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Talk About Tough Specs
Mine apparatus must resist static build up and provide RFI shielding
Doug Smock, Contributing Editor -- Design News, October 8, 2007
Applications for specialty plastics continue to expand. A housing for a self-contained breathing apparatus used in mine rescues uses a specially compounded polycarbonate beefed up with stainless-steel fibers. The material was chosen by engineers using a matrix approach that eliminated other options such as a polycarbonate alloy with an inherently dissipative polymer that could potentially have released some of its chemically bound water molecules. In a new application for in-line skates, acetal polymer is toughened with aramid fiber. Aramid is short for aromatic polyamide.
Tough Specs for Housing
Thermoplastics for the new BioPak 240R Self-Contained Breathing Apparatus (SCBA) must be rugged while providing protection against radio interference. It is described as the industry's most advanced and easiest to use long-duration "rebreather" on the market. Rebreathers provide a breathing gas containing oxygen and recycled exhaled gas. The BioPak includes 6 l volume, disposable solid carbon dioxide scrubbers and quick-change coolant. The BioPak 240R rebreather is designed for use in mine and tunnel rescue, industrial accidents, hazmat clean-up, search and rescue and military or homeland security actions. Premix, a specialty compounder, developed a stainless-steel fiber polycarbonate with impact modification. The housing must withstand continuous temperatures of 190F (88C) without deforming. In addition to 15 sec of direct flame without burning or showing, it also needed to have a surface resistivity of less than 1-e9Ω in order to control static build up and charges.
PC Scores For Euro 2008
Lexan Thermoclear sheet is being used for the roofs of three stadiums under construction for the Euro 2008 football championship. The glazing is used in part because of its ability to be easily formed into compact shapes. Engineers can achieve glass-like clarity, but with significantly less weight. Lexan Thermoclear sheet is an impact-resistant, multi-wall polycarbonate (PC) material. It features a proprietary surface treatment on one or both sides that provides resistance against degradation from UV radiation, while transmitting visible light very well. It withstands high winds, snow loads and storms. The multi-wall construction also provides thermal insulation.
Great for Grinding
Rollerblade will use Delrin acetal and Zytel nylon for frames that raise the bar on in-line sliding. New advanced skates require high-abrasion materials to execute a technique called grinding, which refers to sliding along the edge of a rail. The frame is made of acetal resin compounded with Kevlar aramid. "It is the first time that this recently developed material has been used for an in-line skate frame," said Lino Piva of Rollerblade's R&D group. "Delrin has an inherently low-friction surface that makes it ideal for grinding and other aggressive techniques. The tougher-than-steel Kevlar reinforcement adds abrasion-resistance for greater durability." The frame of the mid-range DT 4 is injection-molded from a nylon 66 reinforced with 33 percent glass fiber, which boosts tensile strength, stiffness and abrasion-resistance. In addition, it contains a lubricant, which lowers the friction coefficient to give better sliding action.
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Talk About Tough Specs
Mine apparatus must resist static build up and provide RFI shielding
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