The molecular weight of the chain guide gives it excellent serviceability, and it is a thermoplastic engineering plastic that is affordable and excellent in performance. It has almost the advantages of various plastics, and has unparalleled wear resistance, impact resistance, and ordinary polyethylene and other engineering plastics. Self-lubricating, corrosion resistance, impact energy absorption, low temperature resistance, not easy to adhere, not easy to absorb water, low density and other comprehensive properties. In fact, there is no single polymer material that has so many excellent properties.
Abrasion resistance of chain guide
The wear resistance of chain guide rails exceeds some metals. Figure 1 shows the wear resistance of UHMWPE compared with other materials. As can be seen from Figure 1, compared with other engineering plastics, the mortar wear index of UHMWPE is only 1/5 of PA66, 1/10 of HEPE and PVC; compared with metal, it is 1/7 of carbon steel, and brass 1/27. Such a high abrasion resistance makes it difficult to test the degree of abrasion resistance by ordinary plastic abrasion test methods, so a mortar abrasion test device is specially designed. UHMWPE wear resistance is directly proportional to molecular weight. The higher the molecular weight, the better the wear resistance.
The impact strength of the chain guide is better in all engineering plastics. Figure 2 shows the comparison of the impact strength of UHMWPE and other engineering plastics. From Figure 2, it can be seen that the impact strength of UHMWPE is about twice that of the impact-resistant PC and 5 of ABS 10 times more than POM and PBTP. The impact resistance is so high that it is difficult to break it by the usual impact test method. Its impact strength increases with increasing molecular weight, reaches a value when the molecular weight is 1.5 million, and then gradually decreases as the molecular weight continues to increase. It is worth pointing out that it can also maintain excellent impact strength in liquid nitrogen (-195 กใ C), which is a characteristic that other plastics do not have. In addition, it has higher surface hardness in repeated impacts.
UHMWPE has a very low friction factor (0.05 to 0.11), so it has excellent self-lubricity. Table 1 shows the comparison of friction factors between UHMWPE and other engineering plastics. It can be seen from Table 1 that the dynamic friction factor of UHMWPE is 1/2 of PA66 and POM under water lubrication conditions, and is second only to self-lubricating polytetrafluoroethylene (PTFE) in plastic under non-lubricated conditions; When sliding or rotating, it has better lubricity than steel and brass after lubrication. Therefore, in the field of tribology UHMWPE is known as a friction material with excellent cost / performance.
UHMWPE has excellent chemical resistance. In addition to strong oxidizing acids, it can withstand a variety of corrosive media (acids, alkalis, salts) and organic media (except solvents) in a certain temperature and concentration range. It was immersed in 80 kinds of organic solvents at 20 กใ C and 80 กใ C for 30 days, without any abnormal appearance, and other physical properties were also hardly changed.
The chain guide has excellent impact energy absorption. The impact energy absorption value is high in all plastics, so the noise damping performance is very good, and it has excellent clipping effect.
For the nuclear industry
The chain guide has excellent low temperature resistance and is ductile at liquid helium temperature (-269 กใ C), so it can be used as a low temperature resistant component in the nuclear industry.
Chain guides are hygienic and non-toxic and can be used in contact with food and medicine.
The surface of the chain guide rail has a very weak adsorption capacity, and its anti-sticking ability is second only to the non-sticky PTFE in plastic, so the surface of the product is not easy to stick to other materials.
The chain rail has a low water absorption rate; generally less than 0.01%, only 1% of PA66, so it is generally unnecessary to dry before forming.
Compared with other engineering plastics, the density of chain guides is relatively low.
Because the chain guide has the structural characteristics necessary for the tensile orientation, it has unmatched ultra-high tensile strength, so the fiber with ultra-high elastic modulus and strength can be produced by gel spinning method, and its tensile strength is as high as 3 ～ 3.5GPa, tensile elastic modulus is as high as 100 ～ 125GPa; the fiber specific strength is high among all the fibers that have been commercialized so far, 4 times larger than carbon fiber, 10 times larger than steel wire, and 50% larger than aramid fiber.