Patent Application
20240409708
The present invention generally relates to a 3D printable polymeric material. More particularly, the invention relates to a 3D printable polymeric material carbonated with gas.
As engineering requirements for materials become stricter, engineers need a greater selection of materials from which to choose. Composites serve as an effective approach to this demand since they are tailorable to a myriad of applications. Furthermore, the option of creating complex shapes from the composite provides an additional expansion of its use.
Engineers have increasingly turned to polymer composites to fill their material needs. Polymer composites are comprised of two parts: the light-weight polymer matrix, which constitutes the bulk of the material and functions as the major load bearer, and the filler which functions as an enhancement to the polymer matrix. The effective composition of these polymer composites provides solutions to problems where ordinary polymers and metals fail. For example, the composition of the polymers and filler exhibit useful properties including increased surface area, conductivity, and high strength. When fillers, such as, metal or nonmetal micro or nano-particulates are included in the polymer matrix a multifunctional polymer composite material is created that is versatile, light-weight, and easily formable.
Polymer composites which incorporate solid particulates or fibers within a polymeric matrix have been instrumental in structural and functional applications in a myriad of fields, including medical, aerospace, vehicular and the electronic industry. Voids or gas bubbles are inherently introduced into the composite during the manufacturing process which adversely affects the properties of the material. What is needed is a way for gas bubbles to enhance functionality of the polymer material just as solid particulates do within a composite, thereby expanding the definition of polymer composite materials to include gas bubbles as matrix fillers. If such a polymer could be 3D printed, the polymer would further enhance the functionality and applicability of the material.
The present invention may be understood with reference to the following drawing figures in which like elements and numerals denote like elements, and in which:
The present invention teaches using gas molecules as a filler within a polymer matrix. This suggestion is largely counter-intuitive, since generally, pockets of air (gas) or voids in composites and in materials are categorized as defects and cause adverse effects to the overall material property and performance. Indeed, extensive work has been done to find ways to detect voids (gas bubbles) and their formation to identify structural weaknesses in the polymeric composite. Even more research has been directed to avoiding and removing gas bubbles from resin during manufacturing.
Contrarily, instead of removing the gas, the present invention teaches intentionally introducing gas microbubbles in a polymer matrix to create a carbonated polymeric material (“carbonated polymer”) that exhibits a wider thermal range and more suitable mechanical properties for engineering design than conventional composite or materials. The invention further teaches that the carbonated polymers may be 3D printed into any 3D printable shape using Digital Light Projection (DLP).
The present invention teaches including gas microbubbles in a composite polymer as a filler. It is well known that the term “gas” refers to a state of matter in which substances are in a gaseous form, characterized by having no definite shape or volume. Gases are composed of gas molecules as their basic unit. The behavior and properties of gases, such as their expansion, compression, diffusion, and the relationship between pressure, volume, and temperature, are all understood through the study of gas molecules and their interactions.
A suitable gas useful with this invention has a gas molecule with molecular weight of 30 amu or greater and a density greater than 1.204 kg/m{circumflex over ( )}3. The present invention is described using carbon dioxide as a filler only by way of example. The invention contemplates using other gases in the carbonated polymer design, where such gas meets the molecular requirements described above.
The exemplary embodiment of the invention described herein use carbon dioxide (CO2) as the filler constituent of a polymeric composite created according to the present invention.
In one exemplary embodiment of the invention, the printed polymeric composite including the CO2 filler may be used to store CO2 for later use. For example, the present invention teaches a system and storage medium that may be used to store a personal, portable, and on-demand CO2 phase transformation.
Recently, in his work titled “Syntheses, properties, and applications of CO2-based functional polymers,” Tang et al reviewed CO2-based functional polymers in which CO2 was used to create enhanced polymers. Tang et al reported that by using CO2 as a precursor, advanced polymers could be formed. For example, CO2-based polycarbonates showed superior thermal properties over typical PPCs. Tang, et al. also reviewed CO2-derived polyhydroxyurethanes (PHUs) which were found to be 3D printable by extrusion-based fused deposition modeling.
In contrast to Tang et al, the present invention doesn't use CO2 as a precursor. The present invention teaches 1) infusing CO2 in its gas state (microbubbles) into a photosensitive thermoset polymer to create a carbonated polymer composite, and 2) 3D print the now carbonated polymer composite. Contrary to Tang, et al, which uses extrusion-based deposition, the present invention uses Digital Light Projection (DLP).
In accordance with various embodiments of the invention a photosensitive resin is carbonated. A gas is forced into the photosensitive resin at room temperature and pressure using forced carbonation in similar manner as is done with carbonating liquids and recently, cement. By “carbonate” what is meant is high pressure carbon-dioxide gas is passed through the photosensitive resin, wherein a portion of the carbon dioxide dissolves and remains in the photosensitive resin. A suitable photosensitive resin for use with the present invention may be any composition of a water-soluble polymer such as isomalt or a non-water-soluble polymer such as acrylate with a UV photoinitiator such as a norrish type II free-radical generator.
Cap 104 may include an aperture 108 to accommodate a pipette tip 110. Pipette tip 110 may be further connected a tube assembly 112 for the flow of CO2. Tube assembly 112 may further include a valve 116 for regulating the flow of the CO2. Tube assembly 112 may be further connected to a CO2 canister 114 for providing CO2. The present invention uses a 16-gram canister of CO2 as the source of the CO2 for carbonating photosensitive resin 106. In one particular embodiment, canister 114 may include CO2 gas under pressure.
Vial 102 may be a dark container and have an inner lining which will not chemically react with the resin or gas being used. In one particular embodiment, a dark brown glass vial may be used. This is required since the resin is sensitive to light, Further, the dark vial minimizes or eliminates the exposure to ambient light during the carbonation process. Tube assembly 112 may be any tube assembly capable of transporting CO2 from a canister. A suitable canister 114 for use with this invention may be any canister capable of storing CO2 gas and providing CO2 gas for use in a carbonation process. An exemplary canister 114 may be, for example, a 16-gram canister of CO2 sold by Leland Gas Technologies. Valve system 116 may be any suitable valve for regulating the flow of gas in a tube, such as for example a Presta™ Valve Stem.
During operation, CO2 canister 114 is connected to tube assembly 112, such that canister 114 provides CO2 gas to tube assembly 112. Tube assembly 112 transports the CO2 gas to valve 116. Valve 117 may be in communication with pipette tip 110. Pipette tip 110 may be placed into aperture 108 for providing CO2 gas into atmospheric air 118 under pressure. Pipette tip 110 may be placed in cap 104 such that the CO2 does escape from and remains in vial 102. Pipette tip 110 may be sealed to aperture 108 using, for example, a conventional O-ring or other suitable rubber seal. In another suitable sealing arrangement, aperture 108 may be itself sealed with a puncturable film, such as silicon. In which case, pipette tip 110 may pierce the silicon film to provide the CO2 to vial 117.
Valve 116 may regulate the gas flow flowing from the tubing assembly 112 into vial 102 of resin. As previously noted, the CO2 gas contained in canister 102 is under pressure. As such, the vial cap aperture 108 may be sealed around pipette tip 110, such that any CO2 included in vial 102 does not leave. In one exemplary embodiment, aperture 108 may be sealed. The sealed vial 102 may be placed into a mixer for mixing (not shown) the constituents included in shaker mill, or laboratory grinder used to grind, pulverize, or mix samples to analytical fine matter. The sealed vial 102 may then be shaken for intervals of 5, 10, 15, 20, 25, 35, and 45 seconds to generate carbonated photosensitive resin 120, shown in
With brief reference to
In one embodiment, referring now to
It is important to note that the parameters for 3D printing discussed herein may differ depending on the gas used, resin formulation used, and the desired 3D print as determined by the 3D printer used.
It is important to note that the microbubbles CO2 gas behaves as a solid filler component in a composite material. Therefore, the microbubbles CO2 gas may not be interpreted as pores or voids and do not directly factor into the change in the porosity. Instead, the change is due to surface interfacial voids that are formed between the microbubbles and the polymer matrix.
Additive manufacturing of the carbonated polymer composite proved possible using the digital light projection (DLP) 3D printing technique. Characterization revealed that the CO2 gas molecule physically behaves as a solid particulate filler. This observation gives rise to the consideration of utilizing an assortment of other gas molecules and mixtures with unique properties as polymer enhancement fillers, thereby expanding the selection of polymer composite materials and manufacturing processes.
Considering the application of the carbonated polymer composite given the results found potential utility of the printed carbonated composite is as a personal, portable, and on-demand CO2 phase transformation storage medium. The critical point to transform the gas into a supercritical fluid occurs at a minimum temperature and pressure of 30.98° C. and 72.79 atm (7.38 MPa), respectively.
Exemplary process parameters that may be used with this invention are summarized in Table 1 below. As previously noted, the parameters may be modified to accommodate the requirements of the gas used or the printer employed for 3D printing.
