Superdrawn crystalline polymers: A new class of high‐strength fiber

Clark, Edward S.; Scott, Lois

doi:10.1002/pen.760141004

Cited by 145 publications

(36 citation statements)

References 29 publications

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“…Examples include industrial grades of POM [14], PEO [105], and i P4MP [27]. However, the moduli of the medium-molecular-weight materials and maximum achievable draw ratios are inferior to those of the ultra-high molecular weight fibers, due to extensive stretching of the chains (see Fig.…”

Section: Role Of Entanglementsmentioning

confidence: 97%

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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Section: Role Of Entanglementsmentioning

confidence: 97%

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

1999

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“…Drawing in this range is accompanied by migration and removal of defects and by an increase in crystal continuity [19]. Figs.…”

Section: Deformation Of An As-extruded Filamentmentioning

confidence: 98%

The plastic deformation of ultra-high molecular weight polyethylene

1985

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Gel-spun filaments of different initial morphologies have been subjected to controlled drawing at elevated temperatures. The drawn samples have been examined by highresolution scanning electron microscopy. The deformation mechanism at temperatures up to 120 ~ C is very similar to crazing, especially in the case of unoriented gel-spun filaments. Filaments exhibiting a shish-kebab morphology offer the opportunity of examining the deformation of elementary fibrils in a quantitative way. The transformation of individual lamellae into fibrils is the initial deformation mode, which is followed by slip of fibrils at a later stage. This is concluded from a comparison of experimental data and model calculations of the maximum draw ratio. Drawing at 144 ~ C results in the formation of globular aggregates of lamellae, with a characteristic long period of 40 nm. This long period persists until all the globules have been converted, by micronecking, into aggregate fibrils of extended-chain character. On a molecular scale, the various processes can be described as the temperature-dependent flow behaviour of an entanglement network.

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“…For this purpose extension and alignment of macromolecules have been studied throughout the years. Nowadays a variety of methods are known to produce orientation in polymers, such as cold, hot and zone drawing, direct and hydrostatic extrusion and radial compression of polymer rods [1][2][3][4][5][6][7][8][9]. In these methods the polymer is processed below its end melting point.…”

Section: !Ntroduetionmentioning

confidence: 99%

Ultra-high-strength polyethylene filaments by solution spinning/drawing

1980

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This paper deals with ultra-high-strength monofilaments of linear polyethylene that are produced by solution spinning and subsequent hot drawing at 120 ~ C. The influence of the draw ratio on the mechanical and thermal properties of the fibres was investigated. Some salient features of a polyethylene filament with a draw ratio of 31.7 are: tensile strength at break = 3.0 GPa, Young's modulus = 90 GPa and DSC-melting point at a scan speed of 10 ~ Cmin -1 = 145.5 ~ C. The modulus was found to depend linearly on the draw ratio. The tensile strength tended, by contrast, to approach an upper limit at high draw ratios. Additional morphological and X-ray studies revealed an extremely good orientation of the macromolecules in the fibre direction of the highly drawn polyethylene monofilaments.

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Superdrawn crystalline polymers: A new class of high‐strength fiber

Cited by 145 publications

References 29 publications

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

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

The plastic deformation of ultra-high molecular weight polyethylene

Ultra-high-strength polyethylene filaments by solution spinning/drawing

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