Long Glass Fiber Reinforced Polypropylene Material Development of The Difficulty and Focus

- Dec 20, 2017 -

The development trend of automotive materials, mainly: low odor, environmental recycling simple, but also minimize the types of materials. Long glass fiber reinforced PP is precisely because of the above advantages, the gradual replacement of short glass fiber reinforced nylon in the car. Today we come to understand the long glass fiber reinforced polypropylene material development of the difficulty and focus;


Long glass fiber reinforced polypropylene materials in the automotive parts research and application, is one of the hot spots in recent years. Long glass fiber reinforced polypropylene plastic refers to the length of 10 to 25 mm in glass fiber modified polypropylene composite material, after injection molding process to form a three-dimensional structure, the English Long Glass Fiberpolypropylene, abbreviated as LGFPP. There is also a lot of information at home and abroad will long-fiber reinforced thermoplastics referred to as LFT, Abbreviation of Long fiber reinforce thermoplastic. From the material definition, LGFPP belongs to LFT.

Pellet Comparison1 .jpg

Figure: Long glass fiber with the end of glass fiber length comparison

Material characteristics

The microstructure determines the macro performance, so 10 ~ 25mm long glass reinforced plastic (abbreviated LGFPP) has higher strength, stiffness, toughness, Low curvature and other advantages. In addition, long glass-fiber reinforced polypropylene does not exhibit significant creep even at elevated temperatures of 100 ° C and offers better creep resistance than short-glass-reinforced polypropylene.

In the finished injection, long glass fiber cross into a three-dimensional network structure, even if the polypropylene substrate burning, the long glass fiber network still forms a certain degree of strength of the glass fiber skeleton, and short glass fiber after burning generally become no strength fibers skeleton. The reason for this is mainly because the ratio of the length to diameter of the reinforcing fibers determines the reinforcing effect. The critical length = L / D, the filler having a critical length to diameter ratio of less than 100 and short glass fibers have no reinforcing effect, and the critical length to diameter ratio is less than 100 Glass fiber plays a reinforcing role.

Compared to metal and thermoset composites, long glass-fiber plastics have a low density and reduce the weight of the same parts by 20 to 50%. Long GF plastics offer designers greater design flexibility, such as the ability to shape complex-shaped parts , The number of integrated components to use, saving mold costs (usually long glass plastic injection mold costs about 20% of the cost of metal stamping die), reduce energy consumption (long fiberglass plastic production energy consumption is only 60 ~ 80%, 35 ~ 50% of aluminum products), simplifying the assembly process.

Based on the application advantages of long glass fiber materials, it has become more and more widely used in automotive applications. We have seen more and more of the following components adopting long glass fiber reinforced polypropylene, long fiber reinforced polypropylene Is used for car dashboard body skeleton, battery bracket, front-end module, power control box, seat support, spare placenta, fender, chassis cover, noise barrier, rear door frame.

Material development difficulty and focus

(1) The concept of EVI (Early Vehicle Involvement): Material supplier system component suppliers, involved in the new model project during the conceptual development stage, fully understand the OEM's needs for materials to improve the performance-changing products and services; If only the benchmark car material as a material selection basis, then the car market and the benchmark car has about 5 years of material selection gap.

(2) Cost Analysis: If the cost of raw materials alone is considered, the price per kilogram of plastic is higher than that of metal materials. However, the investment in mold cost is relatively low. The plastic injection molds are only 50% of the steel mold parts. Steel mold 30 ~ 40%; Integrated peripheral components, modular supply, you can further save the cost of the host plant assembly, reduce assembly tools and save space.

(3) other aspects: changes in the types of materials used in the parts, materials shrinkage changes need to develop new molds; the same time for long glass special materials, the need to use different from conventional injection molding machines and other processing equipment. Although, as a purchased part of most of the technical tackle by a supplier to undertake, but in the OEM need to do a long glass fiber material industrialization process of various technical problems in the response.

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