Glass fibers physical properties

With the exception of glass fiber, asbestos (qv), and the specialty metallic and ceramic fibers, textile fibers are a class of soHd organic polymers distinguishable from other polymers by their physical properties and characteristic geometric dimensions (see Glass Refractory fibers). The physical properties of textile fibers, and indeed of all materials, are a reflection of molecular stmcture and intermolecular organization. The abiUty of certain polymers to form fibers can be traced to several stmctural features at different levels of organization rather than to any one particular molecular property. 

Aluminosilicate Fibers. Vitreous alurninosihcate fibers, more commonly known as refractory ceramic fibers (RCF), belong to a class of materials known as synthetic vitreous fibers. Fiber glass and mineral wool are also classified as synthetic vitreous fibers, and together represent 98% of this product group. RCFs were discovered in 1942 (18) but were not used commercially until 1953. Typical chemical and physical properties of these materials are shown in Table 3. 

Other Bulk Physical Properties. The hardness of asbestos fibers is comparable to that of other crystalline or glassy siHcates. Compared to glass fibers, amphiboles have similar hardness values, while chrysotile shows lower hardness values. 

Some of the common types of plastics that ate used ate thermoplastics, such as poly(phenylene sulfide) (PPS) (see Polymers containing sulfur), nylons, Hquid crystal polymer (LCP), the polyesters (qv) such as polyesters that ate 30% glass-fiber reinforced, and poly(ethylene terephthalate) (PET), and polyetherimide (PEI) and thermosets such as diaHyl phthalate and phenoHc resins (qv). Because of the wide variety of manufacturing processes and usage requirements, these materials ate available in several variations which have a range of physical properties. 

Polyester resins, reinforced with glass fibers, are used widely in the construction of process equipment. Some physical and mechanical properties are presented in Table 3.48. Table 3.49 lists various materials used as filler and the properties they impart to different plastics. 

As is known of glass fiber-reinforced plastics, the mechanical and physical properties of composites, next to the fiber properties, and the quality of the fiber matrix interface, as well as the textile form of the reinforcement primarily depend on the volume content of fibers in the composite. 

Generally, the mechanical and physical properties of natural fiber-reinforced plastics only conditionally reach the characteristic values of glass fiber-reinforced systems. By using hybrid composites made of natural fibers and carbon fibers or natural fibers and glass fibers, the... 

The mechanical properties of composites are mainly influenced by the adhesion between matrix and fibers of the composite. As it is known from glass fibers, the adhesion properties could be changed by pretreatments of fibers. So special process, chemical and physical modification methods were developed. Moisture repel-lency, resistance to environmental effects, and, not at least, the mechanical properties are improved by these treatments. Various applications for natural fibers as reinforcement in plastics are encouraged. 

At present, the most promising fillers are those with 1/d P 1, i.e. fibers and flaky fillers that make it possible to reduce filler concentration in a composite and, thus, facilitate the processing and improve physical-mechanical properties [17]. Besides cut carbon fibers, carbon fibers coated with a layer of Ni that have higher conductivity have been developed (American cyanamid) [14]. Glass fibers with a layer of aluminium (MB Associates, Lundy Electronics) [16] are in production. 

Within the limitations on the physical properties which generally restrict plastics to low precision optics, plastics materials have found wide applications in optical products that range from lights to binders for electroluminescent phosphors to fiber optics and lasers. They represent an easily worked material with a wide range of desirable optical properties in simple to complex shapes. In this review the discussion has been limited to the differences between plastics and optical glass materials and to some of the unique design possibilities that are especially important for plastics. Using the optical arts and the... 

A symmetry boundary condition was imposed perpendicular to the base of the mold. Since the part is symmetric, only half of the part cross-section needed to be simulated. The initial conditions were such that resin was at room temperature and zero epoxide conversion. The physical properties were computed as the weight average of the resin and the glass fibers. 

Glass fiber diameter can also affect the physical properties. In general, fiber diameters from 6-17. im have been used in PBT, with the narrower fibers giving slightly better properties. However, fiber length distribution and fiber content may play a more important role than diameter [32], Fiber content in a PBT composite is often measured by specific gravity and by ash content. Both of these measurements need to be corrected in cases where the blend is pigmented or combined with other materials. 

Since unsaturated polyester resins alone would have insufficient strength for structural application, reinforcements are used to enhance the physical strength of such resins. Typically, tensile strength, impact strength and stiffness are the physical properties of most interest. Reinforcements can be regular particulates, as in glass microspheres, irregular particulates, as in flakes, or fibers. 

Stretching denotes a monoaxial or biaxial mechanical stress of a molded article close to the glass transition temperature. This leads to a controlled orientation of the molecular chains in the direction of stretching and thus to a substantial change in some physical properties. Fibers and foils made of synthetic polymers gain their optimal properties only by this mechanical post-treatment. Stability, stiffness, and dimensional stability of fibers, for example, increase nearly proportionally with the stretch ratio, whereas stretchability decreases. In practice, the stretch ratio is between 1 2 and 1 6, depending on the polymer material and the desired properties. 

Physical properties of solid polyphosphate glasses and their melts are also in accord with the conclusions drawn from chemical studies. The X-ray diffraction pattern shows the polyphosphate anions to consist of long chains of P04 tetrahedra (32) and the same conclusion is reached by studying the double refraction of fibers formed by rapidly drawing supercooled melts of Graham s salt (101). 

The glass transition temjierature of PPBT is about 52 C 1125 Fi. Melting point is about 230°C (440°F). Unrcinforccd l BT is obtainable in several molecular weights. Compounded resins are available with numerous types and levels of fillers and reinforcements. Glass fiber reinforcement has a wide spectrum of physical properties. These materials can be made flame-retardant through the use of additives. 

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