A New High-temperature Resistance Polymer System

Recently, CRG (Cornerstone Research Group Inc.) has introduced a completely new polymer system that has demonstrated high-temperature resistance like a polyimide (service temp. 300-450°C) as well as ultra-low flammability, heat release and smoke release, yet is similar to two-part epoxy resins in processability and cost. Moreover, these systems cure to a thermoplastic state at temperatures below 110 °C, cross-link to a thermoset at temperatures above 110 °C and can be converted to an almost pure carbon material at higher temperatures.

MG Resins can be combined with fiber reinforcement using conventional processing techniques, offering the potential for low-cost, high temperature structural composites. Water is the only volatile generated, thus processing does require management of porosity, similar to condensation-reaction polymers like phenolics and polyimides. However, initial testing of MG Resin composites shows an order of magnitude lower heat release vs. phenolics.

MG 1000 test samples were made using glass and carbon fiber fabrics and carbon fiber felt using vacuum infusion and hand layup. Carbon fiber panels and carbon felt panels were autoclave cured at 200-250°C and 100 psi with a 2-hr post-cure at either 250°C or 315°C. Glass fiber specimens were oven-cured at 250°C. MG 3000 test samples were prepared in a similar manner. Syntactic test panels were also produced using milled fiber and resin in an effort to explore low-density materials for potential use in ablative and thermal protection systems (TPS) for spacecraft. Overall, the resulting composites processed well, though further optimization of polymer formulations, processing and cure cycles is ongoing to reduce void content. Programs are also in progress to fully characterize the MG 1000 and MG 3000 resin systems and composite laminates.

E-glass Fiber Showed in IBEX 2015

International Boatbuilders’ Exhibition & Conference (IBEX) 2015 was held Sep. 14-16 in Louisville, KY. The show drew 4,700 attendees and 545 exhibitors, 110 of which were new to IBEX

COMPOSITE FABRICS OF AMERICA showed samples of new hybrid fabrics that not only offer toughness, but also truly unique aesthetics. The 2x2 twill at left features 3K carbon, aramid and E-glass fibers in a 7.3 oz (248 gsm) areal weight fabric while the 3K carbon fiber/Innegra S houndstooth at right is a 218 gsm fabric.

MAHOGANY COMPANY celebrates its 75th anniversary this year and highlighted its prefabricated sandwich panels made with a variety of skin materials, including carbon fiber, carbon fiber/E-glass hybrids and KEVLAR aramid fiber/E-glass hybrids. The panels can be cut to net-shape and kitted for boatbuilder use as doors, bulkheads, floors/soles and more. Panel skins most often feature quadraxial and biaxial noncrimp fabrics, but the company’s 4’ x 8’ and 5’ x 10’ presses are amenable to a wide range of materials, depending on customers’ needs for weight and labor savings. Renowned builder Viking Yachts is using lightweight composite panels from Mahogany in all of its models to reduce weight and boost performance.

Mahogany Company’s prefabricated composite sandwich panels with carbon fiber and hybrid skins (left).  Viking Yachts uses a variety of Mahogany composite panels, for example in the Viking 92 bulkheads (right), to reduce weight and boost performance.

Glass Fiber in Composite Material

SICHUAN SINCERE & LONG-TERM COMPLEX MATERIALS CO.,LTD. is a modern high-tech corporation which is professionally engaging in the glass fiber products exploring, designing,producing and application. The structural properties of composite materials are derived primarily from the fiber reinforcement. In a composite, the fiber, held in place by the matrix resin, contributes high tensile strength, enhancing performance properties in the final part, such as strength and stiffness, while minimizing finished component weight.

Fiber properties are determined by the fiber manufacturing process, the fiber's chemical constituents and the coating chemistries that adapt the fiber for adhesion to the resin matrix and protect it during further processing.

Glass fibers

The vast majority of all fibers used in the composites industry are glass. Glass fibers are the oldest and, by far, the most common reinforcement used in most end-market applications (the aerospace industry is a significant exception) to replace heavier metal parts. Glass fiber weighs more than the second most common reinforcement, carbon fiber, and is not as stiff, but is more impact-resistant and has a greater elongation-to-break (that is, it elongates to a greater degree before it breaks). Depending upon the glass type, filament diameter, coating chemistry and fiber form, a wide range of properties and performance levels can be achieved.

During glass fiber production, raw materials are melted and drawn into delicate and highly abrasive filaments, ranging in diameter from 3.5 to 24 μm. Silica sand is the primary raw ingredient, typically accounting for more than 50% of glass fiber weight. Metal oxides and other ingredients can be added to the silica and processing methods can be varied to customize the fibers for particular applications.

Glass filaments are supplied in bundles called strands. A strand is a collection of continuous glass filaments. Roving generally refers to a bundle of untwisted strands, packaged, like thread, on a large spool. Single-end roving consists of strands that made up of continuous, multiple glass filaments that run the length of the strand. Multiple-end roving contains lengthy but not entirely continuous strands, which are added or dropped in a staggered arrangement during the spooling process. Yarn is a collection of strands that are twisted together.

Different Glass Fibers in Composites

There are different kinds of glass used in composites.  Such as E-glass, S-glass, C-glass. Electrical or E-glass fiber, so named because its chemical composition makes it an excellent electrical insulator, is particularly well suited to applications in which radio-signal transparency is desired, such as aircraft radomes, antennae and printed circuit boards. However, it is also the most economical glass fiber for composites, offering sufficient strength to meet the performance requirements in many applications at a relatively low cost. It has become the standard form of fiberglass, accounting for more than 90% of all glass-fiber reinforcements. At least 50% of E-glass fibers are made up of silica oxide; the balance comprises oxides of aluminum, boron, calcium and/or other compounds, including limestone, fluorspar, boric acid and clay.

When greater strength is desired, high-strength glass, first developed for military applications in the 1960s, is an option. Known by several names — S-glass in the US, R-glass in Europe and T-glass in Japan, its strand tensile strength is approximately 700 ksi, with a tensile modulus of up to 14 Msi. S-glass has appreciably greater silica oxide, aluminum oxide and magnesium oxide content than E-glass and is 40-70% stronger than E-glass.

E-glass and S-glass lose up to half of their tensile strength as temperatures increase from ambient to 540°C, although both fiber types still exhibit generally good strength in this elevated temperature range. Manufacturers are continually tweaking S-glass formulations. A new S-3 UHM (for ultra-high modulus) Glass, for example, was introduced by AGY (Aiken, SC, US) in 2012. The new S-3 glass has a tensile modulus of 14,359 — higher than S-glass and 40% higher than E-glass — due to improved fiber manufacturing as well as proprietary additives and melt chemistry. 

Although glass fibers have relatively high chemical resistance, they can be eroded by leaching action when exposed to water. For example, an E-glass filament 10μ in diameter typically loses 0.7% of its weight when placed in hot water for 24 hours. The erosion rate, however, slows significantly becuase the leached glass forms a protective barrier on the outside of the filament; only 0.9% total weight loss occurs after seven days of exposure. To slow erosion, moisture-resistant sizings, such as silane compounds, are applied during fiber manufacturing.

Corrosion-resistant glass, known as C-glass or E-CR glass, stands up better to an acid solution than does E-glass. However, E-glass and S-glass are much more resistant to sodium carbonate solution (a base) than is C-glass. A boron-free glass fiber, with performance and price comparable to E-glass, demonstrates greater corrosion resistance in acidic environments (similar to that of E-CR glass), higher elastic modulus and better performance in high temperatures than does E-glass. In addition, taking boron out of the manufacturing process produces fewer environmental impacts, a decided advantage.

Fiber Reinforce Composites Material (3)

Woven roving is mad of E glass fiber with plain weave. It is manily used in hand lay-up and compression molding FRP production. The typical products include boats, storage tanks, large sheets and panels, furniture, etc. It is relatively thick and used for heavy reinforcement, especially in hand layup operations and tooling applications. Due to its relatively coarse weave, woven roving wets out quickly and is relatively inexpensive. Exceptionally fine woven fiberglass fabrics, however, can be produced for applications such as reinforced printed circuit boards.

Hybrid fabrics can be constructed with varying fiber types, strand compositions and fabric types. For example, high-strength strands of S-glass or small-diameter filaments may be used in the warp direction, while less-costly strands compose the fill. A hybrid also can be created by stitching woven fabric and nonwoven chopped strand mat together.

Multiaxials are nonwoven fabrics made with unidirectional fiber layers stacked in different orientations and held together by through-the-thickness stitching, knitting or a chemical binder. The proportion of yarn in any direction can be selected at will. In multiaxial fabrics, the fiber crimp associated with woven fabrics is avoided because the fibers lie on top of each other, rather than crossing over and under. This makes better use of the fibers inherent strength and creates a fabric that is more pliable than a woven fabric of similar weight. Super-heavyweight nonwovens are available (up to 200 oz/yd²) and can significantly reduce the number of plies required for a layup, making fabrication more cost-effective, especially for large industrial structures. High interest in noncrimp multiaxials has spurred considerable growth in this reinforcement category.

Fiberglass Weaving Fabric

Our Fiberglass weaving fabric including E-glass Chopped strand mat, fiberglass woven roving, fiberglass stitched mat, combo mat etc.

Fiberglass Mats are nonwoven fabrics made from fibers that are held together by a chemical binder. They come in two distinct forms: chopped and continuous strand. Chopped strand mats contain randomly distributed fibers cut to lengths that typically range from 38 mm to 63.5 mm. Continuous-strand mat is formed from swirls of continuous fiber strands. Because their fibers are randomly oriented, mats are isotropic — they possess equal strength in all directions. Chopped-strand mats provide low-cost reinforcement primarily in hand layup, continuous laminating and some closed molding applications. Inherently stronger continuous-strand mat is used primarily in compression molding, resin transfer molding and pultrusion applications and in the fabrication of preforms and stampable thermoplastics. Certain continuous-strand mats used for pultrusion and needled mats used for sheet molding eliminate the need for creel storage and chopping.

Woven fabrics are made on looms in a variety of weights, weaves and widths. Wovens are bidirectional, providing good strength in the directions of yarn or roving axial orientation (0º/90º), and they facilitate fast composite fabrication. However, the tensile strength of woven fabrics is compromised to some degree because fibers are crimped as they pass over and under one another during the weaving process. Under tensile loading, these fibers tend to straighten, causing stress within the matrix system.

Several different types of weaving are used for bidirectional fabrics. In aplain weave, each fill yarn (i.e., yarn oriented at right angles to the fabric length) alternately crosses over and under each warp yarn (the lengthwise yarn). Other weaves, such as harness, satin and basketweave, allow the yarn or roving to cross over and under multiple warp fibers (e.g., over two, under two). These weaves tend to be more drapable than plain weaves.

Fiber Reinforce Composites Material (1)

Depending on different applications, glass fibers used to reinforce composites are supplied directly by fiber manufacturers and indirectly by converters in a number of different forms.

Roving is the simplest and most common form of glass fiber. It can be chopped, woven or otherwise processed to create secondary fiber forms for composite manufacturing, such as chopped strand mats, woven fabrics, braids, knitted fabrics and hybrid fabrics. Rovings are supplied by weight, with a specified filament diameter. The term yield is commonly used to indicate the number of yards in each pound of glass fiber rovings. Similarly, tow is the basic form of carbon fiber. Typical aerospace-grade tow size ranges from 1K to 24K (K = 1,000, so 12K indicates that the tow contains 12,000 carbon filaments). PAN- and pitch-based 12K carbon fibers are available with a moderate (33-35 Msi), intermediate (40-50 Msi), high (50-70 Msi) and ultrahigh (70-140 Msi) modulus. (Modulus is the mathematical value that describes the stiffness of a material by measuring its deflection or change in length under loading.) Newer heavy-tow carbon fibers, sometimes referred to as commercial-grade fibers, with 48K-320K filament counts, are available at a lower cost than aerospace-grade fibers. They typically have a 33-35 Msi modulus and 550-ksi tensile strength and are used when fast part build-up is required, most commonly in recreational, industrial, construction and automotive markets. Heavy-tow fibers exhibit properties that can approach those of aerospace-grade fibers but can be manufactured at a lower cost because of precursor and processing differences. 

A potentially significant recent variation is carbon fiber tow that features aligned discontinuous fibers. These tows are created in special processes that either apply tension to carbon tow at differential speeds, which causes random breakage of individual filaments, or otherwise cut or separate individual carbon filaments such that the filament beginnings and ends are staggered and their relative lengths are roughly uniform so that they remain aligned and the tow maintains its integrity. The breaks permit the filaments to shift position in relation to adjacent filaments with greater independence, making the tow more formable and giving it the ability to stretch under load, with greater strength properties than chopped, random fibers. Fiber forms made from aligned discontinuous tows are more drapable; that is, they are more pliable and, therefore, conform more easily to curved tool surfaces than fiber forms made from standard tow.