With the development of resins/ hot melt glue technology, composite pipelines have being used in more and more fields. Higher standard and requirement are put forward, such as high strength, high pressure resistance, corrosion resistance, wear resistance. Therefore, besides of the materials for plastic pipeline and reinforced layer, high-performance adhesive resins also are acquired in composite pipeline production. Ad resin manufacturer, how to choose a high-performance adhesive resin needs to focus on the following aspects.
5.1 Polarity and cohesive energy
Firstly, the adhesive strength of hot melt glue is closely related to the polarity of material. The bigger polarity of hot melt adhesive resin is, the stronger adhesive strength will be. On the other hand, it is recognized that the destruction of high-performance adhesive resin should take place at material inner, rather than the interface between adhesive resin and material to be bonded, which acquires that adhesive resin have enough cohesive energy.
1.2 Molecular weight of hot melt glue composition
Because of the low molecular weight of polymers the intermolecular interaction is weak, which leads to weak material strength and adhesive strength of adhesive resin. With the increase of molecular weight of polymer, the interaction between molecules increase, and the adhesive strength will obviously increase. However, the wettability of adhesive resin reduced when the molecular weight is high enough. Thus, adhesive strength of adhesive resin can be affected by weight of polymer in adhesive resins.
1.3 Structure of main chain and side chain of hot melt adhesive
Flexibility of molecular chain in adhesive resin depends on the structure of polymer main chain. Good flexibility of polymer can improve the shock resistance of materials. If there were rigid structures in polymer main chain, the flexibility of polymer will reduce, which leaded that the adhesive strength and shock resistance reduced but heat resistance of adhesive resin elevated. Therefore, a adhesive resin with excellent comprehensive performance need to coordinate the flexible and rigid structure in polymer main chain. Side chain also played a important role in the performance of adhesive resin by influencing the flexibility of polymer main chain
1.4 Crosslinking degree in adhesive resin
The cross-linked reaction at material inner can elevate cohesive energy of adhesive resin layer. Therefore, moderate crosslinking will improve the adhesive strength of adhesive resin. However, if the crosslinking degree is too high, the flexibility of polymer and the wettability of adhesive resin will reduce to seriously affect the adhesive property.
1.5 Crystallization behavior of adhesive resin
The crystallization behavior greatly affect the adhesive property of adhesive resin. It is recognized that the cohesive energy, strength, modulus and heat resistance will increase with degree of crystallinity of adhesive resin whereas the flexibility and adhesive strength is not. Therefore, moderate crystallization behavior contribute to elevate the adhesive strength of adhesive resin.
With the rapid development of composite pipeline industry, there is an increasing performance requirement on adhesive resin in production. We will steadily improve the adhesive and application performance by researching the structure, synthetic and cohesive mechanism of adhesive resin, and develop high-performance and widely applied new products. Adhesive resin must play a active role in the development of composite pipeline industry.
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