Physical structure of elastic “hard” fibers

Quynn, G. R.; Brody, H.; Sobering, E. S.; Park, K. K.; Foley, L. R.; Noethe, D. H.; Whitney, W.; Pritchart, R.; Seiminki, A. M.; Hutchison, D. J.; Wagner, Leopold; Sumit, Jadhav; Sakaku, K.; Karneluisson, R.

doi:10.1080/00222347008217135

Cited by 28 publications

(4 citation statements)

References 1 publication

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“…6,7,[10][11][12][13] An ideal model of hard elastic material presents its structure as a combination of stacks of lamellae arranged perpendicular to melt flow direction. [1][2][3][4][5][15][16][17] In Figure 5, it is shown that the ER becomes larger as V 1 , DDR, and annealing temperature increases. Considering the slope of ER against V 1 and DDR, it is also observed that the ER appears to be more dependent on the DDR rather than the V 1 , which is consistent with our previous results on the BR.…”

Section: Resultsmentioning

confidence: 93%

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] They are characterized by high modulus of elasticity, reversible deformation, energetic retractive force, and constant cross-sectional area during deformation. These unusual properties are believed to be due to their ''row-nucleated lamellar crystalline'' structures that comprise rows of crystalline lamellae arranged preferentially normal to draw direction and connected by tie chains.…”

Section: Introductionmentioning

confidence: 99%

“…The lamellar crystalline structure can be formed when polymers having high degree of crystallinity are melt-extruded with experiencing elongation stress and then recrystallized, which is called as stressinduced crystallization. [1][2][3][4][5][6][7][8][9] When the hard elastic polymer is annealed and extended in the orientation direction, the portions of crystalline lamellae that are not connected by tie chains move apart, which leads to the bending of crystalline lamellae and the formation of micropores between them. [10][11][12][13][14] Therefore, to have a comprehensive understanding of the microporous membrane formation, a more quantitative analysis on the processing-structureproperty relationship of hard elastic precursor films should be preceded.…”

Section: Introductionmentioning

confidence: 99%

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Effects of melt‐extension and annealing on row‐nucleated lamellar crystalline structure of HDPE films

Lee¹,

Park²,

Song³

2006

J of Applied Polymer Sci

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The row-nucleated lamellar crystalline structure of high-density polyethylene (HDPE) films was prepared by applying elongation stress to HDPE melt during T-die cast film extrusion and subsequently annealing the extruded films. This unusual crystalline structure was analyzed in terms of lamellar crystalline orientation, long-period lamellar spacing, crystallite size, and degree of crystallinity. The contribution of melt-extension represented by draw-down-ratio (DDR) to the overall orientation was found to be most noticeable than other processing variables. Meanwhile, the long-period lamellar spacing, the crystallite size, and the degree of crystallinity were influenced predominantly by the annealing temperature. Finally, the processing (melt extension and annealing temperature) -structure (lamellar crystalline structure) -property (hard elasticity) relationship of HDPE films was investigated.

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Section: Resultsmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effects of melt‐extension and annealing on row‐nucleated lamellar crystalline structure of HDPE films

Lee¹,

Park²,

Song³

2006

J of Applied Polymer Sci

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“…This patent states that the fiber produced under specified conditioning will exhibit an elongation at break of from 100 to 700 percent while at the same time demonstrating a tensile recovery of at least 82 percent after sustaining a 25 percent elongation. Additional work on this material has been reported by others (5)(6)(7)(8) which, among other things, has demonstrated that this form of polypropylene exhibits a porosity of a peculiar nature, i.e., the porosity may be vaned widely by extending to different strain levels. The practical implication of this property should indicate its usefulness as a candidate membrane for separation process studies.…”

Section: Introductionmentioning

confidence: 64%

The mechanical behavior of springy polypropylene

Cannon

Statton

Hearle

1975

Polymer Engineering & Sci

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To obtain further details of the unusual behavior of the “hard elastic,” “springy” form of polypropylene (SPP), various loading conditions were studied with an Instron model 1130. Specifically, the variation of the elongation at rupture with change in gauge length and strain rate has been determined. The nature and degree of the specimen hysteresis resulting from various loading cycles have been characterized. The ability of this material to recover from large extensions customarily expected to be permanent deformation has been identified and the time dependency of this recovery has been determined for strain levels of 10, 25, 50, and 100 percent of the original sample length. The effects of submitting the material to conditioning treatments, e.g., immersing in saline solutions of various electrolyte concentrations and autoclaving for 30 min at 250°F and 15 psig have been studied. Characterization of the stress relaxation behavior of the polymer has been made. Fatigue behavior has been identified utilizing a novel testing apparatus which permits load‐cycling of the fiber. Rheovibron work has facilitated calculation of the activation energy of the second order relaxation of SPP from tan δ vs temperature data. Stoll abrasion testing results on SPP tubular knit fabric and multifilament yarn have been compared to normal polypropylene and Dacron®.

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Structural characterization of Celgard® microporous membrane precursors: Melt‐extruded polyethylene films

Chen

Saw

Jamieson

et al. 1994

J of Applied Polymer Sci

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SYNOPSIS"ROW nucleated lamellar" structures are formed when highly crystalline polymers are meltextruded and recrystallized under high stress. Polyethylene ( P E ) and polypropylene (PP) films with row lamellar structures have been utilized to produce microporous membranes. Birefringence measurements of melt-extruded P E films show that improved film orientation can be achieved by annealing, extruding a t higher speed, and using higher molecular weight polymers. Images from scanning tunneling, atomic force, and field emission scanning electron microscopy (STM, AFM, and FESEM) clearly show the lamellar structures in the melt-extruded P E and PP films. Microscopy results also show that surface lamellar textures are more pronounced with thicker lamellae and are better aligned along the extrusion direction after annealing. X-ray diffraction results show that the increase in film orientation can be attributed to increased lamellar perfection and orientation during annealing and also to better crystallite alignment along the machine direction with higher extrusion speed or with higher molecular weight. High-resolution capabilities of STM, AFM, and FESEM prove to be very effective tools in elucidating lamellar structures in polymeric membrane precursors and can be used as an aid in establishing structure-process-property relationships in making microporous membranes.

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Physical structure of elastic “hard” fibers

Cited by 28 publications

References 1 publication

Effects of melt‐extension and annealing on row‐nucleated lamellar crystalline structure of HDPE films

Effects of melt‐extension and annealing on row‐nucleated lamellar crystalline structure of HDPE films

The mechanical behavior of springy polypropylene

Structural characterization of Celgard® microporous membrane precursors: Melt‐extruded polyethylene films

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