In terms of surface treatment
1. Cleaning treatment: - Thoroughly remove impurities such as oil, dust, rust, and release agents from the surface of the materials to be bonded. For example, for metal surfaces, they can be wiped with organic solvents (such as acetone). For plastic surfaces, they can be washed with mild detergents and then rinsed clean with water. These impurities will hinder the close contact between the adhesive and the surface of the adherend, thus reducing the bonding strength.
2. Surface roughening: - Roughen the surface of the materials to be bonded by mechanical grinding, sandblasting, or other means. For example, when bonding metals, sanding the surface with sandpaper can increase the contact area between the adhesive and the material surface. Meanwhile, the rough surface also provides a better mechanical anchoring effect for the adhesive, just like small hooks, enabling the adhesive to adhere better to the material surface.
3. Chemical treatment: - According to the properties of the materials to be bonded, use appropriate chemical reagents for treatment. For instance, for some plastics (such as polyolefins), chromic acid solution can be used for treatment to generate polar groups on the surface, increase the surface energy, and enhance the chemical affinity with epoxy adhesives, thereby improving the bonding strength. In terms of adhesive formulation optimization

1. Selecting appropriate curing agents: - Different curing agents have a great impact on the performance of epoxy adhesives. For example, amine-based curing agents can make epoxy adhesives have higher strength and hardness. Aliphatic amines cure relatively quickly and can achieve a relatively high initial strength in a short time. While epoxy adhesives cured with aromatic amines have better heat resistance and chemical resistance, thus maintaining better bonding strength during long-term use.
2. Adding toughening agents: - Adding toughening agents to epoxy adhesives can improve their toughness and reduce the risk of brittle fracture. For example, adding rubber toughening agents (such as liquid nitrile rubber), these toughening agents can form an "island" structure during the curing process of the adhesive, absorb and disperse stress. When subjected to external forces, the toughening agent particles can prevent the expansion of cracks, thereby improving the bonding strength, especially in environments subject to impact and vibration.
3. Application of fillers: - Appropriate fillers such as silica and calcium carbonate can be added. Fillers can improve the rheological properties of the adhesive, prevent excessive shrinkage of the adhesive during the curing process, and reduce internal stress. Meanwhile, some functional fillers can also improve the temperature resistance, water resistance and other properties of the adhesive, indirectly enhancing the bonding strength.

 In terms of curing process
1. Controlling curing temperature and time: - Strictly control the curing temperature and time according to the instructions of the adhesive. Generally speaking, appropriately increasing the curing temperature can accelerate the curing speed, enabling the formation of a tighter cross-linking structure among the adhesive molecules and thus improving the bonding strength. However, if the temperature is too high, it may lead to the adhesive curing too quickly, generating internal stress, or causing the adhesive to decompose. So it is necessary to find a suitable curing temperature range. The curing time is also important. Incomplete curing will result in insufficient bonding strength.
2. Controlling curing pressure: - Applying appropriate pressure during the curing process can make the adhesive have better contact with the materials to be bonded, expel air and excess adhesive, and reduce the generation of bubbles and pores. For example, when bonding flat materials, clamps or weights can be used to apply a certain amount of pressure to make the adhesive distribute evenly and improve the compactness and strength of the bonding.