The synthetic polymers can be gotten by three processes, involving reactions of addition, condensation and modification of other polymers. (MARINE, 2005). The PP, material to be used in the process of injection for attainment of the components of the fans manufactured for the G12 is gotten through the process of poliadio reaction, where the monomers almost always they present pairs linkings between carbon atoms. It does not have by-product formation and the molecular weights can reach very high values. (I FLOW, 2000). See New York Museums for more details and insights. The polypropylene is a thermoplastic resin made from the propileno gas the originary oil, that is, a by-product of the fine oil. In its natural state, the resin is half-translucent and milky and of excellent coloration, being able later to be aditivado or to be pigmented.
This product is used in the cases where a bigger chemical resistance is necessary. One of the advantages is that it can be welded, allowing to the manufacture of tanks and connections. The majority of polypropylenes is produced by moldings, injection, blow or drawing, from strengthened composites and without reinforcements. Other applicable processes to polypropylenes are the strengthened standardized foam molding with fibre glass. As much the destined resins the moldings how much destined for drawings they can be pigmented through any respective conventional process. The PP presents the following characteristics: Good chemical resistance; Low cost amongst plastics; To regulate resistance to the attrition; Good thermal stability; It can be aditivado; High resistance to the notch; Low humidity absorption; Easy usinagem; Good resistance to the impact; Weldable and moldvel; Atxico Comprovadamente; It operates until 115C; The slightness 0,92 – it has more led of plastics; In covering until 90C it can substitute the PVC; Antiaderente.
The polypropylene is a resin of low density that offers a good balance of thermal properties, chemical and electric, folloied of moderate resistance. The resistance properties can significantly be increased or be improved through fibre glass reinforcements. The tenacity is improved through special glass staple fibre reinforcements in modified graduations of raised molecular weight with illustrated rubber as in figure 4.1. The electric properties of polypropylenes they are affected in some degrees of temperature of service. With increase of this temperature, the dielectric constant remains constant reasonable; however, the resistance or the dielectric power increases, while volumetric resistivity is reduced, this can be understood by the representation of figure 4.1. Figure 4.1 also illustrates as the polypropylene resists the chemical attacks and they are not affected by watery solutions of you leave acid inorgnicos or and mineral bases, exactly in high temperatures. They are not attacked by the majority of the chemical agents of organic nature. However, they are attacked by halogenados composites, acid nitric smoky and other active oxidantes agents, beyond being also attacked for aromatical hydro-carbons and chromium platings, in high temperatures. Figure 4.1? Characteristics of the PP. (VICK, 2010). The polypropylene presents resistance limited to the heat; they exist, however, stabilized types term destined the applications that demand drawn out use raised temperatures. The useful life of parts with such graduations can reach five years 120C, ten years 110C and twenty years 90C. Types especially stabilized are classified by the UL for continuous services 120C. The polypropylene resins are inherently unstable in the presence of oxidantes agents and the presence of rays ultraviolet. Although some of its graduations are steady until certain point, systems of stabilization are used frequently destined to adjust a special formula