《纺织复合材料》课程参考文献（Fiber-Reinforced Composites，THIRD EDITION）02 Materials

1.60 1.20 0.80 0.40 0.00a 0.00 0.02 0.04 0.06 Strain FIGURE 2.8 Tensile stress-strain diagram of an untwisted E-glass fiber bundle contain- ing 3000 filaments. of the fiber is determined from the compressive strain at the fiber surface. In general,compressive strength of fibers is lower than their tensile strength, as is shown in Table 2.2.The compressive strength of boron fibers is higher than that of carbon and glass fibers.All organic fibers have low compressive TABLE 2.2 Compressive Strength of a Few Selected Reinforcing Fibers Tensile Compressive Fiber Strength"(GPa) Strength(GPa) E-glass fiber 3.4 4.2 T-300 carbon fiber 3.2 2.7-3.2 AS 4 carbon fiber 3.6 2.7 GY-70 carbon fiber 1.86 1.06 P100 carbon fiber 2.2 0.5 Kevlar 49 fiber 3.5 0.35-0.45 Boron 3.5 5 Source:Adapted from Kozey,V.V.,Jiang.H.,Mehta,V.R.,and Kumar,S.. J.Mater..Res.,10.1044,1995. a In the longitudinal direction. 2007 by Taylor Francis Group.LLC

of the fiber is determined from the compressive strain at the fiber surface. In general, compressive strength of fibers is lower than their tensile strength, as is shown in Table 2.2. The compressive strength of boron fibers is higher than that of carbon and glass fibers. All organic fibers have low compressive 0.00 0.02 0.04 0.06 Strain 0.00 0.40 0.80 1.20 1.60 Stress (GPa) FIGURE 2.8 Tensile stress–strain diagram of an untwisted E-glass fiber bundle contain￾ing 3000 filaments. TABLE 2.2 Compressive Strength of a Few Selected Reinforcing Fibers Fiber Tensile Strengtha (GPa) Compressive Strengtha (GPa) E-glass fiber 3.4 4.2 T-300 carbon fiber 3.2 2.7–3.2 AS 4 carbon fiber 3.6 2.7 GY-70 carbon fiber 1.86 1.06 P100 carbon fiber 2.2 0.5 Kevlar 49 fiber 3.5 0.35–0.45 Boron 3.5 5 Source: Adapted from Kozey, V.V., Jiang, H., Mehta, V.R., and Kumar, S., J. Mater. Res., 10, 1044, 1995. a In the longitudinal direction.
2007 by Taylor & Francis Group, LLC

strength.This includes Kevlar 49,which has a compressive strength almost 10 times lower than its tensile strength. 2.1.1 GLASS FIBERS Glass fibers are the most common of all reinforcing fibers for polymeric matrix composites (PMC).The principal advantages of glass fibers are low cost,high tensile strength,high chemical resistance,and excellent insulating properties. The disadvantages are relatively low tensile modulus and high density (among the commercial fibers),sensitivity to abrasion during handling (which fre- quently decreases its tensile strength),relatively low fatigue resistance,and high hardness(which causes excessive wear on molding dies and cutting tools). The two types of glass fibers commonly used in the fiber-reinforced plastics (FRP)industry are E-glass and S-glass.Another type,known as C-glass,is used in chemical applications requiring greater corrosion resistance to acids than is provided by E-glass.E-glass has the lowest cost of all commercially available reinforcing fibers,which is the reason for its widespread use in the FRP industry.S-glass,originally developed for aircraft components and missile casings,has the highest tensile strength among all fibers in use.However, the compositional difference and higher manufacturing cost make it more expensive than E-glass.A lower cost version of S-glass,called S-2-glass,is also available.Although S-2-glass is manufactured with less-stringent nonmili- tary specifications,its tensile strength and modulus are similar to those of S-glass. The chemical compositions of E-and S-glass fibers are shown in Table 2.3. As in common soda-lime glass (window and container glasses),the principal ingredient in all glass fibers is silica(SiO2).Other oxides,such as B2O3 and Al2O3,are added to modify the network structure of SiOz as well as to improve its workability.Unlike soda-lime glass,the Na2O and K2O content in E-and S-glass fibers is quite low,which gives them a better corrosion resistance to water as well as higher surface resistivity.The internal structure of glass fibers is a three-dimensional,long network of silicon,oxygen,and other atoms arranged in a random fashion.Thus,glass fibers are amorphous (noncrystalline)and isotropic (equal properties in all directions). TABLE 2.3 Typical Compositions of Glass Fibers (in wt%) Type SiO2 Al203 Cao MgO B203 Na2O E-glass 54.5 14.5 17 4.5 8.5 0.5 S-glass 64 26 10 2007 by Taylor Francis Group,LLC

strength. This includes Kevlar 49, which has a compressive strength almost 10 times lower than its tensile strength. 2.1.1 GLASS FIBERS Glass fibers are the most common of all reinforcing fibers for polymeric matrix composites (PMC). The principal advantages of glass fibers are low cost, high tensile strength, high chemical resistance, and excellent insulating properties. The disadvantages are relatively low tensile modulus and high density (among the commercial fibers), sensitivity to abrasion during handling (which fre￾quently decreases its tensile strength), relatively low fatigue resistance, and high hardness (which causes excessive wear on molding dies and cutting tools). The two types of glass fibers commonly used in the fiber-reinforced plastics (FRP) industry are E-glass and S-glass. Another type, known as C-glass, is used in chemical applications requiring greater corrosion resistance to acids than is provided by E-glass. E-glass has the lowest cost of all commercially available reinforcing fibers, which is the reason for its widespread use in the FRP industry. S-glass, originally developed for aircraft components and missile casings, has the highest tensile strength among all fibers in use. However, the compositional difference and higher manufacturing cost make it more expensive than E-glass. A lower cost version of S-glass, called S-2-glass, is also available. Although S-2-glass is manufactured with less-stringent nonmili￾tary specifications, its tensile strength and modulus are similar to those of S-glass. The chemical compositions of E- and S-glass fibers are shown in Table 2.3. As in common soda-lime glass (window and container glasses), the principal ingredient in all glass fibers is silica (SiO2). Other oxides, such as B2O3 and Al2O3, are added to modify the network structure of SiO2 as well as to improve its workability. Unlike soda-lime glass, the Na2O and K2O content in E- and S-glass fibers is quite low, which gives them a better corrosion resistance to water as well as higher surface resistivity. The internal structure of glass fibers is a three-dimensional, long network of silicon, oxygen, and other atoms arranged in a random fashion. Thus, glass fibers are amorphous (noncrystalline) and isotropic (equal properties in all directions). TABLE 2.3 Typical Compositions of Glass Fibers (in wt%) Type SiO2 Al2O3 CaO MgO B2O3 Na2O E-glass 54.5 14.5 17 4.5 8.5 0.5 S-glass 64 26 — 10 — —
2007 by Taylor & Francis Group, LLC

Raw materials Clay Hopper Binder formulation Glass Platinum batch bushings (electrically Tank heated and (melting refining) electncallv ⊙①③①①⑦ ■0 controlled) Screw feeder Filaments Automatic controls Inspection Binder and applicator weighing Strand Mixer High speed wnder Continuous strand forming packages Inspection and nachine Chopped strand Creel Roving mat Loom Continuous Woven Creels roving roving Chopping machine Chopped strand Finished E-glass products Calcium i 54.0% 20写 14.0 002... ⊙⊙ Calcium fluoride.... 1.0 Packaging Magnesia.. 0.5 and palletizing Total minor oxides... 1.0 Shipping Bare glass composition...100.0% Plus binder.... 0.5%-2% FIGURE 2.9 Flow diagram in glass fiber manufacturing.(Courtesy of PPG Industries. With permission.) The manufacturing process for glass fibers is depicted in the flow diagram in Figure 2.9.Various ingredients in the glass formulation are first dry-mixed and melted in a refractory furnace at about 1370C.The molten glass is exuded 2007 by Taylor Francis Group.LLC

The manufacturing process for glass fibers is depicted in the flow diagram in Figure 2.9. Various ingredients in the glass formulation are first dry-mixed and melted in a refractory furnace at about 13708C. The molten glass is exuded Raw materials Limestone Clay Coal Automatic controls Fluorspar Hopper Tank (melting & refining) Binder formulation Platinum bushings (electrically heated and electrically controlled) Mixer Screw feeder Continuous strand forming packages Hopper Creels Loom Woven roving Mat machine Roving winder Chopped strand mat Creels Chopping machine Continuous roving Chopped strand Finished E-glass products Silica.... 54.0% 20.5 14.0 8.0 1.0 1.0 0.5 100.0% 0.5%–2% 1.0 Calcium oxide.... Alumina.... Boron oxide.... Soda.... Calcium fluoride.... Magnesia.... Total minor oxides.... Bare glass composition.... Plus binder.... Inspection and weighing Shipping Trucks Packaging and palletizing Oven heat treating Glass batch Filaments Strand High speed winder Inspection and weighing Binder applicator Silica sand Boric acid FIGURE 2.9 Flow diagram in glass fiber manufacturing. (Courtesy of PPG Industries. With permission.)
2007 by Taylor & Francis Group, LLC

through a number of orifices contained in a platinum bushing and rapidly drawn into filaments of ~10 um in diameter.A protective coating (size)is then applied on individual filaments before they are gathered together into a strand and wound on a drum.The coating or size is a mixture of lubricants (which prevent abrasion between the filaments),antistatic agents(which reduce static friction between the filaments),and a binder (which packs the filaments together into a strand).It may also contain small percentages of a coupling agent that promotes adhesion between fibers and the specific polymer matrix for which it is formulated. The basic commercial form of continuous glass fibers is a strand,which is a collection of parallel filaments numbering 204 or more.Other common forms of glass fibers are illustrated in Figure 2.10.A roving is a group of untwisted parallel strands (also called ends)wound on a cylindrical forming package. Rovings are used in continuous molding operations,such as filament winding and pultrusion.They can also be preimpregnated with a thin layer of polymeric resin matrix to form prepregs.Prepregs are subsequently cut into required dimensions,stacked,and cured into the final shape in batch molding oper- ations,such as compression molding and hand layup molding. Chopped strands are produced by cutting continuous strands into short lengths.The ability of the individual filaments to hold together during or after the chopping process depends largely on the type and amount of the size applied during fiber manufacturing operation.Strands of high integrity are called "hard"and those that separate more readily are called "soft." Chopped strands ranging in length from 3.2 to 12.7 mm(0.125-0.5 in.)are used in injection-molding operations.Longer strands,up to 50.8 mm(2 in.)in length,are mixed with a resinous binder and spread in a two-dimensional random fashion to form chopped strand mats(CSMs).These mats are used mostly for hand layup moldings and provide nearly equal properties in all directions in the plane of the structure.Milled glass fibers are produced by grinding continuous strands in a hammer mill into lengths ranging from 0.79 to 3.2 mm (0.031-0.125 in.).They are primarily used as a filler in the plastics industry and do not possess any significant reinforcement value. Glass fibers are also available in woven form,such as woven roving or woven cloth.Woven roving is a coarse drapable fabric in which continuous rovings are woven in two mutually perpendicular directions.Woven cloth is weaved using twisted continuous strands,called yarns.Both woven roving and cloth provide bidirectional properties that depend on the style of weaving as well as relative fiber counts in the length (warp)and crosswise (fill)directions(See Appendix A.1).A layer of woven roving is sometimes bonded with a layer of CSM to produce a woven roving mat.All of these forms of glass fibers are suitable for hand layup molding and liquid composite molding. The average tensile strength of freshly drawn glass fibers may exceed 3.45 GPa (500,000 psi).However,surface damage (flaws)produced by abrasion, either by rubbing against each other or by contact with the processing 2007 by Taylor Francis Group,LLC

through a number of orifices contained in a platinum bushing and rapidly drawn into filaments of ~10 mm in diameter. A protective coating (size) is then applied on individual filaments before they are gathered together into a strand and wound on a drum. The coating or size is a mixture of lubricants (which prevent abrasion between the filaments), antistatic agents (which reduce static friction between the filaments), and a binder (which packs the filaments together into a strand). It may also contain small percentages of a coupling agent that promotes adhesion between fibers and the specific polymer matrix for which it is formulated. The basic commercial form of continuous glass fibers is a strand, which is a collection of parallel filaments numbering 204 or more. Other common forms of glass fibers are illustrated in Figure 2.10. A roving is a group of untwisted parallel strands (also called ends) wound on a cylindrical forming package. Rovings are used in continuous molding operations, such as filament winding and pultrusion. They can also be preimpregnated with a thin layer of polymeric resin matrix to form prepregs. Prepregs are subsequently cut into required dimensions, stacked, and cured into the final shape in batch molding oper￾ations, such as compression molding and hand layup molding. Chopped strands are produced by cutting continuous strands into short lengths. The ability of the individual filaments to hold together during or after the chopping process depends largely on the type and amount of the size applied during fiber manufacturing operation. Strands of high integrity are called ‘‘hard’’ and those that separate more readily are called ‘‘soft.’’ Chopped strands ranging in length from 3.2 to 12.7 mm (0.125–0.5 in.) are used in injection-molding operations. Longer strands, up to 50.8 mm (2 in.) in length, are mixed with a resinous binder and spread in a two-dimensional random fashion to form chopped strand mats (CSMs). These mats are used mostly for hand layup moldings and provide nearly equal properties in all directions in the plane of the structure. Milled glass fibers are produced by grinding continuous strands in a hammer mill into lengths ranging from 0.79 to 3.2 mm (0.031–0.125 in.). They are primarily used as a filler in the plastics industry and do not possess any significant reinforcement value. Glass fibers are also available in woven form, such as woven roving or woven cloth. Woven roving is a coarse drapable fabric in which continuous rovings are woven in two mutually perpendicular directions. Woven cloth is weaved using twisted continuous strands, called yarns. Both woven roving and cloth provide bidirectional properties that depend on the style of weaving as well as relative fiber counts in the length (warp) and crosswise ( fill) directions (See Appendix A.1). A layer of woven roving is sometimes bonded with a layer of CSM to produce a woven roving mat. All of these forms of glass fibers are suitable for hand layup molding and liquid composite molding. The average tensile strength of freshly drawn glass fibers may exceed 3.45 GPa (500,000 psi). However, surface damage (flaws) produced by abrasion, either by rubbing against each other or by contact with the processing
2007 by Taylor & Francis Group, LLC

Filament Strand(a bundle of filaments) Continuous strand roving Woven roving Chopped strands Chopped strand mat Woven roving mat FIGURE 2.10 Common forms of glass fibers.(Courtesy of Owens Corning Fiberglas Corporation.) 2007 by Taylor&Francis Group.LLC

Strand (a bundle of filaments) Woven roving Filament Continuous strand roving Woven roving mat Chopped strands Chopped strand mat FIGURE 2.10 Common forms of glass fibers. (Courtesy of Owens Corning Fiberglas Corporation.)
2007 by Taylor & Francis Group, LLC