International Journal of Applied Glass Science-Stickel and Nagarajan Vol.3,No.2,201 impossible d locais un it re that every filament is the same length and iformly and in the absence of a resin matrix to load transfer between the filaments this method yields low values with poor repeatability. For these reasons, ASTM D2343 impregnated strand testing is preferred. The tensile strength data in Fig. 5 was generated on 4000-filament rovings utilizing the same multi-com patible sizing, MCX21. Rovings were produced and tested during April 2011. Sample size was 30 or for each filament diameter. As shown, there is FiLament Dameter (n) tion in tensile strength on the order of 15% wl ter is increased from 9 to I' Fig. 5. Impregnated strand tensile strength verus flament In addition to higher strengths another reason fine high-performance fibers are preferred is for downstream The tex of a roving is its linear density in g/km processability in composite applications. These fibers Tex typically ranges from 300 to 4800 and is governed are significantly stiffer, up to 25%, relative to standard by the bushing design(the number of holes)and th reinforcing fibers. In composite processes like filament desired filament diameter. For example, the rovings later, rovings must used to generate the data in the previous section were pass through guide eyes and around tight radii en route produced on the same 4000-hole bushing. For 9 um to the composite part. Finer filaments will more readily filaments, a 675 tex roving strand is produced. When bend around these contact points whereas coarser fila- 17 um filaments are required, the winder speed is ments can break and fuzz reduced and the resultant bundle tex is 2400 Figure 5 shows impregnated strand tensile strength Clearly, a 2400 tex strand will provide significantly data, generated by ASTM D2343, for epoxy-impreg- more glass-on-the-part coverage for a given distance nated Owens STrand"S-glass when making (Owens Corning, Toledo, OH, USA)at different fila- rovings are often preferred for low to medium strength ment diameters. XStrand", developed for inc ndustrial applications where part manufacturing efficiency may applications, is part of a family of high-perfc rmance be the more important driver to the composite fabrica- reinforcements(HPR) with improved strength, stiffness, tor. In addition, fabricators may have physical limita and temperature stability versus conventional reinforce- tions in terms of shop floor or creel rack space, leading ments.Other products in the HPR line include Flite- them to prefer input rovings of higher tex. For this Strand, ShieldStrand", and WindStrand. Target reason, high-performance reinforcements like XStrand application areas are aerospace, defense/security, and S, are frequently offered as multi-end rovings: tensile ind energy, respectively strength can be preserved as a result of the fine filament The ASTM D2343: Standard Test Method for Ten- diameter and manufacturing efficiency maximized by sile Properties of Glass Fiber Strands, Yarns, and Rovings combining multiple ends Used in Reinforced Plastics method is used frequently as Tex consistency is important to ensure consistent an indicator of glass tensile performance. Single, pristine glass fiber content in a composite part. This is of particu filament tensile testing does not accurately represent lar significance in high-performance applications, such as how a glass will perform when bundled into a roving of aerospace components, which demand the highest several thousand-filaments. Unfortunately, rovings can- strength at the lowest weight. In defense and security not accurately be tested when un-impregnated with applic /ing correct, consistent tex in a rovin resin. A dry strand tensile testing procedure (ASTM ensures that weight and tensile strength are balanced D2256: Test Method for Tensile Properties of Yarns by the both the reinforcement fabric and the armor made Single-Strand Method) does exist. However, because Tex measurement is a standard quality controlIn addition to higher strengths another reason fine high-performance fibers are preferred is for downstream processability in composite applications. These fibers are significantly stiffer, up to 25%, relative to standard reinforcing fibers. In composite processes like filament winding, which will be discussed later, rovings must pass through guide eyes and around tight radii en route to the composite part. Finer filaments will more readily bend around these contact points whereas coarser fila￾ments can break and fuzz. Figure 5 shows impregnated strand tensile strength data, generated by ASTM D2343, for epoxy-impreg￾nated Owens Corning XStrand® S-glass rovings (Owens Corning, Toledo, OH, USA) at different fila￾ment diameters. XStrand®, developed for industrial applications, is part of a family of high-performance reinforcements (HPR) with improved strength, stiffness, and temperature stability versus conventional reinforce￾ments. Other products in the HPR line include Flite￾Strand®, ShieldStrand®, and WindStrand®. Target application areas are aerospace, defense/security, and wind energy, respectively. The ASTM D2343: Standard Test Method for Ten￾sile Properties of Glass Fiber Strands, Yarns, and Rovings Used in Reinforced Plastics method is used frequently as an indicator of glass tensile performance. Single, pristine filament tensile testing does not accurately represent how a glass will perform when bundled into a roving of several thousand-filaments. Unfortunately, rovings can￾not accurately be tested when un-impregnated with resin. A dry strand tensile testing procedure (ASTM D2256: Test Method for Tensile Properties of Yarns by the Single-Strand Method) does exist. However, because it is impossible to ensure that every filament is the same length and loads uniformly and in the absence of a resin matrix to facilitate load transfer between the filaments, this method yields low values with poor repeatability. For these reasons, ASTM D2343 impregnated strand testing is preferred. The tensile strength data in Fig. 5 was generated on 4000-filament rovings utilizing the same multi-com￾patible sizing, MCX21. Rovings were produced and tested during April 2011. Sample size was 30 or greater for each filament diameter. As shown, there is a reduc￾tion in tensile strength on the order of 15% when fila￾ment diameter is increased from 9 to 17 µm. Tex The tex of a roving is its linear density in g/km. Tex typically ranges from 300 to 4800 and is governed by the bushing design (the number of holes) and the desired filament diameter. For example, the rovings used to generate the data in the previous section were produced on the same 4000-hole bushing. For 9 µm filaments, a 675 tex roving strand is produced. When 17 µm filaments are required, the winder speed is reduced and the resultant bundle tex is 2400. Clearly, a 2400 tex strand will provide significantly more glass-on-the-part coverage for a given distance when making a composite laminate, so higher tex rovings are often preferred for low to medium strength applications where part manufacturing efficiency may be the more important driver to the composite fabrica￾tor. In addition, fabricators may have physical limita￾tions in terms of shop floor or creel rack space, leading them to prefer input rovings of higher tex. For this reason, high-performance reinforcements like XStrand® S, are frequently offered as multi-end rovings: tensile strength can be preserved as a result of the fine filament diameter and manufacturing efficiency maximized by combining multiple ends. Tex consistency is important to ensure consistent glass fiber content in a composite part. This is of particu￾lar significance in high-performance applications, such as aerospace components, which demand the highest strength at the lowest weight. In defense and security applications, having correct, consistent tex in a roving ensures that weight and tensile strength are balanced in both the reinforcement fabric and the armor made from it. Tex measurement is a standard quality control Fig. 5. Impregnated strand tensile strength versus filament diameter. 126 International Journal of Applied Glass Science—Stickel and Nagarajan Vol. 3, No. 2, 2012