Exterior automotive applications

Automotive manufacturers have recognized the inherent benefits of PAB s for exterior automotive applications. These include ... 

Blends of PPE and PA-66 are suited for exterior automotive applications, where they produce class A surface on body panels, because they combine the processing and solvent resistance of polyamides with the moisture resistance and dimensional stability of PPE. Therefore, they have good heat resistance, impact resistance, moldabUity, paint adhesion and chemical resistance. 

There has been a trend in recent years to move towards the electrostatic deposition of paints for exterior automotive applications. Reasons for this include improved paint transfer efficiency. Normally, plastic parts need to be painted with a conductive primer prior to the electrostatic painting of base and clear coats. One of the most recent developments in the area of external automotive applications is that of intrinsically conductive resins for electrostatic painting. Currently there are commercial applications for body panels that utilize PPE/PA that contains carbon black as the conductive component. In the USA, a mirror shell application uses PPE/PA where the conductivity is achieved through the incorporation of graphite nano-tubes. 

Polyamide/polycarbonate blends have been evaluated for exterior automotive applications such as bumper beams. Their dimensional stabil-... 

General Motors R D and Montell U.S.A. have developed thermoplastic olefin (TPO) clay nano composites with reduced weight and good dimensional stability for exterior automotive applications [24]. PE nanocomposites have also been made effectively by ethylene homo- and copolymerization in the presence of organoclays (see Chapter 5), catalyzed with methylalnminoxane (MAO)-activated zirconocene, nickel, and palladium catalysts [25]. 

In addition, PET and PBT are relatively moisture insensitive under ambient conditions, unlike the polyamides (PA-6 and PA-66), which can absorb significant levels of moisture. Moisture absorption in polyamides leads to significant growth in dimensions and loss in modulus and strength. Although PPE/PA blends exhibit lower moisture absorption than the standard polyamides, they are still not suitable for some exterior automotive applications such as vertical door panels and many electrical and electronic applications, which require stringent moisture resistance and dimensional stability. 

Considerable amounts of EPM and EPDM are also used in blends with thermoplastics, eg, as impact modifier in quantities up to about 25 wt% for polyamides, polystyrenes, and particularly polypropylene. The latter products are used in many exterior automotive applications such as bumpers and body panels. In blends with polypropylene, wherein the EPDM component may be increased to become the larger portion, a thermoplastic elastomer is obtained. Provided the EPDM phase is vulcanized during the mixing with polypropylene (dynamic vulcanization) to suppress the flow of the EPDM phase, it gives the end product good set properties (54). 

Most TPOs cost less than TPVs. IPOs are becoming a more common choice in order to save on production costs. Some TPOs have an advantage over traditional thermo-set rubber compounds in the appearance they impart. The feel or texture is sometimes uniquely superior to conventional vulcanized rubber. TPOs are increasingly being used in both interior and exterior automotive applications. One great advantage they have is their recyclability. 

Microcellular Injection Moulding on the Structure Property Relationships of Engineering Thermoplastics Used in Exterior Automotive Applications, ANTEC (2004), p. 2537-2541... 

This paper will examine the scratch whitening resistance of PP rich, injection molded Thermoplastic Polyolefins (TPOs) for exterior automotive applications. Significant attention will be given to the influence of the molecular architecture of the polypropylene (PP) component on the surface morphology and resultant scratch whitening resistance of the injection molded part. Material parameters and surface crystallinity which contribute to enhanced scratch whitening resistance will be highlighted. 

As the technological advances in the area of thermoplastic polyolefins (TPOs) continue to develop, the performance demands for TPOs in interior and exterior automotive applications have also increased. 

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