Modified plastics for automobile generally refer to the plastics with large production, good formability, low price and widely used. It contains five varieties, polypropylene (PP), polyethylene (PE), polyvinyl chloride (PVC), polystyrene (PS), acrylonitrile butadiene styrene copolymer (ABS).

　　1、PP

　　Polypropylene, commonly known as hundred fold glue, is similar to white wax, transparent, light weight, good fluidity in injection molding, water absorption is less than 0.02%. The shrinkage of PP is 1.0-3.5%, and the suitable thickness is 1.5-2.5mm. There are two main problems in the wide use of PP in the automotive field: it is easy to burn (it will drip combustibles) and it is brittle in low temperature environment. In view of these two problems, PP was modified by adding appropriate additives in industrial application. It is easy to burn and flame retardant will be added; It is brittle at low temperature. It is mainly modified and toughened by adding other ductile materials, rigid particles or elastomers, such as rubber (EPDM), talcum powder (TD), glass fiber (GF), etc. There are many automobile products made of PP resin, such as instrument panel, door guard, pillar guard, bumper, water tank and decorative panel. The application of PP in automobile has more and more trend.

　　2、PE

　　Polyethylene, one of the very light plastics, translucent white waxy material, good water resistance, acid and alkali resistance, organic solvent resistance, excellent electrical insulation. The shrinkage is 1.5-4.0%, and the suitable thickness is 1.0-2.5mm. The disadvantage of PE as an automobile material is that it is easy to burn. A simple and common method is to add appropriate flame retardant to improve the combustion performance of PE. The automobile products made of PE mainly include fuel tank, air duct, decorative cover of front seat, air duct assembly (HDPE), left and right ventilation pipe assembly, connecting bars of up and down wind blades, left and right foot vent assembly, etc.

　　3、PVC

　　PVC, commonly used PVC, is a multi-component plastic, because the content of each component is different, it forms a variety of PVC particles with different mechanical properties and different hardness, which are generally divided into soft PVC and hard PVC. Shrinkage: 1-1.5% for hard PVC, 2-2.3% for soft PVC, and 2-3.5mm for suitable thickness. PVC is the most commonly used plastic material in automobile plastic products. Automobile plastic products made of PVC can be seen everywhere, such as PVC instrument panel skin, PVC plastic steering wheel, PVC plastic lining, PVC plastic automobile flooring materials. This is not only because the price of PVC resin is economical, but also because the processing performance and comprehensive mechanical properties are better.

　　4、PS

　　Polystyrene, commonly known as hard rubber, is a transparent glass like material with good fluidity and no water absorption. Due to its brittleness, PS is often grafted with other substances, such as butadiene to form hips. The impact strength and surface hardness are greatly improved after rubber is contained in the composition. Shrinkage 0.4-0.7%, suitable thickness 2-3mm. PS is mainly used in the automobile instrument shell, lampshade and lighting products. Polystyrene can also be used to produce packaging materials and thermal insulation materials by foaming, and it can also be used to produce ceiling. In addition, polystyrene can be grafted and modified with other materials to obtain many kinds of PS family alloy plastics, such as SMA, which is used to make automobile dashboard framework.

　　5、ABS

　　Acrylonitrile butadiene styrene copolymer, commonly known as super unbreakable rubber, body is white. The shrinkage is 0.4-0.7%, and the appropriate wall thickness is 1.8-3MM. ABS is widely used in automobile field because of its variety, good surface treatment effect and low price. In view of the poor weatherability of ABS, AES, ASA and other materials with high weatherability have been widely used in commercial vehicles to supplement ABS. When the product needs to do surface treatment (such as water transfer film, spray), use ABS; ASA and AES are used when surface treatment is not needed. Typical automotive products are decorative strip, shift handle head, inner handle, license plate decorative plate, rear spoiler assembly, rear-view mirror body, radiator grille body, armrest, etc.