1、乙烯
乙烯-醋酸乙烯共聚物（EVA）是由乙烯和乙酸乙烯（VA含量5%-40%）共聚而成的通用高分子聚合物，燃烧时无刺激性气味，其性能随VA含量变化而改变：VA含量越高，透明度、柔软度和坚韧度越高。
2、Research on the Influence of Molecular Chemical Compositions on
The relationship between EVA emulsion structure and thermal, mechanical, and wettability properties is established by dissecting the molar ratio of vinyl acetate to ethylene in industrially produced EVA emulsions.
3、Evaluation of Flow Ability Response in EVA Emulsion Preparation with
Ethylene–vinyl acetate (EVA) copolymers were chosen for this work because they show different characteristics depending on their vinyl acetate (VA) percentage.
4、Ethylene Vinyl Acetate Copolymer
Ethylene-vinyl acetate (EVA) copolymer is defined as a water-insoluble copolymer of ethylene and vinyl acetate that can be processed to tailor its permeability and release kinetics, making it suitable for applications such as sustained release tablets and intravaginal rings.
Typical formulation for an emulsified EVA copolymer.
This study considered the effect of the incorporation of different antifreeze agents into ethylene vinyl acetate emulsions that are used as pour point depressants.
Miniemulsion Copolymerization of Ethylene and Vinyl Acetate
The copolymerizations of a gaseous monomer (ethylene) and a liquid monomer (vinyl acetate) via emulsion and miniemulsion polymerizations are reported. Reactions in which the vinyl acetate was introduced in both batch and semibatch modes are carried out.
Preparation of ethylene vinyl acetate copolymer latex by flow induced
Ethylene vinyl acetate (EVA) copolymer was emulsified in the melt state using hydrophobically modified water soluble polymers (HMWSPs) as surfactants and the flow induced phase inversion (FIPI) emulsification technique.
Ethylene Vinyl Acetate, EVA – RIXIN
The performance adjustment of EVA is mainly achieved by changing the ratio of ethylene to vinyl acetate, controlling the molecular weight and molecular weight distribution of the copolymer, and adjusting the subsequent processing process.
PREPARATION AND DEVELOPMENT OF AN ETHYLENE VINYL ACETATE (EVA
PREPARATION AND DEVELOPMENT OF AN ETHYLENE VINYL ACETATE (EVA) COPOLYMER EMULSIFICATION SYSTEM FOR POUR POINT DEPRESSANT (PPD) APPLICATION
Ethelene Vinyl Acetate Emulsion (EVA Emulsion)
EVA Emulsion is a general purpose copolymer Water Based Emulsion that can be used in the Film Bonding, Paper Bonding, Floor, Wall and Ceiling Adhesive. In the general formulation it can be combined with Plasticizers, Solvents, Thickening Agents, Extenders etc.
Ethylene-Vinyl Acetate (EVA) emulsion is a commonly used building coating and adhesive, widely applied in waterproofing, corrosion protection, and other fields. due to its primary components—ethylene and vinyl acetate—these materials are prone to hydrolysis in acidic environments, leading to reduced emulsion stability. adjusting the pH of EVA emulsion is critical to ensuring its performance.
I. Composition and Properties of EVA Emulsion
EVA emulsion is primarily composed of ethylene and vinyl acetate monomers, formed through copolymerization. This emulsion exhibits excellent film-forming properties, flexibility, and water resistance, making it widely applicable in various building materials and industrial products. due to its compositional characteristics, EVA emulsion tends to hydrolyze in acidic conditions, resulting in decreased stability and compromised performance and application outcomes.
II. Impact of pH on EVA Emulsion
- Hydrolysis Reactions
In acidic environments, ethylene and vinyl acetate undergo hydrolysis, producing byproducts such as acetic acid and ethanol. These byproducts reduce emulsion stability, leading to issues like precipitation, delamination, or clumping. Additionally, hydrolysis lowers the emulsion’s viscosity, negatively affecting its coating performance and drying speed.
- Stability and Application Effects
To maintain EVA emulsion performance and prolong its shelf life, appropriate pH adjustment is essential. Generally, the pH of EVA emulsion should remain neutral or slightly alkaline. Excessively high pH values cause acetate ions to bind with calcium ions, forming calcium acetate precipitates that destabilize the emulsion. Conversely, excessively low pH values lead to the combination of hydroxide and acetate ions, forming sodium acetate precipitates, which also harm stability.
III. Methods for pH Adjustment
- Addition of Alkaline Substances
To adjust the pH of EVA emulsion, alkaline substances such as sodium hydroxide (NaOH) or potassium hydroxide (KOH) can be added. Moderate addition reduces acetate ion concentration, slowing hydrolysis. Care must be taken to control dosage, as excess alkaline substances may increase viscosity or cause other adverse effects.
- pH Regulation of Solutions
Alternatively, the pH of the solution can be adjusted using pH meters or litmus strips to target the desired range. Chemical agents like ammonia or hydrochloric acid may also be employed for precise pH tuning.
IV. Practical Applications and Precautions
- Practical Applications
In production, pH adjustments via alkaline additives or solution regulation improve emulsion stability and performance. For example, in coatings manufacturing, adding controlled amounts of alkaline substances optimizes the emulsion for specific coating formulations.
- Precautions
- Select appropriate alkaline substances and严格控制dosage to avoid viscosity spikes or other issues.
- Choose pH targets based on practical requirements to ensure optimal performance.
- Prioritize safety: wear protective gear to prevent skin or eye contact with chemicals.
The pH of EVA emulsion significantly impacts its stability and performance. By adding alkaline substances or regulating solution pH, emulsion properties can be optimized, and shelf life extended. In practice, tailored pH adjustment methods ensure product quality meets industry standards.
