Aramid reinforcement

Composite materials, such as glass, carbon and aramid reinforced plastics, are principally used for their mechanical rigidity and strength. The most significant degradation mechanisms are therefore also mechanical or have mechanical consequences. Even when... 

Several materials combinations were examined and it was determined that fabrics made from fibers with expansions significantly lower than that of conventional E-glass have to be used to make boards that have the desired thermal expansion characteristics. Aramid reinforced laminates appear to be particularly useful in this application and their thermal expansion characteristics were studied using several experimental techniques and using a computer model to study the effect of resin content, resin modulus and resin Tg on these materials. 

Non-woven Aramid Reinforcements Controlled Thermal Expansion Prepreg and Laminate for Printed-Wiring Boards, Nepcon West, New Substrates, Sessions TS-01 and TS-00 (Mar. 27, 1995). 

Epoxy prepreg tapes, with carbon, glass, or aramid reinforcement, have been used for production of tooling. They require an initial cure at 20-80C (68-176F) and offer a maximum service temperature of at least 200C (392F) in air. A low-temperature cure means very low residual stress levels. Low-temperature master models can be used directly without... 

Many thermoplastic polymers are reinforced with fibers. Reinforcement is nsed to improve physical properties— specifically heat deflection temperature. Glass fibers are the most commonly used reinforcing material. The wear resistance and abrasion resistance of the thermoplastics pol)nners are improved by the use of aramid reinforcing. Although fibers can be used with any thermoplastics polymer, the following are the most important ... 

Aramid reinforcement is also available as paper and sold under tradenames of Nomex by DuPont and TP Technora from Teijin America. Aramid paper is used in circuit boards to improve crack resistance and to... 

Manual transmissions use a clutch facing made from a resin impregnated wound structure composed of staple yarns, p-Aramid in yam form provides more strength and durability than a pulp-based paper sheet in this more demanding application. Although aramid reinforced facings have sufficient thermal stability for this application, compositions based on glass and metal fibers dominate this market. 

Use of p-aramids in molded or extruded thermoplastic parts offers performance advantages over neat resins or glass-reinforced resins. Aramid reinforced parts exhibit improved mechanical and thermal properties and superior wear resistance with no abrasion to the counter surface. Because the fiber is not abrasive, there is less damage to processing equipment and machining of parts is simplified. 

Small deviations from the intended fibre orientation within a nominally unidirectional ply can reduce the mechanical strength and stiffness of continuous fibre laminates considerably, especially with aramid reinforcement. Wisnom [6] has investigated the reduction in strength caused by misalignment of unidirectional carbon fibres in XAS/914 carbon/epoxy... 

The Japanese are also active in the application of fibre reinforced plastics to reinforced concrete structures to improve their earthquake resistance. Kabatake et al [22] reported on 14 cases in which chimneys were retrofitted with fibre reinforced plastics and were judged by the Building Disaster Prevention Association of Japan to be one of the most effective retrofitting methods. In this retrofitting programme, carbon fibre tapes impregnated with an epoxy resin were wound and adhered to the exterior of the chimney. Sumida et al [ 23] have described experiences with aramid reinforced... 

The functional properties of the aramid-reinforced composites have been reviewed [9]. These depend primarily on the properhes of the aramid reinforcing hbers, since the frachon of the hber conshtuent in the reinforced composites is quite high. The properhes of the aramid fibers can be tailored by their chemical composihon and manufacturing condihons. 

Denchev Z, Dencheva NV. Manufacturing and properties of aramid-reinforced composites. In Bhattacharyya D, Fakirov S, editors. Synthetic polymer-polymer composites. Miinchen Hanser 2012. p. 251-80. ISBN 9781569905104 [chapter 8]. 

The functional properties of the aramid-reinforced polymer composites depend primarily on the properties of the aramid reinforcing fibers, since the fraction of the fiber constituent in FRP is quite high, usually well above 30% by volume. The properties of the aramid fibers, in turn, depend on their chemical composition and manufacturing conditions both of these determine the fibers physical structure and mechanical properties. The chapter will focus on these issues. Some specific problems related to the fiber-matrix interaction in aramid-containing FRP will also be addressed. 

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