First, it's important to understand that the K-value isn't always a perfect predictor of the performance of a PVC resin. The K-value can also be affected by the molecular weight, which is the amount of material that is in a single molecule. The molecular weight can also be affected by the molecular orientation, which is the direction that the molecules are oriented.
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Paste viscosity
Among different PVC resins, PVC Paste Resin is one branch. This type of PVC resin has good pasting performance and has a broad market application. Its advantages continue to grow.
PVC paste resin is used in a variety of industries, such as automobile decoration material, wallpaper, and glove material. Its processing method is simple and cheap. The product has good thermal stability, high plasticizer absorption, and clarity. The product is also suitable for flexible profile extrusion, blown film, and calendared sheet applications.
The paste resin has a median size of 0.5-2 m m. Its mean polymerisation degree is 1600-1900 sticks. The paste has good transparency, defoaming performance, and rapid plasticization. Its processing process is simple, and it has a wide application range.
The process for preparing a standard paste is simple and efficient. The paste can be characterized on the basis of basic polymer parameters, such as polymerisation degree, molecular mass, and polymerization temperature.
Correlation with molecular weight
Molecular weight is an important factor in the properties of PVC resins. It is believed that higher molecular weights increase the tensile strength, impact resistance, and chemical resistance of materials. However, it does not account for all of the differences in properties.
The molecular weight of a PVC resin varies between 57 K and 2504 g/mol. The average molecular weight of synthesised compounds was 1571 to 2504 g/mol.
PVC resins have interchain interactions of polar carbon-chlorine bonds. These bonds are located at 650 to 600 cm-1. The plasticizer molecules contain hydroxyl groups, aromatic rings, and ester groups. These groups provide donor-acceptor interactions with PVC. These interactions result in good plasticizing efficiency.
Plasticizers can be divided into two categories: primary and secondary plasticizers. Primary plasticizers are commonly small molecules that are used for good plasticizing efficiency. Secondary plasticizers are used to replace part of the primary plasticizer. The molecules of secondary plasticizers have lower molecular weights and lower glass transition temperatures than the primary plasticizer.
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Improvement of mechanical properties by molecular orientation
Molecular orientation has been shown to improve the mechanical properties of PVC resin. While this is true, it does not make the material any less functional. Molecular orientation can be achieved by stretching or cold drawing. The benefits of orientation include improved strength, stiffness, impact resistance, and resistance to presses. The efficiency of the orientation process is largely related to the molecular weight of the material.
One of the most common polymers is polyvinyl chloride. A molecular weight of less than fifty kilograms per cubic meter has been shown to have a pronounced effect on mechanical properties. A study is underway to determine the optimum value for PVC.
In addition to the molecular weight, the optimum value for a given material will depend on the K value, the processing temperature, and the loads. This study uses a two-part formulation of PVC and a stabilizer, Ca/Zn.
Reducing viscosity and K-value
Various factors affect the reduced viscosity of PVC resins. One of these factors is the molecular mass of the polymer. Another factor is the molecular orientation of the polymer. Both factors influence the properties of the polymer. The effects of both factors can be measured by X-ray diffraction, density measurement, and optical microscopy.
The average molar mass of the polymer can be determined from solution viscosity measurements. A typical commercial polymer has a molar mass of 40,000-480,000. This value may be higher or lower depending on the manufacturer's molar mass grade. The higher molar mass grades will increase the ratio of M-w to M-n. However, the increase in molar mass does not lead to a significant improvement in the mechanical properties of the polymer.
The reduced viscosity of PVC resins is also dependent on the concentration of solution. When solution concentrations are identical, reduced viscosity and PVC resin K-values are similar. However, when solutions are mixed, the values may differ.
