polyvinyl alcohol resin

Film-forming agents are important adjuvants in pesticide seed coatings and are key functional ingredients in seed coatings. The inclusion of film-forming agents allows seed coatings to form a film on the seed surface, distinguishing them from other formulations such as dry powders, dispersible powders, liquids, and emulsions. The primary function of the film-forming agent in seed coatings is to adhere the active ingredient to the seed surface and form a uniform, smooth film. Film-forming agents need to be water-resistant to hold up in wet conditions like rice paddies, but they also need to let some water through so seeds can grow. It’s also good if they can soak up a bit of water from the soil, which helps seeds grow when it’s dry. Most polymers are good at one of these things, but not all. For example, it's hard to find something that’s both waterproof and lets water pass through. Right now, seed coatings often use just one polymer, so it’s tough to get all these properties at once. This is a main problem for making better seed coatings for rice fields.   Polyvinyl Alcohol (PVA), with its excellent film-forming, swelling, and water permeability, is currently the most widely used film-forming agent in seed coatings. However, its poor water resistance makes it susceptible to water erosion after seed coating, making it unsuitable for use alone in paddy fields or in high-humidity areas. VAE Emulsion (Vinyl Acetate–ethylene Copolymer Emulsion) exhibits strong water resistance, but VAE films only swell in water, not dissolve, and are impermeable to water. Clearly, VAE alone is also unsuitable as a seed coating agent. To address these issues, we used a solution blending method to prepare a series of blended films using PVA and VAE in varying ratios, hoping to improve the water resistance of Polyvinyl alcohol film (PVA film).     1. Microscopic Observation of the Blend System Figure 3-a shows that the PVA colloidal particles exhibit distinct micellar behavior, while the VAE colloidal particles exhibit relatively regular spherical shapes with particle sizes ranging from 700 to 900 nm and unclear outlines (Figure 3-b), consistent with literature reports. After blending, the outlines of the PVA and VAE colloidal particles clearly exhibit a core-shell structure (Figure 3-c), indicating that hydrogen bonding within the blend system alters the electron density around the particles. Furthermore, the particles of each phase are evenly distributed within the blend system, with no apparent interface formation, indicating good compatibility.     2. Water Resistance and Permeability of the Blend System The test results for the water permeability of the blend system are listed in Table 1. After the addition of PVA, the water permeability of VAE was significantly improved. The water permeabilities of vp10, vp20, vp30, and vp40 were ideal, meeting the requirements of seed germination and generally consistent with the results of the seed germination test. When we looked at how long it took for water to pass through, we found that as the VAE content went up, it took longer for water to start permeating: 0.2 hours (vp0), 0.25 hours (vp10), 0.5 hours (vp20), 0.75 hours (vp30), 1.2 hours (vp40), 2.5 hours (vp50), and over 6 hours (vp60-100). Except for vp0, all groups lasted the whole 24 hours without dissolving, which shows that adding VAE really made the material more water-resistant. The national standards GB 11175-89 and GB 15330-94 test water resistance and permeability by checking how much the film swells. These tests cannot fully capture the water permeation, water erosion, and subsequent dissolution of seed coating films used in this test. Visual assessment of these indicators is also difficult to accurately determine. The "L-shaped glass tube method" proposed in this paper measures the water permeability and water resistance of latex films. In principle, this method directly measures water permeation, water dissolution, and water solubility. Precise measuring instruments such as automatic samplers and pipettes are used for indicator control. Visual assessment of the "water permeation and dissolution" indicators and time measurements are easily determined. The experimental procedure is simple and can accurately reflect the actual performance of the membrane.     3. Effect of Modified Films on Seed Germination Rice seed germination tests (see Table 2) showed that blend films with less than 30% VAE didn't really change how well the seeds sprouted, so they should work fine for coating seeds. But, if the VAE is over 70%, the seeds didn't sprout well at all. None of the other samples sprouted well enough after 7 days to meet the standard.     Structural characterization of the blend films revealed good intermolecular compatibility between PVA and VAE after solution blending. The micelles in the PVA solution were opened, and no interface between the two phases was observed, demonstrating the feasibility of using VAE to modify PVA. The performance of PVA/VAE blend films at mass ratios of 80:20 and 70:30 was suitable for rice seed coating applications. Compared with PVA films alone, the introduction of VAE significantly improved the water resistance of the blend films, maintaining suitable water permeability and having no significant effect on seed germination. The method of modifying PVA blends with VAE emulsion is feasible for application in the film-forming agent field of pesticide seed coating agents.   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com

Redispersible emulsion powder is a modified emulsion powder obtained by spray drying of a binary or ternary copolymer of vinyl acetate and tertiary vinyl carbonate -VeoVa or ethylene or acrylic ester, which has good redispersibility and is re-dispersed into emulsion when it is in contact with water, and its chemical properties are exactly the same as the initial emulsion. After mixing with the water in the mortar, it emulsifies and disperses in the water to form a stable polymerization emulsion. After dispersing in water, the water evaporates, forming a polymer film in the mortar after drying, improving the performance of the mortar. Different dispersible latex powders have different effects on the dry mortar. 1. Improve the impact resistance, durability and wear resistance of mortar The rubber powder particles fill the cavity of the mortar, the densification of the mortar is increased, and the wear resistance is improved. Under the action of external forces will produce relaxation and not be destroyed. The polymer film can exist in the mortar system for a long time.   2. Improve the bonding strength and cohesion of mortar As an organic binder, dispersible emulsion powders provide high tensile strength and bonding strength on different substrates. It plays a very important role in the adhesion between mortar and organic materials (molded plates, extruded plates) and smooth surface substrates. The film-forming polymer rubber powder is distributed in the whole mortar system as a reinforcing material to increase the cohesion of the mortar.   3. Improve the mortar's weatherability, freeze-thaw resistance and prevent mortar crackingThe RDP emulsion powder is a thermoplastic resin adhesive powder with good flexibility, which can make the mortar cope with the external cold and hot environment changes and effectively prevent the mortar from cracking due to the change in temperature difference.   4. Improve the hydrophobicity of mortar and reduce water absorptionThe RDP emulsion powder forms a film in the mortar cavity and surface, and the polymer resin film will not disperse twice after encountering water, preventing the invasion of water and improving the impermeability. Enhanced dispersible adhesive powder with hydrophobic effect has better hydrophobic effect.   5. Improve the bending strength and flexural strength of mortar The polymer film formed by dispersible emulsion powder has good flexibility. The film is formed in the gap and surface of cement mortar particles to form a flexible connection, so that the brittle cement mortar becomes elastic. The mortar added with dispersible emulsion powder has much better tensile and flexural properties than ordinary mortar.   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com   ElephChem Holding Limited, professional market expert in Polyvinyl Alcohol(PVA) and Vinyl Acetate–ethylene Copolymer Emulsion(VAE) with strong recognition and excellent plant facilities of international standards.

ElephChem Polyvinyl alcohol (PVA) is a synthetic polymer that is commonly prepared through the hydrolysis of polyvinyl acetate. The process involves converting polyvinyl acetate, which is a resin, into ElephChem Polyvinyl alcohol by replacing the acetate groups with hydroxyl groups. Here is a simplified overview of the preparation of polyvinyl alcohol:   Steps in the Preparation of Polyvinyl Alcohol: 1.Hydrolysis of Polyvinyl Acetate: ElephChem Polyvinyl alcohol (PVA,PVA 100-27S & PVA 1799S) is typically synthesized through the hydrolysis of polyvinyl acetate, a polymer derived from vinyl acetate monomers. The hydrolysis reaction involves treating polyvinyl acetate with an aqueous solution of a strong base, usually sodium hydroxide (NaOH) or another alkali. [CH2CHOOCCH3]n+NaOH→[CH2CHOHCH3]n+NaOC(O)CH3 In this reaction, the acetate groups (-OC(O)CH3) are replaced by hydroxyl groups (-CHOH-) in the polymeric chain.   2.Neutralization and Washing: After hydrolysis, the resulting polyvinyl alcohol is often neutralized to remove any excess alkali. The polymer is then washed to remove by-products and impurities, ensuring the purity of ElephChem Polyvinyl alcohol.   3. Drying: The purified ElephChem Polyvinyl alcohol is usually dried to remove residual water and obtain the final polymer in a solid form.   Additional Considerations: Degree of Hydrolysis: The extent of hydrolysis determines the degree of alcoholysis in the ElephChem Polyvinyl alcohol. A higher degree of hydrolysis means more acetate groups are replaced by hydroxyl groups, resulting in a higher concentration of hydroxyl groups along the polymer chain. Polymerization Method: The initial polyvinyl acetate polymer is often prepared through free radical polymerization of vinyl acetate monomers. This polymerization process results in a polyvinyl acetate resin, which is then subjected to hydrolysis. Quality Control: The quality of the ElephChem Polyvinyl alcohol is crucial for its intended applications. Manufacturers employ various analytical techniques to monitor and control the degree of hydrolysis, molecular weight, and other properties of the final product.   It's important to note that the detailed process may vary depending on the specific manufacturing conditions and desired properties of the ElephChem Polyvinyl alcohol. ElephChem may use different catalysts, concentrations, and reaction conditions to achieve the desired characteristics for various applications, such as adhesives, coatings, films, and textiles.