PVA is the abbreviation of polyvinyl alcohol, which is a water-soluble polymer material with high hydrophilicity. PVA is often used in the manufacture of cosmetics, paper, glue, coatings, food packaging and other fields. PVA has good solubility. The dissolution method of PVA varies depending on the application field and demand, and each method has its own unique advantages and disadvantages. Choosing a suitable dissolution method can improve the solubility and stability of PVA, making it more widely used in different fields.
1. Temperature rise dissolution method
The temperature rise dissolution method is one of the most commonly used methods for dissolving PVA. Add PVA powder to an appropriate amount of water, then stir evenly and heat to an appropriate temperature to completely dissolve the PVA. Normally, the dissolution temperature of PVA is between 60 and 95 ℃. The dissolution temperature of PVA is related to its degree of polymerization and acetate content. The higher the degree of polymerization, the more acetate content, and the higher the dissolution temperature. The solubility and dissolution rate of PVA can be controlled by changing the temperature and time.
2. Dissolution by auxiliary agent
In addition to directly adding PVA to water for dissolution, the solubility and stability of PVA can also be improved by adding auxiliary agents. Common auxiliary agents include acetone, methanol, ethanol, phenol, etc. These auxiliary agents can form hydrogen bonds or other interaction forces with PVA, thereby improving solubility. The addition of auxiliary agents can also shorten the dissolution time of PVA.
3. Slow cooling and dissolution
The slow cooling method is a special PVA dissolution method, which is suitable for the preparation of polymers, micro-nano particles, films, fibers and other materials. The basic principle of the slow cooling method is to add PVA powder into water, heat it to dissolve it, and then slowly cool it down to make the PVA molecules self-assemble to form nanoparticles, nanofibers or films. The slow cooling rate has an important influence on the self-assembly process of PVA. Generally speaking, the slower the slow cooling rate, the more complete the structure of the PVA self-assembly. The slow cooling method is mainly suitable for the preparation of micro-nano materials.
4. Gas phase dissolution
The gas phase method is a relatively new PVA dissolution method. In this method, the PVA solid enters the atmosphere through the dissolution hopper. By controlling the temperature, pressure and atmosphere composition, the PVA solid is directly evaporated into gaseous molecules, and then transported to other equipment through a transmission pipe for reaction or solidification to form a corresponding block. Unlike the traditional dissolution method, the gas phase method can prevent the PVA molecules from being affected by water decomposition, thereby maintaining the integrity and quality of the material.
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