What is scanning electron microscopy (SEM) and what is its function

2025-08-07

Scanning electron microscope (SEM) is a key tool for modern scientific exploration of the microscopic world. It plays an irreplaceable role in scientific research and industrial applications by enabling us to gain insights into the microscopic structure of matter through high-resolution electronic imaging technology. SEM scans the surface of the sample with a high-energy electron beam to collect signals generated by the interaction between electrons and the sample, including secondary electrons, backscattered electrons, and X-rays, in order to obtain detailed morphology, composition, and structural information of the sample surface. This technology provides higher resolution than traditional optical microscopes, allowing observation of nanoscale microstructures such as nanoparticles, viruses, and organelles.

Components and imaging process of SEM

SEM consists of main components such as electron gun, electromagnetic lens, scanning coil, sample chamber, and detector. The electron gun generates an electron beam, which is focused into small probes by an electromagnetic lens. The scanning coil controls the scanning path of the electron beam on the surface of the sample. The detector receives and converts the signal generated by the interaction between electrons and the sample, and finally generates an image on the display. By adjusting the parameters of the electron beam and the detector settings, different information about the sample can be obtained. Jinjian Laboratory has rich experience in this area and can provide professional guidance for customers in sample preparation and imaging processes, ensuring the acquisition of high-quality images and accurate analysis results.

Key operating parameters of SEM

1. Acceleration voltage: It affects the energy and penetration ability of the electron beam and needs to be selected based on the characteristics of the sample. 2. Working distance: It affects the focusing and resolution of the electron beam and needs to be adjusted according to experimental requirements. 3. Sample preparation: It is an important step in SEM analysis, and different samples require different preparation methods to ensure image quality and accuracy of analysis results. Jinjian Laboratory provides professional sample preparation services to ensure that the processing of different types of samples meets experimental requirements, thereby improving image quality and accuracy of analysis results.

The Importance of Sample Preparation

Sample preparation is crucial for SEM analysis. Conductive samples can be directly observed, while non-conductive samples may require gold or carbon spraying treatment to improve conductivity. Biological samples typically require steps such as fixation, dehydration, drying, and may require gold spraying to enhance their conductivity and stability.

The Wide Application of SEM

1. Materials Science: Used to characterize the microstructure, crystal structure, and chemical composition of materials, such as fracture analysis of metal materials, microstructure of alloys, and grain structure of ceramic materials. 2. Microelectronics and Semiconductors: Detecting manufacturing defects in integrated circuits, analyzing device failure mechanisms, and characterizing the structure of nanodevices. 3. Biomedicine: Observing the surface morphology, tissue structure, and surface properties of biological materials. 4. Environmental science: Analyze the morphology, composition, and sources of environmental samples, such as atmospheric particulate matter and water sediment. 5. Archaeology and cultural relic protection: Analyze the structure, composition, and microscopic morphology of ancient bones and teeth of cultural relics. SEM is not only a super eye for exploring the microscopic world, but also an important tool in scientific research. It enables us to delve into the internal structure of matter, revealing hidden details, thereby driving scientific development and technological innovation in multiple fields. Jinjian Laboratory is committed to providing customers with the most professional SEM analysis services, promoting scientific development and technological innovation, and providing strong support for research in various fields.

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What is the boron carbide powder and its application

2025-08-07

What is boron carbide powder?

Nano boron carbide and ultrafine boron carbide powder were prepared by variable current laser ion vapor phase method. Boron carbide, also known as black diamond, has a molecular formula of B4C and is usually a gray black micro powder. It is one of the three hardest materials known (the other two being diamond and cubic boron nitride). Hard black glossy crystal.

The hardness is lower than industrial diamond, but higher than silicon carbide. Compared to most pottery, it has lower fragility. Has a large thermal neutron capture cross-section. Strong chemical resistance. Not susceptible to corrosion by hydrogen fluoride and nitric acid. Dissolved in molten alkali but insoluble in water and acid.

boron carbide powder

What is the application of boron carbide powder

The product has high purity, small particle size, uniform distribution, large specific surface area, high surface activity, and low loose density. It is an artificially synthesized superhard material with a hardness second only to diamond, a Mohs hardness of 9.46, a microhardness of 5600-6200Kg/mm, a specific gravity of 2.52g/cm, a melting point of 2250C, and does not react with acid and alkali solutions. It has high degree of oxidation, neutron absorption, wear resistance, and semiconductor conductivity. It is one of the substances that is stable to acids, and is stable in concentrated or dilute acidic or alkaline aqueous solutions. Has stable physical and chemical properties, suitable for grinding, grinding, drilling, and other applications of hard materials.
1. Neutron absorption and radiation protection materials: Element B has a neutron absorption cross section of up to 600 bar and is the main material used for deceleration elements - control rods or radiation protection components in nuclear reactors;
2. Composite armor materials: Utilizing their lightweight, superhard, and high modulus properties, they are used as lightweight bulletproof vests and bulletproof armor materials. The bulletproof vest made of boron carbide is more than 50% lighter than the same type of steel bulletproof vest. Boron carbide is also an important bulletproof armor material for land-based armored vehicles, armed helicopters, and civil aviation aircraft. Helicopters such as the AH-64 Apache, Super Cobra, Super Puma, and BlackHawk are equipped with boron carbide armor;
3. Semiconductor industrial components and thermoelectric components: Boron carbide ceramics have semiconductor properties and good thermal conductivity, and can be used as high-temperature semiconductor components as well as gas distribution disks, focusing rings, microwave or infrared windows, DC plugs, etc. in the semiconductor industry. The combination of B4C and C can be used as high-temperature thermocouple elements, with temperatures up to 2300 ℃, and can also be used as radiation resistant thermoelectric elements;
4. Mechanical seal components: The superhard properties and excellent wear resistance of boron carbide make it an important material for mechanical seals. Due to its relatively high cost
Mainly used in some special mechanical seal applications: 5. Nozzle material: Boron carbide CY-B4C1. Its high hardness and excellent wear resistance make it an important nozzle material. Boron carbide nozzles have the advantages of long lifespan, relatively low cost, and time-saving. The lifespan of boron carbide nozzles is tens of times that of alumina nozzles, and many times longer than that of WC and Sic nozzles;

6. Refractory materials, fine engineering ceramics, such as high-precision nozzles, sealing rings, nuclear industry, and defense industry.

How to store this product
This product should be stored in a cool, dry room and avoid heavy pressure. Untreated powders should not be exposed to air during use to prevent moisture absorption and aggregation, which may affect dispersion performance and effectiveness.

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What is the grain growth during sintering process

2025-08-07

The sintering of materials involves at least two processes: densification of the body and growth of grains in the body.

The longevity of grains is usually achieved through the movement of grain boundaries. According to the classical theory of grain growth kinetics, the difference in free energy between the two sides of a curved grain boundary is the driving force that causes the interface to move towards the center of curvature. In the blank, most grain boundaries are curved. From the center of each grain, some grain boundaries are concave while others are convex. The interface energy of a convex surface is greater than that of a concave surface, so atoms or ions will transition from the convex surface to the concave surface, causing the grain boundary to move towards the center of curvature of the convex surface. The result is that some grains with concave grain boundaries grow, while others with convex grain boundaries shrink or disappear. The ultimate result is the growth of the average grain size. However, actual sintering is very complex. Taking grain growth as an example, there are other ways besides this classic method.

One method is to merge two adjacent grains into one large grain. In the formed blank, the orientation of each grain is random. In most cases, grain boundaries form at the neck due to the different orientations of adjacent grains. During the subsequent sintering process, grain boundaries migrate, with some grains growing and others becoming smaller or disappearing. But there are also some adjacent grains with consistent or almost consistent orientations. During sintering, the lattice of these grains will automatically match, the grain boundaries will disappear, and a continuous structure will be formed. Two small grains will grow into one large grain. Sometimes, two adjacent grains can also rotate to achieve matching.

The second is gas-phase transmission. The saturated vapor pressure on the surface of grains of different sizes is different. The finer the grains, the higher the saturated vapor pressure, and the easier it is for the material to vaporize. After gasification, the material is transported through the pores between grains and condensed on the surface of coarser grains, causing these grains to grow. An interesting phenomenon is that when grain growth mainly relies on gas-phase transport mechanisms, even if there is no densification of the billet during the process, the grains will still grow. For example, studies have found that sintering titanium oxide bodies in HCl steam results in an initial particle size of 0.2 microns and a density of only 45% after sintering, which is basically the same as the density of the green body. But at this point, the average size of titanium oxide grains has grown to 6 microns.

The third is liquid-phase transport. We know that a mass transfer process during liquid-phase sintering is dissolution precipitation. The dissolution precipitation mass transfer can be divided into two types. One is mass transfer on the same grain, which dissolves at the sharp points of the grain (or at the contact interface with other grains) and deposits on other flat surfaces of the grain through liquid phase transfer. The other is due to the uneven grain size inside the billet, which causes small grains to dissolve due to the difference in curvature between grains and deposit on larger grains through liquid phase transfer. The former mass transfer process only causes changes in grain shape, while the latter mass transfer process causes grain growth (accompanied by the disappearance of fine grains). At this point, the densification process of the billet is also a process of grain production.

However, the liquid-phase sintering process mentioned above has a prerequisite that the liquid phase can wet the solid phase. If wetting is not possible, although a liquid phase is formed during the sintering process, it can only be isolated between solid phases and cannot form a continuous phase to encapsulate the solid phase, making it difficult to form effective sintering. But under such conditions, the grains will still grow, relying not on dissolution precipitation mass transfer, but on the migration of solid solid grain boundaries.

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What is the reason for the shift of XRD (X-ray diffraction) peaks?

2025-08-07

The reasons for peak shift in XRD (X-ray diffraction) usually involve changes in the properties of the sample itself or the influence of experimental conditions, which can be analyzed from the following aspects:
1. Sample factors
1.1 Residual stress or lattice strain Residual stress: Residual stress inside the material (such as compressive stress or tensile stress) can cause changes in the lattice constant, thereby altering the interplanar spacing (dd value).
Compressive stress → decrease in interplanar spacing → peak position shifts towards higher angles (2 θ increases).
Tensile stress → increase in interplanar spacing → shift of peak position towards lower angles (decrease in 2 θ).
Microscopic strain: Local lattice distortion in nanomaterials or amorphous materials may cause peak shift or broadening.

1.2 Composition Change Solid Solution Formation: Doping, alloying, or ion substitution (such as Co ² ⁺ replacing Fe ² ⁺) can alter the lattice constant. The following is the XRD analysis of Cu doped NCM:

(a) XRD patterns of synthesized materials, and selected insets of peaks (b) (003) and (c) (004)

It can be seen that the parameter of lattice NCM-0 is the smallest among all samples. When the content of Cu is 0.5%, the peaks of (003) and (104) shift towards lower directions due to the larger radius of Cu2+. As the Cu content gradually increases, Ni2+(0.069 nm) oxidizes to Ni3+(0.056 nm), resulting in lattice shrinkage.

If the solute atom radius is larger than the solvent atom → lattice expansion → peak position shifts towards lower angles. On the contrary, the lattice shrinks and the peak position shifts towards higher angles. Non stoichiometric ratio: When the composition of oxides (Fe ∝ O ₄ vs. FeO) or sulfides deviates from the stoichiometric ratio, changes in lattice parameters lead to peak shift.

1.3 Temperature effect thermal expansion/contraction: When tested at high or low temperatures, the lattice constant changes due to thermal expansion, resulting in peak shift (high temperature → lattice expansion → low angle shift). Therefore, the XRD testing room should maintain stable temperature and humidity.

Phase transition: Temperature changes may induce phase transitions (such as tetragonal phase → cubic phase), resulting in significant peak shifts or the appearance of new peaks.

1.4 Preferred orientation (texture)
If there is a preferred orientation during the sample preparation process, it may lead to abnormal diffraction intensity of certain crystal planes, but it usually does not affect the peak position. If the orientation difference leads to lattice distortion (such as strain in thin films), it may indirectly cause peak shift.

2. Instrument and experimental conditions factors

2.1 Zero point calibration error of the angle measuring instrument: Failure to calibrate the zero point of the angle measuring instrument will result in overall displacement of all diffraction peaks (systematic error), which needs to be calibrated with a standard sample (such as silicon powder).

2.2 Sample placement deviation: The surface of the sample is not aligned with the axis of the angle measuring instrument (such as height deviation or tilt), which can cause peak position deviation. This can be solved by optimizing the sample loading.

2.3 When using different target materials (such as Cu K α vs. Co K α), the wavelength difference of the X-ray source will cause an overall shift in peak position (according to the Bragg equation). Need to confirm if the test parameters are consistent.

2.4 Scanning mode or parameter settings errors. Improper parameter settings for continuous scanning mode and step scanning mode (such as scanning speed and step size) may cause slight peak shift, but usually affect peak shape more than peak position.

3. Sample preparation issues: Excessive grinding: Mechanical grinding may introduce strain or nanocrystallization, resulting in peak shift or broadening. Non uniformity: Uneven composition or thickness may lead to differences in local peak positions. Surface pollution or oxidation: Surface oxidation or pollution may produce additional phases that overlap with the original peak, resulting in apparent shift.

4. Data analysis error peak finding algorithm error: If the background is not properly subtracted or noise interference occurs during automatic peak finding, the peak position may be misjudged. Instrument broadening effect: If the instrument broadening function is not calibrated, it may lead to peak fitting deviation.

The core reason for XRD peak shift is the variation in interplanar spacing (d value), which may be due to internal factors (stress, composition, phase transition) or external factors (instrument errors, preparation issues) of the sample. Comprehensive analysis should be conducted based on experimental conditions, sample history, and auxiliary characterization methods.

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What is vanadium dioxide VO2 powder and its application

2025-08-07

The properties of vanadium dioxide:

The molecular formula of vanadium dioxide is VO2, with a molecular weight of 82.94. It is a dark blue crystal powder with a monoclinic crystal structure. Insoluble in water, easily soluble in acid and alkali. When dissolved in acid, it cannot generate tetravalent ions, but generates positive divalent vanadium oxide ions. When heated to red heat in a dry hydrogen stream, it is reduced to vanadium trioxide, and can also be oxidized by air or nitric acid to produce vanadium pentoxide, which dissolves in alkali to form vanadate. It can be produced by reducing vanadium pentoxide with carbon, carbon monoxide, or oxalic acid. Used as a coloring agent for glass and ceramics.

Vanadium dioxide is a metal oxide with phase transition properties, with a phase transition temperature of 68 ℃. The structural changes before and after the phase transition result in a reversible transition of infrared light from transmission to reflection. Based on this characteristic, it has been applied in the field of intelligent temperature control thin films. Due to its excellent conductivity, it is also applied in electronic devices.

Vanadium oxide materials exhibit multiphase competition as insulators at relatively low temperatures. However, since the 1960s when research on vanadium dioxide began, this peculiar phase behavior has remained unknown to people. American scientists announced on November 23, 2010 that through systematic research on the phase transition of vanadium dioxide (from metal to insulator), they have uncovered a mystery that has plagued the academic community for decades. They found that the multiphase competition phenomenon of vanadium dioxide is purely caused by lattice symmetry, and believed that the vanadium dioxide lattice can undergo "folding" in different ways during cooling, so the phenomenon observed by people is the different folding forms of vanadium dioxide.

Several main applications of vanadium dioxide:

1. Wisdom Window

It is an optical device composed of a substrate (such as glass or other transparent materials) and a dimming substance. It can undergo coloring or fading reactions in certain sections of the solar spectrum under certain physical and chemical factors (such as light, electromagnetic radiation, electric field, gas, temperature), causing changes in the optical properties of the dimming substance. As a result, the spectrum selectively absorbs or reflects solar radiation, achieving the purpose of shielding ultraviolet rays, adjusting indoor sunlight intensity and indoor and outdoor heat exchange, reducing cooling and heating energy consumption, and reducing carbon emissions According to their different incentive methods, smart windows can be divided into three categories: thermally induced color change, gas induced color change, and electrically induced color change.

2. Terahertz metamaterials

The abrupt change in resistance before and after the phase transition of VO2 reaches the order of 104, and this change is reversible, making VO2 an excellent optoelectronic switch material. When the temperature is higher than the phase transition temperature, the resistance of VO2 is very small, almost like a conductor, which makes the circuit connected; When the temperature is below the phase transition temperature, the resistance of VO2 increases, causing the circuit to disconnect. This achieves intelligent control of temperature on the circuit. General VO2 thin film materials are suitable for working environments with lower currents, and the thermal hysteresis loop of the film material must be steep. However, block materials made of VO2 powder can withstand larger currents, making their application range more extensive.

3. Lithium battery cathode material

B-phase vanadium dioxide is mainly prepared by hydrothermal method, which has a high charge discharge specific capacity and great potential for application in lithium ion pool cathode materials. Synthesis of hydrated vanadium pentoxide nanoribbons modified with reduced oxidized alkenes via hydrothermal method. Then annealed at 300 ℃ in nitrogen to obtain the cathode electrode of the lithium battery. This VO2./RGO thin film grid structure provides an efficient conduction pathway for electrons, while also reducing the diffusion distance of lithium ions. Electrochemical tests have shown that the cathode membrane can provide high reversible specific capacity and good cycling stability.

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Which preparation methods will affect the specific surface area of the powder

2025-08-07

The preparation method is one of the key factors affecting the specific surface area of oxide powders. Different preparation methods can lead to differences in the size, shape, and porosity of powder particles, thereby affecting their specific surface area.
For example, the sol gel method can prepare oxide powders with high specific surface area, uniform particle size and fine size; The co precipitation method can optimize the specific surface area of the powder by controlling the precipitation conditions. Therefore, when selecting the preparation method, it is necessary to choose the appropriate process according to the specific application requirements.
1) Sol gel method: characteristics: solid precursor is formed through sol polymerization and gel process, and oxide powder is obtained after heat treatment. Comparison of surface area effects: High specific surface area, uniform particle size, and fine oxide powders can be prepared. The specific surface area of the powder can be adjusted by controlling the concentration of sol, gel conditions and heat treatment temperature.
2) Co precipitation method: Characteristics: The precursor is obtained by precipitating the uniformly distributed components in the solution according to the stoichiometric ratio, and then the oxide powder is obtained through calcination and other treatments. The influence of surface area comparison: oxide powders with good dispersibility and high specific surface area can be prepared. By controlling the precipitation conditions (such as pH value, temperature, stirring speed, etc.) and parameters such as calcination temperature and time, the specific surface area of the powder can be optimized.

3) Mechanical ball milling method: Characteristics: Grinding raw material powder into finer particles through mechanical force. The impact of surface area comparison: Although mechanical ball milling can reduce particle size, it often leads to irregular particle shapes and increased surface defects, thereby affecting the precise control of specific surface area. However, by optimizing ball milling parameters such as milling time, milling medium, ball to material ratio, etc., the specific surface area of the powder can be increased to a certain extent.

4) Chemical Vapor Deposition (CVD): Characteristics: Gaseous precursors are deposited on a substrate through chemical reactions at high temperatures to form oxide films or powders. The influence of surface area comparison: CVD method can prepare high-purity and high specific surface area oxide powders or films. By controlling parameters such as sedimentation temperature, gas flow rate, and reaction time, the specific surface area of the powder can be precisely regulated. 5) Spray pyrolysis method: features: metal salt solution or sol is sprayed into the high-temperature pyrolysis furnace through a spray to rapidly evaporate the solvent and generate pyrolysis reaction, forming oxide powder. High sphericity and narrow particle size distribution oxide powders can be prepared. Applicable situation: Suitable for the preparation of spherical oxide powders with high specific surface area and uniform particle size distribution.

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Why Has Aluminum Nitride Become the Preferred Material for Electronic Packaging?

2025-08-01

In today's era of high-power, highly integrated electronics, aluminum nitride (AlN) ceramics have emerged as the packaging material of choice due to three core advantages. First, its exceptional thermal conductivity (170-210W/m·K) is 6-8 times higher than traditional alumina, effectively addressing thermal challenges in 5G base stations, electric vehicles, and other applications. Second, AlN's thermal expansion coefficient (4.5×10⁻⁶/℃) perfectly matches silicon chips, significantly reducing thermal stress and improving device reliability by over 10 times. Most importantly, as a non-toxic, environmentally friendly material, it completely avoids the safety hazards of beryllia while offering comparable thermal performance.

High-purity aluminum nitride powder

Market data shows that AlN packaging can reduce power module operating temperatures by 30-45°C, extend lifespan by 2-3 times, and actually lower total costs by 15-30%. With the explosive growth of 5G, AI, and electric vehicles, AlN's penetration rate in high-end packaging is expected to exceed 40% within three years. For electronics manufacturers pursuing high performance and reliability, early adoption of AlN technology will be key to winning the next-generation product competition. We offer complete solutions from sample testing to mass production support to help customers achieve rapid technology upgrades.

High thermal conductivity aluminum nitride substrate

About Xiamen Juci Technology Co., LTD

Xiamen Juci Technology Co., Ltd. is the largest manufacturer of aluminum nitride powder in China in terms of output. The aluminum nitride powder and customized ceramics produced by Xiamen Juci Technology Co., Ltd. feature higher thermal conductivity and more competitive prices. We are committed to providing customers with advanced thermal management technologies and offering effective thermal management solutions for industries such as 5G, semiconductors, new energy, aerospace, etc.

Media Contact:
Xiamen Juci Technology Co., Ltd.

Phone: +86 592 7080230
Email: miki_huang@chinajuci.com

Website: www.jucialnglobal.com

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Analysis of factors affecting the comprehensive performance of chloroprene rubber 2442

2025-07-30

Chloroprene rubber (CR) is a synthetic rubber obtained by polymerization of chloroprene. It is widely used because of its excellent aging resistance, oil resistance, corrosion resistance and other properties. Polychloroprene Rubber CR2442 vulcanized rubber has good physical properties and can be used in many occasions (Such as chloroprene rubber adhesive). However, since the process of CR2442 in internal mixing, open mixing and vulcanization is not easy to master, the physical properties of the prepared vulcanized rubber are sometimes poor, which affects its production and application.

1. The influence of process parameters on the preparation of mixed rubber and vulcanized rubber

1.1 Internal mixer mixing process

CR2442 has high requirements for the mixing process. When preparing CR2442 mixed rubber, the initial temperature, mixing time and rotor speed of the internal mixer have a great influence on the discharge temperature. The discharge temperature is an important parameter for measuring the mixing process. The optimal discharge temperature of CR2442 is 110℃. The order of adding various materials during the mixing process is also important. The correct way to add materials to CR2442 during the mixing process is: add CR2442 and small materials at the same time → add carbon black → add white carbon black and operating oil in sequence.

1.2 Mixing process of open mill

After the mixed rubber prepared by the internal mixer is cooled, the vulcanization system is added on the open mill. The vulcanization system includes vulcanizing agent and accelerator. The correct way to add is to add accelerator first and then vulcanizing agent. When adding the vulcanization system to the mixed rubber on the open mill, it is generally required that there is accumulated rubber on the roller. With the shearing and extrusion of the open mill, the roller temperature will increase significantly. When the temperature of the rubber is too high, the rubber should be cut, pulled out and cooled, and then the rubber should be mixed after it is completely cooled.

1.3 Vulcanization process

After adding the vulcanization system on the open mill, the rubber is cooled and placed for 16~24h before vulcanization. Since the CR2442 mixed rubber is easy to crystallize at low temperatures, it is generally necessary to perform indirect heating treatment in an oven. The vulcanization time of CR2442 was set to 30, 40, 50, 60, 70 and 80 minutes respectively. After many tests, it was found that the tensile strength and elongation at break of the vulcanized rubber were the largest when the vulcanization time was 60 minutes. Therefore, the optimal vulcanization time of CR2442 was determined to be 60 minutes.

1.4 Bonding operation

In the process of bonding the mixed rubber and brass, the rubber is first cut into sheets with the same length and width as the mold. After the mold is preheated, the cut film is placed in the mold cavity. Since the mold is heated, placing it too slowly will cause early vulcanization of the rubber, reduce the fluidity of the rubber, make the bonding insufficient, and then reduce the bonding force. Therefore, the scorch time should be controlled to be much longer than the placement time of the film.

2. Influence of vulcanization system, reinforcement system and bonding system

Vulcanization system: When CR2442 uses only zinc oxide and magnesium oxide for vulcanization, the resulting rubber's physical properties are worse compared to when zinc oxide, magnesium oxide, sulfur, and accelerator DM are used as a system.

Reinforcement system: The reinforcement system of CR2442 is often based on carbon black and supplemented by white carbon black.

Bonding system: Rubber as a single material can no longer meet the needs of society, and it is often necessary to bond rubber to metal to expand its scope of use. CR2442 is usually bonded to metal using a resorcinol-methylene-white carbon black-cobalt salt bonding system.

3. Conclusion

When mixing, it's important to think about temperature, how long you mix, and how fast the rotor spins. Also, when you add the vulcanization system using the open mill, pay attention to the order you add things. The heat from the rollers can really change things.For vulcanization and bonding, if you make sure the scorch time is longer than it takes to place the sample, you can get better quality vulcanized rubber and better bonding with other types of materials. The CR2442 discharge temperature matters too. It's a good idea to add white carbon black as a reinforcement in CR2442. This helps control how fast vulcanization and bonding happen.

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Development of binary grafted chloroprene rubber adhesive

2025-07-30

Chloroprene rubber adhesive is the largest and most widely used variety among rubber adhesives. It can be sorted into a few groups, like resin modified, filler, grafted, and latex types. Grafted chloroprene rubber adhesive, which is made mostly of chloroprene rubber and a grafted modifier, is known as easy to their usage, strong bonds, high initial adhesion, and many uses. As early as the 1950s, the shoemaking industry began to use chloroprene rubber adhesive. As shoemaking materials and styles change, standard chloroprene rubber adhesive may not be strong enough. This can cause the upper and sole of shoes, or composite soles, to separate. This issue harms shoe quality and limits growth in the adhesive shoe business. To solve this problem, we used a variety of graftable chloroprene rubbers at home and abroad as graft bodies and used MMA to study their grafting modification.

1 Grafting mechanism

2 Experimental part

2.1 Raw materials and polymerization formula

2.2 Polymerization Procedure

Add CR to the solvent. Heat the solution to 50 °C and stir until the CR is completely dissolved. Raise the temperature to 80°C, and slowly add the MMA solution that contains BPO while stirring. Maintain the temperature and continue stirring until the viscosity reaches a suitable level (about 40 minutes). Immediately add hydroquinone to stop the reaction. Keep warm for 4 to 6 hours. After the reaction is complete, cool down to 40°C; add thickening resin, vulcanizing agent, antioxidant and filler, and finally keep warm for 2 to 3 hours, cool down to room temperature, and obtain the product. A small amount of toluene can be added to adjust the viscosity. The obtained graft copolymer (CR-MMA) is a brown-yellow transparent viscous liquid. The viscosity measures between 1000 and 1500 mPa·s. Solid content ranges from 15% to 25%, and the strength registers at 34 N/cm².

2.3 Product analysis

2.3.1 Determination of adhesive viscosity

The viscosity value (mPa·s) was tested in a 25℃ constant temperature water bath using a rotary viscometer (Shanghai Optical Factory, NDI-1 type).

2.3.2 Determination of adhesive solid content

The film after vacuum drying and constant weight of the adhesive was wrapped with filter paper and placed in a fat extractor. It was extracted with acetone in a 65℃ constant temperature water bath for 48 hours (to remove PMMA homopolymer in copolymerization). The solid content (W%) was calculated according to the following formula:

W %=W₂ / W₁×100%

Wherein, W₁ is the mass of the grafted adhesive, and W₂ is the mass of the film after vacuum drying and constant weight.

2.3.3 Determination of peel strength of artificial leather/artificial leather (PVC/PVC) bonded by adhesive

The soft PVC sheet was wiped with acetone or butanone to remove the oil stains on the surface. The entire process was in accordance with GB7126-86.

3 Results and discussion

3.1 Solvent selection

The solvent used in chloroprene rubber adhesive is very important. It affects the solubility of chloroprene rubber, the initial viscosity of the adhesive, stability, permeability to the adherend, bonding strength, flammability and toxicity, etc. Therefore, the selection of solvents should take into account many factors.

Commonly used solvents include toluene, ethyl acetate, butanone, acetone, n-hexane, cyclohexane, solvent gasoline, etc. The test confirmed that when the solvent cannot dissolve chloroprene rubber alone, two or three solvents can be mixed in appropriate proportions to have good solubility, viscosity and low toxicity.

3.2 Effect of CR type and concentration on the performance of grafted products

Different types of chloroprene rubber (CR) show differences in how quickly they form crystals and how deep their colors are. These factors can change how well the grafted materials initially stick together and how they look. Tests show that using Denka A120 Chloroprene rubber and Chloroprene Rubber SN-244X to graft chloroprene rubber results in good initial adhesion and color. The amount of CR does not change peel strength much, but it does affect how well copolymerization works. When the CR concentration is too high, that is, the viscosity is high, MMA is difficult to diffuse and has a strong tendency to self-polymerize. Maintaining the appropriate CR concentration is necessary; if it's too low, the MMA volume will be too small, which slows down the grafting copolymerization. CR concentration works best between 11% and 12%.

3.3 Effect of reaction time on the performance of grafted products

Generally speaking, the longer the reaction time, the higher the grafting rate and viscosity value. At the beginning, the initial and final adhesion strengths increase with the extension of reaction time and the increase of viscosity. Extended reaction times coupled with high viscosity can actually reduce both initial and final adhesion. Experiments suggest reaction times should ideally fall between 3.0 and 5.0 hours.

3.4 Effect of reaction temperature on grafting reaction

When the reaction temperature is lower than 70℃, the reaction is slow, which is due to the slow decomposition of BPO. Because BPO decomposes quickly above 90℃, leading to a rapid increase in viscosity and poorer processing, we set the reaction temperature between 80°C and 90℃.

4 Conclusion

Our initial tests included scaled-up experiments and pilot production runs, which successfully yielded acceptable products. They were supplied to many leather shoe factories and achieved satisfactory results. The quality met the various standards required for shoemaking.

CR-MMA grafted adhesive shows better peel strength on PVC artificial leather compared to regular CR adhesive used for boots.The addition of a small quantity of isocyanate (5-10%) can serve as a temporary curing agent. The -NCO group in the isocyanate then reacts with active hydrogen in the rubber, creating an amide bond. This reaction strengthens the rubber's internal structure, improving the overall bond strength.

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#chloroprene and neoprene #Polychloroprene Rubber CR2442 #Chloroprene rubber adhesive #Chloroprene Rubber SN-245 #Denka A120 Chloroprene rubber #Baypren 350-2 #Polychloroprene Rubber CR244A #Baypren 350

Modern Neoprene Innovations & Outlook

2025-07-30

Chloroprene rubber (CR) is one of the commonly used rubber varieties. The strength of vulcanized rubber without carbon black reinforcement can reach 28MPa, and the relative elongation is about 800%. It has the characteristics of oil resistance, flame resistance, oxidation resistance and ozone resistance. It is soluble in benzene and chloroform. It swells slightly but does not dissolve in mineral oil and vegetable oil.

1. Progress in CR Technology Abroad

Monomer Production

DuPont in the U.S. came up with a liquid method to make chloroprene from butadiene. This is safer than the gas method that was first used. It can produce higher yield products at a lower cost, improve safety, and reduce maintenance costs. In 1992, the company upgraded its monomer production line, moving from a single-loop control system to a computerized distributed control system.

Post-processing technology

Recent progress in CR post-processing tech is apparent in the developments related to spiral extrusion dehydration and drying. Chloroprene latex and coagulant go into a screw extruder that has a specific design. The coagulated latex removes most of the water in the dehydration section of the extruder by the back pressure. The success of this process has created conditions for the industrial production of CR and asphalt and CR and short fibers, thereby increasing the operational flexibility and being able to handle CR varieties with poor freezing film-forming and tape-forming properties. In 1992, DuPont launched a series of elastomer masterbatches including CR with Kevlar (polyarylamide) short fibers as reinforcement materials, proving that this process has begun to be used in the production of blended products.

Development of new varieties

There are hundreds of foreign brands. Companies in the United States and Japan have developed many high-performance special CR based on a series of mature brands. In order to improve the thermal stability of CR, Bayer has developed copolymers of chloroprene (CD) with carboxylic acid amide, carboxylic acid anhydride and (or) carboxylic acid monomers. These new CR also have better spraying and brushing characteristics. Denka Corporation of Japan has also improved traditional products and launched a new generation of CR (Denka chloroprene rubber). For example, the DCR 20 series. Tosoh Corporation of Japan is also developing special shock-absorbing CR, and has produced CR latexes with high softening temperature, good normal temperature and high temperature adhesive properties, high water resistance and stability (SKYPRENE Chloroprene Rubber).

2. Progress in domestic CR technology

In 1958, Changshou Chemical Plant in Sichuan, my country built a device for producing CR by acetylene. The main CR production in China does not control the conversion rate, and many places use manual operations, which is basically a workshop-style production status. Besides the earlier producers of CR glue like Chongqing Changshou Chemical Co., Ltd., Shanxi Synthetic Rubber Company, Jiangsu Lianshui Chemical General Plant, and Tianjin Donghai Adhesives Company, Shandong Laizhou Kangbaili Glue Industry Co., Ltd. developed in October 2003 a new CR glue. They carefully chose and mixed the composite solvent.

3. Suggestions for the development of domestic CR industry

Strengthen technology development

For domestic carbon black firms, boosting investment in science and tech, along with adopting and assimilating advanced foreign tech, is key. These actions should lower consumption and costs, and it should raise acetylene use from 57% to over 70% quickly.

Strengthen the development of new varieties

To maintain the Mooney viscosity in current products, we will create new types. The focus will be on making functional latex, like carboxyl and copolymer latex. Our goal is to bring high Mooney, non-sulfur regulated WHV to industrial production.

Increase market share

In the next few years, the market of CR in my country will be saturated, and relevant manufacturers can consider developing overseas markets. At present, the development trend of CR in the world is that the European and American markets are shrinking, while China, Eastern Europe, Russia and Southeast Asia are in the rising stage. CR can not only contend with imported goods locally, but can also progressively expand sales to North America, Eastern Europe, Russia, East Asia, and Southeast Asia.

Website: www.elephchem.com

Whatsapp: (+)86 13851435272

E-mail: admin@elephchem.com

#chloroprene rubber price #Rubber-based Adhesives #Chloroprene rubber adhesive #Synthetic chloroprene rubber #Denka chloroprene rubber #TOSOH SKYPRENE #Denka Neoprene 750 #SKYPRENE Chloroprene Rubber

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