Classification and characteristics of engineering plastics

Engineering plastics refer to engineering structural materials that can replace metals. Compared with ordinary plastics, it has better comprehensive properties, greater mechanical strength, better chemical resistance, and a wider working temperature range; compared with metal materials, Engineering plastics have lower costs and lighter weight. Therefore, the proportion of engineering plastics in the plastics industry has increased year by year, and has been widely used in many engineering fields such as automobiles, construction, machinery, office equipment, electronics and electricity, aerospace, etc. The development of engineering plastics not only plays a supporting role in the country's pillar industries and modern high-tech, but also promotes the reform of traditional industries and the adjustment of product structure.

Engineering plastics can be divided into two categories: general engineering plastics and special engineering plastics. Common general engineering plastics include nylon (PA), polycarbonate (PC), polyacetal (POM), thermoplastic polyester (PBT), and polyphenylene oxide (PPO). Common special engineering plastics include polyphenylene sulfide (PPS), liquid crystal polymers (LCP), polyketones (such as polyetheretherketonePEEK), etc. The comprehensive properties of special engineering plastics are better than those of general engineering plastics, but the cost is relatively higher.

Other characteristics of engineering plastics:

1.& nbsp;

The relative density of low-density and light-weight engineering plastics is between0.9 and 2.3 g/^cm3, which is much smaller than that of metal materials. Therefore, they can replace some metal materials in the fields of automobiles and aerospace, reduce weight and reduce energy consumption.

2.& nbsp;

Glass fiber and carbon fiber are added to engineering plastics with high specific strength. These fibers form a strong mechanical bond in polymers, improving the strength of engineering plastics, and even partially exceeding steel: the tensile strength and quality of engineering plastics The ratio can usually reach 1500- 1,700, while the specific strength of steel is 1600 and the specific strength of aluminum is 1500.

3.& nbsp; Engineering plastics are used as friction parts with excellent wear resistance and self-lubricating properties

. The relative wear amount to wear-resistant metals is less than 1:5. Many friction-resistant parts use this property of engineering plastics to reduce wear and reduce costs.

4.& nbsp; Good electrical insulation properties

Almost all plastics have excellent electrical insulation properties, such as minimal dielectric loss and excellent arc resistance characteristics.

5.& nbsp; Good chemical resistance

Compared with metal materials, engineering plastics have no threat of corrosion and oxidation; compared with ordinary plastics, the chemical properties of engineering plastics are more stable.

6.& nbsp; Engineering plastics with good processing properties

have low processing temperatures (usually below 400 ℃); their shrinkage rate is lower than that of metal materials, which can well ensure the stability of the size of the part; compared with metal processing, it saves energy consumption, time and cost.

7.& nbsp; Heat resistance is good.

After glass fiber reinforcement, the long-term use temperature of general engineering plastics and modified engineering plastics is inthe range of 100~150 ℃, while the long-term use temperature of special engineering plastics is above 150℃, which can adapt to most engineering applications.

8.& nbsp; Good light transmission performance and protective performance

. The light transmission performance of engineering plastics reaches <span style="font-size: 16px; font-family: Calibri;">87%~91%, close to glass, but its protective properties are better than glass and can be used to make aviation glass.

9.& nbsp; Engineering plastics with good mechanical properties

usually have good impact and fatigue resistance.

技术支持：郭洪华

编辑：刘康利