Aramid fiber-reinforced polymer-matrix

Short fiber reinforcement of TPEs has recently opened up a new era in the field of polymer technology. Vajrasthira et al. [22] studied the fiber-matrix interactions in short aramid fiber-reinforced thermoplastic polyurethane (TPU) composites. Campbell and Goettler [23] reported the reinforcement of TPE matrix by Santoweb fibers, whereas Akhtar et al. [24] reported the reinforcement of a TPE matrix by short silk fiber. The reinforcement of thermoplastic co-polyester and TPU by short aramid fiber was reported by Watson and Prances [25]. Roy and coworkers [26-28] studied the rheological, hysteresis, mechanical, and dynamic mechanical behavior of short carbon fiber-filled styrene-isoprene-styrene (SIS) block copolymers and TPEs derived from NR and high-density polyethylene (HOPE) blends. 

Composite In polymer technology a combination of a polymeric matrix and a reinforcing fiber with properties that the component materials do not have. The most common matrix resins are unsaturated thermosetting polyesters and epoxies, and reinforcing fibers are glass, carbon, and aramid fibers. The reinforcing fibers may be continuous or discontinuous. Some matrix resins are thermoplastics. 

Advanced polymer composites, which are high-performance materials consisting of a polymer matrix resin reinforced with fibers such as carbon, graphite, aramid, boron, or S-glass, have their market in aerospace. This is also expected to be the fastest growing sector of plastics sales, with growth projected at 22% a year. 

Aramid fibers are widely used as reinforcing fibers in high performance composites. One disadvantage is the poor adhesion to the matrix materials. This arises from the lack of functional groups in the polymer. To overcome the lack of adhesion, the fibers are treated by so-called finish formulations, which is essentially a surface treatment. 

Suppliers and commercial grades are shown in Table 13.6. Aramid fibers are used for uncountable other matrix polymers as reinforcing fibers. These types are not included in Table 13.6. Tradenames appearing in the references are shown in Table 13.7. 

Reinforced pol)nners are those to which fibers have been added that increase the physical properties—especially impact resistance and heat deflection temperatures. Glass fibers are the most common additions, but carbon, graphite, aramid, and boron fibers are also used. In a reinforced polymer, the resin matrix is the continuous phase, and the fiber reinforcement is the discontinuous phase. The function of the resin is to bond the fibers together to provide shape and form and to transfer stresses in the structure from the resin to the fiber. Only high-strength fibers with high modulus are used. Because of the increased stiffness resulting from the fiber... 

Description and general properties. Polymer matrix composites (PMCs) consist of a pol)oner matrix or resin reinforced with glass fibers and to a lesser extent carbon, boron and pol)r-aramide fibers. The resin systems used to manufacture advanced composites are of two basic types thermosets and thermoplastics (see Chapter 11). Thermosetting resins predominate today, while thermoplastics have only a minor role in advanced-composite manufacture. Thermoset resins require the addition of a curing agent or hardener and impregnation onto... 

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. 

The use of reinforcing fillers and fibers in polymers to improve their mechanical properties is commonly encountered in polymer technology. Conventional fibers such as carbon fibers, glass fibers, gel-spun polyethylene fibers, and aramids are routinely used in composites of a range of different polymers (Chronakis 2005). The improvement in modulus and strength achieved by using even low levels of a reinforcing fiber in a composite is impressive. Some of this improvement is due to the properties at the fiber/matrix interface and therefore dependent on the surface area of the... 

For a wide range of apphcations, composites reinforced with continuous fibers are the most efficient structural materials at low to moderate temperatures. Consequently, we focus on them. Table 5.3 presents room-temperature mechanical properties of unidirectional polymer matrix composites reinforced with key fibers E-glass, aramid, boron, standard modulus (SM) PAN (polyacrylonitrile) carbon, intermediate modulus (IM) PAN carbon, ultrahigh modulus (UHM) PAN carbon, ultrahigh modulus (UHM) pitch carbon, and ul-trahigh thermal conductivity (UHK) pitch carbon. The fiber volume fraction is 60 percent, a typical value. 

Polymer-Matrix Polymer-matrix composites are the most common they may be reinforced with glass. Composites carbon, and aramid fibers. 

There are many fibers of S3mthetic origin, most of them spun or extrusion-drawn semicrystalline polymers (e.g., polyolefins, polyamides, polyesters), which are not used as fillers for polymers. The main reason is that, for a material to play a potential reinforcement role as a filler for polymer, large differences in certain key properties must exist between the filler and the polymer matrix. It follows that only three types (or classes) of fibrous products can be considered as valid short synthetic fibers candidates for polymer reinforcement glass fibers, carbon fibers and aramid fibers. 

C. Vajrasthira, T. Amomsakchai, S. B.-Limcharoen. Fiber-matrix interactions in aramid-short-fiber-reinforced thermoplastic polyurethane composites.. Appl. Polym. Sci., 87,1059-1067,2003. 

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