Polyvinyl Alcohol 0488

The core of polyvinyl alcohol (PVA) performance lies in its degree of hydrolysis. The 88 Series PVA, which is partially hydrolyzed (usually around 87.0 to 89.0 mol%), differs from the fully hydrolyzed 99 Series in that it provides better flexibility, interfacial activity, and water solubility that can be adjusted. When PVA is partially hydrolyzed, about 11% to 13% of vinyl acetate groups (-OAc) are kept in the molecular chain. Because of these hydrophobic groups, the 88 Series PVA acts as an amphiphilic substance with high interfacial activity, unlike the 99 Series. Because of this, it works well as a protective colloid in emulsion polymerization and as a flexible base for strong adhesives and coatings with specific functions.     1. Molecular Structure Determines Function: Amphiphilicity and Protective Colloid Mechanism 1.1  Amphiphilicity Due to Hydrophobic-Hydrophilic Balance Partially hydrolyzed 88 series PVA molecular chains possess two functional groups with vastly different polarities: Hydrophilic groups: A large number of hydroxyl groups (-OH). Hydrophobic groups: A small number of evenly distributed vinyl acetate groups (-OAc). This structure makes PVA a highly effective high-molecular-weight surfactant or protective colloid. When dissolved in water, the molecular chains adsorb at the water-oil (monomer) interface, with the hydrophobic groups tending to embed into the oil phase, while the hydrophilic groups extend toward the water phase. This unique arrangement forms a stable, high-molecular-weight physical barrier (i.e., a protective steric barrier) around the oil phase particles, effectively preventing aggregation of emulsion particles during polymerization, storage, or mechanical shear, and is the core mechanism for ensuring emulsion stability. 1.2 Reduced Crystallinity and Improved Water Solubility Unlike the highly regular structure of the 99 series, the irregular distribution of vinyl acetate groups on the molecular chain disrupts the regular packing of PVA molecules, resulting in: Reduced crystallinity: The proportion of crystalline regions decreases, weakening the hydrogen bond network. Improved cold-water solubility: Lower crystallinity allows water molecules to more easily penetrate and disrupt the amorphous region structure. Therefore, 88 series PVA can dissolve quickly or even completely at lower temperatures (typically 40°C to 60°C), greatly simplifying dissolution operations during formulation and production.   2. Effect of Degree of Polymerization on Rheological Properties and Stability Given a consistent level of partial hydrolysis, the key differences between different PVA grades are mainly in their average degree of polymerization (DP) or molecular weight (MW). The DP has a direct impact on the viscosity of the PVA solution, the thickness of the steric barrier layer, and how the emulsion ultimately performs. The refined positioning of Shuangxin's 88 series grades: Shuangxin PVA Average degree of polymerization Average molecular weight Core application positioning 2688 / 2488 2400~2650 118000~130000 High molecular weight: Provides the strongest steric protection and is used in emulsion polymerizations requiring the highest stability (such as high-performance VAE emulsions). 2088 / 1788 1700~2100 84000~104000 General purpose: Balances viscosity and protection for general-purpose PVAc and VAE emulsions and adhesives. 1792 1700~1800 54000~60000 Medium-low molecular weight: Suitable for specialty water-soluble fibers and viscosity-sensitive coating systems. 0588 / 0488 420~650 21000~32000 Ultra-low molecular weight: Minimal effect on solution viscosity, suitable for inks, inkjet coatings, or as a co-stabilizer in emulsions. High degree of polymerization (Polyvinyl Alcohol 2688/2488): Long molecular chains provide a stronger steric hindrance. In emulsion polymerization, long chains help distribute and stabilize monomer droplets and polymer particles, which is needed for high-solids, high-viscosity emulsions. Ultra-low degree of polymerization (Polyvinyl Alcohol 0488/0588): These stabilizers function similarly to small-molecule emulsifiers, but provide improved polymer adhesion. Their low viscosity allows them to be used in high-solids coatings and slurry systems without affecting the rheological properties of the final product.   3. Analysis of Key Industrial Applications of Partially Hydrolyzed 88 Series PVA The interfacial activity and controllable water solubility of the 88 series PVAs give them core competitiveness in the fine chemicals, adhesives, and specialty materials sectors: 3.1 Emulsion Polymerization Industry: Stabilizers and Protective Colloids This is the core and irreplaceable application of the 88 series PVAs. It is widely used in the polymerization of monomers such as vinyl acetate (VAc), acrylates, and styrene-acrylates, and is a key additive in the manufacture of PVAc, VAE, and acrylate emulsions. Mechanism: 88 Series PVA acts as a protective colloid, not only stabilizing the emulsion during the initial polymerization phase but, more importantly, determining the freeze-thaw resistance, mechanical shear stability, and rewettability of the final emulsion. Applications: Architectural coating emulsions (such as interior wall latex paint), wood adhesives (white latex), textile nonwoven adhesives, carpet adhesives, etc. 3.2 Water-Solubility and Functional Films/Fibers The low crystallinity of partially hydrolyzed PVA makes it easier to dissolve quickly in cold water, making it a preferred environmentally friendly packaging material. Water-Soluble Packaging Film: Used for quantitative packaging of products such as pesticides, dyes, detergents, and laundry detergent beads. Upon application of water, the film quickly dissolves, releasing the contents, providing both convenience and environmental friendliness. Water-Soluble Fiber: Used in the textile industry as temporary support yarn or "sacrificial" yarn. After the fabric is finished, the PVA fibers dissolve in warm water, leaving behind a fabric with a special openwork or structural effect. 3.3 Adhesive and Coating Systems Adhesives: Due to the retention of hydrophobic groups in the molecular chain, 88-series PVA has better affinity and adhesion to certain hydrophobic surfaces and organic materials than 99-series PVA. It is widely used in specialty paper adhesives and rewettable adhesives (such as postage stamp adhesives). Specialty Coatings: Ultra-low molecular weight grades (such as 0488) can be used as ink-receiving coating additives for inkjet printing paper, providing excellent pigment binding and fast drying properties without significantly increasing coating viscosity. 3.4 Other Fine Chemical Applications Suspension Polymerization Dispersant: Used in the suspension polymerization of PVC resins, it helps control the size, porosity, and density of PVC particles, which is crucial to the processing properties of PVC resins. Ceramic Binder: Used as a temporary binder for bonding ceramics before molding and sintering. After sintering, it can be completely burned and vaporized, leaving no residue.   4. Conclusion: Continuous Innovation in Partially Hydrolyzed 88 Series PVA Shuangxin partially hydrolyzed 88 Series PVA takes full advantage of both hydrophilic and hydrophobic elements in its molecular structure. This allows for careful control during emulsion polymerization and affects how well it sticks and dissolves in water. If the 99 Series is the "rebar" of structural materials, then the 88 Series is the "stabilizer" and "flexibility controller" of fine chemical systems. Partially hydrolyzed 88 Series PVA is still critical to the growth of modern fine chemicals and sustainable materials. This is due to the continued expansion of markets, like those for green water-based coatings, good emulsions, and biodegradable packaging, along with PVA's special interfacial chemistry and grade system.   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com