Automotive trim, polypropylene

Thermoplastic polyolefins (TPOs) are based on blends of polypropylene with ethylene-propylene rubbers. Many perform well as hose, exterior automotive trim and bumpers without chemical linking of the main polymeric components. 

Compounds based on S—EB—S usually contain polypropylene, which improves solvent resistance and processibiUty and raises upper service temperatures. Compounds intended for use in the automotive industry are able to survive 1000 hours air exposure at temperatures of 125°C with only minor changes in properties (54). Very soft compounds have been developed to replace foam mbber for interior trim parts. In this and similar appHcations, these soft compounds are usually insert molded over polypropylene or metal and then coated with flexible polyurethane paint (55). Other automotive appHcations include products intended for sound deadening, flexible air ducts, and gear shifter boots, as weU as improving the properties of sheet mol ding compounds. 

The article describes the process of producing expanded polypropylene foam parts with a solid integral skin on one side, citing a bicycle helmet moulded from BASF s Neopolen EPP bead, as an illustration. The self-skinning EPP process reqnires some modification of standard beadmoulding equipment, needing an extra steam chamber. Automotive interior trim is a potential application for the process. 

Polypropylene is extensively used in injection molding because of the wide range of physical properties and melt flow rates available. The principal markets served include transportation (primarily automotive), appliances, consumer products, rigid packaging, and medical products. Polypropylene use has increased in the automotive industry because of the wide availability of high melt flow rate impact copolymers for use in large thin parts, such as interior trim. 

Impact modified polypropylene is used for injection molding automotive, consumer and appliance parts. For example, the medium impact PP is widely used for automotive interior trim. High impact PP is used for battery cases, fender and truck liners. Impact PP is also used extensively in the houseware and appliance markets. 

In the automotive industiy, unpainted, unskinned polypropylene-based interior-trim components such as piUars, IPs, cluster bezels, center consoles, door panel components, handles, swatches and buttons, sills, and package shelves are candidates. The ability to add a highly durable, decorative mark to unskinned, unpainted components in economy vehicles, light trucks, and other industrial vehicles has strong economic incentives. 

Polypropylene nanocomposites are remarkable for their better mechanical properties, such as high tensile strength and modulus, and for their dimensional stability. They have a wide range of applications in the automotive sector [7-11]. The PP composites are used in automotive industry as battery supports, instmment panel carriers, body panel reinforcements, front-end modulus, underbody aerodynamic covers, electronic boxes, pedals and their supports, door panels and door modules, bumper beams, fender extensions, wheel covers, hub caps, and trim rings for wheels (Fig. 11.4). 

Polypropylene (PP) fibre is one of the most widely used synthetic fibres in the textile industry. PP has some advantages it is cheaper and stronger than many other synthetic fibres and it has been applied widely in various fields, e.g., carpets, automotive interior trim, films, packaging, protective cover, and cables. In particular, it is used for healthcare applications such as surgical masks, babies nappies, and filters, which need to display antibacterial effects. 

Talc has been the second mineral of choice to fill polypropylene. Such applications have usually been automotive and industrial. Talc is a general purpose filler mineral and is highly compatible with polyolefins. It is widely used to increase stiffness and heat resistance in polypropylene automobile trim parts that do not require high reinforcement. 

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