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Separating Fillers

U.S. Patent 8,871,863 (October 28, 2014), “Production of Thermoplastic Polymer Matrices,” Daniel Hideki Di Petta, Karla Krivtzoff Laguens, Leo Ricardo Bedore Dos Santos, Tarcis Cordeiro Bastos, and Thomas Canova (Rhodia Poliamida e Especialidades LTDA, Sao Paulo, Brazil).

Adding silicate and barium sulfate fillers to polymers is difficult because of agglomeration and degradation. Di Petta et al. found that dispersing silicate and barium sulfate particles in the monomer before polymerization prevents agglomeration and degradation, and even enables spinning to form fibers and yarns. These additives also prevent obstruction of die holes and filtration media.

This works for polyamides and polyesters as well their copolymers. The fillers were suspended in water and added to a mixture of monomers. After polymerization, the melt can be spun into fibers and yarns.

Molding Composites

U.S. Patent 8,877,114 (November 4, 2014), “Method for Removing a SMP Apparatus from a Cured Composite Part,” David E. Havens, Matthew C. Everhart, Kristin Marie Cable, Eric W. Traxler, Carl Ray Fiegenbaum, Jeffrey W. Priest, and Kodi Elizabeth Ann Caster (Spirit Aerosystems, Inc., Wichita, Kansas, USA).

The most difficult part of fabricating composites is their removal from the mold or mandrel after curing. Removal often requires sacrificing or destroying the mandrel by cutting, dissolving, or bead-blasting it. Destroying the mandrel prevents it from being used again, and damages the composite part.

Havens et al. developed a method of fabricating composites using a mold or mandrel with a shape-memory polymer liner. The composite is assembled and heated for curing on the lined mold or mandrel. During heating, the shape-memory polymer expands, putting pressure on the composite. After curing and cooling, the polymer relaxes, and the composite can be easily removed without damage to the part or mold. 

The shape-memory polymer can be any polymer with the proper transition temperature, including epoxies, polyurethanes, or polyimides and their copolymers. The transition may be induced by heating, electric current, water, or light.

Nanoparticle Mixtures

U.S. Patent 8,871,844 (October 28, 2014), “Composite Particles having Organic and Inorganic Domains,” Abdulmajid Hashemzadeh (Wacker Chemie AG, Munich, Germany).

Composite particles consisting of inorganic/organic components are useful for a variety of reasons. However, mixing different particles leads to agglomeration, resulting in gelation and speck formation.

Hashemzadeh coupled inorganic and organic materials by mixing sub-1000 nm inorganic oxide particles, resin, and coupling reagents. The polymers contain more than 4.9 wt% ethylenically unsaturated carboxylic acids, such as vinyl esters of carboxylic acids. The coupling agents are alkylalkoxysilanes. The final particles are 20 to 1000 nm in size with 2 to 500 nm inorganic domains. The components are dispersed in a liquid and mixed at 30-100°C and neutralized.

Ultraviolet Fluorescence

U.S. Patent 8,889,785 (November 18, 2014), “Production Method of Thermoplastic Resin Composition, Molded Body, and Light Emission Body,” Hiroshi Niino and Mitsufumi Nodono (Mitsubishi Rayon Co., Ltd., Tokyo, Japan).

Some metal oxides and metal complexes can emit visible light after ultraviolet irradiation. Thus, metal oxides and metal complexes can be used as fillers in plastics to make them fluorescent. However, most filled plastics have low fluorescence because of particle aggregation.

Niino and Nodono developed a fluorescent, filled thermoplastic resin with good light emission by ultraviolet irradiation. They mixed 0.001 to 50 parts of a metal complex and a metal halide with 0.001 to 30 parts polyalkylene per 100 parts thermoplastic resin, and heated the mixture to 100-320°C. The molecular weight of the thermoplastic is 10,000 to 50,000. Zinc acetylacetonate particles and a metallic chloride with a polyethylene glycol can be mixed without agglomeration.

Two-Step Injection Molding

U.S. Patent 8,894,399 (November 25, 2014), “Injection Molding Tool with Integrated Gate Removal for High-Volume Manufacturing,” Craig M. Stanley, William Bredall, and Kurt R. Stiehl (California, USA).

Injection molding is the most popular process for manufacturing plastic products. In some cases, a molded part is modified by a second molding step. Transferring a molded object to a second mold is difficult and cumbersome, preventing cost-effective high-volume molding.

Stanley et al. developed a transfer tool for two-step injection molding in high volumes, in which molded parts are transferred from one mold to another without separating the molded part from runners. This single-step transfer, which can be performed without degating or separating the molded parts from one another, simplifies the process and reduces cycle time. The second tool has cavity spacing that matches the cavity spacing of the first tool. It also can have a device for removing the previous gate in the second mold before the final molding step.

High-Temperature Biopolyesters

U.S. Patent 8,889,820 (November 18, 2014). “Amorphous, High Glass Transition Temperature Copolyester Compositions, Methods of Manufacture, and Articles thereof,” Navinchandra S. Asthana and Ganesh Kannan (Saudi Basic Industries Corp., Riyadh, Saudi Arabia).

Polyesters have many desirable properties. However, most of the commercially available amorphous polyesters, such as polyethylene terephthalate (PET), glycol-modified PET (PETG), and glycol-modified polycyclohexylene dimethylene terephthalate (PCTG), have relatively low glass transition temperatures, limiting their applications.

Asthan and Kannan developed an amorphous polyester with a glass transition temperature of 107-110°C. They formed polyesters from 1-phenylindane dicarboxylic acid and a terephthalyl
component, together with 1,4-cyclohexanedimethanol. The terephthalyl component is derived from recycled polyesters, including post-consumer waste and scrap polyester. In addition, a bio-based terephthalic acid is derived from a plant or microbial source rather than a petroleum source.

Railroad Ballast

U.S. Patent 8,876,014 (November 4, 2014), “Polyurethane Ballast Layer, The Method for Preparing the Same and the Use thereof,” Chenxi Zhang, Gang Sun, Yi Shen, and Hui Zhao (Bayer MaterialScience AG , Germany).

A railroad track bed consists of a ballast layer of crushed rock set on the road base supporting rails and ties. This ballast distributes the heavy train load onto the road base, reduces road base distortion, and enables smooth and safe travel with impact reduction and shock absorption. However, ballast maintenance is essential—and costly, involving large equipment.

Zhang et al. developed a poly­urethane spray for ballast consisting of polyisocyanates with alkyl groups, polyether polyols or amines, and a blowing agent. The porous coating reduces ballast crashing, shifting, and cracking under heavy loads. This prevents dirt, snow, and wastes from entering into the interstitial spaces of the ballast, thus extending the track bed’s maintenance cycle—reducing costs as well as improving safety.