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V. A. Beloshenko - One of the best experts on this subject based on the ideXlab platform.

  • Encyclopedia Of Polymer Science and Technology - Solid‐State Extrusion
    Encyclopedia of Polymer Science and Technology, 2015
    Co-Authors: V. A. Beloshenko, Ya. E. Beygelzimer, Yuri Voznyak
    Abstract:

    Solid-State Extrusion (SSE) is a method for attaining a highly oriented state of polymers, and is based on polymer deformation at temperatures just below the polymer melting temperature, or for amorphous polymers just above the glass-transition temperature mainly by Extrusion through conical or slit dies. SSE is used for shape forming and structure modification of various polymer materials (homopolymers, polymer blends, filled polymer composites) and makes it possible to produce fibers, films, pipes, shapes including those of large cross section and of different configurations, possessing high strength–stress characteristics. In this article, much attention is given to the most known SSE versions—plunger Extrusion and hydrostatic Extrusion with the information on the influence of process controlling parameters on Extrusion pressure, velocity of product exiting, value of extrudate swell, structure and properties of the processed material. There exists a region of controlling parameters where the process is stable; outside the region, the polymer flow is discontinuous, extrudate shape is imperfect and, finally, its failed. Two new techniques of SSE are presented in brief, namely the equal channel angular Extrusion and the twist Extrusion which, in contrast to the conventional ones, are based on polymer simple shear, not drawing. These techniques are found to be promising for structure modification of polymers. Keywords: polymer; Solid-State Extrusion; equal channel angular Extrusion; twist Extrusion; Extrusion conditions; deformation mechanism; structure; properties

  • Solid‐phase Extrusion of polyamide‐6 by using combined deformation schemes
    Polymer Engineering & Science, 2011
    Co-Authors: V. A. Beloshenko, V. N. Varyukhin, A. V. Voznyak, Yuri Voznyak
    Abstract:

    Potentialities of new combined deformation schemes, including the solid state Extrusion through conical die (ED) and equal-channel multiple angle Extrusion (ECMAE) implemented in different sequence to modify structure and properties of semicrystalline polymers, have been studied for polyamide-6 as an example. It is shown that deformation by the ED-ECMAE scheme gives the best complex of physical and mechanical properties. A significant improvement in elastic and strength properties of polyamide-6 with the conserved high level of plastic characteristics has been observed. There was only a slight anisotropy and dispersion of microhardness across the extrudates. A more uniform oriented structure with lamellae orientation along extrudate's axis has been formed in semicrystalline polymer because the ED-ECMAE scheme implementation. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

  • Modification of polyamide-6 structure by combined methods of solid-phase Extrusion
    High Pressure Research, 2011
    Co-Authors: V. A. Beloshenko, A. V. Voznyak, Yuri Voznyak
    Abstract:

    Potentialities of new combined deformation schemes, including the Solid-State Extrusion through conical die (ED) and equal-channel multiple angle Extrusion (ECMAE) implemented in different sequences to modify the structure and properties of semicrystalline polymers, have been studied for polyamide-6 (PA-6) as an example. It is shown that deformation by the ED–ECMAE scheme gives the best complex of physical and mechanical properties. A significal improvement of elastic and strength properties of PA-6 with a conserved high level of plastic characteristics has been observed.

  • Thermal shrinkage of polymer mixtures obtained by Solid-State Extrusion
    Polymer, 2000
    Co-Authors: V. A. Beloshenko, Ya. E. Beygel’zimer, V. N. Varyukhin
    Abstract:

    The peculiarities of the process of thermal shrinkage of polymer-mixture specimens obtained by plunger Extrusion of powder billet have been studied. Shrinkage has been found to be accompanied by the increase of extrudate volume, which is connected with the formation of discontinuities at the interface. The proposed model explains material loosening under shrinkage.

  • Solid-State Extrusion of polymerization-filled polymer compositions
    Mechanics of Composite Materials, 1999
    Co-Authors: V. A. Beloshenko, Ya. E. Beygelzimer, V. N. Varyukhin, V. G. Grinev
    Abstract:

    The mechanical properties of ultra-high molecular polyethylene and filled compositions based on it produced by Solid-State Extrusion of powder semifabricates have been investigated. It is shown that high-level properties are obtained by extrudates with fillers possessing high disposition to adhesive interaction with the polymer matrix. A mathematical model of Solid-State Extrusion of the compositions is derived considering the possibility of compaction and loosening of the material in the process of deformation. Satisfactory agreement of the calculated and experimental data is obtained.

Miko Cakmak - One of the best experts on this subject based on the ideXlab platform.

  • Processing characteristics and structure development in solid‐state Extrusion of bacterial copolyesters: Poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)
    Journal of Applied Polymer Science, 1996
    Co-Authors: Y. D. Wang, T. Yamamoto, Miko Cakmak
    Abstract:

    The bacterial copolyesters poly(3-hydroxybutyrate-co-3-hydroxyvalerate) have been successfully commercialized by ICI and are currently being distributed worldwide. Because of their bacterial origin, they are completely biodegradable. This has opened up numerous opportunities to develop new environmentally friendly products. The Solid-State Extrusion of a series of biodegradable copolyesters (P(3HB-3HV)) was performed in our laboratory with the aim of gaining fundamental understanding about their processability below their melting temperatures. The extrudability windows were found to span the temperature range from 135 to 150°C, depending on the composition of the samples under our experimental setup. The Solid-State extrudates were found to exhibit an extra melting endotherm about 15–20°C above their normal melting temperature. This high temperature melting peak increasingly became dominant at lower Extrusion temperatures. Wide angle X-ray diffraction studies did not indicate any phase change that might be responsible for this increase in the melting point. Contrary to the expectations, the Solid-State extruded samples did not show significant chain orientation along the Extrusion direction. This might be a result of fracture of the mass in the barrel into smaller pieces and their randomization during the course of their passage through the die. When the Extrusion temperature was raised closer to the melting temperature, the quality of the extrudates was improved, and this was reflected in improvement of their mechanical properties. © 1996 John Wiley & Sons, Inc.

  • Processing characteristics and structure development in Solid-State Extrusion of a new semicrystalline polyimide (BTDA–DMDA)
    Journal of Applied Polymer Science, 1995
    Co-Authors: Y. D. Wang, Miko Cakmak, F. W. Harris
    Abstract:

    In this article, we present detailed processing characteristics and structure development in a thermoplastic polyimide BTDA–DMDA in the Solid-State Extrusion process. This fully imidized polyimide polymer is known to crosslink at fast rates when it is brought to a molten phase even for short periods of time. This characteristic makes it difficult to process it in the molten phase and attempts at melt processing result in melt fracture and highly distorted extrudates. However, this polymer can be shaped into high-quality extrudates when it is processed below its melting temperature directly from its postpolymerization powdered state. The Solid-State Extrusion of precompacted BTDA–DMDA powder was studied in the temperature range from 250 to 320°C. At the temperatures from 290 to 320°C, high-quality extrudates were obtained. Below 290°C, Solid-State Extrusion was not possible due to the limitation of the load cell capacity of the capillary rheometer used in this research. Above 320°C, the extrudates were found to be of poor quality as a result of degradation and crosslinking in the molten phase. Structural characteristics of the samples produced by Solid-State Extrusion was investigated by the microbeam X-ray diffraction technique. The thermal behavior of the extrudates was also characterized by differential scanning calorimetry (DSC). The DSC results show that at low Extrusion temperatures the samples exhibit dual endothermic peaks and are highly crystalline in an extruded state. The higher melting peak located at about 350°C is due to the melting of the new crystalline phase that has developed partially during the Solid-State Extrusion process and partially during the recrystallization process that takes place at temperatures at and slightly above the primary melting process during the DSC heating scan. This has been confirmed by DSC, depolarized light hot-stage video microscopy, and wide-angle X-ray diffraction studies. The long spacing of the higher melting crystals was found to be much larger than that of the lower melting crystals, as evidenced by the small angle X-ray scattering studies. © 1995 John Wiley & Sons, Inc.

  • processing characteristics and structure development in solid state Extrusion of a new semicrystalline polyimide btda dmda
    Journal of Applied Polymer Science, 1995
    Co-Authors: Y. D. Wang, Miko Cakmak, F. W. Harris
    Abstract:

    In this article, we present detailed processing characteristics and structure development in a thermoplastic polyimide BTDA–DMDA in the Solid-State Extrusion process. This fully imidized polyimide polymer is known to crosslink at fast rates when it is brought to a molten phase even for short periods of time. This characteristic makes it difficult to process it in the molten phase and attempts at melt processing result in melt fracture and highly distorted extrudates. However, this polymer can be shaped into high-quality extrudates when it is processed below its melting temperature directly from its postpolymerization powdered state. The Solid-State Extrusion of precompacted BTDA–DMDA powder was studied in the temperature range from 250 to 320°C. At the temperatures from 290 to 320°C, high-quality extrudates were obtained. Below 290°C, Solid-State Extrusion was not possible due to the limitation of the load cell capacity of the capillary rheometer used in this research. Above 320°C, the extrudates were found to be of poor quality as a result of degradation and crosslinking in the molten phase. Structural characteristics of the samples produced by Solid-State Extrusion was investigated by the microbeam X-ray diffraction technique. The thermal behavior of the extrudates was also characterized by differential scanning calorimetry (DSC). The DSC results show that at low Extrusion temperatures the samples exhibit dual endothermic peaks and are highly crystalline in an extruded state. The higher melting peak located at about 350°C is due to the melting of the new crystalline phase that has developed partially during the Solid-State Extrusion process and partially during the recrystallization process that takes place at temperatures at and slightly above the primary melting process during the DSC heating scan. This has been confirmed by DSC, depolarized light hot-stage video microscopy, and wide-angle X-ray diffraction studies. The long spacing of the higher melting crystals was found to be much larger than that of the lower melting crystals, as evidenced by the small angle X-ray scattering studies. © 1995 John Wiley & Sons, Inc.

  • Solid state Extrusion of vinylidene fluoride (VF2)/vinylidene trifluoride (VF3) copolymers. I: Dynamics of solid state Extrusion
    Polymer Engineering and Science, 1993
    Co-Authors: J. S. Lee, Miko Cakmak
    Abstract:

    Solid state Extrusion dynamics of poly(vinylidene fluoride) and its copolymers have been studied using an Instron capillary rheometer with specially designed die set. At and above the Curie transition temperatures, the copolymers rapidly soften while preserving the semicrystalline structure. This allows them to be solid state extruded between this temperature and melting temperature. The processing windows within which high quality extrudates can be obtained were established for two copolymer compositions and they were found to be much wider than those typically observed in semicrystalline homopolymers such as polyethylene and polypropylene. Extrudate swell under all solid state Extrusion condition remains constant and is always less than 1 and it was found to increase above this value as the Extrusion temperature increased through the melting region which is typical of melt Extrusion of these polymers.

  • Solid state Extrusion of vinylidene fluoride (VF2)/vinylidene trifluoride (VF3) copolymers. II: Structure development
    Polymer Engineering and Science, 1993
    Co-Authors: J. S. Lee, Miko Cakmak
    Abstract:

    Copolymers of vinylidene fluoride (VF2) and vinyltrifluoride (VF3) exhibit Curie transition temperatures well below their melting points. Above these endothermic transitions, they soften and this behavior helps in their solid state extrudability. In this paper, the effects of Extrusion speed, temperature, and draw ratio on structure development in 60/40 and 72/28 VF2/VF3 copolymer compositions are presented. With the increase of Extrusion draw ratio the Curie transition temperature of the extrudates decreased and melting temperature increased. This behavior suggested that the chains in the crystalline regions contain higher levels of conformational defects while overall crystallinity is increased. Unoriented polymers were optically opaque and extrudates were found to be transparent as a result of breakdown on the superstructural level which decreases the scattering effects in the visible wavelength range. The micro beam WAXS studies on the samples taken from the entrance of the dies revealed that the unoriented core is surrounded by alternating unoriented and oriented layers close to the core. The remainder of the skin layers are found to be oriented with local symmetry axes and main chain orientation being parallel to the die wall surface. The regions that are found to be oriented were also found to be optically translucent and unoriented regions were optically opaque. This structure turns uniformly transparent–and thus oriented‒as the polymer enters the die. The existence of layered structure suggests that highly localized yielding occurs during early states of deformation at the converging entrance region of the die. Examination of the radial structural variation in extrudates with micro beam X-ray diffraction technique revealed that the local symmetry axes are tilted away from the Extrusion direction and this tilt angle reduces at the sample macro-symmetry axis at the core of the samples. This indicated that the tilted structure developed at the converging entrance region is partially preserved through the die. While the orientation of local symmetry axes varies from skin to core in the extrudates, the orientation of chains with respect to these local symmetry axes remains relatively unaffected.

Zaifu Lin - One of the best experts on this subject based on the ideXlab platform.

  • Engineering Porous Poly(lactic acid) Scaffolds with High Mechanical Performance via a Solid State Extrusion/Porogen Leaching Approach
    Polymers, 2016
    Co-Authors: Hua-mo Yin, Jing Qian, Jin Zhang, Zaifu Lin
    Abstract:

    A knotty issue concerning the poor mechanical properties exists in the porogen leaching approach to porous scaffolds, despite its advantage in tuning pore structure. To address this hurdle, solid state Extrusion (SSE) combined with porogen leaching was utilized to engineer porous scaffolds of poly(lactic acid) (PLA). Advances introduced by poly(ethylene glycol) (PEG) caused the PLA ductile to be processed and, on the other hand, enabled the formation of interconnected pores. Thus, a well-interconnected porous architecture with high connectivity exceeding 97% and elevated porosity over 60% was obtained in the as-prepared PLA scaffolds with the composition of NaCl higher than 75.00 wt % and PEG beyond 1.25 wt %. More strikingly, the pore walls of macropores encompassed countless micropores and rough surface topography, in favor of transporting nutrients and metabolites as well as cell attachment. The prominent compressive modulus of the PLA scaffolds was in the range of 85.7–207.4 MPa, matching the normal modulus of human trabecular bone (50–250 MPa). By means of alkaline modification to improve hydrophilicity, biocompatible porous PLA scaffolds exhibited good cell attachment. These results suggest that the SSE/porogen leaching approach provides an eligible clue for fabricating porous scaffolds with high mechanical performance for use as artificial extracellular matrices.

  • engineering porous poly lactic acid scaffolds with high mechanical performance via a solid state Extrusion porogen leaching approach
    Polymers, 2016
    Co-Authors: Hua-mo Yin, Jing Qian, Jin Zhang, Zaifu Lin
    Abstract:

    A knotty issue concerning the poor mechanical properties exists in the porogen leaching approach to porous scaffolds, despite its advantage in tuning pore structure. To address this hurdle, solid state Extrusion (SSE) combined with porogen leaching was utilized to engineer porous scaffolds of poly(lactic acid) (PLA). Advances introduced by poly(ethylene glycol) (PEG) caused the PLA ductile to be processed and, on the other hand, enabled the formation of interconnected pores. Thus, a well-interconnected porous architecture with high connectivity exceeding 97% and elevated porosity over 60% was obtained in the as-prepared PLA scaffolds with the composition of NaCl higher than 75.00 wt % and PEG beyond 1.25 wt %. More strikingly, the pore walls of macropores encompassed countless micropores and rough surface topography, in favor of transporting nutrients and metabolites as well as cell attachment. The prominent compressive modulus of the PLA scaffolds was in the range of 85.7–207.4 MPa, matching the normal modulus of human trabecular bone (50–250 MPa). By means of alkaline modification to improve hydrophilicity, biocompatible porous PLA scaffolds exhibited good cell attachment. These results suggest that the SSE/porogen leaching approach provides an eligible clue for fabricating porous scaffolds with high mechanical performance for use as artificial extracellular matrices.

V. N. Varyukhin - One of the best experts on this subject based on the ideXlab platform.

  • Solid‐phase Extrusion of polyamide‐6 by using combined deformation schemes
    Polymer Engineering & Science, 2011
    Co-Authors: V. A. Beloshenko, V. N. Varyukhin, A. V. Voznyak, Yuri Voznyak
    Abstract:

    Potentialities of new combined deformation schemes, including the solid state Extrusion through conical die (ED) and equal-channel multiple angle Extrusion (ECMAE) implemented in different sequence to modify structure and properties of semicrystalline polymers, have been studied for polyamide-6 as an example. It is shown that deformation by the ED-ECMAE scheme gives the best complex of physical and mechanical properties. A significant improvement in elastic and strength properties of polyamide-6 with the conserved high level of plastic characteristics has been observed. There was only a slight anisotropy and dispersion of microhardness across the extrudates. A more uniform oriented structure with lamellae orientation along extrudate's axis has been formed in semicrystalline polymer because the ED-ECMAE scheme implementation. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

  • Thermal shrinkage of polymer mixtures obtained by Solid-State Extrusion
    Polymer, 2000
    Co-Authors: V. A. Beloshenko, Ya. E. Beygel’zimer, V. N. Varyukhin
    Abstract:

    The peculiarities of the process of thermal shrinkage of polymer-mixture specimens obtained by plunger Extrusion of powder billet have been studied. Shrinkage has been found to be accompanied by the increase of extrudate volume, which is connected with the formation of discontinuities at the interface. The proposed model explains material loosening under shrinkage.

  • Solid-State Extrusion of polymerization-filled polymer compositions
    Mechanics of Composite Materials, 1999
    Co-Authors: V. A. Beloshenko, Ya. E. Beygelzimer, V. N. Varyukhin, V. G. Grinev
    Abstract:

    The mechanical properties of ultra-high molecular polyethylene and filled compositions based on it produced by Solid-State Extrusion of powder semifabricates have been investigated. It is shown that high-level properties are obtained by extrudates with fillers possessing high disposition to adhesive interaction with the polymer matrix. A mathematical model of Solid-State Extrusion of the compositions is derived considering the possibility of compaction and loosening of the material in the process of deformation. Satisfactory agreement of the calculated and experimental data is obtained.

  • Properties of ultra-high-molecular polyethylene and related polymerization-filled composites produced by Solid-State Extrusion
    Acta Polymerica, 1997
    Co-Authors: V. A. Beloshenko, V. N. Varyukhin, G. V. Kozlov, V. G. Slobodina
    Abstract:

    The structural, shrinkage and mechanical characteristics were studied of specimens of ultra-high-molecular polyethylene (UHMPE) and polymerization-filled composites UHMPE-A1 and UHMPE-bauxite produced by plunger Extrusion of powder material. It is shown that the dependence of the strain-stress characteristics of UHMPE and its composites on the Extrusion ratio varies considerably in the presence of a filler. Mechanisms explaining the behavior of the polymer material under study are proposed.

Roger S. Porter - One of the best experts on this subject based on the ideXlab platform.

  • Formation properties of solid‐state extruded high density polyethylene fibers
    Journal of Polymer Science: Polymer Symposia, 2007
    Co-Authors: William T. Mead, Roger S. Porter
    Abstract:

    Extrusion rates have been measured for high density polyethylene fibers prepared by Solid-State Extrusion through a conical die with maximum draw ratio of 52, using constant pressure and temperatures ranging from 0.12 to 0.49 GPa and 60° to 140°C and molecular weights from 5 × 104 to 6 × 106. The processing variables are reported in terms of an apparent elongational viscosity. The logarithm of the Extrusion rate was proportional to the applied pressure. Deviation from the Eyring theory of viscosity was found, since lowering of the Extrusion temperature to 60°C produced an anomalous decrease in the Extrusion rates. The anomaly was explained by the increased friction between die and polymer, the pressure dependence of the yield stress, and by the pressure dependence of the α-relaxation mechanism. Apparent activation energies of 60 and 100 kcal/mole were calculated for the Solid-State Extrusion in the region 100°–130°C and 80–100°C. Three modes of deformation were observed for each Extrusion, consisting of an unsteady state, a second stage of drawing in which the Extrusion rate approached a constant value, and a fracture region. The first mode corresponded to orientation and rotation of the crystalline lamellae, as shown by the rapid increase and plateau region of the crystalline and noncrystalline orientation functions. During the second stage of deformation, the apparent elongational viscosity ηE increased linearly with draw ratio, as did the modulus, and this mode was found necessary for the attainment of high modulus fibers. The second mode of deformation was associated with the deformation of the crystalline lamellae and strain hardening in which ηE-approached that for a glass. Strain hardening readily occurred with decreasing temperature, and increasing draw ratio and molecular weight. Continuous Extrusion producing uniform modulus fibers was only possible when the maximum draw ratio of the die was less than the fiber draw ratio, where strain hardening occurred. The third mode of deformation limited the maximum modulus obtainable and consisted of fracture or kink planes oblique to the fiber axis. The relations between the processing variables used in the Solid-State Extrusion and the resulting fiber properties are discussed.

  • Properties of oriented polyethylene bars of large cross section
    Journal of Applied Polymer Science, 1994
    Co-Authors: Gregory J. Courval, Li-hui Wang, Roger S. Porter
    Abstract:

    The Solid-State Extrusion technique has been used to prepare uniaxially oriented polyethylene bars with rectangular end cross sections of 6 × 50 mm2. They were extruded at 110°C from billets of high density polyethylene. The tensile modulus and strength for the extrudate with a draw ratio (DR) of 14 were 17.9 and 0.32 GPa, respectively. The mechanicals were also measured in the transverse direction by means of the proportional elastic limit (PEL) bending test. The PEL results do not change after DR 14 due to the fibrillate structure formation. Crystallinity and shrinkage tests were made on samples taken over the bar cross section. They show that uniform properties were achieved across the width of the bar with proper die design. © 1994 John Wiley & Sons, Inc.

  • The characterization and properties of nylon 13,13
    Polymer, 1993
    Co-Authors: Li-hui Wang, Tetsuo Kanamoto, F.j.balta Calleja, Roger S. Porter
    Abstract:

    Abstract The physical properties of the nylon with the longest number of methylene segments, nylon 13,13 have been characterized. Studies are reported of thermal analysis, X-ray scattering and for mechanical properties including hardness. The crystal of nylon 13,13 has been found to have a monoclinic form with a = 4.9 A , b = 9.22 A , c = 34.40 A and β = 121.08°. Also, studies were carried out on the mechanical properties of nylon 13,13 that had been uniaxially drawn by Solid-State Extrusion at 125 and 135°C. The highest draw ratio obtained was 4.5. The maximum melting point, heat of fusion and amorphous density were estimated to be ⩾ 183°C, 230 J g−1 and 1.01 g cm−3, respectively. The crystallinity, melting temperature and tensile modulus increased with draw ratio. The glass transition temperature of the undrawn polymer was 56°C. For the sample with a draw ratio of 4.0, the tensile modulus and the X-ray crystal orientation function reached 2 GPa and 0.94, respectively.

  • Crystallization of poly(ether ether ketone) oriented by Solid-State Extrusion
    Macromolecules, 1991
    Co-Authors: Youngchul Lee, Roger S. Porter
    Abstract:

    Semi crystalline and amorphous PEEK were drawn at 154 and 149°C, respectively, using the Solid-State Extrusion technique. The crystal orientation and total orientation of drawn PEEK were determined. The relationships between deformation history and crystallization have been investigated. Previously drawn PEEK was crystallized nonisothermally and isothermally from the melt. Results show that the crystallization of drawn PEEK is slower than that of the undrawn initial films. An orientation-induced crystallization was found during the Solid-State Extrusion of amorphous PEEK films at 149°C