1、Journal of Applied Polymer Science
Abstract Three kinds of polyfunctional polyols with hydroxyl values of 180–320 mg/g were prepared by the reaction of hydrogenated terpinene–maleic ester type epoxy resin with secondary amines (diet...
2、Role of Hydrogen
Hydrophilic surfaces can essentially be characterized by the concentration of hydroxyl groups on the surface. McCafferty and Wightman used X-ray photoelectron spectroscopy to experimentally determine the densities of hydroxyl groups on several oxide films.
3、Epoxy Resin Characterization: NMR, SEM, and Chemical Analysis
Determination of hydroxyl value Hydroxyl value is defined as the number of milligrams of KOH (equivalent to the amount of acetic acid) that reacts by acetylating with 1 g of a hydroxyl group containing material. It can be calculated using equation 1.
4、Toughness and its mechanisms in epoxy resins
Compared with unmodified epoxy resins, the UPy modified epoxy resins improved toughness and elasticity. The energy generated by external forces could be efficiently dissipated through the fracture of the quadruple hydrogen bond formed between the UPy groups.
On synthesis process of hydrogenated bisphenol A epoxy resins
Powder coatings based upon cationically catalyzed resins (typically epoxy resins) are described including bisphenols, bisphenols modified by novolac, as well as aliphatic type epoxides including hydrogenated bisphenol-A, glycidyl methacrylic, ...
Determination of hydroxyl value (DIN EN ISO 4692
The determination described in this report is based on the standards DIN EN ISO 4629-2:2016 (Hydroxyl value) and DIN EN ISO 2114:2002-06 (acid value). These standards are valid for resins, binders for coating materials, primary alcohols, glycol und fats.
Properties of Epoxy Resins
Therefore, when controlling the curing process of epoxy resin paint, the hydroxyl content of epoxy resin must be determined. There are two most used methods to express the hydroxyl content. The hydroxyl value F is the amount of hydroxyl contained in 100g of epoxy resin, the unit is mol/100g.
12 EPOXY RESINS
ce is required. High molecular weight resins with EGC lower than 600 are used for cross-linking through hydroxyl and epoxy groups using urea formaldehyde or phenol form
Synthesis, characterization, and properties of polyols from
The results show that these epoxy–urethane polymers, with glass‐transition temperatures (Tg's) in the range −5 to 37°C, had good thermally resistant properties, and the temperatures at 5% weight loss were in the range 235–280°C.
Role of Hydrogen
The hydroxyl group of the epoxy resin model acts as an H-bond donor–acceptor with the hydroxyl groups of both slab model surfaces. These H-bond distances are within the typical distance range.
In modern materials science, hydrogenated epoxy resins have garnered significant attention due to their unique properties and widespread applications. These materials not only exhibit excellent mechanical properties, thermal stability, and chemical resistance but also demonstrate unique functionalities and application potentials due to their distinctive hydroxyl structure. This article delves into the hydroxyl value of hydrogenated epoxy resins, explores how it influences the physical and chemical properties of the material, and investigates its importance in practical applications.
I. Definition and Importance
First, it is essential to clarify the concepts of hydrogenated epoxy resins and their hydroxyl value. Hydrogenated epoxy resins are modified epoxy resins produced through hydrogenation reactions, characterized by a molecular structure containing abundant epoxy groups and fewer hydroxyl groups. This structure allows the resins to form three-dimensional network structures during curing, resulting in enhanced mechanical strength and improved heat resistance.
The hydroxyl value is an indicator of the hydroxyl content in hydrogenated epoxy resins. A higher hydroxyl value corresponds to a greater number of hydroxyl groups, which increases the reactivity of the resin. This improvement enhances properties such as adhesive performance, wear resistance, and chemical corrosion resistance. understanding and controlling the hydroxyl value of hydrogenated epoxy resins is critical for optimizing their performance.
II. Preparation Process and Influencing Factors
The preparation of hydrogenated epoxy resins involves multiple key steps, including mixing, reaction, and post-processing. Controlling the hydroxyl value during preparation is crucial. To achieve high hydroxyl values, appropriate catalysts and reaction conditions must be selected. For example, acidic catalysts can promote reactions between epoxy groups and alcohols, thereby increasing the hydroxyl value. Additionally, factors such as reaction temperature and time significantly impact the hydroxyl value.
Beyond preparation conditions, environmental factors like temperature and humidity may also affect the hydroxyl value. Under specific conditions, certain reactions may accelerate or decelerate, leading to variations in the hydroxyl value. Thus, in practical applications, adjustments to the preparation process based on specific conditions are necessary to ensure the desired performance of hydrogenated epoxy resins.
III. Physical and Chemical Properties
Hydrogenated epoxy resins exhibit a range of exceptional physical and chemical properties due to their unique hydroxyl structure, enabling diverse applications across fields:
- Mechanical Properties: The high crosslinking density of hydrogenated epoxy resins results in superior hardness and compressive strength compared to conventional epoxy resins. This makes them suitable for manufacturing wear-resistant and high-strength components, such as gears and bearings.
- Thermal Stability: Hydrogenated epoxy resins maintain excellent mechanical properties at high temperatures, offering broad prospects for aerospace and aviation applications.
- Chemical Resistance: Their robust chemical stability enables resistance to various corrosive substances, making them valuable in industries like chemicals and petroleum.
- Adhesive Performance: The high hydroxyl value enhances adhesion properties, facilitating applications in electronics and automotive sectors.
- Optical Properties: Characteristics such as high light transmittance and low dispersion make hydrogenated epoxy resins useful in optical instruments and fiber optic communications.
- Electrical Insulation: Their high electrical resistivity prevents current penetration, enabling use in electrical equipment and motors.
- Environmental Friendliness: Free of volatile organic compounds (VOCs), hydrogenated epoxy resins align with eco-friendly applications.
IV. Application Cases and Future Prospects
As a high-performance material, hydrogenated epoxy resins have been widely adopted in fields such as aerospace (e.g., aircraft engine components and satellite antennas), automotive systems (e.g., transmission and braking systems), and electronics (e.g., circuit boards and packaging materials). With technological advancements and expanding market demands, their application scope is expected to grow further.
Looking ahead, advancements in new material technologies may enhance the properties of hydrogenated epoxy resins. For instance, novel synthesis routes and improved preparation processes could boost mechanical strength, thermal stability, and corrosion resistance. The development of functional fillers and plasticizers could introduce new performance characteristics. Additionally, growing emphasis on sustainability will likely drive eco-friendly applications of hydrogenated epoxy resins.
the hydroxyl value of hydrogenated epoxy resins significantly impacts their physical and chemical properties. By thoroughly understanding and controlling this parameter, superior-performing resins can be engineered to meet diverse needs. As technology progresses and market demands evolve, hydrogenated epoxy resins will play an increasingly vital role in the realm of advanced materials.
