WO1992004176A1 - Membrane polymere a orientation triaxiale - Google Patents

Membrane polymere a orientation triaxiale Download PDF

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Publication number
WO1992004176A1
WO1992004176A1 PCT/US1991/006188 US9106188W WO9204176A1 WO 1992004176 A1 WO1992004176 A1 WO 1992004176A1 US 9106188 W US9106188 W US 9106188W WO 9204176 A1 WO9204176 A1 WO 9204176A1
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membrane
draw
rolltrusion
workpiece
ipp
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Joseph H. Magill
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University of Pittsburgh
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University of Pittsburgh
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
    • B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
    • B29C55/18—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets by squeezing between surfaces, e.g. rollers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0002—Organic membrane manufacture
    • B01D67/0023—Organic membrane manufacture by inducing porosity into non porous precursor membranes
    • B01D67/0025—Organic membrane manufacture by inducing porosity into non porous precursor membranes by mechanical treatment, e.g. pore-stretching
    • B01D67/0027—Organic membrane manufacture by inducing porosity into non porous precursor membranes by mechanical treatment, e.g. pore-stretching by stretching
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/26—Polyalkenes
    • B01D71/261—Polyethylene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/26—Polyalkenes
    • B01D71/262—Polypropylene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/48—Polyesters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/50—Polycarbonates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/56—Polyamides, e.g. polyester-amides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/76—Macromolecular material not specifically provided for in a single one of groups B01D71/08 - B01D71/74
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/08—Specific temperatures applied
    • B01D2323/081—Heating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/43—Specific optical properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
    • B29K2995/0037—Other properties
    • B29K2995/0065—Permeability to gases

Definitions

  • the invention relates to an improved polymer membrane or thin-like film used in chemical technology. More particularly, the invention relates to a triaxially oriented polymer membrane produced by the rolltrusion process.
  • Polymers by definition, are long chain molecules in which the atoms are bound to one another by means of strong covalent bonds. Hence one would expect exceptionally high strength and stiffness values in the chain direction since the applied load would then be opposed by the covalent bond themselves. On the contrary, most of the commercial polymers exhibit strength and stiffness values far below their theoretical limits. It is established that the modulus values of most of the commercial polymers are at least an order of magnitude less than their theoretical limits, thus severely limiting their use in many structural or load bearing applications. One of the many ways to improve engineering properties lies in the preparation of highly chain extended/oriented polymers.
  • Solid State Deformation of Polymers Amongst the orientation techniques mentioned, solid state deformation of polymers has been extensively researched because of its technological and commercial importance.
  • A. Cold Drawing This is the foremost amongst the various deformation techniques used in the preparation of highly oriented crystalline and amorphous polymers. Cold drawing is usually carried out by drawing the specimen on a tensile testing machine. The extent of drawing is highly dependent on deformation conditions such as draw temperature and speed, and also on material properties, such as molecular weight, molecular weight distribution, and to some extent on the initial morphology of the polymer. The method is limited in practice due to the batch nature of the process and its inability to process large sections of polymer.
  • E. Cold Extrusion The process consists of forcing the solid polymer through a tapered die by means of a ram or plunger.
  • the technique has been successfully employed in the preparation of highly oriented polyethylene, polypropylene and several other polymers.
  • the limitations of this technique are (a) requirement of extremely high pressures for the attainment of high draw ratios; (b) appearance of cracks on the extrudated surfaces at high draw ratios; and (c) inability to process certain types of polymers.
  • This solid state deformation technique was developed by Applicant and co-workers for the preparation of triaxially oriented polyolefins, nylons, ethylene/propropylene block copolymers, polyvinylidene fluoride, poly(ethyleneterephthalate), polycarbonates, poly(aryletheretherketone) (PEEK), and polyester polymers from commercial plastics.
  • the technique in principle, is relatively simple and is a continuous deformation process, which is now shown as employable in the fabrication of highly doubly, or triaxially oriented polymers from such plastics. It overcomes the processing limitations imposed by die drawing, like fixed die dimensions, that limit the processing of large sheets and rods.
  • (B) Biaxial Orientation - In this case, the polymer molecules are preferentially aligned along two different deformation directions usually perpendicular to one another. Film blowing processes normally lead to biaxial orientation; and (C) Triaxial Orientation - When an uniaxially oriented polymer is rolled under suitable conditions, one of the crystallographic planes usually lies parallel to the molecular axis and becomes oriented within the plane of rolling. Triaxially oriented polymers may be produced in several ways, as illustrated in
  • Rolltrusion is a one step operation, which is demonstrably more effective to achieve this orientation. All other known state of the art processes are multi-step operations. Rolltrusion is the method used to produce the membrane of the invention.
  • Triaxially Oriented Polymers Triaxially oriented polyethylene, polypropylene, nylon 6, nylon 66 , and some other polymers, have been produced by various researchers using mainly a two stage process. However, a detailed review of the literature has shown that these polymers have been employed mainly: (i) to detail the structural changes in oriented polymers upon deformation, and (ii) in basic morphological investigation of crystalline polymers. Few, if any, have approached triaxial orientation as a viable alternative for the preparation of high strength/modulus polymers in bulk; hence, the lack of systematic studies on processing- morphology-properties relations in triaxally oriented polymers prior to the present invention. The mechanisms of deformations of semicrystallines are well known.
  • Applicant and co-workers investigated the processing-structure-property relations in rolltruded polyethylene sheets up to draw ratios of about 30:1, and as high as 60:1 for polypropylene. See “Preparation of Highly Doubly Oriented Polymers”; (J.H. Magill et al.. Jour, of Material Science Letters, 5, 267-269, March 1986). Applicant and other co-workers investigated the morphology in deformed polypropylene and propylene/ethylene block copolymers. See Prague Conference Proceedings on Polymer Morphology, July 1985.
  • the rolltrusion process is based on the following considerations
  • the technique produces triaxial orientation, i.e., the crystallographic directions of the crystallites are usually well aligned triaxially with respect to the deformation directions
  • An object of the invention is to provide a membrane or thin-like film comprising a polymer material with a triaxial orientation morphology produced by a rolltrusion process and having a periodicity consisting essentially of crystallites and amorphous materials with no spherulitic textures remaining after said rolltrusion process.
  • a further object of the invention is to provide a membrane or thin-like film comprising a polymer material with a three dimensional morphology having a periodic distribution of crystalline and intercrystalline tie molecular regions.
  • a further object of the invention is to provide a morphology of material made from a crystalline or potentially crystallizable polymer by the rolltrusion process in the form of a relatively thin film which functions as a membrane for the concentration, separation, or removal of gases and small molecules.
  • a still further object of the invention is to provide a porous or a non-porous homogeneous polymer membrane produced by the rolltrusion process and used in gas separation technology.
  • a still further object of the invention is to provide a relatively thin membrane which is both strong and rugged for use in chemical technology.
  • the Young's moduli of HDPE and iPP double oriented specimens prepared by this procedure were enhanced x25 and xl5 times, respectively, over that for the original polymers received from the manufacturer. Tensile strength of these products were significantly improved at least x8 (HDPE) and x30 (iPP) over the original polymer. Draw ratios of x30 for HDPE and x60 for iPP have been obtained.
  • the conditioned plastic workpiece is deformed in its solid state by passage through the rollers (either fixed or rotating) at a nominal deformation of at least 2:1, by means of drawing the workpiece from the downstream end of the rollers.
  • the workpiece is subjected to considerable compression and take-off tension simultaneously depending upon the dimensions of the workpiece and the processing temperature (between greater than Tg and less than Tm) among other factors. It is simultaneously compressed and drawn in a single pass under processing conditions (draw temperature, speed and ratio), to produce triaxially oriented polymer, of good quality and improved mechanical properties, such as tensile strength, tensile modulus, enhanced creep resistance, and based on the triaxial orientation induced by the disclosed rolltrusion process.
  • the wear resistance and other practical aspects of plastic material properties have been measured and thus shown to be improved by the present invention. This technique of process control distinguishes the rolltrusion technique from all prior techniques.
  • the material produced has a triaxially oriented, two-phase morphology. This was characterized by conventional molecular orientational analytical methods for assessing the effect of processing condition on mechanical properties. Good quality processed polymers with greatly enhanced properties were obtained and characterized. The procedure has now been applied to many plastics producing materials all of which demonstrate enhanced moduli and tensile strengths, and higher toughness, triaxial orientation, crystallinity, enthalpy, crystallite size, and so on. Correlations between properties and macroprocessing conditions have been established and are optimized through process modeling protocols presented below.
  • the polymer workpiece may be preconditioned to a temperature below its melting point, but above its glass transition temperature, to insure a high enough draw ratio that will affect triaxial orientation.
  • Preconditioning is conducted in its solid state to a range of 0° to 350°C, so that the deformation may be carried out at least 20°C. below the thermodynamic melting point.
  • the draw temperature used was in the range from 20° to 125°C, permitting a maximum draw ratio ranging from 5 to 30.
  • Amorphous polymers are processed less than 20°C above their respective glass transition temperatures. The draw speed was varied tenfold, ranging from
  • the draw temperature is in the range of 50 to 165°C, permitting a draw ratio ranging from 12.5 at 140° to a draw ratio of 60 at rollers temperature of 158°C. Again, draw ratio was essentially independent of the draw speed, which was in the range 2.6 to 26 mm. per minute. Generally, useful draw ratios range between 5 and 60.
  • the maximum draw ratio usable for a polymeric workpiece is effected by increasing the preconditioning and roller temperatures up to a level clearly below the observed melting point of the workpiece conveniently at least 20°C below the melting point, or less than 20° above the glass transition of the polymer if it is amorphous. Draw speeds of up to 100 mm. per minute are employable with heated rotating rollers.
  • the nominal deformation ratio of the fed billet should be at least 2 to 1.
  • the draw tension at the exit side of the rollers should be sufficient to effect a draw ratio of at least 6.5 to 1, ranging as high as 60 to 1 and above with the polypropylene material, wherein the optimum mechanical properties are gained. This is evidenced by the tensile modulus, tensile strength elongation-at-break and birefringence data presented in the tables. For HDPE a draw ratio of about 22 was used; and for iPP, a draw ratio of about 35 gave the best balance of physical properties for the thusly triaxially oriented workpiece.
  • the invention is particularly concerned with the morphology of the workpiece produced by the rolltrusion process, which workpiece finds particular application as a membrane for the concentration, separation or removal of gases and/or small molecules or particles.
  • iPP isotactic polypropylene
  • PVDF polyvinylidene fluoride
  • PVF 2 polyvinylidene fluoride
  • propylene/ethylene block copolymer Long billets cut from molded or extruded sheets were rolltruded according to established procedures. Draw speeds used were between 0.28 to 6.05 cm/min, in the absence of a preheater. Mechanical properties were found to be independent of draw speed within this range, on the other hand, it was found that draw temperature greatly influenced sample properties as well as morphology. Draw temperatures employed in this study will be discussed further hereinafter.
  • Figure 1 is schematic of changes effected in morphology by rolltrusion
  • Figure 2 is a schematic of a rolltrusion apparatus for triaxial orientation of polymer billets
  • Figure 3 shows the coordinates of triaxially oriented specimens, where the draw or machine direction is Z, the roll plane is YZ, and the transverse load is in X direction;
  • Figure 4 presents the maximum draw ratios obtained as a function of draw temperature for HDPE and iPP samples of specified molecular characteristics
  • Figure 5 presents the plots for Young's modulus for HDPE and iPP as a function of draw ratio;
  • Figure 6 is a plot of
  • Figure 7 is a plot of the percent crystallinity of HDPE and iPP shown as a function of draw ratio for several sets of processing conditions
  • Figure 8 is a plot of the birefringence values of triaxially oriented HDPE and iPP samples as a function of draw ratio
  • Figure 9 presents the plots for tensile strength for HDPE and iPP as a function of draw ratio
  • Figure 10 presents the plots for percent elongation at break of HDPE and iPP as a function of draw ratio
  • Figures 11 and 12 are plots of the Orientation Factors, for both amorphous and crystalline forms, for HDPE and, iPP, as a function of draw ratio;
  • Figure 13 is a schematic of the changes effected in the morphology of a material by the rolltrusion process;
  • Figure 14 is a plot of the relative diffusion rates between biaxial and triaxial polypropylene
  • Figures 15 - 17 are plots showing the mechanical properties of rolltruded iPP specimens as a function of draw ratio
  • Figure 18 is a plot showing the elongation at break as a function of draw ratio for iPP rolltruded at 160°;
  • Figures 19-22 are plots showing mechanical properties for P/E copolymer samples;
  • Figure 23 shows photographs of the triaxial three dimensional morphology of nylon 66
  • Figure 24 shows photographs of the triaxial three dimensional morphology of UHMWPE
  • Figure 25 shows photographs of the triaxial three dimensional morphology of PEEK, a high melting engineering polymer
  • Figure 26 shows X-ray diffraction patterns for polypropylene
  • Figure 27a is a graph of SAXS scattering associated with high density commercial polyethylene
  • Figure 27b is a graph showing SAXS scattering measurements made on PVDF or PVF 2 ;
  • Figure 28 is a graph showing periodic scattering for ethylene/propylene
  • Figure 29 is a graph showing the permeability versus time for C0 2 in iPP.
  • Figure 30 shows graphs for the permeability, diffusivity, and solubility coefficient isotherms as a function of draw ratio in iPP at a constant driving pressure of 25 psia of C0 2 ;
  • Figure 31 is a graph showing the number of moles of C0 2 emerging as a function of time, temperature, and pressure for rolltruded PVF 2 ;
  • Figure 32 is a graph plotting the permeability of several cases as a function of driving pressure in PVF 2 ;
  • Figure 33 is a graph showing the Arrhenius plots for several gases in PVF 2 ;
  • Figure 34 is a graph plotting the deformation ratios for C0 /N 2 for rolltruded iPP.
  • Figure 2 illustrates the rolltrusion design which basically consists of a pair of thermostatted rollers (static or rotating) and a wind-up device to tension and draw the polymer specimen.
  • the specimen or the workpiece is compressed simultaneously as it is passed through the rollers.
  • the specimen may also be preheated using an external device depending on the type and size of the polymer workpiece.
  • the take-off tension and compressive forces applied simultaneously to the workpiece in the nip of the rollers are similarly determined by the workpiece and its mechanical/physical properties.
  • the compressive force in the roller gap coupled with the tensile (drawing) force, induces high- deformation, so that a highly triaxially oriented, rolltruded specimen is produced under steady state processing conditions.
  • the rolltrusion process provides a procedure for the solid phase deformation of a workpiece of an orientable thermoplastic polymer, which process comprises: preconditioning the workpiece in its solid state at a temperature in the range between Tm and Tg, providing the conditioned workpiece, frequently of the essentially unoriented polymer at the entry side of an opposing pair of rollers spaced apart a distance substantially less than the thickness of the workpiece; applying to the workpiece from the exit side of the rollers a draw tension insufficient to cause tensile failure of the workpiece, but sufficient to effect a draw ratio of at least 2 to 1, and upwards.
  • workpiece includes bars, strips, rods, multifilaments, films, and other cross- sections of amorphous or semicrystalline solid stock.
  • the term includes both billets and other forms of stock of greater length; indeed, continuous stock, which may be formed as the process is performed, may be utilized. Examples include a polymer sheathed continuous core such as a metal wire, or continuous polymer rod, film or filaments.
  • the invention is particularly concerned with a membrane or thin film produced as a result of using a polymer as a workpiece.
  • the orientable thermoplastic polymer is desirably a semicrystalline, or potentially crystallizable amorphous polymer, especially one which exhibits sufficient strain hardening and strain rate dependence of the flow stress to stabilize the neck, where the workpiece experiences a triaxially induced stress field formed under the desired drawing conditions.
  • Preferred such polymers are suitably of a homo- or copolymer of polyolefins with at least one comonomer; a vinylidene fluoride polymer, a polyacetate, a polyamide, a polyester or (poly) esteretherketone (PEEK). Both linear and somewhat branched and/or amorphous polymers may be processed.
  • the rolltrusion process is used to produce a triaxially oriented polymer membrane.
  • crystallites highly regulated in three directions (i.e., crystallographically) within the workpiece, but inter-crystallite tie molecules that connect them have varying degrees of tautness determined by the processing conditions.
  • This morphological three-dimensional distribution of crystallites and interconnecting tie molecules arises because of the stress field that the workpiece experiences when tensioned and compressed simultaneously in the nip region of the deformation rollers.
  • Rolltruded specimens have morphological regularity, which is an important and distinct feature that qualifies them as quality membranes where their "porosity" may be regulated through solid deformation processing, without the use of solvents, some of which are noxious and even incapable of dissolving certain polymers.
  • the porous (regions) dimensions or spacing between the crystallites of the polymeric membranes may be controlled by rolltrusion, and material selection and processing conditions.
  • FIG 14 A case in point is Figure 14 which demonstrates the superiority of rolltruded membranes over biaxial ones that are much thinner but still less effective for the same polymer/gas or/small molecule systems.
  • This Figure 14 provides a comparison of a relative diffusion rates between commercial biaxially oriented polypropylene and the triaxial membranes of the invention, which have "controlled" diffusion pathways. The difference is quite obvious from this Figure 14.
  • the crystallites are the diffusion blockers, and the intercrystalline regions comprise the permeable regions of the polymer which are aligned because of the three-dimensional morphology, therefore providing a relatively non-torturous pathway for diffusion and enhanced permeability.
  • the drawing part of the rolltrusion process increases the tautness of the amorphous 5 regions, the permselectivity of the polymer can be expected to increase, which is an important development in gas separation technology.
  • the original HDPE and iPP stock sheets were cut into long billets of at least 48 inches (ranging in cross-sections from 0.5" x 0.5" to 0.15" x 0.15" approximately). Billets of required dimensions were cut from the original stock sheets. The surfaces of the cut billets were subsequently milled with a carbide steel fly wheel or bandsaw to yield desired sample thickness.
  • Triaxially oriented polymer samples were prepared by means of the rolltrusion process.
  • the front end of the polymer sheet or billet was inserted between the processing rollers and then connected to the variable speed wind-up assembly supplying a constant load.
  • the workpiece may also be readily prenecked under tension at elevated temperature(s) and then placed between the rollers for rolltrusion. Initially startup was manually slow until the desired roll gap (specimen thickness) was established. Thereafter, the draw speed was adjusted to produce a stable uniformly wide and thin product after passage through the rollers at a steady rate.
  • the process of triaxial orientation may be carried out in one or two stages.
  • Table 4 lists the processing conditions used in the preparation of triaxially oriented HDPE and iPP polymers, defined in Table 3.
  • Triaxially oriented polymers with varying draw ratios can be obtained by the proper choice of draw temperature, draw speed and roller nip dimensions.
  • the width of the processed or rolltruded specimen is comparable with the starting material width.
  • the thickness is considerably reduced for high DR values. This feature distinguishes rolltrusion from all other state of the art techniques. Analytical Techniques Used in Polymer Evaluation Morphology
  • WAXS Wide Angle X-ray Scattering.
  • Nickel filtered Cu K ⁇ radiation for 4-5 hours at 35 KV and 20 mA.
  • the sample to film distance was 47.35 mm, or the sample to film distance was varied as dictated by the processed workpiece.
  • the diffraction patterns were obtained with X-rays parallel and perpendicular to the roll direction.
  • the samples were scanned at a rate of 0.2°/min. using Cu Ktt * ⁇ radiation of 40 KV and 25 mA. A 1° beam slit and graphite monochromator were used.
  • the average orientation of the crystallites (c- axis orientation) with respect to the roll direction was estimated using the Hermann's orientation function.
  • the crystallite orientation factor was determined using the WAXD azimuthal scanning data obtained from (i) (200) and (020) reflections for HDPE and (ii) (040) and (110) reflections for iPP polymers respectively.
  • the data was obtained with the X-rays parallel to the X direction, which is perpendicular to the directions of rolltrusion. Note that measurements were also made in the Y and Z directions too in order to establish the triaxial sample orientation of the extrudate. (See Figure 3)
  • SAXS Small Angle X-ray Scattering.
  • SAXS small angle X-ray scattering technique
  • the SAXS measurements were carried out using a Rigaku-Denki camera and a rotating anode generator. Nickel filtered Cu K ⁇ ⁇ radiation was used through the X-ray work. The samples were exposed for 4-5 hours at 40 KV and 50 mA. The sample to film distance was 480 mm. The samples were photographed with the X-ray beam parallel to the X, Y and Z directions, respectively. The long period spacing was calculated.
  • DSC Differential Scanning Calorimetry.
  • DSC-2 A Perkin-Elmer differential Scanning Calorimeter (DSC-2), with scanning auto zero and computer integration accessories, was used to determine the melting characteristics and the heat of fusion of the original and deformed polymers.
  • the calorimeter was initially calibrated for temperature measurements using a standard Indium sample (Melting pt. 156.0°C and H 6.8 cal/gm) , and other standards. All the measurements were made at a full scale sensitivity of 10 m cal/sec. and at a scan rate of 10°/min.
  • the melting point was directly determined from the DSC curve by reading the temperature corresponding to the peak maximum of the endothermic traces.
  • the heat of fusion was obtained by integrating the area under the melting peak of the DSC curve. Then the degree of crystallinity of the sample was computed by conventional techniques using the heat of fusion data of 100% crystalline samples. Crystallinity was also determined from density measurements.
  • the intrinsic birefringences of single crystals of HDPE and iPP samples were taken to be 0.060 and 0.030, respectively, while the intrinsic birefringence of the amorphous phases of these polyolefins was assumed to be 0.20 for HDPE and 0.061 for iPP, respectively.
  • E. Electron Microscope Fracture surface morphology of doubly oriented polyethylene and polypropylene polymers along various directions were examined using a JOEL JSM-35 Scanning electron microscope. Morphological characterization of ion-etched polymeric surfaces were carried out. Ion-etching was carried out in a JOEL-JFC 1100 ion sputtering instrument at 500 volts (AC) and 3 mA in air at a chamber pressure of 26.7 Pa for 30 minutes (max) . All samples for scanning electron microscopy were coated with either Au or Au/Pd. Electron diffraction studies were made on thin layers of polymer detached from the surfaces of the ion-etched polymers using gelatin as the adhesive.
  • Tensile Testing Equipment (Model 4042) equipped with a strip chart recorder and a microprocessor. The tensile testing of triaxially oriented HDPE and iPP samples were conducted under the following conditions; test temperature — room temperature ( ⁇ 23°C) ; gage length - 1.0 and 2.0 in. for the HDPE and iPP samples, respectively; and cross-head speed — 0.2 in/min., to comply with ASTM Standard procedures.
  • a workpiece of a homo- or copolymer of ethylene should desirably comprise a polymer having a weight average molecular weight (Mw) less than 5,000,000, suitably from 50,000 to 500,000, preferably from 70,000 to 400,000; one of a linear homo- or copolymer of propylene should desirably comprise a polymer having a Mw from 150,000 to 800,000, preferably from 250,000 to 500,000.
  • Mw weight average molecular weight
  • the rolltrusion process may also be performed, to provide a more advantageous forming procedure for a workpiece of orientable polymer; or from an amorphous non-crystallizable polymer; or from an amorphous, but crystallizable polymer, orientable or semicrystalline, ultra high molecular weight polymer (for example, a linear homopolymer of polyethylene terephthalate having a Mw of 30,000 to 50,000), It may likewise be utilized, if polymers are prepared in relatively low to zero crystallinity, through side chain branching or quenching, or solution precipitation.
  • the draw ratio should be sufficient to draw the workpiece through the rollers but insufficient to cause tensile failure of the article; that is, the draw ratio should be such that the true stress at any point in the workpiece during processing does not exceed its fracture stress at that point.
  • a suitable maximum value of draw ratio has been determined based on the data of Figure 4. Sample molecular weight, and molecular weight distribution affect the draw ratio that is obtainable. For a particular polymer, a steady state process is established for a given set of temperature, draw speed and deformation conditions (draw ratio) .
  • roller temperature which will be only a nominal temperature for the polymer, since the process is not an isothermal one
  • workpiece shape and dimensions and to vary the draw speed to obtain the desired product.
  • the width of the workpiece is essentially invariantly within ⁇ 10% of the original billet, etc.; only the thickness x direction is drastically reduced.
  • the roller temperature may be desirably set at a temperature just above the lowest glass temperature (of the system) and preferably not above melting temperature of the highest melting component of the system. More particularly, for such polymers of fi ⁇ from 50,000 to 150,000, the roller temperature is preferably from 70°C to 130°C.
  • the roller temperature may be set from 20° - 170°C preferably 90° - 160°C.
  • a roller temperature of 80° - 170°C, preferably 110° - 160°C, is suitable for homo- or copolymers of ethylene and propylene, and of 80°C to 180°C is suitable for vinylidene fluoride polymers.
  • Tables 5 and 6 are presented data on the variation in maximum draw ratios with the draw temperature for high density polyethylene and isotactic polypropylene, respectively. From the data, it is evident that the maximum draw ratio increases with increasing roller temperatures. In the case of iPP, it was possible to obtain a draw ratio of 35.0 at the roller temperature of 158°C, compared to a draw ratio of 5.0 at 110°C. Similarly, for the HDPE polymer, the draw ratio increased from 6.5 to 22.0 on raising the draw temperature from 100°C to 120°C. Higher values have been attained. Attempts to draw the billets beyond determined maximum draw ratios often led to the specimen failure in the indicated processing ranges for the specimens of this example.
  • the draw speed corresponds to the constant rate of the wind-up device used in processing. Plots of data on draw ratio as a function of applied draw speeds for the HDPE and iPP specimens of Table 3 indicate that the draw ratio is independent of the draw speed in the range of this disclosure. These results are in agreement with other observations made on other polymers at comparable draw speeds.
  • Optical Transparency Commercial HDPE, iPP, and other polymers are opaque to visible light. This is due to scattering of light by the spherulitic structures and voids in those polymers.
  • the wide angle measurements were made primarily (i) to follow any polymorphic transitions in HDPE and iPP, for example, upon triaxial orientation, (ii) to confirm the triaxial orientation texture in the processed polymers, and (iii) to determine the average crystallite orientation in the roll and transverse X and Y directions.
  • the diffraction patterns of the original HDPE and iPP polymers were recorded using a Statton-type camera. Both patterns consist of concentric rings indicating no preferred orientation in any direction.
  • the HDPE pattern was indexed with reference to an orthorhombic unit cell.
  • the iPP pattern was indexed as the monoclinic structure.
  • SAXS Small Angle X-ray Scattering
  • the original HDPE and iPP samples showed long period spacing o values of 170 and 180 A respectively.
  • the long period spacing increased from 180 A to o 247 A, as the draw ratio increased from 1 to 10.
  • the discrete SAXS reflection sometimes disappears or can only be observed with difficulty.
  • the crystallite size is very dependent upon the draw temperature, whereas the size of the intercrystallite 5 regions relates to the deformation (draw and compression) conditions as in the following equation:
  • the DSC technique has been employed extensively in the thermal analysis of amorphous and crystalline polymers. In the present specification, the technique was used to determine the changes in: (i) the melting characteristics upon double orientation, (ii) the degree of
  • HDPE samples usually showed single melting peak, while iPP specimens exhibited multiple melting peaks. It was also observed that the triaxially oriented HDPE samples exhibited relatively narrow melting profiles as compared to the 5 original commercial polymer.
  • Table 8 presents the melting point data on rolltruded oriented HDPE and iPP samples (K°).
  • the original HDPE and iPP samples had a melting point of 133.5° and 161.0°C, respectively.
  • a plot of melting temperatures, as a function of draw ratios was also made. It showed the peak melting temperature increased to 138.5°C upon increasing the draw ratio to 22.
  • n is defined as the difference in refractive index parallel n , and perpendicular n to the draw direction for a uniaxially oriented polymer.
  • the refractive index in any given direction is related to the polarization properties of the macromolecule in that direction.
  • the birefringence values in all three principal directions are needed to completely characterize the state of molecular orientation in a crystalline polymer. The characterization can be carried out in all three directions, only if one has either a single crystal or a triaxially oriented polymer, which possess a pseudo single crystal-like morphology.
  • Table 9 lists the number average molecular weight (M n ), the weight average molecular weight (M w ) , and the polydispersity values (M w /M n ) for the original, and for the triaxially oriented, HDPE and iPP specimens.
  • the commercial HDPE polymer had M n and M w values of 13,900 and 91,900 respectively, while the triaxially oriented HDPE (DR 20) showed M n and M ⁇ values of 11,300 and 91,200, respectively.
  • DR 20 triaxially oriented HDPE
  • Processing temperatures of 100, 100, 115, 120 and 123°C for HDPE samples, and 140, 145, 150, 155, 158 and 160°C for iPP samples were selected to illustrate the effects of processing temperature on properties. These conditions ensured that molecular mobility, and molecular alignment and extension, occurred in the workpiece well beyond the natural draw ratio attainable in either of these polyolefins. For each draw temperature, presumably a maximum draw, ratio should be reached for the specific workpiece in question.
  • the maximum draw stress along the deformation path determined by the ratio of drawing load to final cross sectional area of the specimen, was found to be dependent on both draw ratio and draw temperature.
  • the maximum draw stress employed for HDPE ranged from 720 to
  • the necked profiles of the polymer specimens were examined during and after drawing.
  • the rolltrusion products had a smooth surface, uniform thickness and high transparency. It is also important to note that dimensional changes of the workpiece were minimal in the rolltruded polyolefins.
  • the Young's modulus of the original iPP sample was 1.8 x 10 5 psi (1.2 GPa) while a highly drawn iPP sample (DR - 35) had a value of 2.5 x 10 6 psi (17.2 GPa). Young's modulus is found to be a unique function of draw ratio for the range of draw temperatures and draw speeds used here.
  • HDPE and iPP are known to exist in several crystallographic forms.
  • HDPE is predominantly orthorhombic and sometimes it occurs in the less stable monoclinic form.
  • the iPP polymer is usually monoclinic form and it sometimes forms a hexagonal crystal structure.
  • the data showed typical diffraction patterns of the unoriented original HDPE and iPP polymers indicating no preferred orientation in any direction.
  • the diffraction patterns were indexed with respect to orthorhombic and monoclinic forms of HDPE.
  • the intensity of the (110) reflection increases with increasing draw ratio. It is found that the intensity of the (200) reflection decreased remarkably with increasing draw ratio in YZ patterns but increased with draw ratio in XZ patterns.
  • Crystallinity values determined from DSC are plotted in Figure 7.
  • the degree of crystallinity was determined as the ratio of the enthalpy change at melting transition to the heat of fusion for an ideal crystal (69 cal/g and 38 cal/g were used for HDPE and iPP, respectively).
  • Density measurements were also made for the rolltruded specimens, but here too the density of the amorphous phase, which is a function of draw ratio (or orientation), must be properly assigned before the degree of crystallinity can be calculated accurately.
  • Trends in crystallinity with processing conditions are in accord using both techniques. Birefringence Sample birefringence as a function of draw ratio is shown in Figure 8.
  • the degree of orientation for the crystallites, f c was determined from WAXS data, using the Hermann's function.
  • the degree of orientation for the amorphous phase, f a was calculated based upon birefringence measurements along with f c results, assuming Stein's additivity equation to be valid.
  • Figures 11 and 12 show the variations of fc and fa, with draw ratio, for the two polyolefins. Both factors increase with increasing draw ratio, but f c tends rapidly towards an asymptotic (limiting) value at high DR values, while f a is found to increase steadily, suggesting that the intercrystallite materials play a very important role in the enhancement of mechanical properties.
  • the tensile properties of the original and the triaxially oriented HDPE and iPP polymers were determined along the roll direction. The details of the testing conditions and the calculation of tensile properties such as modulus, strength, elongation at break and fracture toughness were outlined earlier.
  • isotactic polypropylene as extruded sheet (Boltaron 5500) was cut into billets for triaxial orientation. A variety of thickness from 1/8" to 1/2" and sometimes greater were processed by the rolltrusion method as follows. The polypropylene workpiece was introduced between thermostatted rollers, and the existing end of the workpiece was clamped in a constant speed drawing device (which had a variable drive and variable tension or load capability, that could be used as the need arose) . The load on the clamped workpiece was adjusted as it was pulled between the rollers until the desired thickness at exiting and properties were reached.
  • a constant speed drawing device which had a variable drive and variable tension or load capability, that could be used as the need arose
  • the drawing speed was about 0.3 cm min -1 , and a draw temperature of 158°C, were such that they, and roller compression of desired dimensions, produced highly triaxially oriented transparent plastic from the opaque commercial sample.
  • the cross sectional area of the product could be controlled, as required, covering changes in cross section of the original workpiece from x 2 up to x 60 to 1 in a single pass through the triaxial orientating assembly.
  • the polypropylene was rectangular (strap-like) in shape.
  • the Young's modulus enhancement could be in excess of 2.5 x 10 6 psi, the tensile strength 7 x 10 4 psi, and the toughness with respect to the starting material.
  • the elongation of the processed product was typically below 5%, i.e., manifold reduction, so that elongation or creep of the rolltruded polymer with respect to the original workpiece was significantly changed for better use in many practical applications, where elongation/creep have proven to be a problem in end use applications.
  • the set-up procedure was similar to that cited in Example 1, except that the processing conditions, particularly temperature was considerably lower.
  • the rolltrusion operation was similar to the polypropylene example, and the workpiece was processed to strip-like dimensions of high clarity, strength, modulus, draw ratio and orientation. Typical values for a draw ratio of x 25 are tabulated. This illustration does not represent an upper limit on processability, but it only serves as an example.
  • Example 3 In this example, unoriented Nylon 6, colored (blue dyed), billets (from Cadillac Plastics, Pittsburgh) were cut from a 1/2" sheet of Nylon 6 plastic, prenecked, and then subjected to rolltrusion at elevated temperatures, which were well above the conditions used for processing polypropylene.
  • Nylon 6 workpiece was converted to highly triaxially oriented plastic, with enhanced physical properties and improved wear resistance, demonstrating that the product was capable of much improved quality and improved characteristics as an engineering plastic.
  • Example 4 Commercial sheets of amorphous polyethylene- terephthalate (PET), which is a crystallizable polymer, were processed at not too far removed from their glass transition temperature. Two different examples, one (a) with a workpiece 1/2" wide, and another (b) a workpiece 5 1/2" wide • were used.
  • PET polyethylene- terephthalate
  • rollers were heated and stationary, whereas with (b) they were cold (i.e., kept at room temperature) but the workpiece was preheated before passing through the roller nip which was adjusted to obtain product thickness as required.
  • the workpiece in (b) was comprised of a sheet roll longer than (50 ft.) of amorphous PET, purposely tested to demonstrate the continuous nature of operation.
  • the unoriented relaxed (originally clear amorphous PET) becomes milky white when heated and maintained 180°C for 1 hr., indicating that a clear advantage is to be gained via the triaxial orientation processing described in this example.
  • All polymers tested in these examples were characterized by small and wide angle X-ray diffraction. It was demonstrated that orientation and crystallinity of the triaxially-oriented increased progressively, with conditions finally reaching a morphology in which the molecular chains, in crystalline and amorphous regions, were oriented along the stretch direction, and the other two crystallographic directions were oriented in, and perpendicular to, the rolling plane of the workpiece.
  • a monoclinic component was also noted along with predominant orthorhombic component in polyethylene.
  • the structure is monoclinic; and in PET, it is the usual triclinic structure which predominated.
  • Figure 5 lists the tensile modulus values obtained from triaxially-oriented HDPE samples processed at 110° and 120°C.
  • the tensile strength of the triaxially oriented iPP samples was enhanced over the original polymer by at least a factor of 15.
  • no distinct trend was evident with respect to the draw temperatures and draw speeds used in this work.
  • Table 12 is presented some representative physical data for each of the polyolefins that were extensively studied, indicating the correlation of long period spacing, percent crystallinity and melting point, for the original polymers, and after useful processing according to the present invention. It has thus been established by this array of data as presented in the tables that:
  • the length-to-diameter ratio is found to be smaller than 1.0 for most specimens (aspect ratio of 1.0 is the minimum value recommended by ASTM). It was realized that the friction between the test sample and the compression dies may affect the results significantly so that compressive properties are reported here with some reservation.
  • the cross-heat speed was set at 1.3 mm/min (0.05 in/min) . All the tests were performed at room temperature and the machine compliance of MTS (model 880) was calibrated. Results
  • Figure 15a shows the tensile modulus as a function of draw ratio of iPP rolltruded at 160°C and tested at room temperature along Z direction.
  • Figure 15b shows tensile strength as a function of draw ratio for iPP rolltruded at 125 °C (top curve) and 160°C (lower curve). Tests were made at room temperature along the Z-direction.
  • Figure 16a shows tensile modulus as a function of 5 draw ratio for iPP rolltruded at 160°C and tested at room temperature along the Y direction.
  • Figure 16b shows the tensile strength as a function of draw ratio for iPP rolltruded at 150°C (top curve) and 160°C (lower curve). Tests were made at room temperature along the Y-direction.
  • Figure 17a shows 0 compressive modulus as a function of draw ratio for iPP rolltruded at 125°C (upper curve) and 160°C (lower curve)
  • Figure 17b shows compressive strength as a function of draw ratio for iPP rolltruded at 125°C (top curve) and 160°C (lower curve). Tests were made at room temperature along the X 5 direction.
  • Figure 18 shows elongation at break as a function of draw ratio for iPP rolltruded at 160 ⁇ C. Tensile Tests were made along Z and & directions, respectively. Samples with a draw ratio lower than 22 yielded and necked upon the Y- 0 direction test.
  • PVDF Polyvinylidene Fluoride
  • Figure 19a shows tensile modulus as a function of draw ratio for P/E copolymer rolltruded at indicated temperatures and tested along Z direction.
  • Figure 19b shows tensile strength as a function of draw ratio for P/E copolymer rolltruded at indicated temperatures and tested along Z direction.
  • Figure 20a shows tensile modulus as a function of draw ratio for P/E copolymer rolltruded at 145°C and tested along Y direction.
  • Figure 20b shows tensile strength as a function of draw ratio for P/E copolymer rolltruded at 145°C and tested along Y direction.
  • Figure 21a shows compressive modulus as a function of draw ratio for P/E copolymer rolltruded at 145°C and tested along X direction.
  • Figure 21b shows compressive strength as a function of draw ratio for P/E copolymer rolltruded at 145°C and tested along X direction.
  • Figure 22 shows elongated at break as a function of draw ratio for P/E copolymer rolltruded at 145°C tensile tests were made along Z direction. Discussion
  • WAXD patterns have been recorded for many rolltruded polymers. In all instances their triaxial orientation is evident from section of the rolltruded workpiece depicted as illustrated in Figure 2 and 3.
  • Figure 23 illustrates clearly the triaxial 3D morphology of processed nylon 66, where the patterns are represented for the X-ray beam parallel to x, y, and z direction respectively.
  • the sample was stained with K + I 3 to highlight the different textures.
  • UHMWPE ultra high molecular weight polyethylene
  • the corresponding 3D morphology is shown in Figure 24 for the x, y, and z directions in the workpiece. The triaxial morphology is very clear.
  • 3D rolltruded polymers can be clearly discerned from their small-angle x-ray scattering two dimensional (2D) patterns recorded in three mutually perpendicular directions through the workpiece (illustrated in Figure 3). These patterns may be shown pictorially, but a more illustrative representation is provided by mutually perpendicular intensity scans or slices made in three mutually perpendicular directions. (This was derived from the Oakridge data made at the National Center for small- angle scattering.) Since the WAXD pattern discerns the relative orientation of crystallographic planes, the SAXD measures the periodic SAXS scattering fluctuations due to alternating crystallites interconnected by amorphous regions (variously construed) between them in three directions.
  • Figure 27a shows the periodic SAXS scattering associated with rolltruded high density commercial polyethylene parallel to x and y respectively.
  • Figure 27b shows absolute small-angle scattering measurements made on PVDF in the x, y, and z directions, respectively, where the relative peak heights are related to the square of the electron density fluctuation between the crystallites and the amorphous regions of the triaxially oriented polymer. (This was derived from the Oakridge data made at the National Center for small-angle scattering.) The ratio of peak heights vary as 82:35:1 for x, y, z respectively.
  • Figure 28 discrete periodic scattering is revealed in two directions within the workpiece.
  • the influence of pressure is also indicated in a limited manner. More detailed investigations of the permeability, diffusivity and solubility coefficient isotherms are shown at a constant driving pressure of 25 psia of C0 2 , and are provided in Figure 30.
  • Plots of the separation factor, s as a function of deformation ratio for a C0 2 /N 2 mixture at a constant driving pressure of 75 psia illustrate that the separation factor increases with DR for all temperatures of measurement. This trend is a novel result in gas mixture separation which is in line with the illustration in Figure 14 where one might expect very much improved behavior at even higher DR values for rolltruded polypropylene.
  • rolltruded polyvinylidene fluoride of deformation ratio 5:1 clearly shows an increasing trend in permeability of C0 2 with temperature and with driving pressure.
  • Figure 31 shows the number of moles of C0 2 that have emerged from the bottom surface of the membrane as a function of time, temperature, and pressure.
  • Trends in permeability of several gases with pressure and constant temperature are to be found in Figure 32.
  • Trends in the permeability of these gases N 2 , CH4 and C0 2 at 60°C are well established again as examples using rolltruded membranes.
  • Arrhenus plots are similarly established for gases and mixture in Figure 33.
  • the permeation activation energies for several gases are provided in Table 17. Separation Factor - Deformation ratio plots for
  • C0 2 /N 2 are illustrated for PVDF in Figure 34 where, at all temperatures, there is an increased trend in separation for the various temperatures listed.
  • the separation factors are listed in Figure 34.
  • the uniqueness of rolltrusion membranes or films and their functional ability has been documented through these examples.
  • the model in Figure 13 is commensurate with these investigations.
  • Table 17 are in rough agreement with current data obtained by Elhibri and Pul for uniaxially drawn PVF 2 , though the actual permeabilities here are higher.
  • Arrhenius plots of the diffusivity and solubility values are available but are not shown here.
  • Table 18 shows the actual and ideal separation factors for several of the mixture runs as a function of temperature and pressure.
  • Figure 13 illustrates a morphological model associated with rolltruded materials.
  • the bottom portion shows the spherulites in an underformed specimen prior to the rolltrusion process.
  • the top section show the morphological results of the rolltrusion process in three dimensions.
  • the material has a morphology with a triaxial orientation or symmetry with a periodicity consisting of crystallites and amorphous or tie molecular regions between the crystallites, with no spherulites remaining in the rolltruded section of the workpiece. This is also shown in Figure 1(b), and is discussed hereinbefore.
  • the x, y, z axes are shown.
  • Lx shows alignment of the crystallites in the x-direction
  • Ly shows the alignment of the crystallites in the y-direction
  • Lz shows the alignment or crystallites in the z direction.
  • the end view at the top of Figure 13 shows the crystallites and tie regions or amorphous material between the crystallites.
  • the tie molecules distribution is illustrated as highly anisotropic in the three directions, the tie molecules being more abundant in the draw direction or the z-direction, which is in line with mechanical test results.
  • the rolltrusion process produces an improved film or membrane, in accordance with the teachings of the invention, which can be employed for several purposes.
  • polymer films or membranes can be used for the following purposes a) in the separation, removal or concentration of gases; b) for controlling drug release applications in medicine; c) for the delivery of microbiol herbicides in toxic waste treatments; d) for reverse osmosis; or e) in piezodialysis.
  • semicrystalline or potentially crystallizable polymers that have been studied so far are: polyolefins, for example, polyethylene, polypropylene and ethylene/propylene copolymers; polyamides, such as nylon 6 or nylon 66; polyesters, such as poly (ethyleneterephthalate) ; poly(fluoroalkenes) and poly(ketone) , such as poly (aryletheretherketone) (PEEK).
  • polyolefins for example, polyethylene, polypropylene and ethylene/propylene copolymers
  • polyamides such as nylon 6 or nylon 66
  • polyesters such as poly (ethyleneterephthalate)
  • poly(fluoroalkenes) and poly(ketone) such as poly (aryletheretherketone) (PEEK).
  • Other polymers are in the process of being examined, but it is to be appreciated that all semicrystalline, amorphous and non-crystalline polymers which are potentially crystallizable can be rolltruded to produce a thin film which will function as
  • this morphology has a periodic distribution of crystalline (permeant blockers) and intercrystalline tie regions in the three xyz dimensions. Some dimensions that have been measured by small-angle x-ray scattering show sizes that depend upon the processing temperature and draw or deformation ratio.
  • L is the overall morphology measured in angstroms
  • A. c is the crystalline structure in the rolltruded material
  • L a is the non-crystalline or amorphous structure in the rolltruded material.
  • L c functions as diffusion or permeator "blockers"
  • L a depicts the dimension comprised of variously oriented intercrystallite regions (ranging from relaxed to taut, depending upon the rolltrusion conditions) i.e., the region through which the permeant passes.
  • the non- crystalline structure L a typically varies between 10% and 25% of the overall range morphology, L.
  • Table 13 lists the several polymers for which examples of periodicity of membrane crystalline/amorphous dimensions in the triaxial orientation have been established.
  • polyethylene specifically, the draw temperature used is in the range from 30° to 130°C, permitting a maximum draw ratio ranging from x5 to x30, the original specimen prior to rolltrusion. This sample had an overall morphology, L, ranging from 120A to 400A with 10% to 25% of this range being non-crystalline structure. La, as discussed hereinbefore.
  • the draw temperature is in the range from 50° to 160°C, with a draw ratio ranging from x5 to x60 the specimen prior to rolltrusion.
  • the morphology (L) range is 130 to 500A with approximately 10% to 25% of this range being non-crystalline structure and 75% to 90% being crystalline structure, Lc.
  • the processing temperature varied depending on the copolymer composition.
  • the deformation ratio range is x3 to x30; and the overall morphology range is
  • the deformation ratio was x3 to xl2, and the overall morphology was 120 to 250A.
  • the processing temperature range is 180° to 210°C
  • the deformation ratio range is x2 to x7;
  • ⁇ overall morphology range is 100 to 150A.
  • Nylon 66 has a temperature range of 220 to 260°C, the deformation ratio range is x2 to x7, and the overall morphology range is 100 to 150A.
  • Poly(ethyleneterephthalate) (amorphous) has a temperature range of 60° to 80°C the deformation ratio range is x2 to xlO; and the overall morphology range is 100 to 150A.
  • the temperature range is typically 270°C to
  • the deformation ratio range is x2 to xlO; and the o morphology range is 180 to 250A.
  • the overall morphology, L contains a morphology for the non-crystalline material ranging 10% to 25%.
  • the morphology for the crystalline (Lc) material is approximately 75% to 90% of the overall morphological dimension in the deformation direction.

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Abstract

Le procédé décrit, qui sert à la préparation en phase solide d'un matériau polymère synthétique à orientation triaxiale dans une pièce à travailler en polymère thermoplastique orientable amorphe mais cristallisable ou semi-cristalline, consiste (a) à présenter la pièce à travailler conditionnée à une paire de cylindres pleins opposés, en mode entrée, qui sont espacés avec entre eux une distance sensiblement inférieure à l'épaisseur de la pièce à travailler; et (b) à déformer la pièce à travailler par compression en la faisant passer à travers la paire de cylindres selon des rapports de déformation nominale d'au moins 2 à 1. On effectue l'étirage de déformation à une température comprise entre la température de transition du verre et le point de fusion du matériau polymère, en appliquant une tension d'étirage insuffisante pour produire une rupture par traction de la pièce à travailler. L'invention décrit également une membrane ou un matériau en film copolymère extrudé par cylindre, avec une morphologie à orientation triaxiale, ayant une périodicité composée essentiellement de cristallite et de matières amorphes ou une répartition périodique de régions de liaison cristallines et intercristallines.
PCT/US1991/006188 1990-08-31 1991-08-29 Membrane polymere a orientation triaxiale Ceased WO1992004176A1 (fr)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0487749A4 (en) * 1990-06-15 1993-09-15 Nippon Petrochemicals Co., Ltd. Molded article of crystalline thermoplastic resin with high gas barrier property and production thereof

Citations (3)

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Publication number Priority date Publication date Assignee Title
US3354023A (en) * 1963-04-22 1967-11-21 Du Pont Oriented polymers
FR2282985A1 (fr) * 1974-07-31 1976-03-26 Nippon Petrochemicals Co Ltd Procede de fabrication de feuilles et films calandres, en resines thermoplastiques
EP0264864A1 (fr) * 1986-10-24 1988-04-27 Kraftanlagen AG. Procédé et dispositif pour fabriquer des plaques, des rubans, des produits ou profilés formés analogues à des plaques en matières synthétiques

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Publication number Priority date Publication date Assignee Title
US3354023A (en) * 1963-04-22 1967-11-21 Du Pont Oriented polymers
FR2282985A1 (fr) * 1974-07-31 1976-03-26 Nippon Petrochemicals Co Ltd Procede de fabrication de feuilles et films calandres, en resines thermoplastiques
EP0264864A1 (fr) * 1986-10-24 1988-04-27 Kraftanlagen AG. Procédé et dispositif pour fabriquer des plaques, des rubans, des produits ou profilés formés analogues à des plaques en matières synthétiques

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Title
International Polymer Processing, vol.1, 1987 M.J. Shankernarayanan et al. 'Rolltrusion Doubly -Orientation Processing and Morphology- Property Relationships for Commercial Plastics page 66-76 *
Journal of Materials Science Letters, vol 5,1986M.J.Shanker Narayanan et al. 'Preparation of Highly doubly Oriented Polymers' page 267-269 cited in the application see page 267, line 5 - line 8 *
Plastics Engineering, vol. 43, no.12, 1987 K.R.Tate et al. 'Orienting Polypropylene Sheet by Rolling-Drawing' page 29-31 see figure 1 *
Polymer News, vol. 13, 1988 J.H.Magill 'Rolltruded High Modulus Polymers' page 107-113 *
Welding Journal, vol. 67, no. 7, 1988 A. Cullison 'Conference Punctuates Structural Plastics and Their Joining' page 63-65 see paragraph High-Strength Plastics and Their Manufacture *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0487749A4 (en) * 1990-06-15 1993-09-15 Nippon Petrochemicals Co., Ltd. Molded article of crystalline thermoplastic resin with high gas barrier property and production thereof

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