Cooling reinforcement content

Fig. 2.18 illustrates the nature of the intensity profiles in pure polyetheretherke-tone (PEEK) and carbon fiber reinforced PEEK composites in the transmission and reflection modes, respectively. The quenched amorphous and slowly cooled crystalline components from PEEK can be separated. The three prominent diffraction peaks from the crystalline components in Fig. 2.18(a) correspond to the three uniform rings which can be detected in X-ray photographs. In contrast, no clearly measurable signal is identified from the PEEK amorphous phase independent of the carbon fiber content. 

This structural information can also help explain changes observed in the mechanical properties of the nanocomposites. As the amorphous content of the samples decreases from UM to dPC and the material becomes more crystalline, the nanocomposites become stronger. Also in the core of the injection moulded test bars where slow cooling is prevalent, the more stable a structure appears to form readily. As the y crystal structure is said to be more ductile than the a, it would be expected that the tensile strength of materials containing mostly a crystals, like DdPC-OdPC, to be much stronger than those with high levels of y crystal in the core. So not only is the increase in modulus due to the reinforcement provided by the clay layers and increase in crystallinity, but also the reduction in y crystal content. 

The forming method has it that isotactic polypropylene is formed as a board on which one or more parallel layers of fibers are applied. Additionally, on one side, the ends of fibers must reach out over the edge of the board to be caught and puUed. Next, the second polypropylene board is applied. The boards are heated to 175-285°C at a constant or increased pressure, and then the set is cooled down. Below 150°C, the fibers are moved to the distance up to few millimeters at 0.01-0.1 m/s. Having obtained the desired shape, the product is cooled down to the ambient temperature [3]. The technique presented in the cited patent description ensures high content of p form in the polypropylene composite reinforced with natural fiber. 

Relevant quality factors for components made out of fiber reinforced plastics are consolidation degree, void content, residual stress, degradation, fiber breaks and inhomogeneous fiber matrix distribution. These factors are influenced by the winding velocity, heating, tension, mandrel material, cooling rate and the number of layers, that is, application thickness. ... 

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