly(1-butene) elucidated by solid-state NMR

Miyoshi

Mamun

2011

Polym J

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“…Unfortunately, the nature of the molecular motions in the crystalline phase of PP has not been clearly identified. From solid-state nuclear magnetic resonance (NMR) spectroscopy, Spiess et al proposed a threefold rotational jump of the PP chains 46 analoguous to the twofold rotational jump of the PE chains, 47 presumably accompanied with a c/3 translation parallel to the chain axis. However, these authors did not mention the localized character of such processes with regard to the stem length.…”

Section: Helix Chain Motion and Screw Dislocation Slipmentioning

confidence: 99%

Plastic deformation of polypropylene in relation to crystalline structure

Séguéla¹,

Staniek²,

Escaig³

et al. 1999

J. Appl. Polym. Sci.

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ABSTRACT:The tensile drawing behavior of quenched and annealed films of isotactic polypropylene is investigated as a function of draw temperature and strain rate. A strain-induced structural change from the smectic to the monoclinic form is observed for the quenched films. A kinetic interpretation is proposed for the phenomenon. Data of thermal activation volume at the yield point indicate two regimes of plastic flow for the quenched sample, between 25 and 60°C, but only one regime for the annealed sample. Homogeneous and heterogeneous crystal slip processes are proposed to account for these regimes in relation to the nucleation and propagation of screw dislocations. The basic mechanism of molecular motion in the polypropylene crystal is suggested to be a wormlike motion of conformational defects along the 3/1 helix chains that allows a 120°rotation and a c/3 translation. The occurrence of the smectic form as a transitory state in the deformation pathway is discussed in terms of plasticity defect generation.

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Polymer ultradrawability: the crucial role of α-relaxation chain mobility in the crystallites

1999

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An explanation of the varying (ultra)drawability of semicrystalline polymers is proposed, based on NMR evidence of αc‐relaxation‐associated helical jumps and chain diffusion through the crystallites of polyethylene and several similarly “αc‐mobile” polymers; these include isotactic polypropylene, poly(ethylene oxide), poly(oxymethylene), poly(tetrafluoroethylene), poly(vinyl alcohol), and several others. The chain motions provide a mechanism by which hot drawing of these polymers can extend an initially formed fiber morphology by an order of magnitude to draw ratios > 30, without melting. A second class of polymers, including nylons, poly(ethylene terephthalate), syndiotactic polypropylene, isotactic polystyrene, and isotactic poly(1‐butene) (form I) lack a crystalline α‐relaxation and the associated chain mobility. Therefore, these polymers are “crystal fixed” and drawability is limited to draw ratios < 14, arising mostly from break‐up of crystalline lamellae and deformation of the amorphous regions. On this basis, we can explain which polymers are drawable to high draw ratios, given a sufficiently low level of entanglement. The motion through the crystallites is thermally activated and the applied stress only biases the direction of the jumps; this explains the crucial role of temperature and rate in tensile drawing and solid‐state extrusion processes. The behavior of the crystal‐fixed, poorly drawable polymers strongly suggests that melting, straight chain pull‐out, and sliding on crystal planes are not significantly operative during ultradrawing, and that weak intermolecular forces are not a sufficient condition for ultradeformation. Various stages of drawing are distinguished and other models of ultradrawability are discussed critically.

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Two-dimensional solid-state NMR studies of ultraslow chain motion: glass transition in atactic poly(propylene) versus helical jumps in isotactic poly(propylene)

Cited by 157 publications

References 6 publications

Critical roles of molecular dynamics in the superior mechanical properties of isotactic-poly(1-butene) elucidated by solid-state NMR

Critical roles of molecular dynamics in the superior mechanical properties of isotactic-poly(1-butene) elucidated by solid-state NMR

Plastic deformation of polypropylene in relation to crystalline structure

Polymer ultradrawability: the crucial role of α-relaxation chain mobility in the crystallites

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