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Extraction-Resistant Pipes

U.S. Patent 9,057,466 (June 16, 2015), “Use of a Composition for Contact with Supercritical Media,” Andreas Dowe, Reinhard Beuth, and Franz-Erich
Baumann (Evonik Degussa GmbH, Essen, Germany).

Deep-water flexible pipes consist of layers of thermoplastics and reinforcements. Modern pipes must be compatible with supercritical fluids such as supercritical carbon dioxide. Supercritical media are very good extraction fluids, attacking polyamide materials. The polyamide layer loses its flexibility because of plasticizer extraction and then shrinks, destroying the pipe’s integrity.

Dowe, Beuth, and Baumann developed an extraction-resistant polyamide resin containing 0 to 99 parts by weight of polyamide, and 1 to 100 parts of polyamide elastomer, such as polyetheresteramide and polyetheramide, and 0 to 9 wt% plasticizer. Low or zero plasticizer content eliminates the extraction problems. This material can contain other additives, such as impact modifiers and other conventional additives, without extraction. The only requirement is that the polyamide must form a continuous network within the material.

High-Strength Polypropylene Fibers

U.S. Patent 9,057,148 (June 16, 2015), “High-Strength Polypropylene Fiber and Method for Producing the Same,” Tatsuya Kitagawa, Tadahisa Iwata, and Chizuru Hongo (Toyota Jidosha Kabushika Kaisha, Aichi-ken, and the University of Tokyo, Tokyo, Japan).

Polypropylene (PP) is a thermoplastic resin with low density, high strength, excellent heat resistance, and good chemical resistance. However, its strength is inadequate for many applications, such as some automotive applications. 

Kitagawa, Iwata, and Hongo produced high-strength PP fibers without special materials or special methods. They formed polypropylene fibers by melt spinning, cooling the fibers and
drawing them using 50 to 750 take-off/extrusion speed ratios. The polypropylene may be a homopolymer, a copolymer, or a mixture of polymers. The PP resin should have a 200,000 to 1,000,000 weight average molecular weight with a M_w/M_n ratio of 5 or less.

In a given example, the extruded fiber was cooled with an ice bath before drawing, and heat-treated at 120°C after drawing. The fiber cooled before drawing had tensile strengths of 1.4-1.7 GPa, compared to 0.8 GPa for fibers drawn without cooling.

Uniform Micro-Beads

U.S. Patent 9,028,730 (May 12, 2015), “Method of Producing Uniform Polymer Beads of Various Sizes,” Serguei Rudolfovich Kosvintsev (Purolite Corp., Bala Cynwyd, Pennsylvania, USA).

Polymer beads of 1 to 300 microns are useful for chromatography, ion exchange resins, particle nuclei, and calibration standards. Uniform size is critical, but conventional production methods, such as stirred batch polymerization, produce large particle size distributions. Moreover, jetting methods are costly, with low output.

Kosvintsev produced uniform micro-particles by dispersing a polymerizable monomer over a double-walled cylindrical cross-flow membrane into water. The shear at the water surface generates uniform 10 to 200 micron monomer droplets for polymerization. Perforated, chemically resistant membranes are preferred. The shear is generated by vibration for breaking jets into particles. Although this works for many mono­mers, styrene and divinyl benzene, alone or with a porogen, are preferred.

Tough & Strong Polyamides

U.S. Patent 9,056,982 (June 16, 2015), “Thermoplastic Composition for Use in High Impact Applications,” Rajeev S. Bhatia (Invista North America S.A.R.L., Wilmington, Delaware, USA).

Nylon polymers are desirable in many applications due to their outstanding elasticity, dye-fastness, and high melting point. Often these resins are reinforced with impact modifiers and reinforcements. However, improving the impact strength of a resin composition with commercially available modifiers generally results in a proportional decrease in tensile strength. There’s a need for compositions with increased impact strengths without reduced tensile strengths.

Bhatia developed a thermoplastic nylon consisting of 50-99 wt% nylon-66 resin, 1-50 wt% impact modifier, and 0.01-25 wt% ultrahigh molecular weight silicone. The silicone additive improves toughness while keeping an ultimate tensile strength that’s at least 80% of the material without the silicone. The silicone is immobile in the continuous phase of the polyamide.

Functional Polyurethanes

U.S. Patent 9,056,991 (June 16, 2015), “Polymeric Pigment Systems and Methods,” Heather E. Clarke (Cabot Corp., Boston, Massachusetts, USA). 

Ink for inkjet printers consists of liquid carriers and suspended dyes or pigments. Pigments are not readily dispersible in liquid vehicles and require dispersants. Polymeric emulsion polymers improve print performance, but they tend to be insoluble, clog nozzles, and agglomerate pigments.

Clarke developed an ink using a pigment and a reactive polymer so that the pigment and polymer remain soluble without additional dispersants. This polymer is a soluble polyurethane in which 5 wt% is attached to pigment particles, 5 wt% is unassociated with the pigment, and 10 wt% is hydrophilic. The pigment should have bisphosphonic acid groups for complexing, and may be a carbon black or color pigment. The polyurethane is a product of an isocyanate and a polyester or polyether diol with molecular weight between 1,000 and 20,000.

Heat Transfer Liquids

U.S. Patent 9,005,471 (April 14, 2015), “Heat Transfer Fluid Containing Nano-Additive,” Satish Chandra Mohapatra (Dynalene Inc., Pennsylvania, USA). 

Efficient heat transfer fluids are critical in modern technology, from nuclear reactors to medicine. Non-aqueous heat transfer fluids are used in extremely low- or high-temperature applications, but they have low conductivities. Improving their efficiency by 2-25% could lead to significant savings in energy and equipment. Suspended copper, silver, and iron nanoparticles can improve
heat transfer, but dispersion is difficult. Surfactants improve dispersion but reduce thermal conductivity.

Mohapatra developed a heat transfer fluid with porous nanoparticles in a non-aqueous fluid. The porosity improves dispersion stability by reducing overall particle density as well as transfer surface area. These nanoparticles have aspect ratios from 1.0 to 10,000; porosity of 40-85%; density of 0.4 to about 3.0 g/cm³; an average pore diameter of 0.1 to 100 nm; and a specific surface area of 1 to 4000 m²/g.

The nano-additive increases the heat transfer efficiency of the heat transfer fluid, and reduces the moisture content. These nanoparticles include molecular sieves, nano-powders, nano-fibers, or desiccants. Examples of carrier fluids are aliphatic and aromatic hydrocarbons, alkyl aromatics, polyalphaolefins, terpenes, alcohols, ketones, silicones, ionic liquids, and fluorocarbons. Porous particles include zeolite, silica, alumina, porous carbon, activated porous carbon, and fibrous carbon.

Radiolabels

U.S. Patent 9,023,317 (May 5, 2015), “Polymer Precursors of Radiolabeled Compounds, and Methods of Making and Using the Same,” Duncan H. Hunter and Mustafa Janabi (University of Western Ontario, London, Ontario, Canada).

Molecules labeled with radioactive isotopes have been used for imaging in medical diagnosis and cancer treatment. Improved radiolabels are needed with reduced toxic by-products, improved isotope purity, and a longer shelf life.

Hunter and Janabi prepared purified radiolabeled compounds with controlled surface reactions. Benzoic acid groups are attached to a solid support and reacted with amines. Label precusors are then attached to the benzamide groups and reacted to form the desired label compounds. Excess precursor and toxic products are removed by rapid and simple filtration, and the radioactive labels are freed with oxidants for use.

Anti-Biofouling Microstructures 

U.S. Patent 8,997,672 (April 7, 2015), “Surface Topographies for Non-Toxic Bioadhesion Control,” Anthony B.
Brennan, Ronald Howard Baney, Michelle Carman Turnage, Thomas G. Estes, Adam W. Feinberg, Leslie H. Wilson, and James Frederick Schumacher (University of Florida Research Foundation, Inc., Gainesville, Florida, USA).

Biofouling refers to the attachment of organisms, such as algae and barnacles, to surfaces in water. It costs the U.S. Navy over $1 billion per year by increasing the hydrodynamic drag of naval ships. Biofouling is even a problem in medicine for implants, including heart valves and stents. Anti-fouling coatings are used to reduce biofouling by releasing biocides such as cuprous oxide or tributyltin, but these and released toxins are an environmental problem, and nontoxic methods are needed.

Brennan et al. developed a surface topography that resists organism adhesion without toxic coatings. This topography consists of a sinusoidal patterns of surface projections leading to complex surface plateaus. The critical feature is the 10 to 100 micron spacing between projections. The pattern must have neighboring features with different spaces described by different sinusoidal waves with a roughness factor of 4 to 50. The smaller spacing must be 0.25 to 0.75 of the smallest dimension of the overall organism structure to prevent adhesion. This means 2 to 5 microns for algae and 0.75 to 2 microns for barnacles. Different dimensions lead to different plateaus, repelling different organisms. These surface patterns are formed by printing, coating, or micro-molding.