As we all know, materials are paramount in all aspects of industry, and materials with different properties have different uses. Polyvinyl alcohol (PVA) is a water-soluble substance with a wide range of applications, including building materials, adhesives, textiles, papermaking, and pharmaceuticals. The key factor that determines its performance is its degree of hydrolysis.

 

1. The Meaning of the Degree of Hydrolysis

PVA is not made directly from ethylene, but is derived from the hydrolysis of polyvinyl acetate (PVAc). During hydrolysis, acetate groups are removed and hydroxyl groups are replaced. A higher degree of hydrolysis indicates purity, while a lower degree indicates impurity. The so-called "degree of hydrolysis" refers to the percentage of hydroxyl groups in the product. A higher degree of hydrolysis indicates a purer PVA.

Based on the degree of hydrolysis, it can be divided into three grades:

Fully hydrolyzed: Hydrolysis rate of 98% or above, nearly pure;

Moderately hydrolyzed: Hydrolysis rate of 90% to 97% with balanced properties;

Partially hydrolyzed: Hydrolysis rate of 85% to 89% with cold water solubility.

 

2. Applications of Hydrolysis Degree

Partially hydrolyzed (85–89%): Cold soluble, best suited for paper coating, textile sizing, soluble films, and adhesives, with excellent emulsification and dispersing properties.

Fully hydrolyzed (≥98%)
Requires hot water dissolution and is commonly used in ceramic molding, construction latex powder (RDP), PVA fibers, and water-soluble films. It produces strong, chemically stable films with excellent solvent resistance.

Medium hydrolyzed (90–97%)
Features balanced properties and is suitable for all industrial applications, such as vinyl emulsions, general adhesives, and paper reinforcement.

 

3. Selecting Grades

When purchasing PVA, it is important to carefully consider the process requirements and select the appropriate grade. For example:

For adhesive production, partially hydrolyzed grades such as PVA 2488 and Selvol™ 203 should be used.

For fiber spinning or film production, fully hydrolyzed grades such as PVA 1799 and Selvol™ 125 should be used.

For emulsions or construction adhesives, moderately hydrolyzed grades such as PVA 205 are suitable.

 

The degree of hydrolysis is the very essence of PVA. Its dissolution speed, adhesion strength, film toughness, and durability are all influenced by it. Therefore, understanding its degree and distinguishing its quality can help us optimize its use, maximize its potential, and achieve twice the efficiency.

 

Our factory specializes in PVA products, offering a wide range of specifications. Customization of hydrolysis degree and mesh size is possible. We offer brands such as Sinopec, Shuangxin, Dadi, Jinshu, and Yinghang. Our quality is reliable, and we offer preferential pricing for large quantities. For more information, samples, or technical data, please contact us.