amics.org/lAGS Glass Fiber-Reinforced Composites viscosity, affinity for the glass, and applicator physical Tex on Position 2 parameters, such as roll speed and material. This amount varies by product form. Chopped strands for making wet-formed mats generally have the least sizing, measured as loss on ignition (LOD), whereas rovings for spray-up or sheet molding compound have the most. 6 Typical LOI or strand solids values for high-perfor mance single- or multi-end rovings in the 0.5-1.0% range. LOI measurement is a standard quality control evaluation that is included on all Owens Corning certificates of analysis. Moisture is removed first to a 50a0snsa01300 ensure an accurate measure of solids. Moisture content is also reported on quality certificates and must not Fig. 6. Tex variation in Owens Corning Shields exceed 0.15% s rovings. The specific components used in a sizing are selected to give the glass fiber reinforcement compati- evaluation and is reported on all Owens Corning certifi- bility with a certain family of resins. Common resins cates of analysis. Figure 6 is a tex control chart from sev- for use in composites include polyester, vinyl ester, eral months of production of ShieldStrand S roving epoxy, phenolic, and polyurethane, plus a vast array of (Owens Corning). Target tex is 362, and lower and thermoplastic fiber with the corred upper control limits are 333 and 391 tex, respectively. is critical to composite mechanical performance and These values were determined in accordance with the durability. A fiber with an inappropriate sizing will not military detail specification for glass fiber-reinforced form an optimal bond with the resin and load will not composite armor, MIL-DTL 64154B, which requires tex be transferred efficiently amongst the load bearing variation to be within +8% fibers. Furthermore, these poorly bonded regions will weee tex is the most common measure of glass strand be the weak link in the system and failure may initiate ght used worldwide. In the United States, yield is within them once load is applied. Even if part failure also used as an indicator of strand weight. Yield is does not occur, the weak interphase will be susceptible reported in yards per pound (yd/Ib). Yield is inversely to microcracking, which allows ingress of environmen- proportional to tex, and can be calculated by dividing tal media and can accelerate corrosion 496055 by tex. Sizing and Resin Compatibility Iry aafter st h boll a glass fiber sizing is a water-based coating applied resin matrix in which it will be used. Sizings protect 2 the glass and improves processing both in fiber forming 50.6 and in composite manufacturing. Sizings are made up of four primary components: film formers, lubricants, coupling agents, and water. Other additives sometimes used in sizings include anti-statics, wetting agents, chopping aids, antioxidants, and pH modifiers. Sizings generally contain 0.05-10% solids, and the remaining balance is water. Sizings may also be nonaqueous, but these are not as common as water-based formulations he amount of active solids that ends up on the Fig. 7. ASTM D2344 short-beam shear testing of Strand S glass surface is related to the sizings solids content,evaluation and is reported on all Owens Corning certifi- cates of analysis. Figure 6 is a tex control chart from sev￾eral months of production of ShieldStrand® S roving (Owens Corning). Target tex is 362, and lower and upper control limits are 333 and 391 tex, respectively. These values were determined in accordance with the military detail specification for glass fiber-reinforced composite armor, MIL-DTL 64154B, which requires tex variation to be within ±8%. Tex is the most common measure of glass strand weight used worldwide. In the United States, yield is also used as an indicator of strand weight. Yield is reported in yards per pound (yd/lb). Yield is inversely proportional to tex, and can be calculated by dividing 496055 by tex. Sizing and Resin Compatibility A glass fiber sizing is a water-based coating applied during forming to give the glass compatibility with the resin matrix in which it will be used. Sizings protect the glass and improves processing both in fiber forming and in composite manufacturing. Sizings are made up of four primary components: film formers, lubricants, coupling agents, and water. Other additives sometimes used in sizings include anti-statics, wetting agents, chopping aids, antioxidants, and pH modifiers. Sizings generally contain 0.05–10% solids, and the remaining balance is water.5 Sizings may also be nonaqueous, but these are not as common as water-based formulations. The amount of active solids that ends up on the glass surface is related to the sizing’s solids content, viscosity, affinity for the glass, and applicator physical parameters, such as roll speed and material. This amount varies by product form. Chopped strands for making wet-formed mats generally have the least sizing, measured as loss on ignition (LOI), whereas rovings for spray-up or sheet molding compound have the most.6 Typical LOI or strand solids values for high-perfor￾mance single- or multi-end rovings in the 0.5–1.0% range. LOI measurement is a standard quality control evaluation that is included on all Owens Corning certificates of analysis. Moisture is removed first to ensure an accurate measure of solids. Moisture content is also reported on quality certificates and must not exceed 0.15%. The specific components used in a sizing are selected to give the glass fiber reinforcement compati￾bility with a certain family of resins. Common resins for use in composites include polyester, vinyl ester, epoxy, phenolic, and polyurethane, plus a vast array of thermoplastics. Selecting a fiber with the correct sizing is critical to composite mechanical performance and durability. A fiber with an inappropriate sizing will not form an optimal bond with the resin and load will not be transferred efficiently amongst the load bearing fibers. Furthermore, these poorly bonded regions will be the weak link in the system and failure may initiate within them once load is applied. Even if part failure does not occur, the weak interphase will be susceptible to microcracking, which allows ingress of environmen￾tal media and can accelerate corrosion.7 Fig. 6. Tex variation in Owens Corning ShieldStrand® S rovings.4 Fig. 7. ASTM D2344 short-beam shear testing of XStrand® S rovings in vinyl ester resin. www.ceramics.org/IJAGS Glass Fiber-Reinforced Composites 127