Hydrostatic extrusion of polyoxymethylene

Coates, P. D.; Ward, I. M.

doi:10.1002/pol.1978.180161112

Cited by 74 publications

(23 citation statements)

References 23 publications

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“…This is also true to some extent of POM [6]. However, in respect of the experimental behaviour described here, we have observed good reproducibility between different samples prepared from the same grade of polymer.…”

Section: Methodssupporting

confidence: 64%

“…In the present series of experiments the amount of die swell was fairly small [5,6] especially for LPE.…”

Section: The Extrusion Processmentioning

confidence: 96%

“…Early work on hydrostatic extrusion included studies of linear polyethylene (LPE) by Buckley and Long [2], and polypropylene by Williams [3]. In this laboratory, hydrostatic extrusion studies have been made on several polymers, including LPE [4,5], polyoxymethylene (POM) [6], polymethylmethacrylate [7], polycarbonate and nylon 6. The aim was to produce oriented rods of considerably larger crosssection than that conventionally attainable by drawing.…”

Section: Introductionmentioning

confidence: 98%

“…The aim was to produce oriented rods of considerably larger crosssection than that conventionally attainable by drawing. Details of the extrusion of LPE and POM, and various physical property measurements on the extrudates have been presented elsewhere [4][5][6][8][9][10]. A summary of much of our recent work on manufacture of high modulus polymers using drawing and hydrostatic extrusion is given in [1 I] Ch.…”

Section: Introductionmentioning

confidence: 99%

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An analysis of the mechanics of solid phase extrusion of polymers

1980

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An analysis is presented for the mechanics of the hydrostatic extrusion of polymers in the solid phase through a conical die. The analysis starts with the lower bound solution proposed by Hoffman and Sachs and includes the effects of strain, strain rate and pressure on the deformation behaviour. It is proposed that this involves knowledg6 of the tensile stress-strain-strain rate relationships for each polymer, and it is shown how such information for polyethylene and polyoxymethylene can be used to explain the observed behaviour of these materials in the solid-phase extrusion process.List of symbols r material radius at a point in the defora die cone semi-angle mation zone fl normal stress coefficient of tensile flow R N = (ro/r~) z nominal extrusion ratio stress R = (ro/r) 2 extrusion ratio at a point in the do initial diameter of billet deformation zone df die exit diameter ao(e) axial tensile flow stress axial strain rate (plug flow)af(e) process flow stress path, related to die ere d shear strain (redundant strain) incurred strain and strain rate fields on crossing die entry or exit boundary qh tensile haul-off stress ax, oy die stresses in deformation zone rl, ~'2 shear yield stress of material at die entry and exit boundaries, respectively v x axial velocity vf extrudate velocity at die exit 6 N = in R N = 21n (do/dr) nominal true strain in extrusion 6f = ~red "~-6N

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Section: Methodssupporting

confidence: 64%

“…In the present series of experiments the amount of die swell was fairly small [5,6] especially for LPE.…”

Section: The Extrusion Processmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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An analysis of the mechanics of solid phase extrusion of polymers

1980

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“…The unidirectionally drawn sample is characterized by 5 mechanical constants, Cll , c12, c13, c33, c44, which were determined as a function of )t, Ta in PE [272,273], in iPP [274], POM [275] and in nylon 6 and 6.6 [276]. From the structure of dynamically strained drawn and annealed iPP L~ and L~ have been derived as function of TA with ta = 1 and 30 min.…”

Section: Mechanical Properties Of the Drawn Samplementioning

confidence: 99%

Drawing and extrusion of semi-crystalline polymers

Peterlin

1987

Colloid & Polymer Sci

246

194

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This review treats mainly the initial transformation of the starting unoriented lamellar material into the final oriented microfibrillar structure and its drawing. If the starting material has partially oriented shish-kebab structure the drawing is a combination of transformation of lamellae into the microfibrils and the drawing of microfibrils. The review artide is based on the literature from the last ten years and relys heavily on recent reviewing [1][2][3]. Older articles are only included if they have contributed to the basic ideas and experiments of drawing.

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Enhancement of the mechanical properties of polylactides by solid-state extrusion. II. Poly(L-lactide), poly(L/D-lactide), and poly(L/DL-lactide)

Ferguson

Wahl

Gogolewski

1996

J. Biomed. Mater. Res.

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Polylactides with various degrees of chain regularity-crystalline poly(L-lactide); amorphous poly(L/D-lactide), and amorphous poly(L/DL-lactide)-were processed into high-strength, high-modulus resorable rods using solid-state extrusion through a conical die. The rods with a highly fibrillated structure had flexural strengths at a yield of up to 215 MPa and flexural modulus of up to 13.7 GPa. The initially amorphous poly(L/DL-lactide) developed approximately 25% of crystallinity after solid-state extrusion. Poly(L/D-lactide) remained amorphous independently of the treatment procedure applied. The shear strengths, flexural strengths, and flexural moduli of the solid-state extruded rods increased with increasing draw ratio. For the semicrystalline materials, solid-state extrusion enhanced the crystallinity. The achievable draw ratios during solid-state extrusion, and in consequence the final mechanical properties, were lower for poly(L/D-lactide) and poly(L/DL-lactide) than for poly(L-lactide).

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Hydrostatic extrusion of polyoxymethylene

Cited by 74 publications

References 23 publications

An analysis of the mechanics of solid phase extrusion of polymers

An analysis of the mechanics of solid phase extrusion of polymers

Drawing and extrusion of semi-crystalline polymers

Enhancement of the mechanical properties of polylactides by solid-state extrusion. II. Poly(L-lactide), poly(L/D-lactide), and poly(L/DL-lactide)

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