Fillers and reinforcements provide a physical barrier to abrasive particles, reducing their penetration into the polymer matrix. This helps prevent wear. Some commonly used reinforcing materials include:
Synthetic fibers: have excellent mechanical properties that significantly improve wear resistance. Examples include glass, carbon and aramid fibers. Short-cut glass fibers (e.g., short, randomly oriented glass fibers) can improve impact and abrasion resistance.
Natural fibers: Can be added to polymers to improve abrasion resistance and provide a more sustainable material. Examples include cotton, flax and other natural fibers.
Glass scales: They are flat, elongated particles with excellent abrasion resistance and dimensional stability. They reinforce the polymer matrix and reduce surface friction.
Silicon Dioxide: This is a common filler with high surface area and reinforcing properties. It improves wear resistance by providing a physical barrier to abrasive particles and enhancing the mechanical strength of the polymer.
Aluminum Oxide: has excellent hardness and abrasion resistance, making it an ideal filler for applications requiring high durability.
Talc: a soft, flaky mineral that improves abrasion resistance by reducing friction and enhancing the surface smoothness of polymers
Mica: It is a layered silicate mineral with excellent mechanical properties and thermal stability that improves abrasion resistance and dimensional stability.
Carbon Black: It is a high coloring power filler with both abrasion resistance and UV protection. Its fine particle size and high surface area help to enhance its performance.
Lubricants
Lubricants reduce the coefficient of friction between the polymer surface and the abrasive particles, thus minimizing wear.
Waxes: Reduce friction between the polymer surface and the abrasive particles. Examples include paraffin, beeswax and other waxes.
Fatty acids: Act as lubricants and improve processing properties. Examples include stearic acid, oleic acid and other fatty acids.
Silicones: Silicone oils and greases provide excellent lubrication and mold release properties.
Fatty acid amides: compounds derived from fatty acids that improve polymer processability and reduce internal friction.
Crosslinking Agents
Crosslinking agents form stronger polymer networks that are less prone to deformation and wear. This improves the wear resistance of the material.
Peroxides: Organic compounds that break down to form free radicals that initiate cross-linking reactions. Common peroxides include benzoyl peroxide and diisopropyl benzene peroxide.
Epoxy Resin: A reactive compound that forms a cross-linked structure when mixed with an appropriate curing agent. Epoxy resins are used to enhance the abrasion resistance of polymers.
Polytetrafluoroethylene (PTFE)
PTFE has the lowest coefficient of friction of all antiwear additives. The PTFE molecules abraded during friction form a lubricating film on the part surface. It provides good lubricity and wear resistance under frictional shear.
PTFE is the best wear additive in high load applications. These high load applications include hydraulic piston ring
seals and thrust washers. The optimum PTFE content is 15% PTFE for amorphous plastics and 20% PTFE for crystalline plastics.
Polysiloxanes
Polysiloxane fluids are migratory wear additives. When added to thermoplastics, the additive slowly migrates to the part surface and forms a continuous film. Polysiloxanes have a wide range of viscosities, measured in centistokes. Polysiloxanes have very low viscosities and will migrate to the part surface as a fluid to provide abrasion resistance. If the viscosity of the polysiloxane is too low, it is more volatile and will quickly disappear from the part.
Molybdenum Disulfide
The common name for molybdenum disulfide is “Moly”. It is a wear additive used primarily in nylon plastics. Molybdenum disulfide acts as a crystallizing agent to increase the crystallinity of nylon. This produces a harder, more wear-resistant surface on the nylon material. It has a high affinity for metals. Once adsorbed on a metal surface, the molecules of molybdenum disulfide fill micropores in the metal surface, making it more slippery. This makes molybdenum disulfide an ideal wear additive for applications where nylon and metal rub against each other.
Other Commercial Additives
A number of additives can modify the surface properties of polymers to make them more resistant to wear. Some commercially available additives that enhance the performance of polymers are described below.
BASF's Irgasurf® SR 100 B: Provides excellent scratch and abrasion resistance. It lubricates the surface and reduces the visibility of scratches. Its dosage is typically 1-3%.
Ampacet's ScratchShield™: Can be used on PET packaging, bottles and preforms. It helps resist scratching and abrasion and also provides anti-slip properties.
SILIKE® LYSI-306 from Chengdu Silicone Technology: This is a pelletized formulation in which 50% of the UHMW silicone polymer is dispersed in
Polypropylene ( PP ). It is widely used as a highly effective additive in PP-compatible resin systems to improve processability and surface quality, such as better resin flow, die fill and release, less extruder torque, lower coefficient of friction, and higher scuff and abrasion resistance.
Silma's SILMAPROCESS: These additives improve the abrasion resistance of rigid plastics ( PE , PP, PS,
HIPS, PA, PET, etc.) and thermoplastic rubbers (SBS/SEBS, TPV, TPE, copolyester, EPR/EPDM, EVA, POE, TPU, etc.). They also improve other surface properties such as surface smoothness, scratch resistance and hydrophobicity.
Polymer Wear Resistance Competition
Different polymers have different abrasion resistance. Some of them are described below.
Nylon or polyamide (PA) is known for its excellent abrasion resistance and for applications where durability is important. Specific abrasion resistance may vary depending on the type and formulation of the nylon. Nylon is a popular choice for sportswear, backpacks and luggage.
Epoxies offer higher abrasion resistance than other polymers such as polyurethanes.
Polysiloxanes have higher abrasion resistance than polyurethanes.
Polyethylene (PE) has a lower coefficient of friction, which allows it to slide over surfaces rather than scrub them.
Polyurethane (PU) has lower abrasion resistance than epoxies and polysiloxanes and may not protect the underlying coating. PU with a durometer of 90 Shore A has higher abrasion resistance than ultra-high molecular weight polyethylene (
UHMWPE).
Polyvinyl chloride ( PVC ) has moderate abrasion resistance, but its performance varies depending on the specific formulation and additives.
Polyetheretherketone ( PEEK ) is a thermoplastic known for its naturally low friction and all-around wear and fatigue resistance. Its outstanding durability and performance in harsh environments make it the material of choice for components in a wide range of industries
Polydicyclopentadiene (PDCP)
Polydicyclopentadiene (PDCPD) is a liquid plastic raw material with excellent abrasion resistance and low friction properties. This thermoset resin is flexible, lightweight, impact resistant and corrosion resistant.
Polyoxymethylene ( POM ) offers low friction, high abrasion resistance, strength and excellent performance in wear applications. High tensile strength, fatigue resistance and creep resistance make it ideal for high-performance parts.
Polyester is a synthetic fiber with excellent abrasion resistance. It is commonly used in upholstery, workwear and outdoor equipment.
