Patent Application
20110227247
The present application discloses, inter alia, polymer articles. Also, the present application discloses methods for making the polymer articles. In addition, the present application discloses dies.
Efforts have been made to produce high-performance polymer fibers. For the category of thermotropic and lyotropic liquid-crystalline polymers, as an example, publications are available where reasonable success is being reported by directly spinning from the thermotropic melt or lyotropic solution and applying relatively high wind-up/extrusion speed (draw down) ratios that induce elongational flow fields causing the polymer molecules to orient in the direction of flow. For examples, see e.g. Muramatsu et al. in Macromolecules 19, 2850 (1986); and Wissbrun et al. in J. Polym. Sci. Pt. B-Polym. Phys. 20, 1835 (1982). Producing high-performance films and foils and other objects of these materials, however, has been less successful in one or more aspects. For examples, see e.g. Calundann et al. in Proceedings of the Robert A. Welch Conference on Chemical Research, XXVI. Synthetic Polymers, 280 (1982); U.S. Pat. No. 4,332,759; U.S. Pat. No. 4,384,016; Ide et al. in J. Macromol. Sci.-Phys. B23, 497 (1985); and Lusignea in Polym. Eng. Sci., 39, 2326 (1999).
In an embodiment, provided are dies having a first section for orienting material being pressed through the die and a second section for shaping the oriented material into a desired form. In an embodiment, the surface area for shaping the oriented material into a desired form is limited.
In an embodiment, provided is a die comprising:
SA<N×D
2
In an embodiment, provided is a die comprising:
EL×WO<N×D
2
In an embodiment, provided is a die comprising:
In an embodiment, provided is a process comprising:
SA<N×D
2
In an embodiment, provided is a process comprising:
W×T<N×D
2
In an embodiment, provided is a process comprising:
In an embodiment, provided is a polymer film having a width of at least 2 cm, a loss modulus greater than 0.75 GPa, and a storage modulus greater than 20 GPa.
In an embodiment, provided is a polymer film having a width of at least 2 cm, a specific loss modulus greater than 75 km, and a specific storage modulus greater than 1000 km.
In an embodiment, provided is a film of liquid-crystalline polymer, the film having:
a width of at least 5 cm; and
a tensile modulus of at least 50 GPa.
In an embodiment, provided are dies having a first section for orienting material being pressed through the die, for instance a spinneret section, and a second section for shaping the oriented material into a desired form. A benefit of such a die is that a reasonable degree of orientation of the material may already be obtained in the shaped part leaving the second section. This, in turn, may limit or avoid having to significantly change the shape of the material leaving the second section to achieve the desired orientation of the material.
In an embodiment, the surface area for shaping the oriented material into a desired form is limited. This may assist, for instance, in better filling of the second section with the material arriving from the first section, which may for instance assist in decreasing or avoiding the void content in the shaped material leaving the second part.
In an embodiment, provided is a die comprising a spinneret part having a plurality of orifices, the orifices having an inlet and an outlet. In an embodiment, the spinneret part assists in orienting the material (e.g. polymer material) passing through the die. The die further comprises a second part having an opening for receiving fibers from the orifice outlets, the opening having an outlet facing away from the orifice outlets. In an embodiment, the second part assists in joining the plurality of fibers into a desired shape, e.g. into a film, a tube, or a bar. In an embodiment, the opening of the second part is in the shape of a slit. In an embodiment, the opening of the second part is circular, e.g. in the shape of a ring. A benefit of using a spinneret part before a second shaping part is that the spinneret part can assist in orienting the material (e.g. polymer material), thereby providing enhanced properties to the article leaving the second part. In an embodiment, the surface area of the outlet of the opening complies with the following formula:
SA<N×D
2
wherein
A benefit of SA being smaller than N×D2 is that the outlet of the opening is better filled with the material being pressed through the opening. This, in turn, may assist in, e.g., preventing void formation in the material being extruded through the outlet of the opening. This may be especially beneficial in situations where, for instance, substantial die swell from the spinneret part is almost absent or, because it would result in disorientation, would be undesirable (i.e., where die swell does not substantially assist in better filling of the opening). In an embodiment, SA is less than N×D2, for instance less than 0.9×N×D2 or less than 0.8×N×D2. In an embodiment, SA is about N×(π/4)×D2. In an embodiment, SA is greater than 0.6 N×D2, for instance greater than 0.7×N×D2 or greater than 0.75×N×D2.
In an embodiment where the outlet of the second part is in the shape of a slit, the surface area SA is the length of the slit L times the width of the slit outlet WO. In an embodiment, L is about equal to the effective length (EL) of the slit, i.e. the length of the slit that is designed to receive material from the spinneret part. In an embodiment, the effective length of the slit is equal to the distance (measured in a direction parallel to the slit and perpendicular to the width WO) between two orifice outlets that are spaced apart furthest.
In an embodiment for making polymer films, provided is a die comprising a spinneret part having a plurality of orifices, the orifices having an inlet and an outlet; a second part having an opening for receiving fibers from the orifice outlets, the opening having an outlet facing away from the orifice outlets;
wherein the die complies with the following formula:
EL×WO<N×D
2
wherein
A benefit of EL×WO being smaller than N×D2 is that the section of the outlet of the opening receiving fibers from the spinneret part is better filled with the material being pressed through the opening. This, in turn, may assist in, e.g., preventing void formation in the material being extruded through the outlet of the opening. This may be beneficial, e.g., in situations where, for instance, substantial die swell from the spinneret part is almost absent or, because it would result in disorientation, would be undesirable (i.e., where die swell does not substantially assist in better filling of the opening).
In an embodiment, EL×WO is less than N×D2, for instance less than 0.9×N×D2 or less than 0.8×N×D2. In an embodiment, EL×WO is about N×(π/4)×D2. In an embodiment, EL×WO is greater than 0.6 N×D2, for instance greater than 0.7×N×D2 or greater than 0.75×N×D2.
In an embodiment, the orifice outlets in the spinneret part are arranged such that when lines are drawn from the center of each orifice inlet, through the center of the corresponding orifice outlet, to the inlet of the second part, then such lines do not cross each other. Arranging the die in such a manner may assist in preventing the fibers to become entangled before being assembled into the desired shape.
In an embodiment, the orifices are provided in a curved part of the spinneret part. In an embodiment, the curved part has the shape of half a cylinder. In an embodiment, the curved part has the shape of half a sphere. In an embodiment, the orifices are arranged in staggered arrays. A curved spinneret part with staggered arrays may assist in arranging the orifices such that the fibers when being formed in the eventually desired shape (e.g. a film) have all had substantially similar deformation history. Also, the curved spinneret part with staggered arrays may assist in providing a relatively large fiber density in the second part.
In an embodiment, the spinneret part has at least 100 orifices, for instance at least 500 orifices, at least 1000 orifices, at least 2500 orifices, at least 5000 orifices, or at least 10000 orifices. In an embodiment, the number of orifices is less than 100000, e.g. less than 50000, less than 25000, less than 10000, less than 5000, less than 2500, or less than 1250.
In an embodiment, the orifice inlet has a greater surface area than the corresponding orifice outlet. Such a configuration may assist in orienting the material, e.g. polymer material, being pressed through the orifices. In an embodiment, the diameter of the orifice inlet is at least 5 times the diameter of the corresponding orifice outlet, e.g. at least 8 times, at least 12 times, or at least 16 times the diameter of the corresponding orifice outlet. In an embodiment, the diameter of the orifice inlet is less than 50 times the diameter of the orifice outlet. In an embodiment, the channel between the orifice inlet and the orifice outlet is cone-shaped.
In an embodiment, the orifice inlet has a surface area that is about the same as the surface area of the corresponding orifice outlet. In an embodiment, the channel between the orifice inlet and the corresponding orifice outlet is straight.
In an embodiment, the orifice outlets have a diameter of less than 5 mm, e.g. less than 500 micrometers, less than 250 micrometers, less than 100 micrometers, less than 50 micrometers, less than 25 micrometers, or less than 15 micrometers. In an embodiment, the orifice outlets have a diameter of at least 1 micrometer, e.g. at least 3 micrometers, at least 10 micrometers or at least 20 micrometers.
In an embodiment, the second part has an opening outlet in the shape of a slit. In an embodiment, the slit has a length L of at least 1 cm, e.g. at least 2 cm, at least 10 cm, at least 50 cm, at least 100 cm, at least 250 cm, at least 500 cm, or at least 1000 cm. In an embodiment, the slit has a length of less than 10000 cm, e,g, less than 5000 cm, less than 1000 cm, less than 200 cm, less than 100 cm, less than 50 cm, less than 20 cm, less than 15 cm, less than 10 cm, or less than 6 cm. In an embodiment, the slit has an effective length EL of at least 1 cm, e.g. at least 2 cm, at least 10 cm, at least 50 cm, at least 100 cm, at least 250 cm, at least 500 cm, or at least 1000 cm. In an embodiment, the slit has an effective length of less than 10000 cm, e,g, less than 5000 cm, less than 1000 cm, less than 200 cm, less than 100 cm, less than 50 cm, less than 20 cm, less than 15 cm, less than 10 cm, or less than 6 cm. In an embodiment, the second part has an opening outlet that has a circular shape. In an embodiment, the second part has an opening outlet that has a ring shape.
An example of a die having a spinneret part and a second part is provided in
Dimensions in
The orifices 130 of the spinneret part 100 of
Another example of a die is provided in
As evident from
An example of a second part that may be combined with the spinneret part of
The orifices 430 of the spinneret part 400 of
Another example of a die 1000 is provided in
Also provided are processes for making articles, e.g. polymer articles, for instance polymer films, laminates, tubes, or bars. In an embodiment, the processes employ dies as described above.
In an embodiment, provided is a process comprising
SA<N×D
2
In an embodiment, provided is a process comprising:
W×T<N×D
2
In an embodiment, the material is a polymer material. In an embodiment, the polymer is a thermoplast. In an embodiment, the polymer is a polyolefin, for instance polyethylene or polypropylene. In an embodiment, the polymer is a fluoropolymer, e.g. a tetrafluoroethylene polymer, for instance a co-polymer of tetrafluoroethylene with a perfluoroalkyl vinyl ether (e.g. perfluoropropyl vinyl ether) or hexafluoroethylene. In an embodiment, the polymer is a liquid-crystalline polymer. In an embodiment, the polymer is a lyotropic liquid-crystalline polymer. In an embodiment, the polymer is a thermotropic liquid-crystalline polymer. In an embodiment, the polymer is a polyaramid, e.g. poly(p-phenylene terepthalamid). In an embodiment, the polymer is a polyester, e.g. a co-polyester, for instance a poly(p-hydroxybenzoic acid-co-2-hydroxy-6-naphtoic acid)copolymer. In an embodiment, the polymer is a poly{diimidazo pyridinylene(dihydroxy)phenylene}, e.g. poly({2,6-diimidazole [4,5-b:4′,5′-e]pyridinylene-1,4(2,5-dihydroxy)phenylene}). In an embodiment, the polymer is a poly(p-phenylene benzobisoxazole). In an embodiment, the polymer is a biodegradable polymer. In an embodiment, the polymer is cellulose or a cellulose derivative. Commercial examples of some of the above-mentioned polymers are, for instance, those available under the tradenames Kevlar™, Twaron™, Vectra™, M5™, and Zylon™. In an embodiment, the material is a polymer blend. In an embodiment, the material comprises, besides one or more polymer grades, one or more additives, adhesives, dyes, antioxidants, monomers, plasticizers, and the like.
In an embodiment, the polymer is in the melt when pressed through the die. In an embodiment, the polymer is in solution when pressed through the die. In an embodiment, the solution is a gel.
In an embodiment, one polymer grade is pressed through the spinneret. In an embodiment, more than one polymer grade is pressed through the spinneret, for instance two polymer grades or three polymer grades, or four polymer grades. In an embodiment, one section of orifices in the spinneret receives one polymer grade, and another section of orifices in the spinneret receives another polymer grade. In an embodiment more than one polymer grade is pressed through the spinneret and separately through different parts of the spinneret one or more additives, adhesives, dyes, antioxidants, monomers, plasticizers and the like. For an example, see
In an embodiment the articles are co-extruded with a material to form a coating on the polymer articles. In an embodiment, the coating is a material that can serve as a glue when laminating polymer films.
In an embodiment, the polymer article is quenched shortly after leaving the die (e.g. by cooling, removal of solvent, or both). A benefit of quenching shortly after leaving the die, for instance in the manufacture of films, is that the width of the film leaving the die is substantially maintained. In an embodiment, the polymer article is quenched by guiding the article in a liquid, e.g. an aqueous liquid, for instance water. In an embodiment, the polymer article is quenched by exposing it to a cold gas, e.g. cold nitrogen gas. In an embodiment, the polymer article is quenched within 10 cm after leaving the die, e.g. within 5 cm, within 3 cm, within 1 cm, or even within 0.5 cm. In an embodiment, the die is in contact with the quenching zone, e.g. the liquid. In an embodiment, the polymer articles is quenched more than 0.1 mm after leaving the die, e.g. more than 0.5 mm or more than 1 mm after leaving the die.
The polymer articles may be post-treated, e.g. annealed, further stretched, cross-linked etc. In an embodiment, the articles are heat-treated (e.g. in the range of 200-280° C., for instance 260° C.) while under tensile stress e.g. at a stress in the range of 1-50 MPa, e.g. 1-10 MPa, 3 MPa, 5-40 MPa, 10-30 MPa, or 15-25 MPa).
In an embodiment, polymer films are provided, e.g. polymer films obtained with the dies described herein and/or the processes described herein. In an embodiment, the films have a width of at least 1 cm, e.g. at least 2 cm, at least 10 cm, at least 50 cm, at least 100 cm, at least 250 cm, at least 500 cm, or at least 1000 cm. In an embodiment, the width is less than 10000 cm, e,g, less than 5000 cm, less than 1000 cm, less than 200 cm, less than 100 cm, less than 50 cm, less than 20 cm, less than 15 cm, less than 10 cm, less than 8 cm, or less than 6 cm. In an embodiment, the films have a tensile modulus of at least 50 GPa. In an embodiment the tensile modulus is at least 25%, e.g. at least 35%, at least 45%, at least 55%, or at least 70% of the theoretically maximum modulus. In an embodiment, the tensile modulus is less than 200 GPa, e.g. less than 150 GPa, less than 100 GPa, or less than 75 GPa. In an embodiment, the tensile modulus is less than 95% of the theoretically maximum modulus, e.g. less than 90%, less than 85%, less than 80%, less than 65%, or less than 50% of the theoretically maximum modulus.
In an embodiment, the polymer films have a loss modulus (E″), as determined with dynamical mechanical thermal analysis at a temperature of 25° C. and a frequency of 1 Hz, of at least 0.75 GPa, e.g. at least 1 GPa, at least 1.5 GPa, at least 2 GPa, at least 2.5 GPa, or at least 2.7 GPa. In an embodiment, the loss modulus is less than 8 GPa, e.g. less than 5 GPa, less than 4 GPa, or less than 3 GPa. In an embodiment, the polymer films have a storage modulus (E′), as determined with dynamical mechanical thermal analysis at a temperature of 25° C. and a frequency of 1 Hz, of at least 20 GPa, e.g. at least 30 GPa, at least 40 GPa, at least 50 GPa, or at least 60 GPa. In an embodiment, the storage modulus is less than 100 GPa, e.g. less than 85 GPa or less than 70 GPa.
In an embodiment, the polymer films have a specific loss modulus, i.e. the loss modulus (25° C., 1 Hz) divided by the density of the film material (at 25° C.), of at least 75 km, e.g. at least 100 km, at least 125 km, at least 150 km, at least 175 km, or at least 200 km. In an embodiment, the specific loss modulus is less than 600 km, e.g. less than 450 km or less than 300 km. In an embodiment, the polymer films have a specific storage modulus, i.e. the storage modulus (25° C., 1 Hz) divided by the density of the film material (at 25° C.), of at least 1000 km, e.g. at least 2000 km, at least 3000 km, at least 4000 km, or at least 4250 km. In an embodiment, the polymer films have a specific storage modulus of less than 10000 km, e.g. less than 7500 km or less than 5000 km.
A combination of good damping (a sufficiently high loss modulus) and good stiffness (a sufficiently high storage modulus), especially on a weight basis, are of interest, for instance, in high performance damping applications (especially when light weight is important). Such as data storage systems, aerospace applications, sporting articles such as tennis rackets, hockey sticks, or any other electrical, acoustical, optical, mechanical or any other object, devise or matter that may be effected by internal or external vibrations in an undesired manner. The favorable damping properties of these tapes could also be of interest as high-damping layers in composites, for example as layers between unidirectional carbon fiber-reinforced composite plies that make up a laminate.
In an embodiment, the films have a thickness of less than 150 micrometer, e.g. less than 100 micrometer, less than 50 micrometer, less than 25 micrometer, less than 10 micrometer, or even less than 5 micrometer. In an embodiment, the films have a thickness of at least 1 micrometer, e.g. at least 2 micrometer, at least 3 micrometer, or at least 4 micrometer.
In an embodiment, the films are laminated. In an embodiment, the laminate consists of 3 layers (e.g. in a 0/60/120 configuration), of 4 layers (e.g. in a 0/45/90/135 configuration), or more than 4 layers. In an embodiment, the laminate comprises less than 20 layers, e.g. less than 15 layers, less than 10 layers, or less than 7 layers.
In an embodiment, the laminate has a tensile modulus of at least 5 GPa in at least 2 perpendicular directions in the plane of the laminate, e.g. at least 8 GPa, at least 10 GPa, or at least 12 GPa. In an embodiment, the laminate has a tensile modulus in all directions in the plane of the laminate of at least 5 GPa, e.g. at least 8 GPa, at least 10 GPa, or at least 12 GPa, or at least 15 GPa. In an embodiment, the laminate has a substantially isotropic tensile modulus in the plane of the laminate.
In an embodiment, the films are laminated using a glue on the surface of the films. In an embodiment, the laminate comprises, relative to the total weight of the laminate, less than 25wt % glue (e.g., epoxies or relatively low melting components), e.g. less than 15wt % glue, less than 10 wt % glue, less than 7 wt % glue, less than 4 wt % glue, or even less than 1 wt % glue. In an embodiment, no glue is used. In an embodiment, the laminate consists essentially of a single polymer grade. A benefit of using limited (or no) amounts of glue is that such glue may have a negative effect on one or more mechanical properties (for instance tensile modulus). In an embodiment, lamination is achieved by stacking tapes and subjecting the stack to elevated temperature and/or elevated pressure. In an embodiment, the films are laminated using relatively low melting components present in the films (e.g., by heating the films to above the temperature of a low melting component but below the melting temperature of a high melting component).
In an embodiment, the polymer articles (e.g. the polymer films, or the polymer laminates) are used in the manufacture of sails. Other applications are, for instance, tubes, pipes, panels, protective sheets, aerospace and automotive applications, sporting articles (e.g. tennis rackets, hockey sticks, running shoes), helmets, protective gear, furniture, containers, tows, fly wheels, high-damping layers in composites (e.g. as a layer between composite plies, e.g. unidirectional carbon fiber-reinforced composite plies, that make up a laminate). In an embodiment, the polymer articles are used in security features. For instance, the films may feature a directional haze. For instance, upon increasing the distance between a film and the text behind it, the latter may remain well-defined along the orientation direction of the foil, while perpendicular to it the image may become blurred.
SA<N×D
2
W×T<N×D
2
wherein a first polymer grade is pressed through the majority of the orifices of the spinneret, and a second polymer grade is pressed through one or more of the remaining orifices.
a width of at least 5 cm; and
a tensile modulus that is 25% or more of the maximum theoretical modulus.
a width of at least 5 cm; and
a tensile modulus of at least 50 GPa.
SA<N×D
2
EL×WO<N×D
2
The following examples are given as particular embodiments of the invention and to demonstrate the practice and advantages thereof. It is understood that the examples are given by way of illustration and are not intended to limit the specification or the claims that follow in any manner.
Mechanical properties: tensile modulus (also referred to below as E-modulus), strength (or stress) at break, and elongation at break were measured under the following testing conditions: gauge length for the samples below comprising poly(p-hydroxybenzoic acid-co-2-hydroxy-6-naphtoic acid)copolymer was in the range of 50 mm-100 mm, crosshead speed was 10% of the gauge length/min (e.g. for a 50 mm sample, the crosshead speed was 5 mm/min), and at room temperature. For the samples below comprising polyethylene, gauge length was 50 mm, crosshead speed 5 mm/min, and at room temperature.
The polymer “Vectra™ A950” referred to in below examples is a poly(p-hydroxybenzoic acid-co-2-hydroxy-6-naphtoic acid)copolymer from Ticona, Germany. It is believed to consist of about 25-27 mole percent of 6-oxy-2-naphthoyl moieties and 73-75 mole percent of p-oxybenzoyl moieties. It is a thermotropic liquid-crystalline polymer with a melting temperature of about 280° C., and a density “p” (at 25° C.) of about 1.4 g/cm3. Before use, it was dried overnight at 80° C. under vacuum.
The single screw extruder referred to in below examples is the Teach-Line E20T SCD15 single screw extruder from Dr. Collin GmbH, Ebersberg, Germany.
The twin screw extruder referred to in below examples is the Teach-Line twin-screw-extruder 2K25T from Dr. Collin GmbH, Ebersberg, Germany.
The material used was Vectra™ A950. Tapes were produced by continuous extrusion at 300° C., using a single screw extruder, equipped with a home-made die similar to the die of
The experiment of example 1 was repeated, but now with a reduced slit width outlet of 0.07 mm (and the range within which the winder speed was varied was less, i.e. max. winder speed was below 125 m/min). Transparent tapes were produced of good quality, including tapes having a tensile modulus in the drawing direction of 59 GPa.
Tape produced by Example 2 was placed slightly above a page of typewritten text, once with the drawing direction of the tape being perpendicular to the sentences on the page, and once with the drawing direction of the tape being parallel to the sentences on the page. When the drawing direction was parallel to the sentences, the sentences could readily be read. When perpendicular, the text was distorted.
Tape of Example 2 was wound under tension around a steel bar. Thickness of the eventual layer wound around the bar was about 1 mm. The bar with tape was exposed for 3 hours to 250° C. under nitrogen atmosphere. The steel bar was then separated from the wound tape. The wound tape formed a hollow tube.
Tape of Example 2 was stacked in a quasi-isotropic tape lay-up (0/45/-45/90). The stack was then exposed to 250° C. for three hours at a pressure of 0.5 MPa in a vacuum mold, resulting in a plate with a thickness of 1.7 mm. The plate had a semi-transparent appearance.
Tape of Example 2 (thickness 0.007 mm, E-Modulus=50 GPa) was stacked into a quasi-isotropic complex. This was done by stacking 4 pieces of tape on top of each other at the following angles: 0/45/−45/90. The stack of tapes was then transferred into a vacuum mold and exposed to 250° C. for 1 hour at a pressure of 0.5 MPa. The resulting sheet had substantially isotropic mechanical properties in the sheet plane, which are listed in the following Table 1.
Vectra™ A950 was fed into a single-screw extruder with a diameter of 20 mm and operated at a temperature of 320° C. and at 80 rpm. The extruder was connected to a same die as in Example 1. The temperature of the die was set to 290° C.
The extruded tape was quenched at a distance of 2 mm from the die by a metallic box which had internal water cooling. A support film, made of polypropylene, was guided over that box to prevent attaching of the extruded Vectra™ film. The Vectra™ tape on the support film was then guided over a set of speed controlling rollers and wound up on a roll. The take up speed was set to 1 m/s.
When the system reached its steady state, the pressure at the end of the extruder barrel was about 60 bars. The Vectra™ tape had a width of 120 mm and a thickness of 0.005 mm. The mechanical properties of the tape are listed in Table 2.
90% wt. of Vectra™ A950 was mixed with 10% wt. polybutylene terephthalate (“PBT”) (Ultradur B 4520, BASF, Germany) using a twin-screw extruder, with a melt pump attached to it to better control the filling of the extruder. The equipment was operated at a temperature of 300° C. The end of the meltpump was provided with a nozzle from which the polymer strand was cooled in a water bath and then granulated with a rotating knife.
Subsequently the granulated material was dried and then fed into a single-screw extruder with a diameter of 20 mm and operated at a temperature of 320° C. and operated at 70 rpm. The extruder was connected to a same die as in Example 1. The temperature of the die was set to 285° C. The speed of the take-up rolls was 0.3 m/s.
When the system reached its steady state, the pressure at the end of the extruder barrel was about 50 bars. The Vectra™/PBT-tape had a width of 120 mm and a thickness of 0.014 mm. The mechanical properties of the tape are listed in Table 3.
Complexes of several layers of the tapes were obtained by pressing them at 250° C. for 15 minutes at a pressure of 1.5 MPa. The temperature of 250° C. was above the melting point of the PBT (220° C.) but below the melting point of the Vectra™ (280° C.).
Vectra™ film obtained in example 7 was exposed to 200° C. in a nitrogen atmosphere at a tension of 20 MPa for 15 hours. Mechanical properties of the thus treated film are listed below in Table 4. E.g., the E-modulus increased by 21% compared to the film before treatment.
Vectra™ film obtained in example 7 was exposed to 230° C. in a nitrogen atmosphere at a tension of 10 MPa for 15 hours. Mechanical properties of the thus treated film are listed In the Table 5 below. E.g., the stress at break increased by 25% and the elongation at break increased by 33% compared to the film before treatment.
A mixture consisting of 15% wt. UHMW PE having a weight-average molecular weight of 8.7·106 g/mol (DSM, The Netherlands, Stamylan® UH 610) and 85% wt. of a paraffin wax having a average molecular weight of 1860 g/mol (Sasol GmbH, Germany, Sasolwax 6403) was prepared by mixing the components in the appropriate amounts in a tumbler at room temperature for one hour. Subsequently, the mixture was transferred to a twin-screw-extruder. Directly connected to the extruder was a melt pump (from Dr. Collin GMBH, Germany, 1.2 cm3/U). The melt pump head was connected to a die as in
Tape of example 11 was immersed in decalin (decahydronaphthalene) for 10 minutes at 80° C. to dissolve the paraffin component of the tape. The tape was constrained in the extrusion direction during the treatment. The thickness of the tape reduced to 0.004 mm. Its mechanical properties are listed in Table 7. The tape displayed a double yield point in the stress-strain curve (therefore, two E-modulus values are indicated in the Table).
Example 11 was repeated, except the die part was changed to a die as depicted in
Example 11 was repeated, except the die consisted only of the slit part which is displayed in
The tape of comparative example A was immersed in decaline (decahydronaphthalene) for 10 minutes at 80° C. to dissolve the paraffin component of the tape. The tape was constrained in the extrusion direction during the treatment. The thickness of the tape reduced to 0.0068 mm. Its mechanical properties are listed in Table 10. The tape displayed a double yield point in the stress-strain curve, (therefore, two E-modulus values are indicated in the Table).
A quantity of 5 g of the lyotropic polymer poly(p-phenylene terepthalamide) was dissolved in 15 ml 98% sulfuric acid at 80° C. Dissolution was carried out over 6 hrs using a glass-walled, stainless steel double-helix mixer under argon atmosphere. The poly(p-phenylene terepthalamide) was obtained from E.I. du Pont de Nemours and had an inherent viscosity of 7.8 dl/g.
The solution was extruded at 90° C. with the SPINLINE tool from DACA Instruments, Santa Barbara, USA (a laboratory-scale, piston-driven extrusion apparatus), equipped with a die as in
Vectra™ tape of Example 7 was tested in a Dynamical mechanical thermal analysis (DMTA, Mettler DMA861e, Greifensee, Switzerland) instrument. Isothermal scans of tapes in the extrusion direction were measured at 1, 10 and 100 Hz in the temperature range from −80 to 140° C. in one degree steps.
The tested sample had a width of 3 mm and a length of 8 mm. The sample was pre-tensioned with a load of 1 N and as maximum values for the excitation a load of 0.25 N and for the amplitude 4 μm were chosen. The storage modulus E′, loss modulus E″ and the loss factor tan(δ)=(E″/E′) were recorded as a function of temperature at three frequencies: 1, 10, and 100 Hz. See Table 11.
This application claims priority to U.S. provisional application 61/193,514 filed 4 Dec. 2008, the content of which is hereby incorporated in its entirety by reference.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2009/066464 | 12/4/2009 | WO | 00 | 5/31/2011 |
| Number | Date | Country | |
|---|---|---|---|
| 61193514 | Dec 2008 | US |
