How to Improve Scratching and Abrasion-resistance of Plastics

Generally, ultra-high molecular weight polyethylene (UHWMPE) is one of the most wear-resistant plastics. Selecting UHWMPE can simply improve the wear resistance of the material. In addition, plastics with high crystallinity and regularity are more wear-resistant, and plastics with higher hardness is more anti-abrasive. Plastics composed of macromolecules such as benzene rings is less resistant to wearing, such as polystyrene (PS). In polypropylene (PP) modification, polyolefin elastomers (POE), ethylene-propylene-diene rubber (EPDM), and thermoplastic dynamic vulcanizates (TPV) (such as dynamically vulcanized PP / EPDM) are usually used to flexibilize PP while the compounded elastomer generally results in a decrease in scratch resistance. Therefore, it is very important to choose a suitable elastomer. The comparison order of the scratch resistance is as follows: TPV> EPDM ＞ POE.

Molybdenum disulfide is a wear-resistant additive mainly used in nylon plastics. Molybdenum disulfide acts like a crystallization agent to increase the crystallinity of nylon, so that the nylon material produces a harder and more wear-resistant surface. Molybdenum disulfide has a high affinity to metals. Once adsorbed on the metal surface, the molecules of molybdenum disulfide will fill the pores on the metal surface that can be seen with a microscope and make the metal surface smoother. Molybdenum becomes an ideal anti-abrasive additive for applications where nylon and metal rub against each other.

The chemical structure of graphite is a unique lattice-like structure. This unique chemical structure allows graphite molecules to easily slide with each other when subjected to small frictional forces. This abrasion resistance is particularly important in environments with water, so graphite, as an ideal wear-resistant additive, is used in parts placed in water such as water-spreading shells, impellers, and value seals.

Glass fiber can form a strong mechanical bond between polymers, so glass fiber can improve the integrity of the thermoplastic structure and improve wear resistance. The reinforcement provided by glass fiber can improve the thermal conductivity and thermal deformation of plastics, and can significantly improve the load resistance and wear resistance of plastics.

Similar to the glass fiber, carbon fiber can greatly improve the integrity, load resistance and wear resistance of the material structure. Unlike glass fiber, carbon fiber is a softer and less scratchy fiber. Carbon fiber does not scratch the iron or steel friction surface that it rubs against.

Aramid fiber is also one of the wear-resistant additives. Unlike glass fiber and carbon fiber, it is the softest and least scratching fiber. This characteristic is the main advantage of aramid fiber in wear-resistant applications.

The friction coefficient of PTFE is very low. During the friction process, PTFE molecules will form a lubricating film on the surface of the part. PTFE has good lubricity and wear resistance under friction. In high load applications, PTFE is the best anti-wearing additive. These high-load applications include hydraulic piston ring seals and thrust washers. The PTFE content is generally 15% in non-crystalline plastics and 20% in crystalline plastics.

Polysiloxane liquid is a kind of migratory wear-resistant additive. When added to thermoplastics, the additive will slowly migrate to the surface of the part and form a continuous film. The lower the viscosity of polysiloxane is, the more quickly it can migrate to the surface of the part to provide abrasion resistance. But the viscosity of polysiloxane cannot be too low, otherwise it is easy to volatilize and will disappear from the part quickly.

When slipping agents such as oleic acid amide and erucamide are added into thermoplastics, they will migrate to the surface of the product to form a wax layer, which reduces the friction coefficient and reduces the visibility of scratches. The disadvantage is difficult to completely avoid surface stickiness.