Safe Drug Disposal

U.S. Patent 9,403,197 (Aug. 2, 2016), “Medical Waste Break Down and Solid Waste Disposal System,” Milton Dallas, Russ Robers and Edward Hermann (Burlington and Greenfield, Wis.)

Disposal of unused, unwanted or expired prescription and non-prescription drugs is a problem. The U.S. Federal Drug Administration recommends mixing prescription drugs with “unpalatable” substances such as kitty litter or coffee grounds and also suggests highly toxic or dangerous prescription drugs, such as morphine, oxycodone and Percocet, be dumped in a sink or toilet. These methods are not perfect. 

Dallas, Robers and Hermann degraded drugs with reactive neutralizing solutions to a safe form. These solutions with a pH of 10 include surfactants such as soaps, wetting agents, nonylphenol-ethoxylates, silicones polyethers and polysaccharides with a neutralizing agent. The neutralizing agent is 0.8 to 1.2% activated carbon with 1 to 25 nm pores. A hardening agent like sodium polyacrylate can be added to solidify the dispersion for safe and convenient disposal.

Injection Molding Natural Materials

U.S. Patent 9,403,291 (Aug. 2, 2016), “Injection Molded Articles from Natural Materials and Methods for Making Them,” Dara L. Woerdeman, Scott Kinney, Marko Koorneef and Ken Bush (Green Material LLC, Merion Station, Pa.)

There is a pressure to have more and more articles made from toxin-free, natural, bio-based materials rather than from synthetic materials that present some environmental problems. Unfortunately, these materials are not easily processed by common plastic processing methods such as injection molding or extrusion. Woerdeman et al first plasticized bio-based materials such as lignin or proteins by mixing with urea/water solutions. The mixture can, then, be processing by conventional plastics processing methods such as injection molding. However, final molding needs to be done in a vacuum to prevent bubbling or void formation.  

Efficient Gas-Assisted Injection Molding

U.S. Patent 9,403,308 (Aug. 2, 2016), “Molding Tool for Producing a Component in a Gas-Assisted Injection Molding Process,” Elmar Fries (Illinois Tool Works Inc., Glenview, Ill.)

In gas-assisted injection molding processes, a plastic melt is first injected into a mold cavity and then pressurized gas is injected directly into the plastic melt. The pressurized gas presses the melt against the walls of the mold, resulting in high-quality surfaces. However, the high pressure must be relieved before demolding. The gas injector must have a very small opening on the order of 0.01 mm to prevent the polymer melt plugging, slowing the gas transfer and requiring cleaning with costly maintenance. 

Fries developed a gas injection device as part of the mold wall and not the injection mechanism. This device is a piston with an injector head that is part of the mold wall and remains closed until pressurized. The plastic is injected into the mold and high-pressure gas is injected into the injector, which forces the head into the melt and opens the piston to a relatively large opening for gas transfer. The gas quickly flows into the melt. As the gas pressure decreases the opening closes and the plunger goes back into the closed position in the wall until the next cycle. The result is an efficient, self-cleaning injector with reduced friction and wear.

Uniform Crosslinking

U.S. Patent 9,403,327 (Aug. 2, 2016), “Method of Making a Crosslinked Overmolded Assembly,” William W. Rowley (Mercury Plastics Inc., Middlefield, Ohio)

For high-performance applications, crosslinking is critical for mechanical stability. Crosslinking can be done during different processing methods such as injection molding or extrusion. However, as important as crosslinking is, uniform crosslinking with precise control is difficult, especially for complex structures with varying thicknesses and materials. Rowley developed a method for crosslinking a complex structure with different components and different crosslinking requirements. 

An electron beam induces the crosslinking reaction and uniformity is achieved by antioxidant content, shielding and local product thickness. The result is uniform crosslinking with a single electron beam treatment. In the example, a complex structure of high density polyethylene was mixed with a crosslinking agent such as triallyl isocyanurate anhydride and crosslinked with an electron beam.  

Precision FRP Structure Molding

U.S. Patent 9,409,321 (Aug. 9, 2016), “Moulded Body for Producing a Fibre Composite Component,” Ralf-Peter Dittmann, Sebastian Kaschel and Lothar Engler (Airbus Operations GmbH, Hamburg, Germany)

In modern aircraft, plant engineering, alternative energy systems and sports equipment, fiber composite components are increasingly being used. Producing complex composite structures requires removable cores for fabrication. These cores are expensive with limited dimensional accuracy, making precision fiber composite structures difficult. 

Dittmann, Kaschel and Engler developed paper or cardboard cores for precise hollow profiles of any desired size or shape. Prepregs are assembled on these cores, impregnated and cured. These cores can be made gas-tight and non-stick with suitable coatings. In addition, after curing, cores are collapsed by a vacuum and removed without unwanted residues.

Efficient Transfer Molding

U.S. Patent 9,409,325 (Aug. 9, 2016), “Molding System and Method Having Dual Split Ring Plunger,” Andrew R Stodgel (Caterpillar Inc., Peoria, Ill.)

During transfer molding, a molten resin is placed into a pot and a plunger pushes the melt through sprues into a mold cavity. The gap between the wall of channel and plunger has to be as small as possible for complete transfer. Larger gaps will result in trapped resin with degradation and sticking. Wear and wobbling leads to trapped resin, sticking and expensive maintenance. Stodgel developed a plunger based on spring-loaded split rings. During transfer the springs drive the split rings apart in contact with the walls for complete resin transfer through the sprues and into the mold. Reversing pulls the rings apart separating from the walls making reversal clean and easy. 

Uniform Microwave Curing

U.S. Patent 9,409,328 (Aug. 9, 2016), “Microwave Curing of Composite Material,” Timothy Sanderson (Airbus Operations Ltd., Bristol, England)

Composite materials used by the aerospace industry typically consist of a fibrous prepreg impregnated with a fluid prepolymer, which is then cured by heat or radiation. Curing a composite component in an autoclave or oven is a time-consuming process, typically lasting up to four hours. This time can be reduced dramatically with microwave heating. The problem with microwave curing is hot spots and cold spots because of nonuniform microwave absorption.  

Sanderson cured composites with microwaves by heating a tool with microwaves rather than heating directly the composite with microwaves. The composite is shielded by reflecting microwaves away from the composite material into a microwave absorbing tool. Heat is transferred from the tool through the shield to the composite. The tool consists of a ceramic sensitive to microwaves containing ferrite, carbon, polyesters, aluminum or metal salts. The heat-conductive shield consists of a flexible sheet of copper or a nickel-coated polyester fabric. 

Self-Healing Flexible Laminates

U.S. Patent 9,415,575 (Aug. 16, 2016), “Self-Healing Laminate System,” Brett A. Beiermann, Michael W. Keller, Scott R. White and Nancy R. Sottos (The University of Illinois, Urbana, Ill.)

More and more high-performance flexible materials are being used for inflatable structures, temporary shelters, protective apparel, and barriers. However, flexible materials often fail by punctures or tears. A flexible material is needed that can self-heal when punctured or torn while maintaining its useful properties. 

Beiermann et al developed a flexible laminate with a self-healing composite layer. This healing layer includes a rubber matrix filled with healing capsules containing a polymerizer and activator. The encapsulated polymerizer contains a polymerizable substance such as a monomer, a prepolymer, or a functionalized polymer having two or more reactive groups. Examples of polymerizable substances are functionalized silicones with two or more reactive groups. Activators include amines and metal salts.

Green Polypropylene Materials

U.S. Patent 9,416,264 (Aug. 16, 2016), “Compatibilized Polypropylene Heterophasic Copolymer and Polylactic Acid Blends for Injection Molding Applications,” Fengkui Li, John Ashbaugh, Gabriel Desille and Caroline Schils (Fina Technology Inc., Houston, Texas).

Synthetic polymeric materials, such as polypropylene and polypropylene that contain rubber are widely used, but recycling and disposal remains an environmental problem. Degradable components such polylactic acid can accelerate degradation in a natural environment. However, application of these “green materials” is often limited by their poor mechanical and physical properties as well as processing difficulties. For example, polylactic acid (PLA) is brittle with low toughness and is difficult to process. Li et al developed compatibilized polymeric polyolefin blends including polypropylene containing PLA. The polyolefin may have at least 10 wt% ethylene. The polyolefin is blended with polylactic acid and a reactive modifier such as glycidyl methacrylate grafted polypropylene. The final PLA content ranges from 1 to 50 wt% and can be extruded or injection molded with good results.

Crosslinked Fibers

U.S. Patent 9,421,296 (Aug. 23, 2016), “Crosslinked Fibers and Method of Making Same by Extrusion,” Ahmad Robert Hadba and Sebastien Ladet (Covidien LP, Mansfield, Mass., and Sofradim Production, Trevoux, France).

Methods for making monofilaments that are suitable to fabricate surgical articles, such as sutures, generally include the steps of extruding at least one bioabsorbable or nonbioabsorbable polymer to provide filaments, drawing or stretching the solidified filaments to achieve molecular orientation, and annealing the drawn filaments to relieve internal stresses. Crosslinking would add strength and durability to the fibers but it is difficult to spin, condition and crosslink fibers in one step. Hadba and Ladet developed a method of forming fibers from fiber precursors with a core and functional group with click reactivity. Heating during extruding crosslinks the precursors while forming fibers. Functional groups with click reactivity includes amine, sulfate, thiol, hydroxyl, azide, alkyne, alkene and carboxyl groups.

Moldable Recycled PET

U.S. Patent 9,421,697 (Aug. 23, 2016), “Method of Using Recycled PET Flake Directly in an Injection Molding Process,” Lawrence Robert Deardurff and Henry A. Schworm (Phoenix Technologies International LLC, Bowling Green, Ohio)

In the past, it has been difficult to use post-consumer, recycled polymeric flake directly in an injection molding process. High contaminant levels that do not melt make direct molding difficult. Deardurff and Schworm developed a method of processing polyethylene terephalate (PET) recycled plastic by first grinding the material to form 10 mm flakes and removing the metals. The metallic contaminants may be removed by electrostatic techniques, electromagnets and eddy current separators. This cleaned flake can be directly injection molded using a simple replaceable filter.

Sterilizing Polyesters

U.S. Patent 9,421,308 (Aug. 23, 2016), “Polyester Compounds Suitable for Hydroclaving,” Jing Liu and Rahul Bhardwaj (PolyOne Corp., Avon Lake, Ohio)

To be useful in the healthcare industry, thermoplastic articles need to be durable enough to withstand repeated steam sterilization. Liu and Bhardwaj developed a material withstanding multiple steam sterilization events using polyester, polysulfone blends with epoxy-functional styrene-acrylate oligomers. The oligomer is essential for sterilization stability. In addition, the material must also have a polysulfone content of greater than 45 wt% to prevent surface stickiness, which can prevent practical use. Polysulfone content of 50 to 60 wt% results in the most desirable sterilizable materials.

ABOUT THE AUTHOR

Dr. Roger Corneliussen is Professor Emeritus of Materials Engineering of Drexel University in Philadelphia. He has been an SPE member since 1962 and an active member of the Philadelphia Section, serving as president and national councilman for several years. The above patents are selected from the 100 to 400 plastics-related patents found by reviewing 3,000 to 7,000 U.S. patents published each Tuesday. Readers are invited to reviewthe complete list of plastics-related patents by week at www.plasticspatents.com