Reinforced-plastic fiber pattern

Spray-up Popular system with reinforced plastic production. An air spray gun includes a roller cutter that chops usually glass fiber rovings to a controlled short length before being blown in a random pattern (manually or automatically) onto a surface of the mold simultaneously the gun sprays catalyzed TS polyester plastic. The chopped fibers are plastic coated as they exit the gun s nozzle. The resulting, rather fluffy, RP mass is consolidated with serrated rollers to squeeze out air and reduce or eliminate voids. A closed mold... 

The behavior of RPs is dominated by the arrangement and the interaction of the stiff, strong fibers with the less stiff, weaker plastic matrix. The features of the structure and the construction determine the behavior of RPs that is important to the designer. A major advantage is the fact that directional properties can be maximized. They can be isotropic, orthotropic, etc. Basic design theories of combining actions of plastics and reinforcements have been developed and used successfully. Different fabric and/or individual fiber patterns are used to develop different property performances. 

The reinforcement type and form chosen (woven, braided, chopped, etc.) will depend on the performance requirements and the method of processing the RP (Fig. 6-15). Fibers can be oriented in many different patterns to provide the directional properties desired. Depending on their packing arrangement, different reinforcement-to-plastic ratios are obtained (Appendix A. PLASTICS TOOLBOX). 

Fig. 8-64 (a) FW layup shows isotensoid pattern of the reinforcing fibers and (b) plastic molded isotensoid case/container. 

Hgure 1 5.8 Views of fiber filament wound isotensoid pattern of the reinforcing fibers without plastic (left) and with resin cured... 

Chapters 15-18 focus on the weathering/mechanical study of lignocellulosic fiber-reinforced polymer composites. The effect of different environmental conditions on the physico-chemical and mechanical properties of the polymer composites is discussed in detail in these chapters. Chapter 15 mainly focuses on the effect of weathering conditions on the properties of lignocellulosic polymer composites. Most of the focus of this chapter is the effect of UV radiation on different properties of composites. Chapter 16 describes the effect of layering pattern on the physical, mechanical and acoustic properties of luffa/coir fiber-reinforced epoxy novolac hybrid composites, and Chapter 17 summarizes the fracture mechanism of wood plastic composites. Chapter 18 focuses on the mechanical behavior of biocomposites xmder different environmental conditions. 

The process consists of a thin, unreinforced outer coat called a gel coat. The reinforcement (normally glass fibers) mixed with resin (usually polyester) is then applied by hand (lay-up) or via a spray gun (spray-up). When the desired amount of resin and reinforcement is in the mold, the air bubbles are pressed out with a roller. The part is then left to set up which, depending on the size of the part and the amount of resin, can take more than an hour. Consequently, many molds are used when higher production volumes are required. The molds themselves are made of plastic cast from a pattern. As such, they have a very short life and must be replaced frequently. Fortunately, they are inexpensive imfortunately, they are not capable of producing fine detail or close tolerances. Since the mold has only one side, only that side of the part has a finished surface the other side is very rough. The... 

High-pressure water can also be used to water jet cut many plastic materials. A fine jet of water (either plain or with abrasives added) is directed at the part at pressures of 60,000 psi from a fine nozzle. Automated robotic equipment is available to water jet cut intricate patterns. This method is very attractive for many hard-to-cut materials such as aramid fiber-reinforced composites. The water jet cuts most materials quickly without a burr and does not introduce stresses in the material. 

Prepreg Term generally used in RPs for a reinforcement containing or combined usually with a TS liquid plastic (TPs are also used) that can be stored under controlled conditions. Reinforcement (such as fibers and/or rovings, woven and/or nonwoven fabrics, etc.) can be in different forms and patterns. The TSs is completely compounded with catalysts, etc. and partially cured to the required tack state in the B-stage. The fabricator completes the cure with heat and pressure. 

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