Design glass-fiber-reinforced composites

Some design factors, however, work against composites. For example, glass fiber-reinforced plastics generally have lower modulus (stiffness) than metals. Thickness and shape adjustments are requited where stiffness is a critical design requirement. With appropriate reinforcement, any modulus, even greater than that of metals, can be achieved. However, it may become expensive and uneconomical to do so. 

Let us consider two hypothetical phases in our composite, A and B, without specifying their physical state. They conld be a polymer melt and a glass fiber reinforcement during melt infiltration processing, a metal powder and ceramic powder that are being snbjected to consolidation at elevated temperatnre and pressure, or two immiscible polymer melts that will be co-extruded and solidified into a two-phase, three-dimensional object. In any case, the surface that forms between the two phases is designated AB, and their individual surfaces that are exposed to their own vapor, air, or inert gas (we make no distinction here) are labeled either A or B. The following three processes are defined as these surfaces interact and form ... 

The basic composition of matter patents had long since expired when Celanese sampled the market in 1970 with a glass fiber reinforced PBT product designated X-917. This product was subsequently called Celanex polyester molding compound. Eastman Kodak followed Celanese early in 1971, and General Electric followed Eastman Kodak later in the same year with Valox PBT polyester resin. Since that time a dozen or more additional companies around the world have entered (and some have subsequently exited) the business. 

Composite is a stmctural material that gains its strength from a combination of complementary materials, i.e., polymer and its reinforcement. The most common type of composite, glass fiber reinforced material, is not a typical example in the case of PVC because of difficulties in design for interaction between both materials and lack of convenient means of adhesion promotion. 

A. Abiy, Design and analysis of bamboo and e-glass fiber reinforced epoxy hybrid composite for wind turbine blade shell, Addis Ababa University, M. Sc. Dissertation, (2013). 

Traditionally, material design requirements that suit such demanding end-use applications have been limited within the domain of engineering plastics based on polyamide 6 or 66, polyester alloys, and polyacetal type resins. However, as described in Chapter 1, glass fiber-reinforced polypropylene (GFRP) composites continue to gain a market share in automotive molded parts. 

At elevated temperatures, the role of glass fiber reinforcement becomes a crucial factor for deciding what base material to use. Before the advent of more efficient chemically coupling combinations, there was a wide performance gap between SGFR composites based on polyamide and polypropylene resins. Obviously, that gap has shrunk significantly by improved interphase design for chemically coupled polypropylene materials. 

The base-layers of the multilayer designs are mostly glass fiber reinforced, in these layers the fiber content is higher, and therefore the fiber properties dominate the properties of the composite. 

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