Kevlar temperature

V-belts are the most commonly used belt in industrial power transmission applications. In addition to V-belts, there are round belts (e.g., O-rings) and flat belts, which are often reinforced with steel or Kevlar. Round belts are generally used in light-duty applications while reinforced flat belts are used in high-temperature applications such as automobiles. 

Fabric Cleaning. The Kevlar-29 woven fabric was obtained through the courtesy of Naval Weapons Center. A special pair of serrated shears was purchased from Technology Associates for cutting the fabric. The fabric (2.5 cm x 18 cm) was placed in a Soxhlet thimble and extracted by 100 ml of chloroform for 24 hours to remove its surface lubricants (about 3% by weight). The fabric was then removed from the thimble and agitated in a 20 ml of hot distilled DMAc for 15 minutes, before it was placed back into the thimble and extracted for another 8 hours using fresh chloroform solvent. The solvent-cleaned fabric was dried in a vacuo at room temperature. 

Photolysis Procedure. The solvent-cleaned Kevlar-29 fabric swatch (2.5 cm x 18 cm) was placed around the outside quartz tube inside the photolysis chamber, which was subsequently evacuated, before - - 02 (99%) was introduced to 0.2 atm. The photolysis chamber was preheated to the specified photooxidation temperature, before the Hg-Xe lamp was turned on. The temperature, which was held constant in the chamber by adjusting the air flow around the lamp, was monitored by a thermocouple placed next to the fabric sample inside the chamber. After the photooxidation had continued for the specified... 

This new and novel method to study the photochemical degradation of Kevlar-29 fabric in air divides into four steps (1) fabric cleaning, (2) photolysis at specified temperature and time in 0.2 atm - 02, (3) preparation of the degraded (DMAc-soluble) sample surface for decarboxylation at 25° and 196°C in the concentrated sulfuric acid, and (4) the total carbon dioxide analyses by gas chromatography and the isotopic carbon dioxide ( °C02 and 48co2) ratios by GC-mass spectrometer. 

Advanced materials can be used in extreme conditions, e.g., high temperatures (> 200°C), severe chemical environments (e.g., polytetrafluoroethylene (PTFE) with concentrated H2SO4). They are often used as a critical component in a workpiece and are frequently reinforced with glass, carbon or aramid (e.g., Kevlar ) fibres. 

Polymers containing no secondary or tertiary C-H or are aromatic (PEEK or Kevlar ) or perfluorpolymers (PTFE) are generally resistant to oxidation and require no anti-oxidant additives. However, the high temperature necessary for curing or fabrication of high performance polymers (especially for aerospace applications) can cause oxidation. For this reason, these materials are often prepared and fabricated under a nitrogen atmosphere. 

Fig. 7,2. Fracture toughness, R, of Kevlar 49-epoxy matrix composites (a) under varying strain rates in three-point bending and (b) at different temperatures under impact loading (O) uncoated fibers (0)41%, (Q) 63% and ( ) 100% Estapol coated fibers (A) silicone vacuum fluid (SVF) coated fibers. After Mai...

Mechanical properties of carbon fiber-epoxy matrix and Kevlar fiber-epoxy matrix composites with and without PVAL coaling at room temperature". 

Commercial applications have been identified primarily in the electronics industry where requirements for dimensional stability, mechanical properties, and high temperature resistance make these systems attractive in advanced circuit board technology. Other commercial applications include high temperature membranes and filters where these materials offer performance improvements over glass, Kevlar, and graphite composites. Industrial development of these types of materials will most likely be dependent on monomer cost and advances in various product properties requirements. 

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