Recent developments in ultraorientation of polyethylene by solid-state extrusion

Zachariades, Anagnostis E.; Mead, W. T.; Porter, Roger S.

doi:10.1021/cr60326a005

Cited by 88 publications

(21 citation statements)

References 21 publications

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“…Solid‐state extrusion is normally performed between glass transition temperature ( T g ) and melting temperature ( T m ) 16–19. Therefore, thermally induced cold crystallization took place when heated through T g of about 70 °C and up to the extrusion temperature of 130 °C, which results in the increase in billet crystallinity prior to solid‐state extrusion.…”

Section: Resultsmentioning

confidence: 99%

Improvement of Flexural Strengths of Poly(L‐lactic acid) by Solid‐State Extrusion, 2. Extrusion Through Rectangular Die

Lim

Kim

Lim

et al. 2003

Macro Materials & Eng

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Solid‐state extrusion of poly (L‐lactic acid) (PLLA) through rectangular die was performed to produce high flexural strength plates that can be used as internal fixation devices. A single‐angle wedge‐shaped rectangular die was utilized having the die exit dimension of 4 mm × 1 mm. Billets were machined out from vacuum compression molded PLLA having different crystallinities to have various thicknesses and thus various imposed draw ratios. Solid‐state extrusion of billets was performed at various drawing rates at 130 °C, above glass transition and below melting temperature. Extruded plates had the width and thickness smaller than the die due to the further drawing outside the die. The decrease in width was larger than the decrease in thickness, and this became more prominent with increasing draw ratio and drawing rate, resulting in a significantly smaller aspect ratio. Contributions of die drawing and further drawing outside the die were estimated from the extruded plate dimensions, by which the drawing rate effect was attributed to the further drawing outside the die. As actual draw ratio increased, crystallinity, melting temperature, crystalline orientation factor, and birefringence increased. Throughout the whole process the decrease in molecular weight was largely suppressed to be about 10%. As billet crystallinity, draw ratio, and drawing rate increased, both flexural strength and flexural modulus increased up to the maxima of 202 MPa and 9.7 GPa, respectively. This enhancement in mechanical properties was correlated with structural developments. Changes in flexural strength of solid‐state extruded PLLA plates as a function of draw ratio (the effect of drawing rate is co‐plotted by hollow symbols at corresponding draw ratio.).magnified imageChanges in flexural strength of solid‐state extruded PLLA plates as a function of draw ratio (the effect of drawing rate is co‐plotted by hollow symbols at corresponding draw ratio.).

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Section: Resultsmentioning

confidence: 99%

Improvement of Flexural Strengths of Poly(L‐lactic acid) by Solid‐State Extrusion, 2. Extrusion Through Rectangular Die

Lim

Kim

Lim

et al. 2003

Macro Materials & Eng

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“…Developments in tlie formation of ultra-oriented polyethylene fibre from its melt were reported by several authors [424][425][426][427][428][429][430][431][432].…”

Section: Polyethylene Fibrementioning

confidence: 99%

“…Extension rate, pressure, temperature, draw ratio, and molecular weight were studied in the light of microstructural details of the drawn fibres [424][425][426][427][428][429][430].…”

Section: Polyethylene Fibrementioning

confidence: 99%

The Structure and Properties of Typical Melt-spun Fibres

Mukhopadhyay¹

1988

Textile Progress

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“…Details of the chemical characteristics of the raw material, that was taken for the solid state extrusion, and a detailed description of the extrusion process are given elsewhere [12]. The character T denotes the extrusion parameter undercooling (i. e. the difference between the melting and the extrusion temperatures) and the following number gives the undercooling in K. The character D stands for the varied nominal draw ratio [13] and the following nuber gives the value for the draw ratio. The character T denotes the extrusion parameter undercooling (i. e. the difference between the melting and the extrusion temperatures) and the following number gives the undercooling in K. The character D stands for the varied nominal draw ratio [13] and the following nuber gives the value for the draw ratio.…”

Section: Materials Description and Sample Preparationmentioning

confidence: 99%

Solid state extrusion of thermoplastic elastomers 4

Bandara

Dröscher

Thomas

1984

Colloid & Polymer Sci

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A solid state extrusion technique is applied as to produce oriented block copoly-(ether ester) under various physical conditions. The morphology of the extruded samples is characterized in relation to the extrusion parameters and hard segment compositions of the polymer, using thermal analysis and X-ray methods. The lateral dimensions of the crystalline domains are found to be approximately 150/k depending on the extrusion conditions, The statistics of the long range periodicity of the structure along the extrusion direction is in agreement with a one-dimensional two phase model, the crystalline portion of which does not vary much in thickness (35 -45 ]l). The unexpected increase in the long period and the thermal shrinkage suggest the existence of strained interlamellar amorphous chains (tie molecules). The observed variations in tensile properties are interpreted under the assumption that both the number of such tie molecules and their fully extended lengths are determined by the hard segment composition and the extrusion conditions. It is also argued that the increase in the glass transition temperature is not only a function of the composition of hard segments in the amorphous phase but also of the number of strained tie molecules.

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Recent developments in ultraorientation of polyethylene by solid-state extrusion

Cited by 88 publications

References 21 publications

Improvement of Flexural Strengths of Poly(L‐lactic acid) by Solid‐State Extrusion, 2. Extrusion Through Rectangular Die

Improvement of Flexural Strengths of Poly(L‐lactic acid) by Solid‐State Extrusion, 2. Extrusion Through Rectangular Die

The Structure and Properties of Typical Melt-spun Fibres

Solid state extrusion of thermoplastic elastomers 4

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