In the field of exhaust fans, PBT (Polybutylene Terephthalate) materials have various applications and advantages. The advantages include: 1. Good chemical stability: It can remain stable under various environmental conditions. 2. High mechanical strength: It can ensure the stability of the exhaust fan during long-term operation. 3. Excellent electrical insulation: It ensures electrical safety during use, and can maintain stable electrical performance in humid and high-temperature environments. It is an ideal material for manufacturing electronic and electrical parts. 4. Good heat aging resistance: The enhanced UL temperature index reaches 120°C - 140°C, and it also has good long-term outdoor aging resistance, which is suitable for the working environment of exhaust fans. 5. High thermal stability: The melting point range of PBT is between 225°C and 235°C. It is a crystalline material with a crystallinity of up to 40%, which enables PBT to maintain its shape and performance under high-temperature conditions. 6. Good processing fluidity: It is easy to be processed and molded, the mold temperature requirement is relatively low, and the cooling time during injection molding is short, which can improve production efficiency. DC fans generally use black modified PBT as the material for the outer frame and fan blades, and it is usually applied in the form of 30% fiber addition, which can make the fan heat-resistant, flame-retardant, insulating and have sufficient mechanical strength. In terms of future development trends, with the continuous development of the exhaust fan market and the improvement of product performance requirements, PBT materials may present the following trends: 1. High performance: Further improve the strength, heat resistance, weather resistance and other properties of PBT to meet the higher requirements of exhaust fan applications. 2. Modified compounding: Obtain more excellent comprehensive properties through modified compounding with other materials, such as improving impact resistance and improving processing performance. 3. Environmental protection: Develop more environmentally friendly PBT materials to adapt to environmental protection regulations and market demands. 4. Lightweight: On the premise of ensuring performance, realize the lightweight of the product and reduce the overall weight of the exhaust fan. 5. Customization: Customize PBT materials with specific properties according to the design and functional requirements of different exhaust fans. In order to improve the performance of PBT materials in exhaust fans, the problem of hydrolysis resistance also needs to be concerned. PBT has defects such as low notch impact strength, large molding shrinkage, poor hydrolysis resistance, and vulnerability to halogenated hydrocarbon erosion. After being reinforced with glass fibers, the inconsistency of the longitudinal and transverse shrinkage rates of the product can easily cause the product to warp. Methods such as adding hydrolysis stabilizers (such as carbodiimide) to consume the carboxyl groups generated by hydrolysis and slow down the acidic hydrolysis rate of PBT polyester; or adding auxiliaries with epoxy functional groups and reacting with the PBT terminal carboxyl groups through the functional group GMA to cap the ends can be adopted to reduce the terminal carboxyl group concentration and improve the hydrolysis resistance of PBT polyester. At the same time, before injection molding of PBT, drying treatment is required. It is recommended that the drying conditions in the air be 120°C for 6 - 8 hours, or 150°C for 2 - 4 hours, and the humidity must be less than 0.03%. If dried with a moisture absorption dryer, the recommended conditions are 150°C for 2.5 hours. During injection molding, the melting temperature is 225 - 275°C, and the recommended temperature is 250°C; the plastic mold temperature for non-reinforced materials is 40 - 60°C. The cooling channels should be well designed to reduce the warpage of the plastic part; the injection pressure is medium (up to a maximum of 1500 bar), and the injection speed should be as fast as possible. It is recommended to use circular runners for runners and gates to increase the pressure transfer. The gate diameter should be between 0.8 - 1.0*t (t is the thickness of the plastic part). If it is a submarine gate, the recommended minimum diameter is 0.75mm. The PBT materials used in exhaust fans need to meet a series of standards to ensure their performance and safety. In China, generally speaking, exhaust fans need to comply with national standards GB4706.1 (General Safety Requirements) and GB4706.23 (Special Requirements for Air Processors and Their Applications). Specifically, it may involve the following aspects: - Electrical safety: Includes safety performance in aspects such as power supply, wires, plugs, etc.; - Mechanical safety: Involves the safety performance of the mechanical structure, rotating parts, protective covers, etc. of the exhaust fan; - Fan performance: Test the rotational performance, wind speed, air volume of the fan, etc. to ensure that its performance complies with standards and product descriptions; - Noise level: The noise level during the operation of the exhaust fan should be within the prescribed range; - Temperature rise test: Conduct temperature rise tests on components such as motors to ensure that they will not overheat during normal use; - Instructions for use and markings: The user manual and markings of the product should provide correct instructions for use and safety warnings. There are also relevant standards for PBT materials themselves, such as the industry standard HG/T 2361-1992 "Naming of Polybutylene Terephthalate (PBT) Thermoplastic Materials", etc. In addition, different manufacturers may adopt specific enterprise standards or refer to other relevant standards according to their own product positioning and quality requirements. To determine the specific PBT material standards, it is recommended to consult relevant product standard documents, industry norms, or consult professional certification agencies and material suppliers. They can provide more detailed and accurate information to meet the requirements of specific exhaust fan products in terms of performance, safety, etc. At the same time, with the development of technology and changes in market demand, standards may also be updated and adjusted, so it is also very important to pay attention to the latest standard dynamics in a timely manner.