Film Formation

PVP is made from monomer vinylpyrrolidone (NVP) as raw material and is obtained through bulk polymerization, solution polymerization and other methods. In the process of bulk polymerization preparation, due to the high viscosity of the reaction system, the polymer is not easy to diffuse, and the heat of polymerization reaction is not easy to remove, resulting in local overheating. Therefore, the molecular weight of the obtained product is low, the content of residual monomer is high, and it is mostly Yellow, not of much practical value. In industry, solution polymerization is generally used to synthesize PVP. There are two main routes for PVP production and polymerization.

The first is solution polymerization of NVP in organic solvents and then steam stripping. The second route is aqueous solution polymerization of NVP monomers and water-soluble cationic, anionic or nonionic monomers. Directly heat the NVP monomer to above 140°C, or add an initiator to the NVP solution for heating, or add an initiator to the NVP solution (the solvent can be water, ethanol, benzene, etc.) to polymerize through free radical solution, or directly use PVP homopolymer can be obtained by irradiating NVP monomer or its solution with light. Different polymerization methods result in different polymer structures and properties. Among them, the polymer obtained by free radical solution polymerization has a more uniform composition and structure. The performance is also relatively stable, and it is the most commonly used method for NVP homopolymerization. By adjusting the monomer concentration, polymerization temperature, initiator dosage and other reaction conditions, PVP homopolymers with different molecular weights and different water solubilities can be obtained.

Configure NVP into a solution with a mass fraction of 50%, use a small amount of hydrogen peroxide as a catalyst, and initiate polymerization at 50°C under the action of azobisisobutyronitrile, so that almost all NVP is converted into PVP. Then add ammonia water to the polymer to decompose the remaining azobisisobutyronitrile. The monomer polymerization conversion rate is nearly 100% and the solid content is 50%.

Add 0.4g of dispersant P (NVP-co-VAc) and 80g of dispersion medium ethyl acetate into a 250 mL four-necked flask. After stirring and dissolving in a 70°C constant temperature water bath, add 20g of monomer NVP and 0.15g of initiator AIBN. , react under a nitrogen atmosphere for 6 hours, cool and filter, and place the insoluble matter in a vacuum drying box for vacuum drying for 24 hours to obtain white PVP solid powder.

Most of the polymerization of PVP uses AIBN as the initiator. There is no literature on using water-soluble azo initiators to initiate the synthesis of PVP, but some people are doing work in this area. Since both NVP monomer and PVP are soluble in water, water-soluble azo initiators can be used to initiate polymerization to generate linear PVP polymers. Moreover, AIBN contains cyano groups that are harmful to the human body, and water-soluble azo initiators Most initiators do not contain cyano groups, and PVP is mostly used in products that come into direct contact with the human body, so water-soluble azo initiators have more advantages than AIBN.

Organic peroxidecrospovidone sds is structurally different from thermoplastics, thermosetting resins and vulcanized rubber. It has a body structure but is not completely cross-linked. The cross-linked area is small and does not have a large cross-linking network like vulcanized rubber. In terms of performance, it has the characteristics of all three, that is, it has both thermoplasticity, hardness, good solvent resistance, high elasticity and excellent low temperature resistance. Whether it is high-density polyethylene or low-density polyethylene, after crosslinking, its tensile strength, heat resistance, aging resistance and weather resistance, dimensional stability, stress crack resistance, abrasion resistance and solvent resistance are all Improved, and excellent creep resistance. The softening point of cross-linked polyethylene can reach 200℃, and the heat resistance can reach 140℃. In addition, it also has excellent electrical insulation, low temperature resistance and radiation resistance. The properties of peroxide cross-linked polyethylene.

M.F.: (C6H9NO)n
M.W.: >1 000 000
CAS No.：9003-39-8
Appearance: White or off-white powder; almost odorless; it's hygroscopic.
Insoluble in water, ethanol, chloroform or ether.
Alpha PVPP is available in two particle size to serve different application requirement.
This product is white or off-white powder; almost odorless; hygroscopic. This product is insoluble in water, ethanol, chloroform or ether. This product has a high capillary/water content capacity, a large specific surface, extremely strong hydration capacity (HK: 5.6), high and rapid water absorption (58.5%), strong water absorption and swelling capacity, a swelling coefficient of 2.25-2.30, and polyethylene Pyrrolidone has the same complexing ability and can complex a variety of substances, such as phenols, iodine, etc.