Exploration of Surface Treatment Technology for PEEK Polymer Materials

Analysis of Surface Treatment Technology for PEEK Polymer Materials The content of this article is:

This article introduces surface treatment technologies for PEEK, such as sandblasting, acid etching, silica coating and silane treatment, low-temperature plasma treatment, and introduces methods for selecting binders, in order to inspire the industry.

 

1 Surface treatment method

 

(1) Sandblasting:

Sandblasting is used to clean any contamination that may prevent chemical bonding, create a rough surface with a locking effect, expand the bonding area, generate micro retention forms, and form effective micro mechanical retention forces, thereby forming a locking connection.

For surfaces with different hardness to be treated, too small sand particles result in insufficient surface roughness and weak bonding strength; If the sand particles are too large, it will cause the surface to peel off and the roughness will decrease, or the interface stress will be concentrated due to the roughness, resulting in a decrease in bonding strength. Schmidlin et al. used 50 μ M and 110 μ The surface of PEEK was treated with m alumina particles for 10 seconds, and then combined with RelyX? Two bonding systems, Unicem and Heliobond/Metric, were used to bond and test the shear strength of the bonded specimens. The results indicate that when using the Heliobond/Metric bonding system, 110 μ After sandblasting with mAl2O3 particles, the shear strength value obtained was 11.9 ± 3.7MPa, using a 50 μ After sandblasting with mAl2O3 particles, the shear strength value obtained was 13.5 ± 2.4MPa. However, when using RelyXUnicem adhesive, the bonding strength was 0. This may be related to the change in interfacial wettability and crystal phase caused by the application of RelyXUnicem adhesive, which changed its properties from hydrophilicity to hydrophobicity.

(2) Acid etching method

In order to increase the bonding strength between repair materials and adhesives, acid etching can also be used as a surface treatment method. Hydrofluoric acid is often used to treat ceramics based on SiO2, which can roughen the surface of the ceramic and form micro mechanical retention at its interface, increasing the bonding strength.

Schmidlin et al. chose to treat the surface of PEEK with 98% concentrated H2SO4, resulting in a highly porous and permeable surface that allows the adhesive to penetrate more easily, thereby increasing the bonding strength. However, the selection of hydrochloric acid and nitric acid, regardless of the concentration chosen, did not cause any surface changes. Stawarczyk's study found that after acid etching treatment, the surface roughness of PEEK decreased, the contact angle increased, but the shear strength significantly increased. However, this phenomenon has not been clearly explained.

(3) Silicon dioxide coating and silane treatment technology

The silicon dioxide coating technology is an improvement of traditional sandblasting technology, which covers the surface of alumina particles with a layer of silicon dioxide. After high-temperature sandblasting treatment, a silicate coating is formed on its surface. This method is also known as frictional chemical coating. This method can not only increase the micro mechanical fixation between PEEK and resin binder like traditional sandblasting treatment, but also introduce silicon element on the surface of PEEK, making the silane coupling agent achieve ideal results.

(4) Low temperature plasma treatment technology?

Through low-temperature plasma treatment, multiple physical and chemical changes occur on the surface of the material, causing the non-polar surface to transform into a polar surface, resulting in etching and roughness, or forming a dense cross-linked layer, increasing the interaction between the bonding interface and improving the bonding performance. Nitrogen, oxygen, argon, and hydrogen are widely used in low-temperature plasma treatment of polymer material surfaces. Zhang et al. compared the bonding strength of semi crystalline PEEK treated with nitrogen, argon, and oxygen as low-temperature plasma, and found that the highest bonding strength was observed after argon low-temperature plasma treatment, while the lowest was observed in the nitrogen treatment group. Jha et al. treated PEEK with plasma at both atmospheric and low pressures, and the research results showed that the bonding force at atmospheric pressure was greater than that at low pressure. After plasma treatment, the surface roughness of PEEK increases, introducing polar groups, resulting in an increase in surface energy and improved adhesion. Moreover, as the plasma treatment time varies, the bonding strength also varies. This may be due to the destructive effect of the plasma treatment time on the active groups that have already formed on the surface of the specimen, reducing the number of active groups and thus affecting the adhesion.

2. Selection of adhesive

With the development of dental materials, adhesives as auxiliary materials for oral restoration materials are increasingly receiving widespread attention from dental material researchers. Adhesive materials play an important role in oral restoration, not only promoting the retention effect of the restoration and improving the bending strength of the restoration and abutment, but also improving the edge sealing effect, reducing edge micro leakage, and avoiding adverse effects on the restoration.

Zinc phosphate adhesive is the earliest bonding material used in oral repair, which essentially relies on mechanical retention and does not have chemical adhesion, only serving as an edge sealing agent. However, due to the solubility of zinc phosphate in saliva, it can cause micro leakage at the edge of the repair body. Therefore, preventing edge micro leakage and improving the bonding performance of zinc phosphate cement are still topics for further research.

Polycarboxylate zinc adhesive has hydrophilicity, expands the bonding area with dentin, and has chemical binding force with dentin in addition to mechanical bonding force. However, this cement has low compressive strength and is not suitable for repairing areas with high chewing pressure.

Glass ionomer adhesive is an ideal adhesive with strong adhesion, high hardness, and anti caries properties. It can form ion bonds with components in dental tissue to generate bonding and retention force. But its elastic modulus is low, making it unsuitable for use in areas with high chewing pressure. In addition, there is a resin reinforced glass ionomer binder, which is formed by modifying traditional glass ionomer binders. The curing method has both ion bonding and photo curing effects, and the mechanical strength and edge sealing have been significantly improved.

In the field of dental restoration, resin adhesives have become the most commonly used adhesive. Due to its superior bonding and aesthetic properties, this material is increasingly receiving widespread attention in clinical work. According to the different curing initiation systems, resin cement can be divided into three types: chemical curing type, light curing type, and double curing type. Dual curing resin is a self-adhesive resin cement that does not require acid etching or adhesive coating on the surface of the adhesive during use. It is easy to operate and has a good bonding effect.