The essence of fisheye is a small amount of ultra-high molecular weight PVC with a molecular structure formed by improper conditions in the polymerization process. Due to its low ability to absorb plasticizers, it can only swell plasticizer under normal processing conditions. Plasticizing, but the fisheye problems encountered by processors are not all such body-shaped structures, most of which are plasticized pseudo fish eyes. These pseudo fish eyes are linear structures with high molecular weight. The physical configuration of the resin is caused by the tightness of the packaging organization.
There are many ways to form fisheyes. For example, the molecular weight distribution of PVC is too wide, which results in low molecular weight plasticization under the same processing conditions, while molecules with high molecular weight are slow to plasticize. If the processing conditions are certain, the plasticized slow polymer will appear in the case of fake fish eyes in the product.
Improper distribution of the initiator will cause the concentration of the initiator in the polymerization system to be too high, causing the local reaction of the polymerization system to be too fast, and the heat is difficult to be transmitted in time, resulting in local overheating to form fish eyes. Inappropriate selection of initiators, easy to lead to pvc cross-linking, the formation of permanent "fish eye", the initiator is not properly matched, due to the difference in reaction temperature before and after, easy to form a temporary fish eye.
If the stirring speed is too slow, the particles are unevenly dispersed and easily opened. However, the stirring speed is too fast, and the oil droplets formed by the stirring shearing slightly rupture the film to cause the particles to be granulated. In both cases, large particles are prone to occur, forming a temporary fisheye. The pH of the polymerization system is generally controlled between 7.0 and 8.5. The poor quality of the desalted water forms the water in the fish eye containing salt. The ions will destroy the dispersant and form the fisheye.
The presence of impurities in vcm, such as the presence of high-boiling chlorinated hydrocarbons in vcm, not only affects the pvc molecular link structure, but also has a strong dissolution effect on pvc, and reduces the porosity of the particles to form a tighter spherical shape. Particles. Such granules are difficult to plasticize during processing and plasticization to form fish eyes. Under normal circumstances, the conversion rate of vcm is greater than 15%, and the condenser is used later. If it is used in advance, the formation of pvc particles is unstable and the adhesion is strong, which will cause impact on the formation of the polymerization system and easily generate large particles. Fisheye.
In the production of ultra-low molecular weight pvc resin, in order to lower the reaction temperature, a chain transfer agent is required, but some chain transfer agents may reduce the protective effect of the dispersant, which may lead to the formation of fish eyes.
Chopped Graphite/Graphite Electrode in different materials have different definition of graphite pieces, some data and literature is not very big graphite particles are called graphite pieces (such as Graphite Powder) some is graphite products have a certain size, for Graphite Broken into patches, we here say of graphite for a second, usually called graphite blocks. Graphite is produced from graphitization and machining process of graphite products. It is used as additive and conductive material in the manufacture of graphite waste in steel and foundry industries, and can also be processed according to customer's requirements. They are also widely used in electric arc furnaces (steelmaking) and electrochemical furnaces (metallurgical and chemical industries).
Main use of graphite
Graphite pieces due to its low ash content, conductive and heat conduction performance is good, so there are a wide range of USES, can be added to the formula of less ash or dust products, graphite broken broken into small particles commonly use. Ingredients to add a certain amount of graphite, the plastic paste after kneading, especially during extrusion can reduce the friction resistance paste to squeeze the mouthpiece, to improve the coefficient of pressure type. Graphite pieces of coal adsorption properties of asphalt is better, to join the carbon block can rise to reduce the "short" waste (i.e., the product after roasting top produce honeycomb structure), and can improve the thermal conductivity of the carbon block and alkali corrosion resistance. The electrode paste used in hermetically-sealed thermal furnace is added to a certain amount of graphite to increase the conductivity and thermal conductivity of the electrode paste and accelerate the sintering speed of electrode paste. When the graphite is ground into small particles or fine powder, it is also used as raw material for the production of graphite chemical equipment (such as graphite-resin tubes). The graphite can also be used as a carbon addition agent for the electric furnace.
Graphite classification
1. Raw and broken. It is a raw blank that is not qualified after molding.
2. Roasting is the cutting debris that is recovered after the roasting of raw billet and after inspection of unqualified waste and the processing of calcined products.
3. The graphite is broken, and it is inspected by the graphite-producing waste and the cutting debris produced by graphite products in the process of processing.
Graphite Broken
Graphite Broken,Broken Graphite Electrode,Graphitized Anode Broken,Graphite Tablets
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