Solid state coextrusion: A new technique for ultradrawing thermoplastics illustrated with high density polyethylene

Griswold, Phillip D.; Zachariades, Anagnostis E.; Porte, Roger S.

doi:10.1002/pen.760181106

Cited by 74 publications

(35 citation statements)

References 9 publications

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“…coextrusion, developed by Porter et al, 12 is a useful technique for the preparation of the ␤-PVDF films with superior mechanical and electrical properties.…”

Section: Resultsmentioning

confidence: 99%

“…The wet gel film was dried in vacuo at room temperature to constant weight. For solid-state coextrusion, 12 a 50 m-thick gel film was placed between two split billet halves of poly(4-methyl-1-pentene) with a diameter of 20 mm, and the assembly was coextruded to the maximum extrusion draw ratio (EDR max ) of 8 at an established optimum extrusion temperature of 160°C.…”

Section: Preparation Of Drawn Filmsmentioning

confidence: 99%

“…3,6 Therefore, the preparation of a ␤-PVDF film with higher crystallinity and higher chain orientation has been a subject of extensive effort. 6,10 In our previous article 11 on solid-state coextrusion, developed by Porter et al, 12 and two-stage drawing of ␣-form PVDF films with a variety of initial morphologies, it was found that the conversion of ␣-form crystals to the ␤-form on draw was significantly affected by both the initial morphologies and draw techniques. The solid-state coextrusion of a dry gel film, prepared from a 10 wt % PVDF solution in cyclohexanone, at 160°C, some 10°C below its melting point, produced a highly oriented and highly crystalline film with only piezoelectric ␤-form crystals.…”

Section: Introductionmentioning

confidence: 97%

See 2 more Smart Citations

Enhanced electrical properties of highly oriented poly(vinylidene fluoride) films prepared by solid-state coextrusion

Nagai

Nakamura

Uehara

et al. 1999

J. Polym. Sci. B Polym. Phys.

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“…coextrusion, developed by Porter et al, 12 is a useful technique for the preparation of the ␤-PVDF films with superior mechanical and electrical properties.…”

Section: Resultsmentioning

confidence: 99%

Section: Preparation Of Drawn Filmsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

See 1 more Smart Citation

Enhanced electrical properties of highly oriented poly(vinylidene fluoride) films prepared by solid-state coextrusion

Nagai

Nakamura

Uehara

et al. 1999

J. Polym. Sci. B Polym. Phys.

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“…For the first-stage drawing, a solid-state coextrusion technique developed by Porter et al 19 was used. For the secondstage, a conventional tensile drawing technique was used.…”

Section: Experiments Almentioning

confidence: 99%

Unusual Stress–Strain Behavior in Ultra-Drawn Films of High Molecular Weight Poly(4-methyl-1-pentene)

Kanamoto

Ohtsu

1988

Polym J

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KEY WORDSPoly(4-methyl-1-pentene) / Ultradrawing / Unusual StressStrain Behavior / Crystal Transformation / New Crystal Form / Recently, ultradrawing of flexible chain polymers has been extensively studied to achieve the maximum mechanical properties.1 -3 Among many polymers studied, only ultrahigh molecular weight (UHMW) polyethylene4-7 and polypropylene 8 -10 have been ultradrawn to the limits in terms of mechanical and physical properties approaching limits.In our current study of ultradrawing of poly(4-methyl-l-pentene) (P4MlP), it was found that single crystal mats of UHMW-P4M 1P could also be drawn to a high draw ratio (DR) of 80 by a two-stage drawing technique. 5 · 8 The ultradrawn films exhibited unusual stress-strain curves for ambient tensile testing. The curve was characterized by three distinct regions consisting of an initial elastic region, a yield region, and finally, a post-yield region. A similar stress-strain curve has been reported only in a few polymers such as wool 11 • 12 and oriented polypivalolactone 13 and poly(butylene terephthalate) 14 where the alpha-beta (helix-planar zigzag or gauchetrans) transformation occurred ·on extension. In contrast to these polymers, however, ultradrawn UHMW-P4MlP showed tensile moduli of 7.5-9.1 GPa in the post-yield region, which were significantly higher than the crystal modulus of 2.9-6.7 GPa 15 ' 16 reported for the ordinary tetragonal form of P4MlP. 17 · 18 In this communication, we report unusual stress-strain behavior observed in ultradrawn films of UHMW-P4MIP and studied in relation to the specific morphology and the crystal structural or conformational changes that occurred during extension at room temperature. EXPERIMENT ALThe UHMW-P4MlP used was a highly isotactic polymer with viscosity average MW of 1.5 x 10 6 • Solution-grown crystals (SGC) were isothermally precipitated from a 0.2 wt% solution in xylene kept at 50°C over 20 h. SGC mats were obtained by slowly filtering the crystal suspension followed by drying at 50°C.A two-stage drawing technique 5 · 8 was utilized for uniaxial drawing of SGC mats of UHMW-P4MlP. For the first-stage drawing, a solid-state coextrusion technique developed by Porter et al. 19 was used. For the secondstage, a conventional tensile drawing technique was used. Extrudates having an extrusion DR (EDR) of 6 prepared at 180cc were drawn at 180-200°C in an air oven equipped with a Tensilon tensile tester HTM-100. The total DR was defined by DR 1 = EDRxDR.179

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“…Draw was made by SSCE, 23 since sc-crystals were produced more efficiently by this technique than for the tensile drawing as reported in our previous work. 21 For SSCE, a strip 10 mm wide and 70 mm long was placed between split billet halves of poly(4-methyle-1-pentene) (P4M1P) and the assembly was coextruded through a conical brass die.…”

Section: Drawingmentioning

confidence: 99%

Development of Oriented Morphology and Mechanical Properties upon Drawing of Stereo-Complex of Poly(L-lactic acid) and Poly(D-lactic acid) by Solid-State Coextrusion

Sawai

Tamada

Kanamoto

2007

Polym J

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ABSTRACT:A semicrystalline film consisting of only stereo-complex (sc) crystals was prepared by casting from a solution of an equimolar blend of poly(L-lactic acid) (PLLA) and poly(D-lactic acid) (PDLA). The film was uniaxially drawn by solid-state coextrusion, and the development of oriented morphology and mechanical properties was investigated by DSC, WAXD, dynamic mechanical analyses and tensile tests. The ductility increased with extrusion temperature (T ext ), reached a maximum at a T ext of 200 C, and at yet higher T ext 's it rapidly decreased. The maximum tensile modulus and strength of 9.5 GPa and 410 MPa, respectively, were achieved for a highly drawn sc-film prepared by coextrusion at a T ext of 200 C and EDR of 16. Such a drawn film consisted of highly oriented sc-crystals and had a crystallinity of c ¼ 59 wt % and a high chain orientation function of f c ¼ 0:993. The oriented sc-films exhibited remarkably enhanced heat-resistance compared to the oriented films of PLLA homo-polymer. The dynamic storage modulus of a sc-film with an EDR of 16, measured at 11 Hz, was 9.5 GPa at room temperature and 2.7 GPa even at 200 C, 20-25 C above the melting temperatures of -and -form homo-crystals. The high thermal stability of oriented sc-films was primarily ascribed to the high melting temperature and weak -relaxation intensity for the sc-films compared to the PLLA films. No existence of a crystalline relaxation in the sc-films also contributed to improve their thermal stability. Poly(L-lactic acid) (PLLA) attracts considerable interest from both fundamental and industrial viewpoints because it can be synthesized from renewable resources, such as corn and potato.1-3 Since PLLA is biodegradable and biocompatible, this polymer has been used for biomedical applications.4-6 Because PLLA has fairly good mechanical properties with a high melting temperature (T m ¼ 170{180 C), its application for more general purposes as an environmentally friendly and economically feasible polymer has been evaluated. [7][8][9] PLLA commonly crystallizes into two crystal modifications; i.e., the -and the -forms, 10-12 both of which have a melting temperature around 170-180 C. It has been reported that an equimolar blend of PLLA and poly(D-lactic acid) (PDLA) forms a mixture of stereo-complex crystals and -form homocrystals when it was crystallized from solutions and melt, depending on the crystallization conditions. 13,14 Homo-crystals, such as -form and -form crystals consist of only PLLA or PDLA molecules, whereas the sc-crystal is composed of PLLA and PDLA chains with opposite helical hand packed side by side. It is interesting to note that the sc-crystal shows a melting temperature of 220-230 C, which is about 50-60 C higher than those for the homo-crystals. Recently, Kimura et al. 15,16 found bacteria which produces Dlactic acid from glucose. This finding may allow to produce D-lactic acid more easily at a lower coast and enhance the application of sc-poly(lactic acid).It has been reported that when an equimolar blend of PLLA and ...

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Solid state coextrusion: A new technique for ultradrawing thermoplastics illustrated with high density polyethylene

Abstract: Ultra-oriented high density pOlyethylene (HDPE)

Cited by 74 publications

References 9 publications

Enhanced electrical properties of highly oriented poly(vinylidene fluoride) films prepared by solid-state coextrusion

Enhanced electrical properties of highly oriented poly(vinylidene fluoride) films prepared by solid-state coextrusion

Unusual Stress–Strain Behavior in Ultra-Drawn Films of High Molecular Weight Poly(4-methyl-1-pentene)

Development of Oriented Morphology and Mechanical Properties upon Drawing of Stereo-Complex of Poly(L-lactic acid) and Poly(D-lactic acid) by Solid-State Coextrusion

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