Originally Published MDDI July 2002
BULLETIN BOARD
High-performance plastic stock shapes available. A full range of PEEK, Ultem, and blended Delrin AF stock shapes for fabricated parts includes ¼- to 6-in. rods and ¼- to 4-in. slabs. Made from 100% virgin resins, PEEK and Ultem products are available in 30%-glass-filled and unreinforced formulations. Delrin AF shapes are manufactured with 13% fibrous PTFE, enhancing friction and wear properties. The products are stress relieved, allowing close tolerances and stable dimensions upon machining. Sustaplast (Edgewood, NY; 800/832-6787), whose line of plastics also includes acetal copolymer, acetal homopolymer, extruded nylon 6/6, and cast nylon 6, can cut to size all inventoried products.
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New material replaces nitrocellulose membrane in lateral-flow immunoassays. A patent-pending material, Lateral-Flo membrane can replace nitrocellulose material with little change to current functionality or to assembly equipment. Developed by Porex Porous Products (Fairburn, GA; 800/565-8777), Lateral-Flo offers a solution to the lot-to-lot variability, lack of stability when stored, flammability, and weak tensile strength associated with nitrocellulose. By fusing dense polyethylene
particles into a single membrane, specially designed production equipment creates a stable base material. The sizing of the spherical particles ensures a consistent reproducibility. A chemical process modifies the structure's surface to increase protein binding and capillary rise, eliminating the need to use surfactants.LCPs feature properties not available in other resins. Unlike other semicrystalline resins, liquid-crystal polymers (LCPs) are made of rigid, well-ordered, rod-like molecules. This structure enables LCPs to display properties unmatched by other resins. Vectra and Vectran LCPs feature consistent flow during the molding of thin-wall parts, dimensional stability of parts at high temperatures, high impact strength, chemical and flame resistance, and a low coefficient of expansion. Vectra LCP provides low moisture absorption to maintain its dielectric properties, and is suitable for high-frequency applications and electronic films. High-temperature resistance makes Vectra an ideal material for use in the manufacture and assembly of miniature devices, while the barrier properties exhibited by Vectran LCP are useful in packaging applications. Both LCPs, manufactured by Ticona (Summit, NJ; 800/833-4882), are part of a line of LCP grades that includes packaging film and high-temperature and FDA grades.
Cross-linking polyethylene used in artificial hips could extend joint life. A team of researchers has been granted a third patent to continue development of a wear-resistant cross-linked polyethylene for use in artificial joints. The research team, working at Orthopaedic Hospital (Los Angeles; 800/339-6784), has been credited with discovering the new cross-linking technology. An implant made from the polyethylene received FDA clearance in 1997. The researchers have found that by cross-linking polyethylene in artificial joints, wear resistance can be increased tenfold. In current development is a new polyethylene that is cross-linked using heat and radiation, followed by gas plasma sterilization to assist in preventing oxidation. This technology could potentially produce more-durable joint implants as well as more-effective surgical procedures. According to researchers, the Marathon cross-linked polyethylene, licensed to DePuy Orthopaedics, is being scrutinized for use in other total joint replacement systems.
Cyanoacrylate adhesives provide high cure speeds. Multigrade cyanoacrylates for adhesion featuring multiple viscosities are available from Dymax Corp. (Torrington, CT; 860/482-1010). For use with acetyl, nylon, rubber, polyethylenes, acrylics, and polycarbonates, the adhesives are solvent-free and compatible with most surfaces. The 222 Series provides high bond strengths and minimizes odor, blooming, and vapors during the bonding process. The supplier is ISO 10993 certified.
Carbon dioxide inert-gas technology ensures instant UV curing. The UVACube inert UV curing chamber eliminates long curing times and incomplete curing of coatings. Manufactured by Honle UV America Inc. (Marlboro, MA; 508/229-7774), UVACube uses CO2 gas to produce efficient, consistent curing on all surfaces, including three-dimensional shapes. CO2 gas reduces atmospheric oxygen inhibition, resulting in low production costs and fast cure times. The UVACube chamber offers timer-controlled shutters, adjustable elevating tables, and residual-oxygen-level monitoring. The chamber lid and shutters interlock to prevent UV leakage and provide safety of operation. UVACube can combine varying UV intensities with multiple spectra and filters, and is intended for laboratory use as well as manual curing applications.
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