Processable polymers, methods and apparatus for additive manufacturing

Abstract

The name of the present invention is a processable polymer, method and apparatus for additive manufacturing. The method of additive manufacturing of an article includes conveying a material through a heated nozzle to form a flowing substance of the material. The material includes a polymer matrix containing a plurality of polymer chains and an alignment additive that can be dispersed in the polymer matrix. The alignment additive is configured to align the plurality of polymer chains in a flow direction of the flowing substance of the material. The method further includes aligning at least a portion of the polymer chains via the alignment additive along a direction of flow through the heated nozzle, releasing the flowing substance of the material from the heated nozzle, and solidifying the material.

Description

Technical Field

[0001] The present disclosure relates generally to the field of polymer engineering, and more particularly to polymer materials with improved processability and the use of such materials in additive manufacturing. Background Art

[0002] Additive manufacturing, or "3D printing," can be used to make articles of virtually any shape or size. In additive manufacturing, a physical, real article is built layer by layer from a digital model that defines the article's topology. The result is a high-fidelity realization of the digital model that is obtained without specialized tools and with minimal human intervention. In a variation of the desired thermoplastic polymer article, a thermoplastic polymer feedstock is directed through a heated nozzle positioned at a locus of material to be deposited on the article. The position of the locus is controlled in real time by moving the article relative to the nozzle and / or rastering the nozzle over the article. After leaving the nozzle, the thermoplastic polymer material cools and adheres to underlying layers of the article.

[0003] A wide range of thermoplastic polymer materials have been used for additive manufacturing, but some materials present specific challenges. One challenge relates to the additive manufacturing of articles comprising high molecular weight polymers that exhibit desirable mechanical properties, thermal stability, and / or chemical resistance. Similar challenges also arise with polymers having functional groups that impart rheologically significant steric bulk. Summary of the invention

[0004] In view of the above, some examples disclosed herein relate to additively manufactured articles, which include a polymer matrix and an alignment additive. The polymer matrix includes a plurality of aligned polymer chains. The alignment additive dispersed in the polymer matrix includes one or more of liquid crystal molecules, hyperbranched macromolecules, nanotubes, and nanowires.

[0005] Other examples relate to materials adapted as feedstock for additive manufacturing. The material includes a polymer matrix and an alignment additive. The polymer matrix includes a plurality of polymer chains and is configured to form a flowable substance at an elevated temperature. The alignment additive may be dispersed in the polymer matrix and configured to align the plurality of polymer chains in a direction of flow through a conduit of an additive manufacturing device.

[0006] Other examples relate to methods for additive manufacturing of articles. The method includes delivering a material through a heated nozzle to form a flowing mass of the material. The material includes a polymer matrix comprising a plurality of polymer chains and an alignment additive dispersible within the polymer matrix. The alignment additive is configured to align the plurality of polymer chains in a direction of flow of the flowing mass of the material. The method also includes aligning at least a portion of the polymer chains along a direction of flow through the heated nozzle via the alignment additive, releasing the flowing mass of the material from the heated nozzle, and solidifying the material.

[0007] Still other examples relate to an apparatus for additively manufacturing an article from a material including a polymer matrix having a plurality of polymer chains and an alignment additive. The apparatus includes a nozzle, an elongated conduit, one or more heaters, and a material conveyor configured to convey the material through the elongated conduit and the nozzle. When the material flows through the conduit at an elevated temperature, the elongated conduit fluidly connected to the nozzle has a sufficient length to achieve alignment of the plurality of polymer chains via the alignment additive. The one or more heaters are configured to heat the elongated conduit and the nozzle to allow the material to flow within the conduit and through the nozzle.

[0008] This summary is not intended to identify key features or essential features of the claimed subject matter. Indeed, the scope of the claimed subject matter is not limited to the contents of this summary, nor to implementations that address any problems or shortcomings noted in any part of this disclosure. The features, functions, and advantages described in this disclosure may be implemented independently in some implementations, and may be combined in other implementations. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The present disclosure will be better understood by reading the following detailed description with reference to the accompanying drawings, in which:

[0010] Figure 1 Aspects of example manufactured products that may include additively manufactured polymeric articles are shown;

[0011] Figure 2A and 2B shows the molecular structure of example polymers that may be suitable for additive manufacturing as disclosed herein;

[0012] Figure 3A Aspects of example apparatus configured for additive manufacturing of polymeric articles are shown;

[0013] Figure 3B and 3C Shows Figure 3A Examples of devices include aspects of material storage and material transport devices.

[0014] Figure 4 illustrates aspects of an example method for additive manufacturing of polymeric articles;

[0015] Figures 5A to 5F Shows the available Figure 4 Examples of the alignment additives in the method include molecular structures of liquid crystal materials;

[0016] Figure 6 Shows the available Figure 4 The molecular structure of an example dendrimer of the method for aligning additives; and

[0017] Figure 7 It shows that according to Figure 4 Aspects of the methods of forming example polymeric articles. DETAILED DESCRIPTION

[0018] Due to the limited fluidity of the polymer raw materials, the additive manufacturing of articles containing thermoplastic polymers may be problematic. In general, the polymer chains of many commonly available high molecular weight polymers are randomly oriented and significantly entangled. These characteristics reduce the fluidity of such polymers at all temperatures. Even in relatively low molecular weight polymers, steric effects in the polymer side chains can also reduce fluidity. Due to reduced fluidity, undesirable high temperatures and / or high pressures may be required to guide the thermoplastic polymer through the nozzle of the additive manufacturing device. Such conditions may increase manufacturing costs, and in the case of using very high temperatures, may limit the scope of available polymers and / or reduce the desired material properties of the polymer, such as optical transparency.

[0019] The inventors of this article have recognized the above problems and discovered several related innovations that can improve the processability of thermoplastic polymers in additive manufacturing. The disclosed examples utilize the incorporation of alignment additives into a polymer matrix of a thermoplastic polymer raw material provided to an additive manufacturing device. Alignment additives are molecular or macromolecular species that are configured to cause alignment of polymer chains in a flowing polymer. In some examples, alignment parallel to the flow direction is achieved. In the aligned state, the polymer chains are more fluid than in a randomly oriented entangled state. Therefore, a polymer matrix containing an alignment additive can provide a suitable raw material for additive manufacturing of thermoplastic articles.

[0020] Various types of alignment additives can be incorporated into the polymer matrix of the feedstock. Example alignment additives include liquid crystal molecules, nanotubes and / or nanowires with high aspect ratios. These species naturally align along the flow direction of the polymer under hydrodynamic action and induce alignment of adjacent polymer chains via intermolecular forces. Alternatively or additionally, the alignment additive may include hyperbranched macromolecules, such as dendritic macromolecules. Hyperbranched macromolecules can reduce the viscosity of flowing high molecular weight polymers, thereby accelerating the alignment of polymer chains due to shear forces.

[0021] The present disclosure is presented by way of example and with reference to the accompanying drawings. Components, process steps and other elements that may be substantially the same in one or more of the accompanying drawings will be identified equally and described with minimal repetition. However, it should be noted that the elements with the same identification may also be different. It should also be noted that these figures are schematic and are generally not drawn to scale. Instead, the various drawing scales, aspect ratios and the number of components shown in the accompanying drawings may be intentionally distorted to make certain features or relationships easier to see. As used herein, the phrase "one or more" precedes the inclusive enumeration of options. Therefore, a phrase in the form of "one or more of A and B" is equivalent to "one or more members of the set {A, B}". The phrase neither excludes nor requires that one or more instances of A coexist with one or more instances of B.

[0022] Before describing additive manufacturing of thermoplastic articles in detail, a background of example applications of such articles will be presented. Figure 1 Aspects of an example manufactured product are shown in the form of an aircraft 100. The aircraft includes, among other things, an aerostructure 102, a power plant 104, a skin 106, and a cabin interior 108.

[0023] The mechanical strength of nearly all structural and / or functional parts of the aircraft 100 may be optimized. Additionally, many of the same parts, etc., may be optimized to reduce weight. Thus, various fuselage parts are constructed from high-strength metals such as steel and titanium, while other parts may be constructed from so-called "performance polymers" - a term that includes selected high molecular weight thermoplastic polymer materials.

[0024] A non-limiting example of a high molecular weight thermoplastic polymer material suitable for use in aircraft construction is polyetheretherketone (PEEK). Figure 2A The chemical structure of PEEK is shown in Figure 1. PEEK has a melting temperature (T) of 341°C. m ) and a glass transition temperature (T g ). In some examples, the molecular weight of the high molecular weight polymer can be 10,000 Daltons or greater.

[0025] PEEK is a semi-crystalline thermoplastic that exhibits high heat, chemical and abrasion resistance in addition to fatigue and creep resistance. PEEK exhibits extraordinary tensile properties that are retained even at elevated temperatures. As a result, the service temperature range of PEEK products can be extended to 260°C. Above the service temperature range, the material remains virtually non-flammable and emits very little smoke or gas when burned. PEEK products can be further strengthened by fiber reinforcement. For example, when reinforced with carbon fiber, 29,000 psi (lbf / in 2) tensile strength. Additional properties of filled and unfilled PEEK materials are summarized in Table 1.

[0026] Table 1. Selected properties of high molecular weight PEEK polymers.

[0027]

[0028] return Figure 1 , polymer articles comprising PEEK and / or other suitable thermoplastics can be incorporated into various parts of the aircraft 100 to take advantage of the desired material properties as mentioned above. For example, in the aerospace structure 102, thermoplastic polymer articles can be used for bearings and bushings, and as reinforcements for composite panels including hard points, thermal insulation and fasteners. In the power plant 104, heat-resistant and chemical-resistant thermoplastic polymer articles can be used in fuel systems, turbines and engine compartments (nacelles), as well as for dry and lubricated material contacts. In the skin 106, ultraviolet (UV) stable and moisture-resistant thermoplastic polymer articles can provide excellent weather resistance. Low flammability thermoplastic polymer articles can also be used in cabin interiors 108 and ducts to protect wires and optical fiber filaments. In order to form such parts, thermoplastic polymers such as PEEK can be conventionally processed via injection molding, extrusion molding, and compression molding. However, due to the reasons discussed above, the use of some thermoplastics such as PEEK in prior art additive manufacturing is problematic. For various other thermoplastics, such as having Figure 2B Polyetherketoneketone (PEKK) of the structure shown in , as well as various nylon compounds, such as nylon 12 (poly(dodecane-12-lactam)), may present the same limitations and many of the same benefits.

[0029] It will be understood that the examples illustrated in this disclosure in no way limit the applicability of the following methods. Indeed, the methods described herein can be applied to the additive manufacturing of a wide range of articles. Such articles may or may not be specifically configured to optimize mechanical strength relative to weight, or to provide heat resistance, chemical resistance or weather resistance, or fire safety.

[0030] Figure 3A Aspects of an example apparatus 300 configured for additive manufacturing of a thermoplastic polymer article 310 are shown. The apparatus 300 includes a chamber 312 that supports the article during an additive manufacturing process. The chamber includes a platen 314 to which the article is secured during the additive manufacturing process. Figure 3AIn the particular example illustrated, substrate 316 of article 310 is secured to a rotating chuck 318 that is mechanically connected to platen 314. As used herein, "substrate" is the base of an article to be formed via additive manufacturing. In some examples, the substrate is a relatively simple topological part that can be formed by conventional machining. Rotating chuck 318 can be used to additively manufacture articles having rotational symmetry, such as bushings. In other examples, a vise or clamp can be used in place of a chuck to secure a substrate or any other part of an article to a platen.

[0031] In apparatus 300, article 310 is formed in layers by spatially selectively adding thermoplastic polymer material to lower layers of the article starting from substrate 316. Accordingly, apparatus 300 includes a material reservoir 320 configured to store a supply of thermoplastic polymer material 322. For example, the thermoplastic polymer material may include filaments, pellets of any size, granules, or a coarse or fine powder.

[0032] The apparatus 300 includes a material conveyor 324 configured to convey a thermoplastic polymer material 322 from a material reservoir 320 and deliver the thermoplastic polymer material to a nozzle 326. The nozzle includes a hole in a conduit through which the thermoplastic polymer material is directed. In some implementations, the nozzle hole is perpendicular to the direction of flow through the conduit and crosses the entire diameter of the conduit, while in other implementations, the nozzle hole can have any other suitable configuration. In some examples, the nozzle hole diameter can be about one millimeter. In other examples, the nozzle hole diameter can be about five millimeters or more. In some implementations, the material conveyor can be configured to forcefully direct the thermoplastic polymer material 322 through the nozzle 326.

[0033] Figure 3B Aspects of an example material reservoir 320B and a material conveyor 324B suitable for storing and conveying a thermoplastic polymer material 322B in pellet, granule and / or powder form are shown. In this example, the material conveyor 324B includes a screw feeder 328.

[0034] Figure 3C Aspects of an example material reservoir 320C and a material conveyor 324C suitable for storing and conveying a thermoplastic polymer material 322C in the form of a filament are shown. In this example, the material reservoir 320C includes a spool 330 around which the filament is wound, and the material conveyor 324C includes a filament feeder 332.

[0035] Now return to Figure 3A, the nozzle 326 of the device 300 is arranged above the trajectory 336, where the thermoplastic polymer material is added to the article 310. The nozzle heater 338 is thermally connected to the nozzle 326. The nozzle heater is configured to heat the nozzle, thereby heating the thermoplastic polymer material flowing through the nozzle to a desired set point temperature or temperature range. In some examples, the nozzle heater 338 is a resistive heater powered via a proportional integral derivative (PID) type temperature controller, which is operably connected to a thermocouple or other form of temperature sensor. In this way, the set point temperature of the flowing thermoplastic polymer material is achieved via closed-loop control. In some examples, the device 300 may include additional heaters, as described below.

[0036] The device 300 includes a translation stage 340 mechanically connected to the platen 314. When the product is formed layer by layer in the device 300, the translation stage can be configured to gradually lower the height of the platen as the successive layers of the product are constructed. The translation stage can also be configured to move the platen laterally to controllably change the relative position of the reference system of the trajectory 336 relative to the platen and the corresponding product 310. The translation stage may include two or more component translation stages (e.g., linear actuators) configured to move the platen in two or more corresponding directions, such as Cartesian X, Y, and Z axes. In some instances, one or more component rotation stages are used instead of one or more component translation stages, or in addition to one or more component translation stages. In other examples equivalent to the present disclosure, the translation stage or the rotation stage is mechanically connected to the nozzle 326, and the platen can be stationary. In still other instances, the platen and the nozzle can be controllably actuated.

[0037] The apparatus 300 also includes a computer 342. The computer 342 is operably connected to the translation stage 340 and is configured to control the relative position of the trajectory 336 relative to the reference system of the platen 314 in real time via a series of actuator-control signals. In addition, the computer is operably connected to the material conveyor 324 and is configured to control the flow rate of the thermoplastic polymer material through the nozzle 326 in real time via one or more material conveying-control signals. The computer 342 is also configured to receive a digital model 344, which represents the topology of the article to be formed. The properties and / or digital data structure of the digital model are not particularly limited. In some instances, the digital model may include a CAD file. The computer is configured to change the output of the actuator-control signal and the material conveying control signal based on the digital model, thereby achieving additive manufacturing of the article defined by the digital model.

[0038] Figure 4 Aspects of an example method 400 for additively manufacturing a thermoplastic polymer article are illustrated. As described above, the Figure 3AThe method 400 is implemented using the apparatus 300 of FIG. 4. However, it will be understood that the method 400 may be implemented using any other suitable apparatus, which may be significantly different from the apparatus 300 in some implementations.

[0039] In optional step 446 of method 400, a substrate for the article is secured to a platen of an additive manufacturing apparatus. For example, the substrate may be secured via, for example, a vise, a clamp, or a chuck. In some examples, the substrate may include a thermoplastic polymer, although this aspect is not strictly necessary. More generally, the substrate may include any structure to which the thermoplastic feedstock will adhere when cured. In some examples, the substrate is milled, lathed, or ground roughened or chemically treated to promote adhesion of the thermoplastic feedstock material to be added.

[0040] At 448 of method 400, a thermoplastic polymer material adapted as an additive manufacturing feedstock is delivered through a heated nozzle to form a flowing mass. In examples where the thermoplastic polymer material is in the form of a filament or thread, the thermoplastic polymer material is delivered via a filament feeder. In some examples where the thermoplastic polymer material is in the form of a pellet, granule, or powder, the thermoplastic polymer material is delivered via a screw feeder.

[0041] The thermoplastic polymer material delivered at 438 includes a polymer matrix including a plurality of polymer chains. The polymer matrix is ​​configured to form a flowable material at an elevated temperature by virtue of its macromolecular structure. Aspects of the macromolecular structure that provide this feature include, for example, the backbone structure including heteroatoms (if any), pendant side chains and functional groups (if any), and the degree of crosslinking (if any), which affects the T m and higher than T m In some examples, the polymer matrix comprises PEEK or PEKK. In some examples, the polymer matrix comprises a nylon polymer. In some examples, the polymer matrix comprises two or more different thermoplastic polymers. As used herein, the example "elevated temperature" is an increase from the melting temperature T of the polymer matrix. m The elevated temperature extends to any temperature within the range of temperatures at which polymer decomposition is observed on the time scale of processing. In a particular example, the elevated temperature includes temperatures above T m Temperature of 30℃.

[0042] The thermoplastic polymer material delivered at 438 also includes an alignment additive that can be dispersed in the polymer matrix. In some examples, the alignment additive accounts for 0.01 mass % to 25 mass % of the thermoplastic polymer material. In a more specific example, the alignment additive accounts for 0.01 mass % to 10 mass % of the thermoplastic polymer material. The alignment additive is configured to align multiple polymer chains in the direction of flow through the conduit of the additive manufacturing device by virtue of its molecular or macromolecular structure. The alignment additive can increase the melt flow index of the thermoplastic polymer material to exceed the melt flow index of the polymer matrix without the alignment additive. In some examples, a specific alignment additive can be empirically selected based on the ability to incorporate a specific alignment additive into the thermoplastic plastic material.

[0043] In some examples, the alignment additive includes a liquid crystal (LC) material that includes a plurality of liquid crystal molecules. Both smectic and nematic liquid crystals can be used. Examples of smectic liquid crystal materials suitable for use as alignment additives include 4-(heptyloxy)benzoic acid, 4-(octyloxy)benzoic acid, and 4-(decyloxy)benzoic acid. Figure 5A The melting point of 4-(heptyloxy)benzoic acid of the structure shown is 146°C and it transforms into an isotropic phase at 146°C. Figure 5B 4-(Octyloxy)benzoic acid of the structure shown has a melting point of 101 to 105°C and transitions to the isotropic phase at 147°C. Figure 5C 4-(Decyloxy)benzoic acid of the structure shown has a melting point of 143°C and transitions to an isotropic phase at 117 to 143°C. Examples of nematic liquid crystal materials suitable for use as alignment additives include 4,4'-azoxyanisole, 4-isothiocyanatophenyl-4-pentylbicyclo[2.2.2]octane-1-carboxylate, and 4-methoxycinnamic acid. Figure 5D The melting point of 4,4'-azoxyanisole of the structure shown is 117 to 119°C and it transforms into an isotropic phase at 136°C. Figure 5E The structure shown, 4-isothiocyanatophenyl-4-pentylbicyclo[2.2.2]octane-1-carboxylate, has a melting point of 73 to 113.5°C and transitions to an isotropic phase at 113.5°C. Fig. 5F 4-Methoxycinnamic acid of the structure shown has a melting point of 170 to 173°C and transforms to an isotropic phase at 190°C.

[0044] In some examples where the alignment additive comprises a liquid crystal material, the liquid crystal material is selected such that it has a melting temperature T of the polymer matrix into which the alignment additive is incorporated. mThe liquid crystal material may undergo a phase transition between an aligned (e.g., smectic or nematic) phase and an isotropic phase at or below the temperature of the thermoplastic polymer material. Such liquid crystal materials may be dispersed in an isotropic phase at elevated processing temperatures and transition to an aligned phase prior to curing of the thermoplastic polymer material, and may help align the polymer chains via this transition.

[0045] Table 2 presents melt flow data collected from thermoplastic feedstock materials having varying concentrations of 4-(heptyloxy)benzoic acid as a liquid crystal alignment additive.

[0046] Table 2. m The above melt flow data is observed for the thermoplastic raw material at 5°C.

[0047]

[0048] The data in Table 2 illustrate that for both PEEK and Nylon-12 polymers, flowability increases significantly with increasing concentration of the alignment additive. Table 3 presents additional data for the PEEK stock material.

[0049] Table 3. Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) of PEEK stock materials.

[0050]

[0051] More specifically, the data in Table 3 show that after adding the aligning additive, even up to 7.5%, there is no change in the heat resistance of PEEK.

[0052] It should be understood that other suitable high aspect ratio species can be incorporated into the thermoplastic polymer matrix as alignment additives to promote alignment of polymer chains therein. In other examples, the alignment additives include nanotube and nanowire materials, which include a plurality of nanotubes or nanowires, respectively. More specific examples include carbon nanotubes and silver nanowires, although nanotubes and nanowires including other elements are also contemplated.

[0053] Furthermore, in some examples, the alignment additive includes multiple hyperbranched macromolecules, such as dendrimers. Example dendrimers include poly(amidoamine) (PAMAM) and poly(propyleneimine) (PPI). The macromolecular structure of PPI dendrimers is Figure 6 As shown in Table 4, PPI dendrimers can be nanoscale, with diameters varying smoothly with generation number.

[0054] Table 4. Molecular weight and diameter versus generation number of PPI dendrimers

[0055]

[0056] Due to their steric morphology, dendrimers generally exhibit low intrinsic viscosity and reduce the viscosity of the polymer matrix they are dissolved in. Furthermore, the intermolecular interactions between the dendrimers and the high molecular weight thermoplastic matrix can be regulated by controlling the surface functionality of the dendrimers.

[0057] In some examples, the thermoplastic polymer material delivered at 438 is a composite material, such as a fiber composite material. More specifically, in some examples, the thermoplastic polymer material further includes a reinforcing additive or filler, such as a fiber additive. Glass fibers and carbon fibers are also among the fiber additives contemplated herein.

[0058] Continue Now Figure 4 At 450 of method 400 , at least a portion of polymer chains of the thermoplastic polymer material are spontaneously aligned along a direction of flow through the heated nozzle via the influence of the alignment additive.

[0059] In examples where the alignment additive comprises a molecule or macromolecular species with a high aspect ratio (such as a liquid crystal molecule, a nanotube, and / or a nanowire), the alignment additive can naturally align in the direction of flow of the polymer under fluid dynamics within the heated nozzle and upstream of the fluid. When aligned in this manner, the alignment additive can induce alignment of adjacent polymer chains via intermolecular forces, such as van der Waals forces, molecular dipole forces, hydrogen bonding, etc. In examples where the alignment additive comprises a relatively low molecular weight, hyperbranched macromolecule (such as a dendrimer), the alignment additive can reduce the viscosity of the flowing high molecular weight polymer and thereby accelerate the alignment of the polymer chains due to shear forces within the heated nozzle and upstream of the fluid.

[0060] At 452 of method 400, a flowing mass of thermoplastic polymer material is released from a heated nozzle at a desired trajectory location for forming an article (eg, on a substrate of the article). At 454, the thermoplastic polymer material is solidified at the trajectory.

[0061] Subsequent layers of thermoplastic polymer material are added to the already formed layer of thermoplastic polymer material at 456. Based on the article topology defined in the digital model, this step may be repeated any number of times until the desired article is constructed.

[0062] At 458, the article is removed from the additive manufacturing apparatus and optionally annealed under controlled temperature conditions for an appropriate period of time. Annealing can be used to reduce the density of defect sites in the additively manufactured article and thereby increase the strength of the article.

[0063] Now back to Figure 3A, the device 300 can improve the process of additive manufacturing suitable for thermoplastic polymer raw materials containing polymer matrices and alignment additives described herein. More specifically, in some examples, the device 300 includes an elongated conduit 360 connected to the nozzle 326 upstream of the nozzle fluid. For example, the elongated conduit can be one to four inches long. In other examples, the elongated conduit can be up to thirty inches long. Elongated conduits of other length ranges can also be envisioned. More generally, when the thermoplastic polymer material flows through the elongated conduit at an elevated temperature, the elongated conduit can have a sufficient length to promote at least partial alignment of the polymer chains of the thermoplastic polymer material through the influence of the alignment additive. In this improvement, the cross-sectional dimensions of the elongated conduit can correspond to the cross-sectional dimensions of the raw material material, and the extrusion rate can be constant relative to the extrusion rate of the unmodified raw material. However, faster and slower extrusion rates can also be envisioned. The set point temperature of the elongated conduit is higher than the melting temperature of the thermoplastic polymer material.

[0064] In these and other examples, the material conveyor 324 is configured to convey the thermoplastic polymer material through the elongated conduit and through the nozzle. The illustrated device also includes a conduit heater 362, which is thermally connected to the elongated conduit 360 and is configured to heat the elongated conduit to an elevated temperature. Considered together, the conduit heater 362 and the nozzle heater 338 are configured to heat the elongated conduit 360 and the nozzle 326 so that the material flows in the conduit and through the nozzle. When the thermoplastic polymer material flows through the elongated conduit at an elevated temperature, the elongated conduit 360 has a sufficient length to promote at least partial alignment of the polymer chains of the thermoplastic polymer material by the influence of the alignment additive. In some examples, the conduit heater 362 and the nozzle heater 338 can be separate heating units, as shown in the figure. In other examples, the conduit heater and the nozzle heater can be integrated into a single heating unit capable of providing the desired temperature of the nozzle 326 and the desired temperature of the elongated conduit 360, even if those temperatures are different.

[0065] Figure 7 It shows that according to Figure 4 400 . In the example shown, the article 710 includes a substrate 716 in addition to a thermoplastic polymer material 762, to which the thermoplastic polymer material 762 is added via additive manufacturing. In some examples, the article can be formed without a substrate and can include only the thermoplastic polymer material. In either case, the thermoplastic polymer material 762 includes a polymer matrix 764 that includes a plurality of aligned polymer chains 766. The polymer matrix can include PEEK or PEKK, but other polymers are also contemplated.

[0066] It will be understood that Figure 7 The illustration in is highly schematic. In actual examples, multiple polymer chains 766 do not need to be perfectly aligned, but can be partially aligned. In other words, alignment can be observed between a portion of a polymer chain and a portion of another polymer chain. Alignment can involve many such chains and can extend a relatively long distance in the polymer matrix 764. In some examples, the degree of alignment of the polymer chains in the article 710 can be evaluated by an X-ray diffractometer and / or other methods for distinguishing isotropic and ordered molecular configurations, as understood in the field of condensed phase chemistry. For example, a matrix of aligned polymer chains can produce relatively sharp peaks in an X-ray diffraction spectrum, while an isotropic matrix of the same composition can produce a more featureless X-ray diffraction spectrum.

[0067] The thermoplastic polymer material also includes an alignment additive 768 dispersed within the polymer matrix 764. In some instances, the alignment additive comprises 0.1 mass % to 25 mass % of the thermoplastic polymer material 762, or in more specific instances 0.01 mass % to 10 mass % of the thermoplastic polymer material. In some instances, the alignment additive comprises one or more of liquid crystal molecules, nanotubes, and nanowires. In some instances where the alignment additive 768 comprises a plurality of liquid crystal molecules, the liquid crystal molecules and at least some of the polymer chains may be aligned substantially in parallel. X-ray diffractometers and other suitable analytical methods may also be used to evaluate this feature. Alternatively or additionally, the alignment additive 768 may comprise hyperbranched macromolecules, as described above. Figure 7 In the example shown, the thermoplastic polymer material 762 also includes a reinforcing filler in the form of a fiber additive 770. In other examples, the fiber additive may be omitted. When included, the fiber additive may include, for example, glass fibers and / or carbon fibers.

[0068] Table 5 presents the Figure 4 The experimental data collected for the additively manufactured products were obtained by using the method.

[0069] Table 5. Tensile strength of PEEK articles as a function of percentage of liquid crystal alignment additives.

[0070]

[0071] The data in Table 5 were obtained according to the American Society for Testing and Materials (ASTM) standard protocol ASTM D638 (Standard Test Method for Tensile Properties of Plastics) using a constant rate crosshead travel type tester. The data show that even at significant concentrations of aligning additives, the tensile strength of the PEEK matrix is ​​only slightly reduced. These data can be checked against the data in Table 2, which show that the flowability of the PEEK stock with 7.5% aligning additives is improved by 2.4 times.

[0072] No aspect of the foregoing drawings or description should be interpreted in a limiting sense, as many variations, extensions, and omissions are also contemplated.

[0073] For example, in an implementation where the feedstock is in the form of a filament, the filament may be pre-processed to provide greater fluidity when used in an additive manufacturing device. In the process of forming such a filament, a thermoplastic polymer material 762 having an alignment additive 768 is directed through a heated elongated conduit and nozzle similar to the elongated conduit 360 and the nozzle 326 of the additive manufacturing device 300 in any suitable physical form. While flowing through the elongated conduit and the nozzle, the alignment additive may align the polymer chains of the polymer matrix in the direction of flow through the nozzle. When the feedstock emerges from the nozzle and is subsequently cooled, the alignment of the polymer chains in the length direction of the cooled filament is locked. The extruded filament pre-processed in this manner is now available as a feedstock in an additive manufacturing device.

[0074] In some examples, the alignment of the polymer chains in the feedstock can be further increased by mechanically pulling partially solidified feedstock material downstream of the nozzle. Extruded pulling filaments pre-processed in this way can also be used as feedstock in an additive manufacturing device. In some cases, the filaments described above can even be used in an additive manufacturing device with an elongated conduit 360 without specific modification, because the increased fluidity is already provided by virtue of the pre-processing.

[0075] Further, the disclosure includes examples according to the following clauses:

[0076] Clause 1. An additively manufactured article comprising:

[0077] a polymer matrix comprising a plurality of aligned polymer chains; and

[0078] The alignment additive is dispersed in a polymer matrix and includes one or more of liquid crystal molecules, hyperbranched macromolecules, nanotubes, and nanowires.

[0079] Clause 2. The additively manufactured article of Clause 1, wherein the alignment additive comprises liquid crystal molecules, and wherein the liquid crystal molecules and the plurality of aligned polymer chains are aligned in parallel.

[0080] Clause 3. The additively manufactured article of clause 1, wherein the liquid crystal molecules are molecules of a material having a phase transition between an aligned phase and an isotropic phase at or below the melting temperature of the polymer matrix.

[0081] Clause 4. The additively manufactured article of clause 1 or 2, wherein the polymer matrix comprises polyetheretherketone.

[0082] Clause 5. The additively manufactured article of any of Clauses 1-4, wherein the alignment additive comprises 0.01 mass % to 25 mass % of the additively manufactured article.

[0083] Clause 6. The additively manufactured article of any of Clauses 1-5, wherein the polymer matrix comprises a thermoplastic polymer.

[0084] Clause 7. The additively manufactured article of any of Clauses 1-6, further comprising a reinforcing additive.

[0085] Clause 8. Materials suitable for use as feedstock for additive manufacturing, including:

[0086] a polymer matrix comprising a plurality of polymer chains, the polymer matrix being configured to form a flowable mass at an elevated temperature; and

[0087] An alignment additive may be dispersed within the polymer matrix, the alignment additive being configured to align the plurality of polymer chains in a direction of flow through a conduit of an additive manufacturing apparatus.

[0088] Item 9. The material of Item 8, wherein the alignment additive comprises a liquid crystal material that undergoes a phase transition between an aligned phase and an isotropic phase at or below an elevated temperature.

[0089] Clause 10. The material according to clause 8 or 9, wherein the alignment additive comprises one or more of a hyperbranched macromolecule, a nanotube, and a nanowire.

[0090] Clause 11. A material according to any one of Clauses 8-10, wherein the polymer matrix comprises polyetheretherketone.

[0091] Clause 12. The material according to any of clauses 8-11, wherein the alignment additive comprises 0.01 mass % to 25 mass % of the material.

[0092] Clause 13. The material of any of Clauses 8-12, wherein the material has a melt flow index greater than the melt flow index of the polymer matrix without the aligning additive.

[0093] Clause 14. A material according to any one of clauses 8 to 13, wherein the material is a composite material including a fiber additive.

[0094] Clause 15. The material of any of clauses 8-14, wherein the material comprises one or more of a powder, pellets, and filaments.

[0095] Clause 16. A material according to any of clauses 8-15, wherein the material comprises filaments wherein the plurality of polymer chains are aligned in a length direction of the filaments.

[0096] Clause 17. A method of additive manufacturing of an article, the method comprising:

[0097] Convey material through a heated nozzle to form a flowing mass of material comprising:

[0098] a polymer matrix comprising a plurality of polymer chains, and

[0099] an alignment additive, which may be dispersed within the polymer matrix, the alignment additive being configured to align the plurality of polymer chains in a direction of flow of a flowing substance of the material;

[0100] aligning at least a portion of the polymer chains in the direction of flow through the heated nozzle via an alignment additive;

[0101] releasing a flowing mass of material from a heated nozzle; and

[0102] Allow the material to cure.

[0103] Clause 18. The method of Clause 17, wherein the alignment additive comprises one or more of liquid crystal molecules, hyperbranched macromolecules, nanotubes, and nanowires.

[0104] Clause 19. The method according to Clause 17 or 18, wherein the polymer matrix comprises polyetheretherketone.

[0105] Clause 20. The method of any of Clauses 17-19, wherein conveying the material comprises conveying one or more of a powder and a pellet via a screw feeder.

[0106] Clause 21. The method of any of Clauses 17-20, wherein delivering the material comprises delivering the filaments via a filament feeder.

[0107] Clause 22. An apparatus for additively manufacturing an article from a material comprising a polymer matrix having a plurality of polymer chains and an alignment additive, the apparatus comprising:

[0108] nozzle;

[0109] an elongated conduit fluidly connected to the nozzle, the elongated conduit comprising a length sufficient to effect alignment of the plurality of polymer chains via the alignment additive as the material flows through the conduit at an elevated temperature;

[0110] one or more heaters configured to heat the elongated conduit and the nozzle to allow material to flow within the conduit and through the nozzle; and

[0111] A material conveyor is configured to convey material through the elongated conduit and the nozzle.

[0112] Clause 23. The apparatus of clause 22, wherein the material conveyor comprises a screw feeder.

[0113] Clause 24. Apparatus according to clause 22 or 23, wherein the material conveyor comprises a filament feeder.

[0114] It will be appreciated that the configuration and / or method described herein are exemplary in nature, and these specific embodiments or examples should not be considered restrictive, because many variations are possible. The specific program or method described herein can represent one or more of any number of processing strategies. Therefore, the various actions illustrated and / or described can be performed in the order illustrated and / or described, in other orders, in parallel or omitted. Equally, the order of the above method can be changed.

[0115] The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various methods, systems and configurations, and other features, functions, acts, and / or properties disclosed herein, as well as any and all equivalents thereof.

Claims

1. An additively manufactured product comprising: a polymer matrix comprising a plurality of aligned polymer chains; and An alignment additive dispersed in the polymer matrix and comprising liquid crystal molecules, wherein the liquid crystal molecules are molecules of a material having a phase transition between an alignment phase and an isotropic phase at or below the melting temperature of the polymer matrix, and wherein the liquid crystal molecules comprise 4-(heptyloxy)benzoic acid, 4-(octyloxy)benzoic acid, 4-(decyloxy)benzoic acid, 4,4'-azoxyanisole, 4-isothiocyanatophenyl-4-pentylbicyclo[2.2.2]octane-1-carboxylate, or 4-methoxycinnamic acid.

2. The additively manufactured article of claim 1, wherein the liquid crystal molecules and the plurality of aligned polymer chains are aligned in parallel.

3. The additively manufactured article of claim 1, wherein the polymer matrix comprises polyetheretherketone.

4. The additively manufactured article of claim 1, wherein the alignment additive comprises 0.01 mass % to 25 mass % of the additively manufactured article.

5. The additively manufactured article of claim 1, wherein the polymer matrix comprises a thermoplastic polymer.

6. The additively manufactured article of claim 1, further comprising a reinforcing additive.

7. The additively manufactured article of claim 1, wherein the alignment additive further comprises a hyperbranched macromolecule.

8. Materials suitable for use as raw materials for additive manufacturing, the materials comprising: a polymer matrix comprising a plurality of polymer chains, the polymer matrix being configured to form a flowable substance at an elevated temperature; and An alignment additive that can be dispersed in the polymer matrix and includes liquid crystal molecules, the alignment additive being configured to align the plurality of polymer chains in a direction of flowing through a conduit of an additive manufacturing device, wherein the liquid crystal molecules are molecules of a material having a phase transition between an aligned phase and an isotropic phase at or below a melting temperature of the polymer matrix, and wherein the liquid crystal molecules include 4-(heptyloxy)benzoic acid, 4-(octyloxy)benzoic acid, 4-(decyloxy)benzoic acid, 4,4'-azoxyanisole, 4-isothiocyanatophenyl-4-pentylbicyclo[2.2.2]octane-1-carboxylate, or 4-methoxycinnamic acid.

9. The material of claim 8, wherein the alignment additive further comprises a hyperbranched macromolecule.

10. The material of claim 8, wherein the polymer matrix comprises polyetheretherketone.

11. The material of claim 8, wherein the alignment additive comprises 0.01 mass % to 25 mass % of the material.

12. The material of claim 8, wherein the material has a melt flow index greater than the melt flow index of the polymer matrix without the aligning additive.

13. The material of claim 8, wherein the material is a composite material including a fiber additive.

14. The material of claim 8, wherein the material comprises one or more of a powder, pellets, and filaments.

15. The material of claim 8, wherein the material comprises filaments, wherein the plurality of polymer chains are aligned in a length direction of the filaments.

16. A method for additive manufacturing of an article, the method comprising: Conveying material through a heated nozzle to form a flowing mass of said material, said material comprising: a polymer matrix comprising a plurality of polymer chains, and an alignment additive dispersible within the polymer matrix and comprising liquid crystal molecules, the alignment additive being configured to align the plurality of polymer chains in a flow direction of a flowing substance of the material, wherein the liquid crystal molecules are molecules of a material having a phase transition between an aligned phase and an isotropic phase at or below a melting temperature of the polymer matrix, and wherein the liquid crystal molecules comprise 4-(heptyloxy)benzoic acid, 4-(octyloxy)benzoic acid, 4-(decyloxy)benzoic acid, 4,4'-azoxyanisole, 4-isothiocyanatophenyl-4-pentylbicyclo[2.2.2]octane-1-carboxylate, or 4-methoxycinnamic acid; aligning at least a portion of the polymer chains via the alignment additive in a direction of flow through the heated nozzle; releasing a flowable mass of said material from said heated nozzle; and The material is allowed to cure.

17. The method of claim 16, wherein the alignment additive further comprises a hyperbranched macromolecule.

18. The method of claim 16, wherein the polymer matrix comprises polyetheretherketone.

19. The method of claim 16, wherein conveying the material comprises conveying one or more of powder and pellets via a screw feeder.

20. The method of claim 16, wherein delivering the material comprises delivering filaments via a filament feeder.

21. An apparatus for additively manufacturing an article from a material comprising a polymer matrix having a plurality of polymer chains and an alignment additive, the apparatus comprising: nozzle; an elongated conduit fluidly connected to the nozzle, the elongated conduit comprising a length sufficient to effect alignment of the plurality of polymer chains via the alignment additive when the material flows through the elongated conduit at an elevated temperature; one or more heaters configured to heat the elongated conduit and the nozzle to allow the material to flow within the elongated conduit and through the nozzle; and a material conveyor configured to convey the material through the elongated conduit and the nozzle, wherein the alignment additive is dispersible within the polymer matrix and comprises liquid crystal molecules, wherein the liquid crystal molecules are molecules of a material having a phase transition between an alignment phase and an isotropic phase at or below the melting temperature of the polymer matrix, and wherein the liquid crystal molecules comprise 4-(heptyloxy)benzoic acid, 4-(octyloxy)benzoic acid, 4-(decyloxy)benzoic acid, 4,4'-azoxyanisole, 4-isothiocyanatophenyl-4-pentylbicyclo[2.2.2]octane-1-carboxylate or 4-methoxycinnamic acid.

22. The apparatus of claim 21, wherein the material conveyor comprises a screw feeder.

23. The apparatus of claim 21, wherein the material transporter comprises a filament feeder.

24. The device of claim 21, wherein the alignment additive further comprises a hyperbranched macromolecule.

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