Patent Grant
8978449
A composition for promoting kinetic mixing of additives within a non-linear viscosity zone of a fluid such as a thermoplastic material.
An extrusion process is one of the most economic methods of manufacturing to produce engineering structural materials. Typically, an extrusion process is used to manufacture lengths of extruded members having a uniform cross-section. The cross-section of the members may be of various simple shapes such as circular, annular, or rectangular. The cross-section of the members may also be very complex, including internal support structures and/or having an irregular periphery.
Typically, an extrusion process utilizes thermoplastic polymer compounds that are introduced into a feed hopper, Thermoplastic polymer compounds can be in powder, liquid, cubed, palletized and/or any other extrudable form. The thermoplastic polymer can be virgin, recycled, or a mixture of both. An example of a typical extruder is shown in
The plastic industry has used fillers to lower resin costs during manufacturing. Typical fillers include calcium carbonate, talc, wood fiber, and a variety of others. In addition to providing a cost savings, adding fillers to plastics reduces the coefficient of thermal expansion, increases mechanical strength, and in some cases lowers the density.
Calcium carbonate and talc have no structural strength or fiber orientation to improve structural stability. Talc is bonded together by weak Van der Waal's forces, which allow the material to cleave again and again when pressure is applied to its surface. Even though test results indicate that talc imparts a variety of benefits to polymers, for instance higher stiffness and improved dimensional stability, talc acts like a micro-filler with lubricating properties.
Calcium carbonate has similar properties, but has a water absorption problem, which limits its application because of environmental degradation. Talc avoids this problem since it is hydrophobic.
Wood fiber adds some dimensional stability because of the fiber characteristics interaction with the plastic but wood fiber also suffers from environmental degradation. All three of these common fillers are economically feasible but are structurally limited.
Research efforts have focused on farm waste fibers such as rice hulls, sugar cane fiber, wheat straw and a variety of other fibers to be used as low-cost fillers inside plastics. The use of wood fiber as a filler presents similar difficulties to the above-referenced farm waste fibers.
There are three types of commonly used mixing principles:
1. Static mixing: liquids flowing around fixed objects either by force produced flow by pressure through mechanical means or gravity induced flow.
2. Dynamic mixing: liquid induced mixing by mechanical agitation with typical impellers, i.e., impellers and wiping blade and sheer designs as well as dual or single screw agitation designs.
3. Kinetic mixing: liquid is mixed by velocity impacts on a surface or impacts of two or more liquids impinging on each other.
All three of the above mixing methods have one thing in common that hinders the optimizing of mixing regardless of the fluid being combined and regardless of whether the materials being mixed are polar, nonpolar, organic or inorganic etc. or if it is a filled material with compressible or non-compressible fillers.
All incompressible fluids have a wall effect or a boundary layer effect where the fluid velocity is greatly reduced at the wall or mechanical interface. Static mixing systems use this boundary layer to fold or blend the liquid using this resistive force to promote agitation.
Dynamic mixing, regardless of the geometry of mixing blades or turbine, results in dead zones and incomplete mixing because of the boundary layer. Dynamic mixing uses high shear and a screw blade designed to use the boundary layer to promote friction and compression by centrifugal forces to accomplish agitation while maintaining an incomplete mixed boundary layer on mechanical surfaces.
Kinetic mixing suffers from boundary layer effects on velocity profiles both on the incoming streams and at the injector tip. However, this system suffers minimal effects of boundary layer except for transport fluid phenomena.
A further explanation of the boundary layer follows. Aerodynamic forces depend in a complex way on the viscosity of the fluid. As the fluid moves past the object, the molecules right next to the surface stick to the surface. The molecules just above the surface are slowed down in their collisions with the molecules sticking to the surface. These molecules in turn slow down the flow just above them. The farther one moves away from the surface, the fewer the collisions affected by the object surface. This creates a thin layer of fluid near the surface in which the velocity changes from zero at the surface to the free stream value away from the surface. Engineers call this layer the boundary layer because it occurs on the boundary of the fluid.
As an object moves through a fluid, or as a fluid moves past an object, the molecules of the fluid near the object are disturbed and move around the object. Aerodynamic forces are generated between the fluid and the object. The magnitude of these forces depend on the shape of the object, the speed of the object, the mass of the fluid going by the object and on two other important properties of the fluid; the viscosity, or stickiness, and the compressibility, or springiness, of the fluid. To properly model these effects, aerospace engineers use similarity parameters which are ratios of these effects to other forces present in the problem. If two experiments have the same values for the similarity parameters, then the relative importance of the forces are being correctly modeled.
As can be seen in
Boundary-Layer Flow
That portion of a fluid flow, near a solid surface, is where shear stresses are significant and inviscid-flow assumption may not be used. All solid surfaces interact with a viscous fluid flow because of the no-slip condition, a physical requirement that the fluid and solid have equal velocities at their interface. Thus, a fluid flow is retarded by a fixed solid surface, and a finite, slow-moving boundary layer is formed. A requirement for the boundary layer to be thin is that the Reynolds number of the body be large, 103 or more. Under these conditions the flow outside the boundary layer is essentially inviscid and plays the role of a driving mechanism for the layer.
Referring now to
This patent focuses on technology breakthroughs in boundary layer mixing, i.e., on the effects of structural mechanical fillers with particle sizes ranging from nano to micron using the static film principal of the boundary layer coupled with the coefficient of friction upon a particle being forced to rotate or tumble in the boundary layer because of fluid velocity differentials thereby promoting kinetic mixing through the use of the structural fillers.
As an example, a hard sphere rolling on a soft material travels in a moving depression. The material is compressed in front and rebounds at the rear and where the material is perfectly elastic, the energy stored in compression is returned to the sphere at its rear. Actual materials are not perfectly elastic, however, so energy dissipation occurs, the result being kinetic energy, i.e., rolling. By definition, a fluid is a material continuum that is unable to withstand a static shear stress, unlike an elastic solid, which responds to a shear stress with a recoverable deformation, a fluid responds with an irrecoverable flow. The irrecoverable flow may be used as a driving force for kinetic mechanical mixing in the boundary layer. By using the principle of rolling, kinetic friction and the increased fluid sticking at the surface of the no-slip zone produces adherents while the velocity adjacent to the boundary layer produces an inertial force upon the particle. The inertial force rotates the particle along the surface of mechanical process equipment regardless of mixing mechanics used, i.e., static, dynamic or kinetic.
Structural filler particle geometry is based on the fundamental principle of surface roughness, promoting increased adherence to the zero velocity zone in the boundary layer. The boundary layer is where the material has its strongest adhesion force or stickiness present. By using a particle that has a rough and/or sharp particle surface, the adhesion to the non-slip zone is increased, which promotes better surface adhesion than a smooth particle with little to no surface characteristics. The ideal filler particle size will differ between polymers because viscosity differs as well as mixing mechanics produced by sheer forces and surface polishing in mechanical surfaces, which creates a variation in boundary layer thickness. A rough and/or sharp particle surface allows the particle to function as a rolling kinetic mixing blade in the boundary layer. The technology breakthrough embodied in this patent focuses on a hardened particle with sharpened edges rolling along the boundary layer producing micro mixing with agitation over the surface area in which the boundary layer exist.
Advantages of this technology include:
Solid particles used for kinetic mixing in boundary layer need to have following characteristics:
Physical Geometry of Particles:
Spherical particles are not ideal because of the following two phenomena that take place simultaneously. The first phenomenon relates to the surface friction of the particle in the non-slip zone and the second relates to the driving force applied to the particle by fluid velocity, which affects the ability of the particle to induce mixing through a tumbling of an irregular shape where a spherical shape tends to just roll along the boundary line. The driving force is produced by fluid flow on the upper half of the boundary layer. Particle shapes can be spherical, triangular, diamond, square or etc., but semi-flat or flat objects are less desirable because they do not tumble well. Semi-flat or flat objects tumble less well because the cross-sectional surface area has little resistance to fluid friction applied to its thickness. However, since agitation in the form of mixing is desired, awkward forms of tumbling are beneficial since the awkward tumbling creates dynamic random generating mixing zones. These random mixing zones are analogous to having big mixing blades operating with little mixing blades. Some turn fast and some turn slow, but the end result is that they are all mixing. In a more viscous material, which has less inelastic properties, the kinetic mixing by the particles will produce a chopping and grinding effect due to surface roughness and sharp edges of the particles.
Typical extruded, as well as injection molding plastics are PP, PE, PB HDPP, HDPE, HDPB, Nylon, ABS and PVC, which are some of the types of plastics used in industry, in which the hardness is proportional to the material properties of the plastic. By adding hard fillers into the plastic, a tougher more durable plastic may be reformulated that is more scratch and/or mar resistant than the inherent physical properties of the plastic. Common fillers are calcium carbonate and talc, each having a Mohs hardness scale rating of between one in two. However, it is desirable to use structural fillers having a hardness of at least 2.5.
A variety of environmentally stable materials suitable for use as hard structural fillers have not been commercially evaluated by the plastic manufacturing industry. These fillers are structural, they are hard, light weight and environmentally stable. Some of the reasons why these fillers have not been used commercially is that they are difficult to formulate and handle. Additionally, these materials may not be as economically feasible as previously used fillers. The following lightweight structural fillers are similar in hardness, density and particle sizes in the micron range but have not been widely accepted for use in the plastics industry.
Glass or ceramic micro spheres have been commercially available for decades. The spheres have had some success in plastic manufacturing but they have been used mainly in the coatings, adhesives and composite market.
Perlite is a naturally occurring silicous rock used mainly in construction products, an insulator for masonry, lightweight concrete and for food additives.
Sodium potassium aluminum silicate (volcanic glass) is a micron powder used as a plastic flow modifier to improve the output as well as to produce enhanced mixing properties for additives as a surface tension modifier in the linear viscosity zone.
The structural fillers that have been previously mentioned have a Mohs scale hardness of 5.5, which is equal to window glass, sand and a good quality steel knife blade.
These structural fillers are not held together by weak forces. Therefore, they keep their rigid shape and do not have lubricating properties associated with cleaving of weak chemical bonds between molecular layers, such as may be seen with talc. Particles having a Mohs scale hardness of 5.5 are as hard as what normally would damage the plastic surface. Therefore, resistance to scratching and/or marring by the sheer hardness of the filler incorporated into the plastic formulation is improved. The structural fillers are preferably lightweight, having a density in the ranges of 0.18 g/cm3 and higher, whereas talc and calcium carbonate have densities ranging 2.50-2.80 g/cm3. Therefore, hard structural fillers can reduce the density of the plastic formula.
Micro spheres have recently become of interest for use with extruded plastics because of their improved strength, which allows them to withstand mechanical pressures without being crushed. As the strength of the micro spheres increases, the manufacture cost decreases, which makes micro spheres an ideal structural filler material for plastics.
Other filler materials for consideration include expanded Perlite. Expanded Perlite has not been commercially used by the plastic industry in extrusion processes because of its micro bubbles and tubes that are natural properties of the material and can not withstand the extrusion pressures without crushing. The crushing effect of the fillers adds to the inconsistency volume flow, which affects the dimensional stability of the extruded product, which may or may not be acceptable depending on the application. For this reason, Perlite has not reached commercial viability as structural filler in the plastics field. Perlite can be finely milled, which greatly improves the crush strength of the product, thereby allowing the material the ability to withstand mechanical extrusion pressures process, thereby gaining dimensional stability. One reason this material has not been adopted as a filler is that the material in its original form has the ability to crush under pressure.
Finely milled Perlite has the same physical properties, just a finer mesh, which will withstand higher pressures.
During a jet mill process, particles strike each other to form a sharp edge via a conchoidal fracture. Even though some particle size selections will produce different effects with differing polymer selections, it is this edge effect that produces their performance. The edge effect on hard structural particles facilitates the incorporation of fillers, structural fillers, pigments, fibers and a variety of other materials into thermoplastics and polymer material.
Materials that will produce sharp edge effects upon jet milling include: pumice, Perlite, volcanic glass, sand, flint, slate and granite in a variety of other mineable materials. There are a variety of man-made materials, such as steel, aluminum, brass, ceramics and recycled and/or new window glass, that can be processed either by jet milling or other related milling processes to produce a sharp edge with small particle sizes. In addition to the listed examples, other materials may also be suitable, provided the materials have sufficient hardness, estimated to be 2.5 on the Mohs hardness scale.
It is clear to see by the Mohs hardness scale that there is a variety of materials that are harder than 2.5 that would work as likely candidates to produce sharpened edge effects, thereby working as kinetic mixing particles relating to the boundary layer as well as a structural filler to be incorporated in today's modern plastics, polymers, paints and adhesives. The Mohs scale is presented below.
The Mohs scale is a purely ordinal scale. For example, corundum (9) is twice as hard as topaz (8), but diamond (10) is almost four times as hard as corundum. The table below shows comparison with absolute hardness measured by a sclerometer.
On the Mohs scale, a pencil lead has a hardness of 1; a fingernail has hardness 2.5; a copper penny, about 3.5; a knife blade, 5.5; window glass, 5.5; steel file, 6.5.[1] Using these ordinary materials of known hardness can be a simple way to approximate the position of a mineral on the scale.
Mineral processing technologies have been around for centuries and are highly specialized. They have the ability to separate particles by multiple methods as well as shape them into smaller particles. In the case of these highly specialized solids or porous materials to produce the desired three-dimensional blade like characteristics with sharpened edges in an aspect ratio greater than 0.7 the material must be an impact jet milled or jet milled process. Impact jet milling is a process where the process material at high velocity hits a hardened surface to produce a shattering effect of particles. In jet milling, opposing jets cause the process material to impact upon itself to produce a shattering effect, i.e., conchoidal fractures on the material. The efficiency of the kinetic mixing particle due to the resulting with surface sharpness, i.e., bladelike edges (see Appendix 1).
A ball mill process tumbles the material in a batch process removing an desired surface characteristic, e.g., sharpness. For use as particles in thermoplastic extrusions, solid minerals or rocks should be refined to particles of 10 to 20 mesh or smaller. This is the typical starting point for feeding material into the impact jet milled or jet milled process. This can be accomplished by a variety of methods that are commonly available and known by the industry to produce desired particle sizes. The preferred mineral or rock should be able to produce conchoidal fracture. This ensures knifelike edge effects with three-dimensional shapes. Refer to Appendix 1 for images of conchoidal fractures. In the case of porous minerals or rocks, the characteristics of the pores being smashed and shattering upon impact during the impact jet or jet milling process creates the three-dimensional knifelike edge shaped particles. Even though rough and uneven surfaces may be sufficient in some mixing applications, in this case, the sharper the particle the better the results. Refer to Appendix 1 for reference particle sizes after jet milling. Man-made materials such as glass, ceramics and metals as well as a variety of other types of materials meeting the minimum hardness of 2.5 by the Mohs scale that produce sharp edges with a three-dimensional shape and an aspect ratio larger than 0.7 can be used. The impact jet or jet milling process typically with these materials produce particles with a mean average of 5-60 μm with a single pass. Man-made materials like glass may be processed into the desired three-dimensional sharp edged particles with an aspect ratio of 0.7 and higher by means of a mechanical roller mill smashing the particles rather than jet milling. This is clearly illustrated in the pictures of Appendices of the raw feed small glass particles before jet milling.
Particle Surface Characteristics:
The mixing efficiency of a particle is increased when surface dynamic characteristics of the particle are increased. Examples of particle surface dynamic characteristics include characteristics such as colloidal fracture that produce sharp bladelike edges, smooth surfaces, roughness or surface morphology, three-dimensional needlelike shape and thin curved surfaces. Increasing surface dynamic characteristics has a twofold effect. The first effect is that surface characteristics and particle geometry of a particle having increased surface dynamic characteristics enhance surface adhesion to the nonslip zone or the sticky or gluey region, which produces resistance to rolling or tumbling of the particle. The second effect of increasing surface dynamic characteristics is an increased resistance of the ability of the particle to roll and tumble, which results in stronger mechanical interaction with the impacting fluid. In the example of a smooth spherical ball rolling across a surface, interaction adhesion with a nonslip zone is minimal and the effects on the polymer do not produce much dynamic mixing. If the material dynamic surface characteristics are increased, the dynamic mixing is increased thereby increasing cohesion forces in the sticky/gluey region, then increased rotational resistance is promoted, which increases the cutting or chopping effects of the sharp bladelike particles' ability to grind and cut during tumbling or rotation, which produces kinetic boundary layer mixing.
Examples of desired characteristics for a particle to interact in the boundary layer to promote kinetic mixing are shown in electron microscope images found in the below referenced appendices.
Images showing particles exhibiting fracture:
Appendix 1. Ash image is: 7, 8 and 9; and
Appendix 3. Expanded Perlite Images: 3, 4 and 5, Recycled Glass Images: 6 through 12.
Even though a variety of materials have the ability to fracture during milling processes, the images of Appendix 1 and Appendix 3, mentioned immediately above, show the characteristics of colloidal fractures that produce sharp edges.
Images showing particles having sharp bladelike edges:
Appendix 1. Ash images: 7, 8 and 9; and
Appendix 3. Expanded Perlite Images: 3, 4 and 5; Recycled Glass Images: 6 through 12.
A variety of materials have the ability to fracture. For example, striated or vitreous minerals propagate fracture on striation lines, which limits their ability to produce sharp bladelike characteristics. As an example, minerals such as flint and obsidian do not fracture along striation lines. As a result, historically these minerals have been useful for making objects with sharp edges, e.g., arrowheads, spearheads, knives and even axes. The images of Appendix 1 and Appendix 3, referenced immediately above, show this characteristic of sharp knife blade-like surface characteristics.
Images showing particles having smooth edges:
Appendix 1. Ash images: 7, 8 and 9; and
Appendix 3. Expanded Perlite Images: 3, 4 and 5; Recycled Glass Images: 6 through 12.
Smooth edges on a knife blade lowers the resistance needed to cut as well as lowering resistance to the force needed to be applied to the holding device. This is the same principle that is imparted in sharp smooth edges of particles, which allow kinetic mixing to take place while remaining in the boundary layer tumbling or rolling along the sticky or gluey region. If the surface of a particle is sharp and rough, the resistance due to the surface roughness would be enough to remove the particle from the boundary layer by overcoming the cohesive forces produced by the sticky or gluey region. This is why particles having the ability to produce sharp smooth bladelike characteristics can remain in the boundary layer to promote kinetic mixing, as shown in the images of Appendix 1 and Appendix 3, discussed immediately above, that show this characteristic used for kinetic mixing in the boundary layer.
Images showing particles having complex surface geometry:
Appendix 1. Ash images: 7, 8 and 9; and
Appendix 3. Expanded Perlite Images: 3, 4 and 5; Recycled Glass Images: 6 through 12.
The complex shapes that are illustrated by the images of Appendix 1 and Appendix 3, referenced immediately above, show bladelike characteristics with dynamic curves to promote surface adhesion in the sticky or gluey region.
The complex three-dimensional surface area of the particle is sufficient to promote tumbling or rolling. The above referenced images that show the ash and the expanded Perlite clearly shows complex surface geometry characteristics used for kinetic mixing in the boundary layer.
Images showing particles having needle-like points and curves:
Appendix 1. Ash images: 7, 8 and 9; and
Appendix 3. Expanded Perlite Images: 3, 4 and 5; Recycled Glass Images: 6 through 12.
The three-dimensional smooth needle-like tips interact by protruding into the moving fluid region adjacent to the boundary layer to promote tumbling or rolling. The smooth needle-like characteristics create enough fluid force to produce rotation while minimizing the cohesive forces applied by the deformation of the fluid flowing around the particle, thereby overcoming aerodynamic lift forces, which are not sufficient to remove the particle from the sticky or gluey region. The images of Appendix 1 and Appendix 3, referenced immediately above, clearly show the embodiment of three-dimensional needlelike characteristics used for kinetic mixing in the boundary layer.
Images showing particles with surface curves:
Appendix 1. Ash images: 7, 8 and 9; and
Appendix 3. Expanded Perlite Images: 3, 4.
The Ash images show a thin smooth curved particle similar to an egg shell. The surface area allows good adhesion to the sticky layer while promoting of dynamic lift on this curved thin particle, which promotes rotation thereby producing kinetic mixing in the boundary layer. The expanded Perlite clearly shows thin curves on a dynamic surface producing kinetic mixing in the boundary layer. The images of Appendix 1 and Appendix 3, referenced immediately above, clearly show the embodiment of thin curved surface characteristics on particles used for kinetic mixing in the boundary layer.
Reactive particle shaping of porous materials:
Appendix 2 Ash unprocessed spheres images: 4-6;
Appendix 1 Ash processed images 7, 8 and 9;
Appendix 4 Course processed expanded Perlite images: 1, 2; and
Appendix 3 Finely processed expanded Perlite images: 3, 4.
These previously mentioned materials because of their unique surface characteristics, Mohs scale hardness of 5.5, thin curved walls, smooth bladelike shape, with three-dimensional surface geometry have the ability under high pressure to change their physical particle size while maintaining dynamic surface characteristics previously mentioned for kinetic boundary layer mixing. For example particles to large can be swept off the boundary layer into the main fluid where they can undergo fracturing produced by high pressure and fluid turbulence reducing their particle size. The appropriate particle sizes after fracturing will migrate towards the boundary layer because of fluid dynamics where they will come in contact with the sticky or gluey region to promote kinetic boundary layer mixing. In conjunction with this example particles sizing may also take place in the boundary layer against mechanical surfaces caused by fluid impacting pressures. The thin smooth walls while undergoing fracturing produce sharp knifelike blade characteristics regardless of fracture point and the hardness of the material helps maintain three-dimensional surface characteristics to promote tumbling or rolling in the boundary layer.
Particle Hardness and Toughness:
Mixing blades and high shear mixing equipment are usually made of hardened steel. Polymers are softer when mechanical agitation is applied during mixing. Since particles added to the polymer are passing through the equipment, the particles need the ability to retain their shape in order to function properly. The chemical interactions between molecules have been tested and organized based on their hardness. A minimal hardness of 2.5 starting with copper on the Mohs scale or harder will be sufficient for a single pass particle to be tough enough for this mixing process.
Filler particles should be sized proportional to the boundary layer region. The size is usually defined arbitrarily as the point where u=0.99 U. Therefore, a particle theoretical starting diameter is the height measured perpendicular to the surface where u=0.99 U. There are many factors that add difficulties in calculating the parameters associated with kinetic mixing in the boundary zone, for example:
The dynamics of mixing is one of the most complex mechanical chemical interactions in the process industry. Particle size will vary from product to product and optimization may or may not be needed.
The chemical industry has produced test methods and tables for homogeneous liquid and the boundary layer relative thicknesses for calculating fluid flow properties useful for mechanical equipment selection and heat transfer properties. The profile assumption may be used as a starting point for the particle size so that the particle will function in the boundary layer to increase mixing.
One approach to selecting a suitable particle size is to determine when a particular particle size creates an adverse boundary layer effect by increasing the drag coefficient. In most processes, this may be identified by monitoring an increase in amp motor draws during the mixing cycle. If the amps increase, then the particle size should be modified in order to overcome increased power consumption.
Another approach is to see if agitation speed can be increased without motor amp draw increasing, which illustrates friction reduction by kinetic mixing in the boundary layer. For example,
Particle Re-Combining to the Boundary Layer:
Particles can be selected to re-interact with the boundary layer if they are swept off into the bulk fluid during mixing. All fluid materials flowing through mechanical agitation take the path of least resistance. The velocity profile is affected in agitation by resistive particles to move in a viscous medium. Therefore, particles that produce resistance to fluid flow are usually directed towards the boundary layer so that the fluid can flow more freely. If the particle size is large, it can become bound in fluid suspension because the cohesive forces in the boundary layer are not sufficient enough to resist fluid velocity force being applied to the boundary layer surface, thereby sweeping the particle back into the fluid suspension. Particles with small sizes will recombine naturally in the boundary layer based on cohesion forces caused by surface roughness to promote kinetic mixing even if the particles become temporarily suspended in the bulk fluid flow.
To verify whether the material is actually enhancing mixing, we mixed a light weight compressible material with poor flow properties with high-density polypropylene. The reason this is significant is wood fiber and polypropylene have no chemical attraction and they mixed well with at higher percentage fill levels while increasing throughput of the combined materials illustrated in
A limiting factor associated with extruding wood plastic composites is “edge effects,” which is where the material shows a Christmas tree like effect on the edges. In some cases, this Christmas tree effect is because of improper mixing and resistance of the material which is dragging on the dye exiting the extruder caused by boundary layer effects producing rough edges. It is common in industry to add lubricants in the formulation to overcome this problem. Lubricants allow the material to flow easier over the boundary layer, thereby allowing the throughput to increase by increasing the rpm of the extrusion screws until the edge effects appear, which indicates a maximum throughput of the process material. Test procedures used that same visual appearance as an indicator of the fastest throughput which was controlled by the extruders screw rpm.
Experiment #1
Base formula measured by mass percent
3 wt % lubricant: a zinc stearate and an ethylene bissteramide wax
7 wt % Talc: a Nicron 403 from Rio Tinto
41 wt % Thermooplastic: HDPE with a MFI of 0.5 and a density of 0.953
49 wt %: wood filler: a commercially classified 60-mesh eastern white pine purchased from American Wood fibers
The materials were dry blended with a 4′ diameter by 1.5′ deep drum blender for 5 minutes prior to feeding.
The extruder was a 35 mm conical counter-rotating twin-screw with a 23 L/D.
The process temperature was 320° F., which was constant throughout all runs.
Two other materials were used and added to the base formula to prove concept these inert hard fillers were:
1. Sodium potassium aluminum silicate (volcanic glass), which is a micron powder used as a plastic flow modifier to improve the output as well as to produce enhanced mixing properties for additives. 800 mesh solid material hardness 5.5 Mohs scale hardness (Rheolite 800 powder); and
2. Expanded Perlite is a naturally occurring silicous rock used mainly in construction products, an insulator for masonry, light weight concrete and for food additives. 500 mesh porous material hardness 5.5 Mohs scale.
Experiment #2
Effects of Sodium potassium aluminum silicate (Rheolite 800 powder) on throughput.
Experiment #3
Effects of Perlite on throughput
Perlite: 8 wt %, rpm 45=21.13 in. an overall increase of throughput 60.9%
Perlite: 16 wt %, rpm 45=19.00 in. an overall increase of throughput 44.8%
Perlite: 25 wt %, rpm 45=15.25 in. an overall increase of throughput 16.2%
Perlite: 33 wt %, rpm 45=13.375 in. an overall increase of throughput 19.0%
The graphical results of Experiment #3 may be found in
The reason the high percentages of Perlite were chosen was to remove the possibility that this material was just a filler. The edge effects of the three-dimensional knife blades particles interacting with the boundary layer even at 33 wt % still showed an improvement of 19% greater than the base material. Throughputs of the material could have been higher but the rpms limitation on the extruder was 45 and the material was being hand fed that is why we believe at 25% the throughput decreased because of difficulties in feeding such a lightweight material for the first time but by the time we got to 33 wt % we had figured it out.
Experiment #4
Effects of wood on throughput
Baseline material maximum throughput before edge effects appeared rpm 25=17.68 in.
Concentration of Perlite was held constant at the starting point of 2 wt %
Wood: 52 wt %, rpm 45=27.6 in. an overall increase of throughput 56.1%
Wood: 59 wt %, rpm 45=26.25 in. an overall increase of throughput 48.5%
Wood: 64 wt %, rpm 45=24.17 in. an overall increase of throughput 36.7%
Wood: 69 wt %, rpm 45=24.33 in. an overall increase of throughput 37.6%
Wood: 74 wt %, rpm 30=22.25 in. overall increase of throughput 25.8%
The graphical results of Experiment #4 may be found in
The reason this test was chosen was because the loading of a lightweight natural organic filler into an organic petroleum based material increased, the edge effects of poor mixing. There was no maximum throughput reached on 52 wt %, 59 wt %, 64 wt % and 69 wt % because the rpm were at a maximum until 74 wt % at which time the rpm had to be decreased to 30 rpms to prevent edge effects. The compressible fibers in the extrusion process act like broom sweeps along the boundary layer. The wood fiber is a compressible filler whose density goes from 0.4 g/cm3 to 1.2 g/cm3 after extrusion against the wall which have the ability to encapsulate these hard particles in the boundary layer and remove them permanently. It is the effect of the three-dimensional particle shape that holds them in the boundary layer with blades that allow this material to cut softer material and not imbed in the wood fiber, preventing them from being swept away even when the wood fiber is undergoing compression in extrusion process.
There was verification that this material operates in the boundary layer and is self-cleaning. The first day of trial runs we ran the materials in the order shown by the graphs. The second day of the trial run before the wood filler experiment under the same conditions, materials and weather the baseline material had a significant increase of throughput.
This was caused by the equipment being polished inside with the high concentrations of Perlite from day one proving itself cleaning the boundary layer. It implies that the material's three-dimensional size and shape with sharpened blade like edges provide excellent kinetic rolling capabilities even if the boundary layers thickness changes slightly due to surface cleaning/polishing because of the surface and continuous compression forces in the dynamic mixing of the extrusion process.
The boundary layer kinetic mixing particles can be introduced throughout industry in a variety of ways. For example, in the plastics market:
The boundary layer kinetic mixing particles can be utilized by the paint industry:
The boundary layer kinetic mixing particles can be utilized by the lubrication industry.
The particles can be incorporated into oils to promote better flow around surfaces by lowering the boundary layer friction zone producing better wetting with no break down of temperature on this additive because it's a solid particle: cars, boats, planes, bicycles internal oil external oil, etc.
The particles can be incorporated into oils for whole household cleaning allowing the oil to spread more evenly as a thinner layer less likely to become sticky over time because the layer is thinner.
The particles can be incorporated into break fluids, hydraulic fluids of all types producing a better response to fluid motion because the boundary layer moves with kinetic mobility when pressure is applied.
The particles can be incorporated into fuel additives promotes better disbursement in the fuel as well as a self-cleaning action due to particles interacting on boundary layers throughout the whole entire flow path of combustion including the exhaust where the particles still have a cleaning effect.
The particles can be added as a lubricant and disbursements directly from the refinery. The particles will not only help a car's lubricating effects and cleaning the system but the particles will also increase the lifespan of the gasoline pumps due to residue build up of sludge type material in the boundary layers.
The boundary layer kinetic mixing particles can be utilized to increase flow properties. Most liquid material flowing through a pipe, pump system and/or process equipment undergo boundary layer effects based on drag coefficient regardless of the surface geometry which this technology can reduce drag by promoting kinetic boundary layer mixing, with a self-cleaning effect. This will allow pipes and process equipment to perform at optimum levels.
The boundary layer kinetic mixing particles can be utilized to increase heat transfer. Because the boundary layer is being kinetically moved it is no longer a stagnant fluid heat transfer zone this increases the heat transfer properties on both sides. Now the stagnant boundary layer has turned into forced convection on both sides not just one, the fluid to fluid and the fluid to surface.
The boundary layer kinetic mixing particles can be utilized by the food, pharmaceuticals and agriculture industry. Because the selection of the particles can be approved by food and drug the processing of food through plants into its packaging can be enhanced and process equipment can mix things more thoroughly.
Thus, the present invention is well adapted to carry out the objectives and attain the ends and advantages mentioned above as well as those inherent therein. While presently preferred embodiments have been described for purposes of this disclosure, numerous changes and modifications will be apparent to those of ordinary skill in the art. Such changes and modifications are encompassed within the spirit of this invention as defined by the claims.
This application is a Continuation of U.S. patent application Ser. No. 13/757,322, entitled, “STRUCTURALLY ENHANCED PLASTICS WITH FILLER REINFORCEMENTS,” filed Feb. 1, 2013, which is a Divisional of U.S. patent application Ser. No. 12/572,942, entitled “STRUCTURALLY ENHANCED POLYMER WITH FILLER REINFORCEMENTS,” filed Oct. 2, 2009, which is a Continuation-in-Part of U.S. patent application Ser. No. 12/412,357, entitled “STRUCTURALLY ENHANCED PLASTICS WITH FILLER REINFORCEMENTS,” filed Mar. 26, 2009, both of which claim priority to U.S. Provisional Patent Application No. 61/070,876 entitled “STRUCTURALLY ENHANCED POLYMER WITH FILLER REINFORCEMENTS,” filed Mar. 26, 2008, the contents of each which are hereby incorporated by reference.
| Number | Name | Date | Kind |
|---|---|---|---|
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| Child | 12572942 | US |
