Ultradrawing of High Molecular Weight Polyethylene Films Produced by Gelation/Crystallization from Solution: Effect of the Number of Entanglements

Matsuo, Masaru; Sawatari, Chie; Iida, Masayasu; Yoneda, Morihiro

doi:10.1295/polymj.17.1197

Cited by 66 publications

(46 citation statements)

References 10 publications

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“…The c-axis turns out to have a preferential orientation perpendicular to the large flat surface of the ribbon. The occurrence of this type of orientation, observed before for mats of single crystals [26] and thin gel films [27][28][29], is confirmed by two equatorial small-angle X-ray scattering (SAXS) measurements taken edge-on and flat-on. In the first case a maximum is observed due to a regular packing of lamellae, whereas for the flat-on measurement the intensity decreases continuously with increasing scattering angle.…”

Section: Resultssupporting

confidence: 69%

“…melt-spinning or fibres prepared from semi-dilute polymer solutions) and the process variables, as extensively described in the literature [27,29,[30][31][32][33][34][35]. During cold-drawing the lamellar structures are transformed into fibrillar structures by rotation/translation of (parts of) lamellae and/or by local melting of the lamellae due to local high stress concentrations.…”

Section: Resultsmentioning

confidence: 99%

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Gel-spun polyethylene fibres

et al. 1988

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In addition to spinning temperature, spinline stretching and spinning speed, the properties of gel-spun polyethylene fibres hot-drawn to the maximum draw ratio also depend on the polymer concentration, molecular weight and molecular weight distribution. Reducing the polymer concentration reduces the number of entanglements, and fibres with better properties are obtained. However, a minimum number of entanglements is necessary to ensure sufficient coherence of the entanglement network and avoid premature breakage of the spinline. Therefore, an optimal concentration exists which is shown to shift to a lower value for polyethylene with a smaller molecular weight distribution. Fibres with a tensile strength exceeding 6 GPa and a modulus of about 160GPa can be prepared as long as spinline stretching is avoided. A smaller molecular weight distribution enhances the deteriorating effect of spinline stretching. The difference in morphologies for as-spun fibres prepared from different gel compositions and under different spinning conditions also strongly affects the cold-drawing behaviour of the extracted as-spun fibres.

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Section: Resultssupporting

confidence: 69%

Section: Resultsmentioning

confidence: 99%

Gel-spun polyethylene fibres

et al. 1988

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“…Figure 7 shows SAXS intensity distribution in the meridional direction for UHMWP (Hercules 1900/90189) crystallized from solutions with 0.1, 0.4, and 0.6 g/100ml concentrations. This figure has already been represented elsewhere 22 but it is shown to discuss the difference of morphological properties between LMWP and UHMWP gels. Among three concentrations, 0.4 gj 100 ml corresponds to the intersection of the two linear lines as shown in Figure 3.…”

Section: Resultsmentioning

confidence: 99%

Molecular Weight Dependence on the Morphological Properties of Polyethylene Gels

Sawatari

Okumura

Matsuo

1986

Polym J

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ABSTRACT:Polyethylene gels were prepared by gelation/crystallization from dilute decalin solutions using five kinds of polyethylenes with different molecular weights and degrees of branching. The decalin was allowed to evaporate from the gels under ambient condition in order to prepare dry gels. The dry gel of ultra-high molecular weight polyethylene (UHMWP) of M w = 6 x 10 6 forms a film but the other low molecular weight polyethylenes (LMWP) with molecular weight lower than 3 x I 0 5 do not form a film. In order to investigate such a difference, the morphological properties of five kinds of dry gels were investigated by scanning electron microscopy, polarized microscopy, small angle light scattering, and small angle X-ray scattering. Within LMWP dry gels, observation reveals spherulitic textures whose crystal lamellae are rotated around a radial direction. In contrast, within the dry gels of UHMWP, there exists rodlike textures as assemblies of large lamellar crystals which are highly oriented with their fiat faces parallel to the film surface. To assure ultradrawing up to consistently high draw ratio, a suitable number of entanglements should be formed by tie molecules which connect the crystal lamellae.

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“…The drawability of the as-prepared gel specimens was found to depend significantly on the compositions of solutions from which gels were made [12][13][14][15][16][17]. Several authors [16,[18][19][20][21][22] reported that the drawing temperature and rate could markedly affect the maximal achievable draw ratio and tensile properties of solution-grown UHMWPE samples. In addition to the gel solution compositions and drawing conditions, it is generally recognized that the conditions used in the formation process after spinning and/or solution casting of gel solutions can also have a significant influence on the morphology, microstructure and drawing properties of the specimens formed during the above mentioned processes [2,19,[23][24][25][26][27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%