By Roger Corneliussen
By Roger Corneliussen
By Roger Corneliussen
Antifriction Surfaces
US Patent 8,759,454 (June 24, 2014), “Low Friction Polymeric Compositions as well as Devices and Device Fabrication Methods based thereon,” Yongmoon M. Kwon and Leonard Pinchuk (Innovia LLC, Miami, Florida, USA).
Various medical devices (such as catheters and guide wires) need hydrophilic coatings to reduce friction for maneuvering through blood vessels. These coating are usually applied in a four step process, adding complexity and cost to fabrication. Kwon and Pinchuk developed a catheter using blends of 50 to 95 wt% hydrophobic polycarbonate polyurethane copolymer and a hydrophilic polyurethane polymer. The hydrophilic polymer absorbs water up to 500% of its dry weight. These components are immiscible resulting in phase separation. The exposed hydrophilic phase reduces friction without needing separate coating steps.
Long Chain Branched PE
US Patent 8,759,460 (June 24, 2014), “Process for the Polymerization of Ethylene, and Ethylene Polymers having Broad Molecular Weight Distribution and Long-Chain Branching,” Eleonora Ciaccia, Iakovos Vittorias, Shahram Mihan, Lenka Lukesova, Dieter Lilge, Maclovio Herrera Salinas, Gerhardus Meier, and Gerd Mannebach (Bassell Polyolefine GmbH, Wesseling, Germany).
Various polymerization methods produce polyethylenes with broad molecular weight distributions, as well as blends such as post reactor melt blending, single stage polymerization with mixed catalysts and multistage polymerization. These processes produce blends of linear polyethylene and resins with short chain branching. However, none produce blends of polyethylene with long chain branches.
Ciaccia et al. developed a catalyst blend of positive Fe and Co catalysts with Ziegler polymerization catalysts, where the catalyst mixture has been annealed at 110 to 140°C. Polymerization is carried out in a single reactor gas-phase where both catalysts are active, resulting in blends including polyethylene with long chain branching and high molecular weights.
Superabsorbent Recycling
US Patent 8,766,032 (July 1, 2014), “Recycled Superabsorbent Polymer Particles,” Marion Michnacs, Carsten Luckert, and Carsten Zetzl (The Procter & Gamble Company, Cincinnati, Ohio, USA).
During high-speed manufacturing of disposable absorbent articles, such as diapers, defective products are discarded in landfills, losing the costly absorbent particles. These superabsorbent particles typically are more than 90% of the absorbent cores.
Michnacs, Luckert, and Zetzl recovered the absorbent particles by mixing the rejects with a thermoplastic melt such as styrene butadiene block copolymers and solidifying and extracting the thermoplastics, additives, and contaminates with a supercritical carbon dioxide or propane, leaving behind active, crosslinked superabsorbent particles.
Cleaning Oil Spills
US Patent 8,785,347 (July 22, 2014), “Gulf Oil Spill Underwater Oleophilic Hydrophobic Oil-Capturing Water Permeable Drag-Net,” William Redvers Belisle (New Orleans, Louisiana, USA).
Cleaning oil spills is still a difficult, inadequate process, in spite of the many new devices and approaches for it. Belisle developed a porous oil-capturing water-repelling and water-permeable net that can be dragged vertically through an underwater oil spill area to collect and remove oil. The net consists of threads and wires knotted, twisted, and woven to form a regular pattern with fine spaces between the threads. Superhydrophobic materials are applied to the net-type material by casting, vapor deposition, particle deposition, or sol-gel techniques and allowed to solidify and bind to the net structure. Natural, organic, inorganic, and synthetic sorbents are applied to the net.
Polypropylene Foams
US Patent 8,785,508 (July 22, 2014), “Pre-Expanded Polypropylene Resin Beads and Process for Producing same,” Taro Kiguchi (Kaneka Corp., Osaka, Japan).
Pre-expanded polypropylene beads are used for molding electronic packaging. However, residual dispersion agents retard fusion of the pre-expanded beads during in-mold foaming, requiring a washing of the beads with a chemical such as nitric acid or phosphate soda before molding.
Kiguchi prepared antistatic pre-expanded polypropylene beads by soaking PP pellets containing the antistatic glycerin esters in a water dispersion of foaming and dispersion agents. The dried pellets are expanded and fused 2 to 60 times their original volume without washing before molding.
Polymerization Reactors
US Patent 8,796,401 (August 5, 2014), “Polymerization of High Viscosity Materials,” Yi-Lin Chu (Princo Middle East FZE, Dubai, United Arab Emirates).
Many polymerization reactions are limited by high viscosity. It is difficult to reach high molecular weights because of slow transport in the viscous media.
Chu developed a polymerization process based on two stages, a mechanical stage using deflecting blades or a rotating disk, and a second stage based on gravity-driven mixing by spinning. The first stage brings the viscosity to 150,000 cP at 300°C, while the second stage brings the viscosity to 400,000 cP or higher at 300°C.
Dielectric Materials
US Patent 8,785,521 (July 22, 2014), “Two-Particle Nanocomposite Dielec-trics,” Seth Adrian Miller and Gary Lynn Duerksen (Empire Technology Development, LLC, Wilmington, Delaware, USA).
Dielectric materials are commonly used in energy storage devices, e.g., to separate opposing electrodes in an electrostatic capacitor. Nanocomposite dielectric materials include inorganic nanoparticles in a polymer base, which together have high dielectric constants due in part to the inorganic nanoparticles while retaining much of the processability of the base polymer. There are still problems, such as inadequate breakdown strength, creating local hot spots.
Miller and Duerksen avoided this problem using mixtures of small (5 to 10 nm) and large nanoparticles (75 nm and larger). The smaller particles increase breakdown strength, and the larger particles increase the dielectric constant. An example consisted of polyvinylidene difluoride containing 5 to 10 nm silica particles and 75 nm barium titanate particles.
Polyphenylene Sulfide Materials
US Patent 8,796,392 (August 5, 2014), “Low Temperature Injection Molding of Polyarylene Sulfide Compositions,” Rong Luo and Xinyu Zhao (Ticona LLC, Florence, Kentucky, USA).
Polyphenylene sulfide (PPS) is a high-performance polymer that can withstand high thermal, chemical, and mechanical stresses. However, molding requires a high mold temperature (130°C or more) and a long cycle time. Luo and Zhao found that adding 0.1 to 8 wt% of an aromatic amide oligomer lowers the crystallization time and temperature, enabling mold temperatures from 50 to 120°C.
Wood Replacements
US Patent 8,802,754 (August 12, 2014) Li Nie, Sukh D. Bassi, Clodualdo C. Maningat, and Michael Douglas Parker (MGPI Processing, Inc., Atchison, Kansas, USA).
In addition to their increasing cost, wood fillers have several drawbacks. These fillers have a strong wood color that is very difficult to hide in plastic resins. In addition, lubricant is needed for extrusion, and the resulting composite is not completely hydrophobic; wood flour and wood fiber readily adsorb large amounts of water.
Nie et al. developed an improved wood replacement consisting of 20 to 80 wt% granular starch replacing wood filler, 0 to 15 wt% fiber, 20 to 78 wt% synthetic resin, and 0.5 to 4 wt% compatibilizer. Other additives such as lubricants, foaming agent, colorants, fillers, antimicrobial agents, and UV stabilizers may be added.
Inorganic/Organic Copolymers
US Patent 8,802,807 (August 12, 2014), “Method for the Manufacture of Polybranched Organic/Inorganic Hybrid Polymers,” Ferdinand Mannle, Christian Simon, Jest Beylich, Keith Redford, Britt Sommer, Einar Hinrichsen, Erik Andreassen, Kjell Olafsen, and Terje Didriksen (Sinvent AS, Trondheim, Norway).
The range of polymers can be greatly expanded by hybrid inorganic/organic copolymers. Mannle et al. produced a star copolymer based on an inorganic silane core with organic polymer branches with specific functional groups. The core is produced by controlled hydrolysis of a silane with functional groups and the branches developed by amine condensation reactions. The resulting products are useful as antioxidants, UV absorbers, radical scavengers, or crosslinking agents.