PVA Polyvinyl Alcohol 088-20

VAE emulsions are environmentally friendly products. Vinyl groups are embedded in the polyvinyl acetate molecular chain, giving the polymer emulsion a low film-forming temperature and excellent film-forming properties. They exhibit strong adhesion to difficult-to-adhere materials such as PET, PVC, PE, and PP. The polymer film produced is very water and weather resistant. It also holds up well to scrubbing and remains flexible even at low temperatures. The thickness of VAE emulsions is impacted by a number of things.    1. Effect of Solids Content on Viscosity We conducted extensive testing on the formulations and process conditions of VAE Emulsion DA-180L and VINNAPAS 400, respectively. The data in the following tables are derived from these tests. The relationship between solids content and viscosity is shown in Table 1. As shown in Table 1, higher solids content increases viscosity. This is because higher solids content increases the number of colloidal particles in the same emulsion mass, reduces the amount of aqueous phase, and increases the total surface area of the particles. This enhances interparticle interactions and resistance to motion, resulting in higher viscosity.   2. Effect of Protective Colloids on Viscosity In emulsion polymerization, protective colloids are often used as emulsion stabilizers to improve emulsifier stability and adjust viscosity. The emulsion stability of partially hydrolyzed PVA is also related to the distribution of acetyl groups on the polymer chain. A higher degree of blockiness in the acetyl group distribution results in greater surface activity, better emulsion stability, and smaller and more viscous emulsions. The higher the PVA degree of polymerization, the higher the viscosity of the polyvinyl alcohol aqueous solution before polymerization, and the higher the viscosity of the VAE. The higher the degree of alcoholysis of PVA, the lower the viscosity of the VAE. PVA's protective colloid ability increases with increasing degree of polymerization. Low-degree PVA forms coarser latex particles and has lower viscosity. An increase in the degree of polymerization improves both the protective and dispersing capabilities. To maintain the dispersion and protective properties of PVA during emulsion polymerization, while only adjusting the viscosity, the total amount of PVA is typically kept constant, with only the ratio between the two adjusted. With other conditions remaining unchanged, adding 4.54 kg of PVA Polyvinyl Alcohol 088-20 will increase the viscosity of each batch by 100 mPa·s. Table 2 lists the molecular weight and molecular weight distribution of high- and low-viscosity VAE emulsions. Table 2 shows that the low-viscosity emulsion has a higher molecular weight, coarser particles, and a wider particle size distribution than the high-viscosity emulsion, resulting in lower viscosity.   3. Effect of Initial Initiator on Viscosity The initiator has a main influence on the speed of polymerization. The more initiator is used, the faster the polymerization reaction is, and the reaction is difficult to control. After the polymerization conditions and the type of initiator are determined, the amount of initiator can be used to adjust the molecular weight of the polymer. The more initiator is used, the smaller the molecular weight of the polymer is, and the viscosity of the emulsion increases, and vice versa. Among them, the amount of initial initiator (ICAT) added has the greatest impact. These data clearly show that the more initial initiator is added, the higher the viscosity of the emulsion. This is because the more initial initiator is added, the more difficult the monomer is to react or the reaction rate is slow in the initial stage, and the resulting polymer has a smaller molecular weight, smaller particle size, and higher viscosity.   4. Conclusions (1) The higher the solid content of the emulsion, the greater the viscosity. (2) The higher the degree of polymerization of the protective colloid PVA, the greater the viscosity of the emulsion, and vice versa. (3) The viscosity of the emulsion when PVA is used as a protective colloid is higher than that when cellulose or surfactant is used as a protective colloid. (4) With the same degree of polymerization, the higher the degree of alcoholysis, the lower the viscosity of the emulsion. (5) The more initial initiator and total amount of initiator added, the higher the viscosity of the emulsion.   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com

VAE emulsion are water-based and good for the environment. They're used a lot as binders in strong glues. As the tech gets better and the emulsion market grows, people want more VAE emulsions, mainly those with a lot of ethylene. These high-ethylene VAE emulsions are great at resisting water and alkali, so they're becoming more popular. How much ethylene is in VAE emulsions depends on things like pressure, temperature, time, how much initiator is used, the type and amount of emulsifier, and how the VAE is added. Lately, the market wants VAE emulsions that bind water really well. This paper looks at how the amount of ethylene in VAE emulsions affects them. We used different molecular weights of polyvinyl alcohols (PVA Polyvinyl Alcohol 088-20 and PVA Polyvinyl Alcohol 0588) as protective colloids, and a special PVA was used as part of the protective colloid to see how these colloids change the VAE emulsion properties.   1.Effect of Emulsifier Content on Emulsion Properties In emulsion polymerization systems, the type and concentration of the emulsifier, as well as various factors that may influence the emulsification effect of the emulsifier, directly affect the stability of the polymerization reaction and, ultimately, the properties of the emulsion. As seen in Table 3 and Figure 2, a rise in emulsifier content leads to a higher conversion rate but a lower gel fraction. If the emulsifier surpasses 4%, the conversion rate drops, suggesting the substance is not chemically stable. Therefore, the optimal emulsifier content for this experiment is 4%.   2. Effect of Initiator Content on Molecular Weight and Emulsion Viscosity The initiator is the most important component in the entire VAE emulsion formulation. It decomposes and releases free radicals, which are the basis for emulsion polymerization. Figure 3 shows that with increasing initiator content, both molecular weight and viscosity show an upward trend, with the optimal initiator dosage being 2.5%.   3. Effect of Reaction Temperature on Emulsion Reaction Table 4 shows that with increasing reaction temperature, the reaction rate accelerates, the residual monomer content decreases, and the amount of aggregates increases. Raising the reaction temperature speeds up how fast the initiator breaks down, making more free radicals and boosting the number of spots where reactions can happen. At the same time, a higher temperature makes latex particles move around more randomly, which means they bump into each other and join together more often. Because of these things, the emulsion becomes less stable and might even turn into a gel or separate. Therefore, the initial reaction temperature is determined to be 65°C, and the later reaction temperature is 70°C to 85°C.   4. Effect of Polymerization Reaction Pressure on Ethylene Content, Solids Content, and Viscosity Figure 4 shows that increasing the reaction pressure within a certain range gradually increases the ethylene content of the VAE emulsion and decreases the glass transition temperature of the product. At a reaction pressure of 7.5 MPa, the ethylene content reaches 21%, and the glass transition temperature lowers to -4°C. As shown in Figure 5, under the best reaction conditions, the solid content goes up as the polymerization pressure increases, but the change is small, staying within (56 ± 0.5)%. The emulsion viscosity first goes up and then down as the polymerization pressure increases, peaking at 3200 mP·s at a polymerization pressure of 6 MPa before going down. This indicates that a certain pressure can facilitate polymerization and increase the emulsion viscosity.   5. Effect of Modified PVA as a Protective Colloid on VAE Emulsion Properties To increase how well VAE emulsions resist water, a PVA, changed to include water-repelling groups, was used to take the place of some of the PVA1788 protective colloid. Table 5 shows how varying amounts of the modified PVA (from 10% to 50% of the total protective colloid) change the VAE emulsions' stability, thickness, and water resistance. The data in Table 5 shows that as the amount of modified PVA goes up, the emulsion stays stable without separating, suggesting the modified PVA doesn't really impact the system's stability. Based on Figure 6, the emulsion gets thicker as the modified PVA content rises, peaking at 4000 mPa·s when the modified PVA makes up 5% of the mixture.   6. VAE Emulsions with Different Ethylene Contents and Properties We made different VAE emulsions by testing how different reaction conditions change the emulsion's properties. These emulsions had different amounts of ethylene, glass transition temperatures, and leftover VAc.   We found that starting the reaction at 65°C works best. The temperature can then be adjusted to between 70°C and 85°C. A 4% emulsifier content and a 2.5% initiator dosage also produce the best results. By controlling the reaction pressure, we were able to create VAE emulsions with ethylene contents from 9% to 23%. By replacing part of the protective colloid with hydrophobic-modified PVA, the water resistance of the emulsions was significantly improved.   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com