Moldings, automotive polymers

Polyesters, which are a class of engineering thermoplastics, are found in a wide variety of applications including carbonated drink bottles, fibers for synthetic fabrics, thin films for photographic films and food packaging, injection molded automotive parts, and housings for small appliances. In this chapter, we svill explore the synthesis of this class of polymers. We will also look at the typical properties and end uses for the most common of these resins, polyethylene terephthalate and polybutylene terephthalate, which are commonly known as PET and PBT, respectively. 

Phlegm, H. K. 2001. A comparison of molded polyaryletherketones and compression molded polyimide polymers in automotive applications. Master s thesis, University of Detroit-Mercy, pp. 1, 7, 11. 

Kohinor. [Pantasote Polymers] Vinyl compds. for inj. molding, automotive applies., etc. 

Chem. Descrip. 2-Flydroxy-4-n-octyloxybenzophenone CAS 1843-05-6 EINECS/ELINCS 217-421-2 Uses Lt. stabilizer, UV absorber for polymers incl. acetals, acrylics, ABS, alkyds, cellulosics, epoxies, PC, thermoplastic and thermoset polyester, polyethylene, PP, PS, SAN, and surface coatings UV absorber for PVC flexible and semirigid applies, such as automotive body side molding, automotive surface coatings costabilizer for polyethylene film in agric. or greenhouse applies. 

The composition of the ABS has a very large bearing on the final performance of the resin. Figure 9.13 illustrates the relationship between composition and structure in ABS. Polymer scientists carefully balance the proportions of these monomers when designing ABS resins for particular applications. Table 9.8 shows properties typical of some commercially available classes of ABS. These material properties are suitable for injection molding automotive parts. 

Kietzmann C, Van der Walt JP, Morsi YS (1998) A free-front tracking algorithm for a control-volume-based Hele-Shaw method. Int J Numer Methods Eng 41 253-269 Kim SH, Kim CH, Oh H, Choi CH, Kim BY, Youn JR (2007) Residual stresses and viscoelastic deformation of an injection molded automotive part. Korea-Australia Rheol J 19 183-190 Klein DH, Leal LG, Garcfa-Cervera CJ, Ceniceros HD (2008) Three-dimensional shear-driven dynamics of polydomain textures and disclination loops in liquid crystalline polymers. J Rheol 52 837-863... 

The dominating chemical pretreatment used in Europe for molded automotive TPO components is flame treatment. The effectiveness of the flame treatment is checked by surface tension measurement and should be a minimum of 45 dynes/cm to ensure acceptable adhesion with solvent-based paints. Chemically, the adhesion effect of flaming is based on a controlled oxidization of the CH2-and CH3 units (7). Also, a degradation of the polymer and polymer melting can occur therefore the flaming needs to be carried out within an upper and lower temperature limit. 

The major uses of aniline are in the manufacture of polymers, mbber, agricultural chemicals, dyes and pigments, pharmaceuticals, and photographic chemicals. Approximately 67% of the wodd production of aniline is used in the manufacture of rigid polyurethanes and reaction-injection-molded (RIM) parts for the constmction, automotive, and durable goods industries. 

Butyl-type polymers exhibit high damping, and the viscous part of the dynamic modulus is uniquely broad as a function of frequency or temperature. Molded mbber parts for damping and shock absorption find wide appHcation in automotive suspension bumpers, auto exhaust hangers, and body mounts. 

Step growth polymerization can also yield highly crosslinked polymer systems via a prepolymer process. In this process, we create a prepolymer through a step growth reaction mechanism on two of the sites of a trifunctional monomer. The third site, which is chemically different, can then react with another monomer that is added to the liquid prepolymer to create the crosslinked species. We often use heat to initiate the second reaction. We can use this method to directly create finished items by injecting a mixture of the liquid prepolymer and additional monomer into a mold where they polymerize to create the desired, final shape. Cultured marble countertops and some automotive body panels are created in this manner. 

Fiber reinforcement of polymers allows us to use them in engineering applications that were previously off limits, We use fiber reinforced injection moldings in many under-the-hood automotive applications, such as rocker box covers and front end modules, which support the radiator, cooling fan, and hood latch, that are subjected to a wide range of temperatures. 

Nylons belong to the class of polymers known as engineering polymers that is, they are strong, tough, and heat resistant. We can readily extrude and mold nylons to form a wide variety of useful objects, such as tubing, furniture casters, and automotive air intake ducts. Nylons are commonly spun into filaments or fibers. These can be used directly, or braided, or twisted to form threads, yarns, cords, and ropes, which may be further woven to make fabrics. In their fibrous forms, nylons are used in carpets, backpacks, and hosiery. 

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