Zhisheng Technology Co., Ltd.

Classification
Banana oil is divided into two types: non-reactive diluents and reactive diluents.
1. Non-reactive diluent
Molecules of non-reactive diluents contain no active functional groups; most are inert solvents such as ethanol, acetone, toluene, etc. They do not participate in chemical reactions during dilution, merely blending with resin to reduce viscosity. Apart from dilution, they exert impacts on mechanical properties, heat deflection temperature, media resistance and aging resistance.
The solvent evaporation rate must be taken into consideration. If evaporation is too fast, a surface film readily forms on the adhesive layer and hinders the escape of internal solvent, resulting in bubbles inside the glue film. If evaporation is too slow, residual solvent remains trapped in the adhesive layer and reduces bonding strength. Solvents with different boiling points are usually blended to adjust evaporation speed.
This type is widely used for rubber-based adhesives, phenolic adhesives, polyester adhesives, epoxy adhesives and so on.
2. Reactive diluent
Reactive diluents feature active functional groups in their molecular structure. They participate in chemical reactions while diluting adhesives and can also provide toughening effects. For example, glycidyl ether of glycerol or butyl glycidyl ether added into epoxy adhesives serves as toughener.
Reactive diluents are mainly applied in epoxy adhesives and less commonly used in other adhesive systems.
Applications
The dissolution characteristics of polymers differ greatly from small-molecule compounds. Low-molecular crystalline substances such as sucrose have a solubility limit expressed as grams of sucrose soluble per liter of solvent. For amorphous polymers, however, solubility normally has no upper limit; polymers can be miscible with solvents in any proportion.
The essence of polymer dissolution can be interpreted as follows: the "voids" between polymer chain segments generated by thermal motion are immediately occupied by more mobile solvent molecules. This process continues until all polymer molecules are separated to form a "solution". The polymer dissolution process can also be regarded as a controlled diffusion process. From a qualitative perspective, it may be described that the polymer dissolves the solvent instead of the other way around.
If polymer molecules are crosslinked, the movement of chain segments is restricted. Slightly crosslinked polymers swell or dissolve slightly in solvent until the penetration/diffusion force balances the elastic contraction force of stretched polymer molecules, yet they will not dissolve into a free-flowing solution. Highly crosslinked polymers have no chain segment mobility and cannot absorb liquid, so no swelling or partial dissolution occurs.
Soluble polymers generally have a critical solution temperature. Below this temperature, the system separates into two phases: insoluble swollen polymer and nearly pure solvent.
Large amounts of non-solvents can often be added into polymer solutions without polymer precipitation. Such non-solvents can improve solubility and are known as latent solvents. There are cases where a mixture of two non-solvents acts as a good solvent for a certain polymer. For instance, nitrocellulose dissolves in ether-alcohol blend. The reverse situation also exists: cellulose acetate dissolves separately in aniline or strong acid, but not in their mixture.
Two effective methods to accelerate the dissolution rate of powdered polymers:
1. Suspend powder raw material in non-solvent first, then add true solvent. This procedure prevents agglomeration between polymer particles.
2. Apply heating to speed up dissolution.