Functional plastic particles (FPPs) play a vital role in numerous industrial sectors due to their unique physicochemical properties. However, their low surface energy often results in insufficient bonding strength with other materials, limiting their further application. Therefore, surface treatment technology is crucial for enhancing the bonding strength of FPPs with other materials.
Surface cleaning is the first and most critical step in the surface treatment of FPPs. During production, storage, and transportation, the surface of FPPs easily adsorbs oil, dust, and other impurities. These contaminants significantly reduce the bonding strength between the particles and other materials. Therefore, thoroughly removing surface contaminants using methods such as solvent cleaning, ultrasonic cleaning, or plasma cleaning is a fundamental step in improving bonding strength. A cleaned surface is not only smoother but also increases the contact area with other materials, creating favorable conditions for subsequent processing.
Physical abrasion is another commonly used surface treatment method. Mechanical abrasion creates micro-uneven structures on the surface of FPPs, increasing surface roughness. This rough surface provides more mechanical engagement points, allowing adhesives or coatings to penetrate and adhere better. Simultaneously, abrasion removes the aged surface layer, exposing a fresh, more active material surface, which is beneficial for improving bonding strength. However, it is important to control the force and uniformity during polishing to avoid over-polishing, which could alter the particle shape or damage the surface.
Chemical etching technology uses specific chemical solutions to corrode the surface of functional plastic particles, creating micropores or grooves. This treatment not only increases surface roughness but also introduces polar groups to the surface, increasing surface energy and thus enhancing wettability and adhesion to other materials. Chemical etching offers high selectivity and controllability, allowing for adjustments to etching depth and morphology to achieve personalized surface treatment effects. However, strict control of solution concentration, temperature, and etching time is crucial to prevent over-corrosion of the particles or the generation of harmful byproducts.
Plasma treatment is a highly efficient and environmentally friendly surface treatment method. It utilizes low-temperature plasma to bombard the surface of plastic particles, introducing oxygen- or nitrogen-containing functional groups, significantly improving surface polarity and wettability. Plasma treatment not only enhances the adhesion of functional plastic particles to adhesives or coatings but also improves their compatibility with other materials, broadening their application range. Furthermore, the plasma treatment process requires no chemical reagents and produces no wastewater or exhaust gas, aligning with the trend of green manufacturing. Besides the methods mentioned above, surface coating technology is also an effective means of enhancing the bonding strength of functional plastic particles. By coating the surface of functional plastic particles with a thin film with specific functions, such as an adhesive layer, compatibilizer layer, or protective layer, the bonding strength with other materials can be significantly improved. The choice of coating material should be based on the specific application scenario and performance requirements. For example, epoxy resins, polyurethanes, or silane coupling agents can all form strong chemical bonds on the surface of functional plastic particles, providing durable bonding strength.
In practical applications, it is often necessary to combine multiple surface treatment technologies to leverage their respective advantages and achieve the best bonding effect. For example, functional plastic particles can first be chemically etched to increase surface roughness and polarity, then subjected to plasma treatment to further improve surface energy and wettability, and finally coated with an adhesive layer to ensure a strong bond with other materials.
