By Roger Corneliussen
By Roger Corneliussen
By Roger Corneliussen
Spider Silk
US Patent 8,729,238 (May 20, 2014), “Method of Producing Nano- and Microcapsules of Spider Silk Protein,” Thomas Scheibel, Daniel Huemmerich, Andreas Bausch, and Kevin Hermanson (Amsilk GmbH, Munich, Germany).
Biodegradable micro- or nano-capsules have great potential for controlled drug release as well as for microdevice building blocks. Synthetic block copolymers tend to be biologically incompatible with poor biodegradability.
Scheibel et al. used spider silk to form nano- and micro-capsules for in vivo applications. They induced self-assembly of the proteins in the interphase of a water/oil emulsion. The minimization of surface energy drove the proteins to the interface and induced an aggregation to a dense polymer network, forming nano/micro spider bags with wall thicknesses of 10 to 70 nm. These bags can be filled with drugs, proteins, reactants, or nano-/micro-particles.
Reinforced Foam
US Patent 8,729,144 (May 20, 2014), “Fibre Reinforced Propylene Foam,” Martin Anker, Per-Ola Hagstrand, and Manfred Stadlbauer (Borealis Technology Oy, Porvoo, Finland).
Steel pipe coatings for deep-water offshore applications need a combination of low thermal conductivity and good mechanical properties. Anker, Hagstrand, and Stadlbauer developed reinforced polypropylene (PP) foam for insulating deep offshore pipes. The material consists of 6 to 15 wt% 1- to 10-mm glass fibers in a blend of high-melt-strength long-chain PP homopolymer and 10 wt% ethylene-propylene block copolymer with high impact strength. The glass fibers improved mechanical properties and decreased thermal conductivity.
Microsilica Flame Retardant
US Patent 8,729,172 (May 20, 2014), “High Performance Engineering Plastics and Additive for use in Engineering Plastics,” Gerd Schmaucks and Jan Olaf Roszinski (Elkem AS, Oslo, Norway).
Fillers such as talc and wollastonite or fibers such as glass and carbon fibers in engineering plastics reduce processability. Furthermore, adding certain flame retardants can result in toxic gas release during a fire.
Schmaucks and Roszinski found that 8 to 50 wt% microsilica (150 nm) in engineering plastics is an effective reinforcement and flame retardant, without the side effects of reduced processability or toxic gas generation during burning.
Suture Fabrication
US Patent 8,739,389 (June 3, 2014), “Compound Barb Medical Device and Method,” Matthew D. Cohen. Nicholas Maiorino, Timothy D. Kosa, Mark S. Buchter, and Michael Primavera (Covidien LP, Mansfield, Massachusetts, USA).
In medicine, barbed sutures enhance tissue holding; however, barbing methods are difficult and costly. Cohen et al. formed barbs in one to three passes using an ultrasonic driven knife at 1 to 100 kHz frequencies. The cut depth and the angle of the barbs are based on the signal amplitude of the ultrasonic signal. Barbs up to 30% of the suture diameter can be formed.
Foam Sorbents
US Patent 8,741,977 (June 3, 2014), “Foam Compositions and Articles including Cyclodextrin Crosslinked with Polyurethane Prepolymer and Preparation thereof,” Anne Marie Paule Wibaux and Bert Paesen (Avery Dennison Corp., Glendale, California, USA).
Personal care applications require foams which are odor absorbing and capable of absorbing large amounts of water. Wibaux and Paesen developed odor- and water-absorbing foams based on cyclodextrin coupled to polyurethane foams. This foam is produced by mixing cyclodextrin and polyurethane prepolymer and reacting the mixture with water. These foams can be basis of bandages, wipes, diapers, protective swimming undergarments, incontinence garments, panty shields, or perspiration shields.
FR Nanocomposites
US Patent 8,742,044 (June 3, 2014), “Method for Producing Polymer Nanocomposite, and Flame-Retardant Polymer Nanocomposite Formed by the Production Method,” Atsushi Takahara, Hideyuki Otsuka, Motoyasu Kobayashi, Hideaki Yukutake, and Tetsuo Kamimoto (Kyushu University, National University Corp., Fukuoka, Japan, and Adeka Corp., Tokyo, Japan).
Polymeric nanocomposites are being developed with high strength, high elastic modulus, heat resistance, and good electrical properties while retaining the flexibility, low specific gravity, and formability of the polymer matrix. Clay is a candidate filler but is difficult to disperse in polymeric resins.
Takahare et al. expanded an interlayer space of a layered clay using an organic onium salt, immobilizing a radical polymerization initiator via covalent bonds in the clay. This combination will induce radical polymerization in a monomer. Polymerization leads to exfoliation and uniform dispersion of the clay particles. The resulting material has a narrow molecular weight distribution with excellent mechanical properties, heat resistance, and flame retardance. The example referred to is a polystyrene-magadiite nanocomposite.
Ion Exchange Epoxies
US Patent 8,742,055 (June 3, 2014), “Production of Epoxy Resins using Improved Ion Exchange Resin Catalysts,” Philip J. Carlberg, H. Robert Goltz, Leming Gu, William I. Harris, David H. West, William G. Worley, and Thomas C. Young (Dow Global Technologies LLC, Midland, Michigan, USA).
Low molecular weight epoxy resins require two reactions: etherification and dehalohydrogenation (epoxidation). One problem is catalyst removal after synthesis.
Carlberg et al. developed an improved synthesis using an insoluble modified amine-functionalized anion exchange resin as the etherification catalyst. A polyhydric phenol is reacted with epihalohydrin with the insoluble catalyst to produce a bishalohydrin ether. This then is dehydrohalogenated with an aqueous inorganic hydroxide. Suitable anion exchange resins include any ion exchange resin consisting of a cation bound to a crosslinked polymer.
Oxygen Scavengers
US Patent 8,748,519 (June 10, 2014), “Thermoplastic Polymers Comprising Oxygen Scavenging Molecules,” Girish N. Deshpande (Plastipak Packaging, Inc., Plymouth, Michigan, USA).
Oxygen scavengers are added to packaging materials to protect oxygen-sensitive materials. Such scavengers react with oxygen in the package or oxygen diffusing in from the outside. But scavenger diffusion to the outside is a problem.
Long-term stability of the scavenging ability would be enhanced if the scavenging groups were attached to the resin molecules. Deshpande developed polymers with allylic or benzylic amide groups covalently bonded to the polymer molecules. These groups have active groups participating in polymerization, such as diacyl halides, hydroxides, or bis amines, resulting in scavengers bound to the polymer chains.
Tissue Adhesives
US Patent 8,748,558 (June 10, 2014), “Biodegradable Macromers,” Walter Skalla, Allison Calabrese, Ahmad R. Hadba, and Nadya Belcheva (Covidien LP, Mansfield, Massachusetts, USA).
There is an interest in replacing or augmenting sutures with tissue adhesives. These adhesives can lead to increased repair speed, complete closure, and bonding without tissue strain. Skalla et al. developed biocompatible polyester adhesives and sealants for surgery by reacting a polyaklkyene oxide with aliphatic dicarboxylic acid to form an aliphatic polyester macromer without solvent or catalyst residues. This can be reacted with a polyisocyanate to form biocompatible adhesives.
High-Weight Polyesters
US Patent 8,748,562 (June 10, 2014), “Process for Preparing High Molecular Weight Polyesters,” Larry W. Leininger and Dong Tian (AWI Licensing Co., Wilmington, Delaware, USA).
High molecular weight polyesters are desired in many applications. Polymerization is an equilibrium condensation reaction leading to side products such as water, making reaching a very high molecular weight very difficult. Removal by vacuum can help; however, increasing melt viscosity makes removing water difficult.
Leininger and Tian achieved high molecular weights by heating a polyester to form a melt, and applying and maintaining a vacuum of between 5 mm and 85 mm of mercury to the melt while passing nitrogen gas through the melt until molecular weight has increased to the desired level. The nitrogen stream effectively and quickly removes the generated water in spite of the increasing melt viscosity.
Geosynthetics
US Patent 8,752,438 (June 17, 2014), “Sensor-Enabled Geosynthetic Material and Method of Making and Using the same,” Kianoosh Hatami and Brian Grady (University of Oklahoma, Norman, Oklahoma, USA).
There is a need for geosynthetic materials that can be continuously monitored to ensure their proper long-term behavior. Hatami and Grady developed a sensor-enabled geosynthetic material based on a polymer filled with an electrically conductive filler. The polymeric material and an electrically conductive filler are combined to create a sensor-enabled geosynthetic material whose function can be continuously monitored. The material is filled with just enough conductive filler with a useful strain sensitivity near the percolation region. This concentration ranges from 0.01 to 30 wt%, depending on the filler and polymer morphology.
Explosive Deactivation
US Patent 8,754,284 (June 17, 2014), “Further Improved Blasting Method,” Richard Goodridge, Deane Tunaley, Steve Kotsonis, Les Armstrong, Brad Beikoff, and Thomas Smylie (Orica Explosives Technology Pty. Ltd., Melbourne, Australia).
Explosives are used in a significant number of commercial applications, such as mining, quarrying, and seismic exploration. In mining and quarrying, a detonator is typically used to initiate a primer charge that in turn detonates the bulk explosive. Often, undetonated charges remain unrecovered in the field and are dangerous because of unpredictable detonation.
Goodridge et al. developed a method to deactivate explosives using enzymes extracted from certain living cells. Microorganisms with effective enzymes include Pseudomonas spp., Escherichia coli, Morganella morganii, Rhodococcus spp., Comamanos spp., and denitrifying bacteria.
Polyethylene Tri-Blend
US Patent 8,759,448 (June 24, 2014), “Polyethylene Moulding Composition with Improved Stress Crack/Stiffness Relationship and Impact Resistance,” Andrey Buryak, Albrecht Dix, and Balakantha Rao Kona (Borealis AG, Vienna, Austria).
In spite of polyethylene developments, there remains a need for a polyethylene material with a balance of impact strength, stress crack resistance, and stiffness—as well as good processability making it suitable for use in injection, blow, and compression molding for producing caps, closures, packaging, and housewares.
Buryak, Dix, and Kona developed a polyethylene with three components, a 15-50 wt% low molecular weight fraction of 15-40 kg/mole, a 15-50 wt% medium molecular weight fraction of 70-180 kg/mol, and a 15-40 wt% high molecular weight ethylene/hexene copolymer of 200-400 kg/mol. This blend can be produced by multistage polymerization or by mechanical blending.